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Onan JB-JC Service Manual 967-500

1. CRANKSHAFT Main Bearing Journal Diameter Main Bearing Clearance Connecting Rod Journal Diameter Rod Bearing Clearance End Play Crankshaft PISTON Piston Clearance to Cylinder Wall Measure 90 to Pin Just Below Oil Ring Groove PISTON PIN Piston Clearance Connecting Rod Bushing Clearance PISTON RINGS Ring Gap ene ae Ring Width Top 2nd 3rd VALVE INTAKE Stem Diameter Guide Clearance Valve Clearance Begin Spec D Prior to Spec D VALVE EXHAUST Stem Diameter Guide Clearance A 0 9 9 9 co 5 9 35 4 44 9 9 3 4 c c 9 n9 9 9 9 o3 9 9 9 on Ce 9 9 3 9 9 9 3 e o v a 9 4 8 9 a 9 9 9 9 4 e a 9 9 9 9 e gt 9 co e V 9 8 5 c c 9 9 7 9 9 8 mo 3 c wo 9 o9 o a 9 9 s c3 Oc
2. SENI 5 0 A INO Gf JC ONLY O6SXINIB STATIC EXCITER WIRING DIAGRAM BEGIN SPEC C PRIOR TO SPEC P 625A42 3 PICTORIAL SCHEMATIC CONTROL WINDING 120 V AC 60 CY NOTE Residual reset switch not used on 06SXINIA earlier model NO 16 WIRE 27 LG SWITCH RESIDUAL RESET NO 14 WIRE 274 RECTIFIER FIELO NEG RECTIFIER CONTROL RESISTOR STABILIZING RECTIFIER FIELD POS REACTOR CONTROL COMPOUND WINDING RESISTOR VOLT CONTROL 6 TURN CALIBRATED RESISTOR DAMPING SHUNT REACTOR GATE DESCRIPTION PARTS LIST POLARITY DOT CONTROL WINDING GATE STATIC EXCITER WIRING DIAGRAM WHEN MOUNTED ON WINDING 120 VAC 60 CY GEN THE POLARIT OTS MODEL DWG NO WILL EACH REACTOR 625A42 3 065 1 STATIC EXCITER WIRING DIAGRAM BEGIN SPEC P BEGIN SPEC L PENN STATE 625 632 PICTORIAL SCHEMATIC COMPOUND WINDING 6 TURN POLARITY DOT ITEM QTY j DESCRIPTION CONTROL PARTS LIST WINDING WHEN MOUNTED ON WINDING AME STATIC EXCITER WIRING DIAGRAM 120 VAC 60 CY GEN THE POLARIT MODEL DwG NO 6254632 76 LL LOW OIL PRESSURE SWITCH VIEW 611 668 START 71 START 1 DISCONNECT IGNITION IGNITION RELAY RELAY 5078557 SOLEWDID N23075623 507840 SUPPRESSORS IGNITION P c FRIE COND 312 2 I 9000 15 OHM
3. Check circuit connections of both reactors and B Control winding C1 C2 or reactor A or B polarized incorrectly Output voltage builds up normally but 150 to 200 percent above rated voltage after build up No regula tion possible Test reactors and B for shorted turn and replace if defective Check continuity from E1 E2 through control circuit Shorted turn in control winding C1 C2 or reactor or B Open in control circuit Incorrect setting on stabilizing Check resistance and reset resistor Generator voltage fluctuating while engine running at constant speed For corrective steps see following page 57 STEP 1 CHECKING RECTIFIERS Disconnect one lead from or remove each rectifier for its individual test Note carefully the direction of mounting of any rectifier removed It must be re mounted in its original direction a Connect the ohmmeter across the rectifier contacts and observe the meter reading b Reverse the connections and compare the new reading with the first reading c If one reading is considerably higher than the other reading the rectifier can be consid ered satisfactory However if both readings are low or if both indicate an circuit replace the rectifier with a new identical part STEP 2 CHECKING REACTORS and Use an accurate ohmmeter when checking resistance values Resistance readings bet
4. 5253 RELAY MH 306 A28 4 TERMINAL K al SWITCH wraoaPise 1 RES det mE ad M EE WHEN USED HIGH TEMPERATURE CUTOFF SWITCH l IGNITION 1 WHEN USED SUPPRESSION f RS LL ad NET ae oe Saves ELECTA CHOKES PANEL CONTROL Box N 30122009 COND CONTROL 9301502008 N 312A TO SPARK PLUGS CWHEN USED COVER CONTROL BOX NS 30151963 vy BRKT CONTROL BOX MTG L H 301 B2010 BRKT CONTROL BOX MTG R H N2 3016201 Laie Bem COVEM RESISTOR 30 8 2012 i I IGNITION l BREAKER POINTS GENERATOR AYTEMCO IGNITION 5 1 72 25W 304 60 IGNITION CONDENSER eJB 3RSPEC IJ 120 240 VOLT IPH 3W 60 2065 Seg 10211 191324 10 o 919 ONINIA OSINOO 77 61tC656 18 61156805 705 5 96 67B 53R 96P VIEW 771 TD START START 1 DISCONNECT f 1 IGNITION IGNITION RELAY START RELAY 2207 4971 GND SOLENDID 55078625 SD N9507B40 supPPRESSORS L NITTOR 1000 IMFD COND 1 15 0 10 WATT BRI FARER Resistor 2304 3 N 304A B oe 1 DAM 10 WATT ram RESISTOR 16
5. 69 GENERATOR WIRING DIAGRAMS NOTE I SPEC P NOTE 2 SPEC 3 T TO CONTROL BOX f 1 NOTED BER TO LOAD SERIES FIELD SHUNT FIEL TO CONTROL NOTE SPEC P NOTE 2 5 j NOTEI BORO OOH a SERIES FIELD ARMATURE COMMUTATOR A C SLIP RINGS Revolving Armature 3 wire Single Phase TO CONTROL BOX Fa NOTE sPEC P NOTE 2 SPEC J e S NOTE 2 a le NOTE 2 a u 5 C SLi P RINGS jm S COMMUTATOR Revolving Armature Reconnectible for 120 240 or 120 240 Volts Single Phase TO CONTROL NOTE SPEC P 4R 120 208 SPEC J ALL UNITS SPEC K 4R 120 208 VOL T ONLY OAD NOTE T COMMUTATOR SHUNT FIELD a e b 2 x Revolving Armature 4 wire Three Phase 70 SERIES FIELD Nore CONTROL NOTEM SPEC 7R 220 380 4XR 277 480 7XR 240 416 i NOTE 2 SPEC 7R 220 380 4XR 277 480 7XR 240 416 D 5 M3 5 5 I A C SLIP RINGS SHUNT FIELD SERIE FIELD TO CONTROL NOTE SPEC 58 240 NOTE 2 SPEC J ALL UNITS BOX 1 70007 SPEC SR 240 VOLT ONLY M3 M2 gt NOTE 2
6. e Je Spark Plug Too Narrow Adjust Gap Leaking Valves or Valve Seals Light or Diluted Oil Sludge on Cup Screen Oil Pump Badly Worn Replace Oil Leve Too Low Oil Too Heavy 8 ejeje T BRERA AREER ERE Dirty Points in Start Solenoid ee ee en ee ee Governor Spring Sensitivity Too Great Piston Rings Worn or Broken Spark Too Far Advanced Retard Timing Clogged Oil Passage Oil Relief Valve Stuck Defective Gauge sel 11 EE HLL Ce te Poor Compression Wrong Bearing Clearance or Worn Bearings i 1 BEREE Spark Plug Gap Too Wide Adjust Gap COOLING SYSTEM JB and JC electric plants use a pressure air cooling system Blades on the engine flywheel draw air into the front of the engine housing and force it past all the cylinders and out the right side of the engine separate blower on the generator rotor draws air into the rear of the generator and forces it out openings near the engine The engine air out let may use an air duct and an optional shutter assembly MAINTENANCE Clean the engine cooling area fins on cylinder block and cylinder heads at regular intervals normally every 1000 hours but more often under dirty opetating condit
7. t 1 1 PANEL CONTROL BOX _ __ 5015196 1 CONTROL BOX mme n N2 30101962 COVER CONTROL BOX __ _ 50181955 A LENOIR t CONTROL BOX MTG LL M N9 SOIBISEA ENGINE WHEN USED BKT CONTROL BOX MTG R H N 30181979 1g RECTIFIER M TG BAT 1 NE305A2 54 ER TROL BOX 230 PRIMER SOLENOID uu IELECTAIC FUEL N3508 9 WHEN USED CHARGE RESISTOR WHEN SILK SCREEN STANDARD _ _ 98 81682 ASSY N2304A505 USED PLUS LOW OIL PRESS RESET AFTER 2 0MM 150 WATT La p MINUTES N9 3294A500 8EF DAY TANK FUEL SOLENOID To MUST WHEN_USED BE GROUNDED To sTATIC 7R CONNECTION SLIP RINGS CHARGING WINDING 8 z Ir ox oz pe ug as 1741 SE B e d 29 88 108 ladC 5sR ETR ISTER 6 2 2657 CK E cg SPEC AE SPECIF START id START DISCONNECT IGNITION RELAY 3 7 5 7 SOLENOID 5078625 3078 40 i r Bl 1 t SPARK PLUG RESISTOR SUPPRESSORS DISTRIBUTOR RESISTOR IGNITION START RELAY f 5 0HiM 0 WATT RES TOR a JMFD COND 5504432 2 CHARGE RECTIFIER TERMI
8. 0 12 Clearance See Text FIGURE 52 STARTER PINION CLEARANCE NOTE On plants built before May 1962 it was necessary to maintain the gap between ring gear and starter pinion in the relaxed position at less than 1 8 to ensure starter engagement When installing these motors check this gap If it is too great a shim kit is available to reduce it Figure 53 Required on some early Be sure install same number of shims removed FIGURE 53 ADDING SHIMS 41 EXHAUST SYSTEM The importance of exhaust systems normally supplied by the customer cannot be over emphasized poor or clogged system causes low power overheating and engine damage poor exhaust system increases back pressure which reduces efficiency If high back pressure is suspected follow pro cedure outlined below Test the exhaust system by installing an adapter or tee 4 5 1 1 3 9 i E N N N N A LL APA POOR 7 A747a M y Y 290 the exhaust line at the manifold Connect a manometer or pressure gauge to the adapter If there is condensation trap next to the manifold use it for the manometer connec tion Run the plant under full load and observe manometer See Fig 54 for maximum values 1f the reading is higher the exhaust system should either be disassembled and cleaned or altered to reduce back pre
9. Undersize bearings and connecting rods are available to work the shaft to 010 020 and 030 undersize If main bearing clearances are greater than the limits or the bearings are worn grooved or broken replace them Pre cision replacement bearing inserts and thrust washers are available for all main bearings Don t ream the precision type bearings Refer to dimension and clearance section for crank shaft tolerances Align the oil holes and press the new bearings into the front and rear housings Insert the JC center bearing when the crankshaft is installed OIL SEAL INSTALL FLUSH WITH OUTSIDE SURFACE LIP FACING OUT FIGURE 73 MAIN BEARING HOUSING 51 MAIN BEARING CAP SIDE MARKED FRONT TOWARD CRANKSHAFT GEAR PLACE UPPER BEARING HOUSING HALF IN POSITION INDICATED BY BROKEN LINE ROTATE INTO POSITION lt t DOWEL PIN CENTER MAIN BEARING HOUSING UPPER HALF BE SURE TO ALIGN OIL HOLES IN BEARING AND HOUSING FIGURE 74 MAIN BEARING INSTALLATION The crankshaft teat oil seal is in the rear beating plate If damaged drive it out from the inside of the plate Using the oil seal installing tool install a new seal with the rubber lip facing outward open side of seal inward Fig 73 Drive the new seal flush with the rear surface of the bearing plate Leave the seal installer on during bearing plate installa tion to protect the oil seal
10. A FUEL PUMP FIGURE 7 CHECKING FUEL PUMP PRESSURE FUEL PUMP Gasoline fuel system fuel pump is located on the left side of the engine If fuel doesn t reach the carburetor make the following checks 1 Check the fuel tank and see that the shut off valve is open Remove the fuel line from the pump outlet and crank the engine over several times On manual models operate the priming lever instead of cranking the engine Fuel should spurt out of the pump If not remove the pump for repair or replacement Testing If the fuel pump delivers fuel test it with a pres sure gauge or manometer Perform these tests before remov ing the pump from the engine Disconnect the pump outlet line and install the pressure gauge Fig 7 Test the valves and diaphragm by operating the priming lever a few times The pressure shouldn t drop off rapidly after priming has stopped Next run the engine at governed speed on the fuel remain ing in the carburetor and measure the fuel pump pressure developed Pressure should be between 2 and 3 psi with the gauge held 16 in above the fuel pump VALVE AND CAGE ASSEMBLIES DI APHRAGM ASSEMBLY DIAPHRAGM SP RING ROCKER ARM BODY ROCKER PRIMING LEVER ARM FILTER BOWL FIGURE 8 FUEL PUMP 13 low pressure reading indicates extreme wear in one part or some wear in all parts overhaul ot replace the pump If the reading is ab
11. MI LOAD AL SLIP RINGS A 2 2 i LLARMATUR COMMUTATOR Revolving Armature 3 wire Three Phase 71 TO TERM 7 TO TERM 9 CONTROL BOX CONTROL BOX TERMINAL BLOCK TERMINAL BLOC BEGIN SPEC P SEE NOTE Ti 7 poc i STATOR 5 T2 T3 T3 F 35 T4 SLIP RINGS CHARGING WINDING Revolving Field 3R Reconnectible for 120 240 or 120 240 Volt Single Phase NOTE T2 must be grounded if the field boost circuit is to work Any other ground may damage the exciter Negative ground only MOTE PRIOR SPEC P WHEN 57 OR 4XR SEE MODEL 19 USED AS 3 WIRE SYSTEM UNGROUND TO TERM 7 TO TERM 9 AND INSULATE WHEN USED AS CONTROL BOX CONTROL BOX 4 WIRE SYSTEM GROUND AS TERMINAL BLOCK TERMINAL BLOLK 1 BEGIN SEE AXR CONNECTION 1 157 7 ITF xc CHAR GING SPEC J ALL UNITS ONLY WIN DING SPEC ALL UNITS EXCEPT 120 208 220 380 Revolving Field Wye Wound 4 wire 3 Phase AR 120 208 Volt 4XR 277 480 Volt 57XR 240 416 Volt NOTE must be grounded if the field boost circuit is to work Any other ground may damage the Negative ground only 72 STATIC TO 7 CONTROL BOX TERMINAL BLOC RES 304 500 UNGROUNDED To SLIP RINGS CHARGING
12. 2 Oil the stem of each valve lightly and insert each in it s own guide 3 Check each valve for a tight seat with an air pressure type tester If a tester isn t available make pencil marks at intervals on the valve face and observe if the marks rub off uniformly when the valve is rotated part of a turn in the seat H the seat isn t tight regrind the valves 4 Using a valve spring compressor compress each valve spring with its spring retainer in place and insert the retainer locks 5 Coat both sides of head gasket with Permatex No 3 pliable sealer Install the head assembly and gasket to the cylinder block Tighten the head bolts one or two turns 6 Make up push rod shield assemblies by installing an 0 ring on one end of the rod and a spring washer and O ring on the opposite end Lift the cylinder heads and install the pushrod shield assemblies Fig 59 7 Tighten the head bolts to 28 to 30 lbs ft following the sequence in Fig 60 NOTE 4 cylinder models observe the following special procedure to align the two heads and prevent air leaks BEFORE TIGHT ENING CYLINDER HEAD BOLTS LIFT HEAD SLIGHTLY WHILE DEPRESSING VAL VE PUSH ROD lt SHIELD AND SPRING E INSERT UPPER END OF 4 SHIELD IN TO HOLE PRO VIDED IN HEAD FIGURE 59 INSTALLING PUSH ROD HOUSING 45 TORQUE 28 30 1 85 FT FIGURE 60 HEAD BOLT SEGUENCE Assemble the heads gaskets and pus
13. 9 X 9 5 9 wy 5 9 9 c on 3 9 9 9 3 n 9 a 9 c5 09 0c 9 5 9 9 e 9 9 9 9 9 9 9 c 5 5 5 gt 09 o9 o9 9 oe c 3 3 9 o3 n 9 3 o on e a c oh c o 1 3 n 9 9 a 9 9 a 6 9 9 3 c5 4 9 e o c V 3 i 9 9 e on o9 9 o9 e 9 2 oso 9 9 9 9 5 3 9 Pe o 3 9 4 4 4 4 o 6 2 o3 c o v 4 on 9 3 9 9 9 t 9 9 c 9 9 P P 44442 9 9 t n esras 9 9o o3 v 3 9 eo c 9 9 c 9 e a tes doa 03 d 9
14. METERING TO SPEC R WELL METERING WELL MAIN JET OPERATING FIGURE 13 MAIN JET OPERATION closed at no load and the intake manifold vacuum is high The pressure difference between the manifold and float chamber causes fuel to flow through the idle circuit The pressure difference draws fuel up through the hollow center of the main adjusting needle through passages in the carbu retor body to the idle port Bleed holes in the main adjusting needle allow air to mix with the fuel When the throttle is almost completely closed the fuel passes out through the idle port As the throttle is opened to increase power it exposes the idle transfer port and fuel is drawn out through this port also When the load increases the engine governor opens the throttle further The carburetor air flow increases which produces a low pressure at the venturi narrow section of the carburetor throat This pressure drop draws fuel up the main nozzle where it mixes with air at the nozzle opening The main adjusting needle controls fuel delivery As the throttle opens the manifold vacuum decreases so the idle circuit becomes less effective In a certain range the two circuits blend both delivering fuel but as load is in creased the load circuit takes over With the load circuit in operation as the load is increased the throttle opens to deliver more fuel The main nozzle won t immediately deliver this increased fuel because the jet is contr
15. Repair Clean all components except the condenser breaker points and bushings in light cleaning solvent Inspect the centrifugal advance component for signs of wear and replace any that appear worn or otherwise damaged Inspect the cam and shaft for wear or score marks If either is scored replace it To check bearing wear set the drive shaft into the body and measure the side play at the top of the cam with a dial indicator Mount the indicator on the distributor body and measure the side play by pulling the shaft directly away from the indicator with a force of about 5 pounds Side play should be less than 005 If not the bearings must be replaced ONAN doesn t recommend field replacement of bronze shaft bearings unless the required equipment is available This can be done by an Authorized service station Assembly Distributor 1 Install the shaft assembly with the upper drive shaft thrust washer in the distributor body Install the lower drive shaft thrust washer and drive gear Install a pin through the drive gear and shaft and peen it into place 2 Check the drive shaft end play Fig 44 It should be between 003 and 010 If end play is too small tap the lower end of the distributor drive shaft lightly with a soft hammer to increase play it is too great check the thrust washer installation or re install the gear 3 Set the centrifugal advance weights into place and install the cam Be sure the pivots on the cam
16. Service Manual JiBeJ C Engine BestManuals net http BestManuals net Best Manttals ya joo Con 967 500 TABLE CONTENTS TITLE PAGE General Information 2 Specifications 3 Dimensions and Clearances 4 Assembly Torques and Special Tools 6 Periodic Service Guide 7 Engine Troubleshooting 8 Cooling System 9 Fuel System eR WOM ERE Se Bane 12 Governor System 24 Oil System 42er rom a a 6 26 Ignition System 29 Starting System 37 Exhaust System 42 Engine 43 AC Generator Maintenance 53 Control System ulcer ble elas aie alee 64 Wiring Diagrams ee ee ee ee 69 ELECTRIC GENERATING PLANTS 967 500 SERIES 7 TYPICAL MODEL JC GENERAL INFORMATION This manual contains information required for proper maintenance servicing and overhaul of Onan JB and JC electric generating plants Onan recommends that you study the entire manual to better understand how the plant functions This will help in maintenance and servicing of the plant which will result in longer life and more reliable
17. 25 I e 60 CYCLE STARTING METHOD HEIGHT LENGTH 60 Cycle intermittent 60 Cycle Continuous 15 000 JC 5 0 6 15B 6 0JB 6 0JB 7 6JB 17 5 Number of Cylinders Vertical in line 2 2 4 Displacement cubic inches 60 60 120 Cylinder Bore 3 1 4 3 1 4 3 1 4 Piston Sttok Ue Ee 3 5 8 3 5 8 3 5 8 RPM toU Cycle dee 1800 1800 1800 RPM 50 Cycle du xr dud up bum ex 1500 1500 1500 Compression Ratio Gasoline Fuel 6 5 I 6 5 1 6 5 1 Compression Ratio Natura Gas and LPG 9 2 1 9 2 1 9 2 1 Oil Capacity Quarts TR E 3 6 Ignition Remote Start Plants Yes Yes Yes Ignition Manual Start Plants Flywheel Magneto Yes Yes No Battery Voltage Remote Start AC 12 12 12 Battery Size Remote Start AC Plants SAE Group lH 2225 4x kA SEA SS Two in Series z SAE Group Amp Hour SAE Rating 20 Hour 105 72 72 Starting System Hand Crank Only Manual Start Yes Yes Exciter Cranking Remote Start Plants Yes No No Solenoid Shift Starting Motor with Overrunning Clutch Yes Ye
18. The four cylinder model uses an additional split center main bearing Remove the crankshaft as follows 1 Remove the lock ring and retaining washer in front of the crankshaft gear 2 Pull off the crankshaft gear It has two 1 4 20 UNC tapped holes for attaching a gear pulling ring Onan tool 4204275 Use care not to damage teeth if the gear is to be reused 3 Remove the oii pan and the piston and connecting rod assemblies 4 FOUR CYLINDER ONLY Remove the bearing cap from the center main bearing 5 Remove the rear beating plate from the crankcase Re tain or measure the thickness of the rear bearing plate gaskets These gaskets determine crankshaft endplay LOCK PIN THRUST WASHER ALIGN OIL HOLES MAIN BEARING MUST BE FLUSH WITH INSIDE SURFACE LOCK PIN 6 Remove the crankshaft through the rear opening in the crankcase 4 Cylinder Only Catch the upper half of the main beating support as it slides off its mounting surface Thoroughly clean and inspect the crankshaft and blow out all oil passages with compressed air Check all journals for out of round taper grooving ridges Pay particular attention to ridges or grooves on either side of the oil hole areas which indicate neglect of oil cleanliness If the journal dimensions not within the limits or the journals are scored machine the crankshaft Crankshaft machining requires a trained and experienced operator and suitable equipment
19. The normal charge rate is about 2 amps and the maximum 5 amps If any curtent drawing accessories such as electric fuel pumps ate installed their current draw must be subtracted from the maximum battery charging current and also for the charge tate registered on the plant ammeter To adjust the charge rate move the tap on the adjustable resistor in the generator air outlet Connecting battery with the wrong polarity will damage the charging circuit within minute or two If the adjustable charge resistor is eliminated or shorted both the circuit and the generator charging wind ing will be damaged in a few seconds of operation The rectifier converts the AC produced by the generator charging winding to DC and also acts as a reverse current relay Incorrect battery polarity can destroy the rectifier If the battery polarity is to be changed reverse the battery polarity reconnection block in the control box Polarity recon nection block not used on Spec P and later models or Penn State models Important Jf you aren t sure which battery polarity to use PRIOR TO SPEC P ONLY TO REVERSE DISCONNECT WIRES FROM TERMINALS TURN THIS BLOCK BOTTOM SIDE UP AND RECONNECT WIRES FIGURE 96 BATTERY POLARITY CONNECTION check this block before connecting the batteries WARNING Spec P models and Penn State models are NEG GROUND ONLY Test the rectifier with an ohmmeter 12 volt test lamp If it is operating correct
20. and remote starting models on 2 and 4 cylinder engines The manual starting 2 cylinder model JE M uses a magneto system The 2 cylinder remote and electric starting plants JB R use a battery ignition system The 4 cylinder model JC uses a battery ignition system with automotive distributor For details of specially suppressed systems not covered here request suppression drawing TESTING Remove each plug install the ignition wire to each plug and hold the plug base against bare engine metal Crank the en gine and watch the spark A good blue spark indicates a healthy ignition system a weak or yellow spark or no spark a poor ignition system The defect can be caused by defec tive breaker points coil condenser or wiring good spark on all but 1 cylinder indicates a defective spark plug or de fective high tension wire BATTERY IGNITION JB Electric and Remote starting Plants This model Fig 33 uses a single coil battery ignition to fire both spark plugs simultaneously one spark plug fires on the exhaust stroke while the other is firing at the end of the compression stroke spark advance on the breaker point mechanism advances the spark from 59 ATC after top center when ctanked to 259 BTC before top center when running at rated speed EXCEPTION Advance 10 more for fuel IGNITION RESISTOR IGNITION A BREAKER POINT MECH ANISM FIGURE 33 BATTERY IGNITION JB IGNITION
21. clamp to the cylinder block 2 from the cylinder block to the starting motor frame and 3 from the battery positive post to the battery terminal stud on the solenoid Each drop should be less than 0 2 volts If extra long battery cables are used slightly higher voltage drops may result Thoroughly clean all connections in any part of the circuit showing ex cessively high voltage drops Starting Motor If starting motor tests are required remove the motor from the plant Complete starting motor tests should include both tests of free running voltage speed and current and tests of stall torque voltage and current To test the free running characteristics connect the starting motor in series with a battery and ammeter and install a tachometer on the motor Read the free running current and Open field circuit open armature coils broken or weakened brush springs worn brushes high mica on commutator Low Free Speed Low Torque Low Current High Free Speed Low Torque High Current 38 Open field winding or high internal resistance due to poor connections defective leads or dirty commutator Shorted field windings Since there is no easy way to detect shorted field coils because of their low resistance replace them and check for improved performance GEAR HOUSING PINION SHIFT LEVER LINK SCREW A711 SHIFTING SOL ENOID FIGURE 49 speed The torque test Fig 48 requ
22. serves as start disconnect R JC R and 50 If any component of the control circuit fails replace it If relay contacts are dirty they can be cleaned by pulling hard paper or gauze soaked in carbon tetracloride between the contacts Starting and Stopping System The starting system includes start ignition relay ignition relay starting solenoid and the centrifugal switch It controls the solenoid shift over run ning clutch starting motor and the ignition coil circuit Fig 94 shows the start cycle To stop the engine the stop switch grounds the ignition relay which opens the circuit to the ignition coil The Start Ignition Relay with metal cover is energized at the beginning of the start cycle by the start switch It de energizes when the centrifugal switch closes completing the starting cycle Test the relay by checking contact con tinuity energized and de energized and coil resistance Coil resistance is about 76 ohms The Ignition Relay is notmally energized throughout plant operation It energizes when the centrifugal switch ending the starting cycle closes and maintains the current to the en gine ignition system To test the relay inspect the contacts check the continuity of each set of contacts and measure the coil resistance Coil resistance is about 15 ohms ping resistor This is a 6 volt relay and in the control circuit it is in series with a 15 ohm drop The Centrifugal Switch is mounted on
23. 1 N9304AZI7 RESIS TOR 1 4 172 04 MAS W N 304A60 t m 1 1 IGNITIDN x CHARGE CONDENSER ait TERMINAL BLOCK RECTIFIER MARKER STRIP N 3232A739 SWITCH CATE VERE HS SDBPIS4 SWITCH STOP START WHEN USED T 11 TERM BRLUCK SN 99552 537 8 prisa it 2 oveeseced f 22 56 CHOKE i Swit Tet 22 WHEN USED CATCH ic Toc SILK SCREEN N 9GBI5B9 VALVE t WOTE ENGINE WHEN USED A C LOAD CONNECTIONS i Le P IPHASE 2WIRE 1PHASE 2 WIRE ELECTRIC FUEL ig0vorr 240 017 CHARGE RESISTOR PUMP ASS Ng 304A505 WHEN USED i 2 0HM 1 50W 4 Ag 3O4 A 500 REF 7 Me STATIC EXITER 120 240 VoLT T2 MUST GROUNDED gr ANY OTHER GROUND WILL CAUSE SERIOUS DAMAGE TO EXCITER CHARGING 2 WINDING IPHASE S WIRE CAUTION 3R 120 240V IPH 3 W 60C Y S3R 120 240V IPH 3 W 50C Y Bi _ 6 805 d 945 uiSeg 31125415 9unsseug MOT YVA 27545 05 8 lt 0 WVH5VIGO 68 6HC804 view dia ELECT START START 4 START i 2 DISCONNECT IGNITION g
24. 16 459 002 005 45 49 1 Prior to Spec P 83 93 Begin Spec P 87 2 97 2 025 020 020 020 012 015 013 020 359 5 BTC 259 259 59 59 SERIES JC 1 25 32 4690 4695 344 345 342 343 467 468 1 547 1 548 1 361 1 362 433 439 1 364 1 365 1 550 1 551 3 64 1 16 459 002 005 45 49 1 Prior to Spec P 83 93 Ib Begin Spec P 87 2 97 2 025 020 020 519 012 015 013 020 359 10 BTC 25 BTC 0 BTC ASSEMBLY TORQUES AND SPECIAL TOOLS Assembly torques assure proper tightness without dan ger of stripping threads If a torque wrench is not avail able estimate the degree of tightness Use reasonable force and a wrench of normal length Special Place Bolts do not require lockwashers ot gas kets Never attempt to use a lockwasher with these bolts it willdefeat their purpose Check ali studs nuts and screws often Tighten as needed Ser sS RECESS A EA UNDER HEAD TORQUE SPECIFICATIONS FT LB Center Main Bolt 4cyl 97 102 Connecting Rod 27 29 Cover Rocker Box 8 10 Cylinder Head 28 30 Exhaust Manifold 13 15 Flywheei Mounting Screw 65 70 Hub to Flywheel Screws 4 1 17 21 Fuel Pump Mounting Screws 15 20 Gear Case Cov
25. 1C 304 97502 NVHDVIO NOD 2995 uag 92055944 ON 9 9 97245 03 58 PARTS LIST CONTROL SCHEMATIC DIAGRAM PART NO DESCRIPTION 302 235 _ 13054254 13076042 112797 _ _ LS Greci 5 he ELEC 79 CHARGE STAR Grane REGULATOR LI 1 i 1 HELE SWITCH START STOP 1 BLOCK TERM 1 1 1 START SOLENDID t 35 BLOCK TERM 332 555 1 5 MARKER 1291 130 1p2908 1 CONTROL BOx 1301225411 PANEL CONTROL EEX ee Ez COVER CONTROL BOX 301820157 BRKT CONTRO_ BOX MTS T 20162011 BRKT CONTROL BOX COvVER RESISTOR START DIS CONNECT List ENG GEN BATTERY 2 CHOKE ENS WHEN USED E2 E3 SFARK PLUSS GENERATOR SOLENOID FUEL WHEN USED RFI j SAGO i IRES IGN HYTEMCOI72 A 25W Bt j1 Sw HiGM TEMP WHEN USES 1 SW IG NIT ON POINTS 5 1 LOW OL PRESSURE SILK SCREEN ELETT STAT H SILK SCREEN START STOP 15 aK SCREEN EMERSENEY BELA laco Oe Ser Fic 1 3 LEADS Pos i 4 AC SLIP RINGS VOITA GENK A Ax ful
26. 2 B R3 WAS SCTE BE z7 COMM BEARING 1 7 210 67 ENS END UFERSEDES 2117797 DATEL 12 27 65 Pel OTHERS HAVE MFD CAPACITOR Qe 09 comenten non TO GROUNC 0 b amp G9 JE KR Monee HEEE bZ D JB x REP GOTI WIRING amp SCHEMAT C bi4 ENGINE GEN CONTROL 12V REMOTE 611C797 STARTING d 9ds 91155924 07 ui 9 9 NVuDVIO 1OHLNOO 78 WIRING DIAGRAM SCHEMATIC DIAGRAM HrRR ETT ft z CURRENT ERS MT SCONNECT Ks 3 CHARGE ji REGULATOR ies Ri R2 134 R 3044251 RE5 STOR 0 0HM SW 519 12 BUTTON 51 308 2 SWITCH MAN ELEC START START 52 3082154 332A609 BSAC SWITCR START STOP BLOCK TERM STRIP MARKER T82 332A537 1 BLOCK TERM 3325526 STRIP MARKER DISCONWECT 44 E 5 4 SERIES FLD 84 pat BRKT CONTROL BOX MTG RH RESISTOR pr i 1 j wiz OUTPUT LEADS 1 0 2 VOLTAGES AC SLIP RASS CADE COMM BEFARING ENE ENO GROUNDED ACLEAD ALL OTHERS HAVE 0 1 MFO CAPACITOR GROUND 61796 d 2995 3 9 1102415 HO MOT ON 819 T
27. 9 e 9 e 9 o3 9 9 Valve RS Valve Clearance Begin Spec D Prior to Spec D a 9 9 9 gt Cr CD a SERIES JB 2 500 2 505 1 1875 1 1880 0012 0037 007 039 Prior to Spec P 7475 7480 7505 7515 Begin Spec P 8725 8730 8755 8765 2 1871 2 1876 1 044 1 045 001 003 3 250 2 2440 2 2445 0014 0052 2 0600 2 0605 001 003 010 015 0012 0032 Thumb Push Fit 0002 0007 010 020 0925 0935 0925 0935 1860 1865 3405 3415 001 003 429 012 010 3405 3415 0030 0050 45 015 013 SERIES JC 2 500 2 505 1 1875 1 1880 1 2580 1 2582 0012 0037 007 039 Prior to Spec 7475 7480 7505 7515 Begin Spec 8725 8730 8755 8765 2 1871 2 1876 1 044 1 045 001 003 3 250 2 2430 2 2435 0024 0052 2 0600 2 0605 001 003 010 015 0012 0032 Thumb Push Fit 0002 0007 010 020 0925 0935 0925 0935 1860 1865 3405 3415 001 003 429 012 010 3405 3415 0030 0050 459 015 013 VALVE GUIDE Length Outside Diameter Inside Diameter After Reaming Exhaust Intake Cylinder Block Bore Diameter VALVE SEATS Stellite
28. IO WATT BREAKER RESISTOR Pr POINTS 35048432 op OHM 10 WATT RESISTOR N X04A277 HYTEMCD IGN JF RESIS TOR 1 72 0 4 25 W 304 IGNITION CONDENSER di CHARGE RECTIFICA NESOSAISS TERMINAL BLOCK 23324704 MARKER STRIP WEIZZATIS IGNITION CENTRIFUGAL H XZ2ATYS SWITCM 1 MARKER XTRIM ha SWITCH LL LSTOR START wMEN USED i TERM BL DOCK ENS NT 3324537 RE MARKER STRIP ELECTRIC CHARGING NZZIZASCE N CHOKE WINDINGS WHEN uses is i ev 7 DELL a eno To RITE i 1 1 ENGINE WHEN USED ALC LUAD CONNECTIUNS STARTER 3 Ww A um 5 FOE JUN ELECTRIC FUEL izovorr 240VOLT PUMP lt a ae WHEN USED 221 EZ E IP HASELZWI mw 120 240 D 5 SEN WILY E CAUSF SERIUUS kd E En TERCER 3Ri 20 240V IPH ZW 60C 538 120 240 X W amp OCY e6l C668 f reds eunssei4g 07 HIA f9 31259 06 97505 ONINIA 1094102 84 611C 664 7OSTa 3RAT VIE 7 6UyB Cc3R Hy START DISCONNECT IE MTTION START RELAY SOLEWOI
29. Lubricate lips with heavy high temperature grease Install the crankshaft as follows after each step turn the the crankshaft to be sure it is not seized 1 Press the front and rear main bearings into place align REAR BEARING PLATE w MEASURE ENDPLAY HERE Refer to table of clearances FIGURE 75 CRANKSHAFT END PLAY 52 the bearing and bearing housing oi holes Don t attempt to drive a bearing into a cold block or rear bearing plate Install the thrust washers and locking pins 2 Oil the bearing surfaces and install the crankshaft from the reat of the crankcase through the rear bearing plate hole 3 Mount and secure the rear bearing plate with the same thickness of new gaskets as removed 4 Heat the crank gear to about 350 F Install the key on the crankshaft then drive the gear into place Install the retaining washer and lockring 5 4 CYLINDER ONLY Set the upper half of the center main housing on the crankshaft and rotate it into place Be sure the side marked FRONT is toward the crank Shaft gear Set the 2 positioning dowels on the upper beating mount Install the center main bearing cap and torque bolts to 97 102 1b ft Fig 74 6 Check the crankshaft end play Use enough rear bear ing plate gaskets to provide 010 to 015 end play Fig 75 7 Install piston assemblies Crankcase On the 4 cylinder models if the center main bearing support requires replacement the whole crankc
30. armature is defective 5 Test for short circuit between the starter windings and replace it ARMA TU ARMATURE FIGURE 87 CHECKING FOR SHORTS the shunt windings Before doing this separate all windings at F Al WHEN USED wnt She poU 2 USED WITH FIGURE 88 FIELD LEADS Commutator Repair The commutator bars eventually wear down so the mica between them extends over the tops of the bars and causes sparking and noisy brushes When the mica on any part of the commutator is touching the brushes it must be undercut suitable undercutting tool can be made from a hacksaw blade Fig 89 Cut the mica to about 1 32 under the bars careful not to damage the bars After undercutting remove any burrs formed on the bars Field Winding Tests Perform the following tests without disassembled the generator The field coil leads must all be disconnected from their terminal points brush rig control TABLE 7 GENERATOR DC VOLTAGE FIELD RESISTANCE MODEL NO LOAD RESISTANCE PER COIL 4 018 Spec A amp B 27 Volts 1 7 Ohms 1 7 Ohms 5 0 B Spec A amp B 27 Volts 1 7 Ohms 1 7 Ohms 4 0 B Spec 31 5 Volts 2 1 Ohms 2 1 Ohms 5 0 Spec 31 5 Volts 2 1 Ohms 2 1 Ohms 6 1JB 35 6 Volts 2 4 Ohms 2 4 Ohms 7 6 35 6 Volts 2 4 Ohms 2 4 Ohms NOTE Values based on standard models 61 HACK SAW WOODEN BLADE 122 TOWARD HANDLE BLADE MICA RIGHT WAY WRONG WAY TO GRIND GRI
31. circuit If the ohmmeter required for this test isn t available check for open circuits with the test lamp 3 If any windings are shorted open circuited or grounded replace the stator assembly Before replacing the assem bly check the leads for broken wires or insulation and replace any defective lead If this does not correct the fault replace the assembly Only a competent rewinding shop should attempt to rewind a defective stator TESTING FOR OPEN CIRCUIT CONTACT ONE TEST PROD TO ONE SLIP RING AND THE OTHER PROD THE SECOND SLIP RING IF GOOD BULB SHOULD LIGHT FIGURE 82 56 Battery Charging Winding Tests Remove the lead from the battery polarity reconnection block to ammeter at the am meter Install a DC voltmeter between the lead and ground At governed engine speed the average DC output should be 19 to 21 volts If the output is defective test for open circuit or grounding in the leads and windings If leads are defective replace them If the winding is defective replace the stator TABLE 5 RESISTANCE VALUES O4SXINIA 04SXINIB 3B O6SXINIA O6SXINIB TESTING FOR GROUNDS CONTACT ONE PROD TO EACH OF THE SLIP RINGS AND THE OTHER PROD TO THE ROTOR SHAFT IF GOOD BULB SHOULD NOT LIGHT 120 VOLT AC TEST LAMP EXCITER TROUBLESHOOTING CHART NATURE OF TROUBLE PROBABLE CAUSE CORRECTIVE ACTION STEP Generator will not build up Circuit breaker in or Reset and close breaker voltage
32. constant speed operation the buildup of deposits in the combustion chambers is proportional to the amount of lead in the gasoline Excessive lead causes more deposits and more frequent head removal for cleaning If plants require frequent combustion chamber cleaning the period between cleaning can often be increased by changing fuel it fuel is stored for any great length of time it can oxidize and form gums the fuel becomes stale ONAN recommends changing fuel stored as often as every season to insure fresh fuel especially where there is a great change in weather between seasons MAINTENANCE On gasoline fuel systems petiodic maintenance consists of GARRETSON REGULATOR CARBURETOR TO CONTROL TERM GROUND TO CONTROL TERM 4 PARALLEL WITH IGNITION DRY FUEL FILTER MANUAL SHUT OFF GAS SOLENOID VALVE FIGURE 5 GASEOUS FUEL SYSTEM 12 FIGURE 6 FUEL SEDIMENT BOWL cleaning the fuel strainer cleaning or replacing the air cleaner carburetor adjustment and complete carburetor cleaning To clean the fuel strainer remove the fuel sediment bowl and the screen Fig 6 and thoroughly wash the screen At the same time remove the carburetor float bowl and clean it Assemble and check for leaks On gaseous fuel systems periodic setvice should include cleaning or replacing the air cleaner carburetor adjustment inspection of hoses etc and cleaning the optional dry fuel filter PRESSURE
33. contains both AC output windings and DC windings to supply the field and battery charging circuit SUPPORT ROTOR WITH HOIST AND SLING TO AVOID BENDING THROUGH STUD TURN NUT OUT TO END OF GENERATOR THROUGH STUD STRIKE WETH SOF T HAMMER WHILE PRYING FIGURE 84 GENERATOR DISASSEMBLY 59 generator is mounted to the engine through the engine to generator adapter and the armature is directly connected a tapered fit to the crankshaft The outboard end of the generator rides on a ball bearing housed in the endbell Because of its construction the generator can t be removed as a unit Generator leads are marked with metal tags for identification Lead and terminal marking codes are noted on the plant wiring diagrams MAINTENANCE Normal maintenance includes periodic inspection of the armature ball bearing collector rings and commutator and the brushes normally every 500 hours Also blow the gen erator clean with compressed air every 1000 hours BRUSHES Remove the endbell band and cover and check the brushes Replace brushes when they wear to about 5 8 long brushes must have at least a 50 percent seat Seat the brush es by sanding see Fig 86 ADJUSTMENTS The engine governor controls generator output frequency Engine speed determines generator output voltage The volt age drop from no load to full load operation is determined by the engine governor sensitivity To change output voltage slig
34. fit into the hole in each weight Secure the cam with the spring clip and install the weight springs 4 Install and secure the breaker plate 5 Mount the breaker arm on its pivot and place the control spring end between the end of the terminal stud and the square metal washer Then tighten the primary terminal 6 Align the contacts so they make contact at the center Bend the stationary contact bracket not the breaker arm to align contacts 7 Check the tension of the breaker spring with a spring scale hooked on the arm at the contact and held at right angles to the contact surfaces Fig 42 Tension Should be 17 to 20 oz Adjust it by loosening the screw holding the end of the contact spring and installing spacing washers or sliding the end of the spring in or out 8 Rotate the drive shaft to obtain maximum breaker gap and set the gap for 020 Fig 41 installation Distributor Install the distributor in exactly the same position before removal When setting the distrib utor into position the rotor should be 1 8 turn counterclock wise from the position when removed to allow the gears to mesh After installing perform the following steps 4 5 and 6 If the exact position of both distributor body and rotor weren t recorded or the crankshaft was rotated use the following procedure 1 Remove the spark plug from 1 cylinder Place a finger over the spark plug hole and rotate the flywheel clock wise until th
35. from the gen erator and connections to the exciter are marked The lead and terminal markings are shown on the plant wiring diagram Magneciter is the trade name of Onan s static exciter system It has no moving parts and uses magnetic amplifiers and rectifiers to supply direct current to the alternator s revolv ing field and to regulate the AC output STATOR WINDINGS MAGNECITER ASSEMBLY nre OUR BLOWER Ime MAGNECIT ER KEYS COVER sini TUAM HN 4 TIT W BEARING HOUSING BEARING HOUSING 45 se END BELL ROTOR COLL ECTOR RINGS FIGURE 77 AC GENERATOR 53 REACTOR REACTOR A STABILIZING RESISTOR NOTE EXCITER PRIOR TO SPEC P LATE MODEL SEE WIRING 7 DIAGRAM FIELD RECT DAMPING RESISTOR ur NN PES lt 2 a 4 mS lt CALIBRATED SHUNT rete REE RECTIFIER FIGURE 78 EXCITER PRIOR TO SPEC P OUTPUT VOLTAGE ADJUSTMENT Controls in the magneciter allow small changes the gen erator output voltage DON T use these controls to increase generator output above rated voltage i e 120 V 240 V On models with an 025 Magneciter adjust the voltage by changing the tap used on the control reactor C1 C2 or C3 The voltage difference between each of the taps is about 4 of the output v
36. loads during balance of break in period to best seat rings for oil control ENGINE DISASSEMBLY During engine disassembly observe the following order i e Flywheel Gear Cover As disassembly progresses the order may be changed somewhat as will be self evident The engine assembly procedure is the reverse of disas POSITION GOVERNOR 50 THAT ROLL PIN FITS INTO HOLE IN CUP BE SURE THAT OIL PASSAGES ARE OPEN sembly Any special assembly instructions for a particular component ate included When reassembling check for special assembly instructions or procedures Flywheel To remove the flywheel first remove the blower housing The flywheel is then removed by using the crank dog as a puller as follows first remove the crank dog and flywheel mounting capscrew Then remove the large washer from the flywheel mountfhg capscrew and reinstall the screw part way Install the washer into the crank dog and mount the crank dog so the washer bears against the end of the fly wheel mounting screw Tighten the 2 crank dog capscrews alternately until the flywheel comes loose Ring Gear Remove the ring gear by sawing part way through then break it using a cold chiesel and heavy hammer To install a new ring gear place it in an oven heated to 380 400 for 30 to 40 minutes When heated properly the ring will fall into place on the flywheel If it binds drive it into place with a hammer Do it fast and don t damage
37. of the emergency stopping devices operates the plant will stop and then crank until the control s cranking limiter opens This High Temperature Cut off Switch Optional is located in the optional air shutter or air duct Normally closed it opens when the air temperature reaches 240 F 6 and closes again when the temperature drops to 195 F 8 The plant cannot be started again until the switch closes This Low Oil Pressure Circuit Optional includes a non 65 adjustable low oil pressure switch and centrifugal switch located on the engine and a latching relay in the control box The circuit shuts the plant down if oil pressure drops below 7 1 psi and prevents it from restarting until the operator pushes a reset button on the control box If low oil pressure occurs the pressure switch closes com pleting the relay coil circuit The relay pulls in and latches after 15 to 20 seconds The centrifugal switch is required to prevent the circuit from latching during the plant starting cycle before oil pressure builds up TESTING AND REPAIR MODELS 705JB Cycle 6JB Rev Field The JB revolving field models and JC control systems use 8 separate starting motor and a rectifier and alternator bat tery charging system separate winding in the generator acts as battery charging alternator Optional high temper ature cut off and low oil pressure cut off circuits are avail able On the JB and JC an engine mounted centrifugal switch
38. or rough so that good brush seating can t be maintain ed remove the armature and refinish the rings in a lathe Shield the ball bearing during refinishing Ball Bearing If the ball bearing becomes noisy worn or otherwise defective replace it Remove the old ball bearing with a gear puller and drive or press a new one into place REPLACE ANY BRUSH WORN 1 2 OR LESS CAUTION WHEN FITTING BRUSHES USE SANDPAPER WIDER THAN TAPE END OF SANDPAP ER TO COMMUTATOR 4214 USE 00 SANDPAPER NEVER USE EMERY CLOTH OR EMERY PAPER FIGURE 86 COMMUTATOR MAINT EN ANCE Preferred Frequency No Load To Ful Load Minimum Frequency At Full Load Maximum Frequency At No Load 64 Cycles 57 Cycles 61 59 TABLE 6 60 3 Test the armature for an open circuit in the DC windings by checking continuity between all adjacent bars of the commutator box and external connections If a defective coil is found disassemble the generetor and replace the defective coil Touch the probes to two adjacent bars and check for 1 With an ohmmeter or continuity lamp check for grounding continuity Move each probe over one bar and again to the generator frame Touch one prod to each coil check Continue around the commutator Any adjacent terminal in turn and the other to clean paint free bars that don t show continuity indicate an open arma part of the frame the test indicates grounding sepa ture winding Test for shor
39. the teflon coating on the throttle shaft which reduces wear and friction between the shaft and carburetor body Assembly and Installation 1 Install the throttle shaft and valve using new screws Install shown in Fig 13 with the bevel mated to the carburetor body On valve plates marked with the install with mark on side toward idle port when viewed from flange end of carburetor To center the valve back off the stop screw close the throttle lever and seat the valve by tapping it with a small screw driver then tighten the two screws 2 Install choke shaft and valve Center the valve in the same manner as the throttle valve Step 1 Always use new screws 3 Install the main nozzle Prior to Spec R making sure it seats in the body casting 4 Install the intake valve seat and valve 5 Install the float and float pin Center the pin so the float bowl doesn t ride against it 6 Check the float level with the carburetor casting in verted See Fig 16 7 Install the bowl ring gasket bowl and bowl nut and main nozzle begin Spec R Make sure that the bowl is centered in the gasket and tighten the nut securely nf NEEDLE m THROTTLE PRIOR TO SPEC R THROTTLE PLATE FIGURE 18 CARBURETOR ADJUSTMENTS 8 Install the load adjusting needle with its spring Turn in until it seats then back out 1 to 1 1 2 turns 9 nstall the idle adjusting screw finger tight Then back out 1 to 1 1 2
40. tripped position Stop plant and check breaker continuity Check AC voltage at 1 2 with the plant operating Voltage Should be 5 percent of the rated voltage not check continuity from E1 E2 back to generator Open in circuit breaker No AC power to Magneciter With plant operating jumper from E2 to heat sink of field rectifier Z until voltage begins to build up Then remove Partial loss of residual in rotor Pair of field rectifiers open either W and Z or X and Y Both field rectifiers X and Y shorted Test rectifiers and replace if defective Test rectifiers and replace if defective Either field rectifier X or Y Test rectifiers and replace if shorted defective Output voltage slow to build up Circuit breaker opens in about 5 seconds Either field rectifier W or Z shorted Test rectifiers and replace if defective Output voltage slow to build up and 5 percent below rated voltage after build up Voltage regulation poor Test rectifiers and replace if defective Check soldered con nections to rectifiers Output voltage slow to build up and higher than rated voltage after build up Open circuit in one or more Control rectifier Test rectifiers and replace if defective If field rectifiers Y and Z check okay check continuities of gate windings G1 G2 Outp
41. turns 10 Reinstall the choke and adjust 11 Install the air horn assembly and gasket 12 Install the carburetor on the engine and connect the gasoline inlet governor mechanism breather hose and choke 13 Install the air cleaner and the air housing top and door CARBURETOR GASEOUS FUEL The gaseous fuel carburetor Fig 17 is similar to the oline carburetor in shape but it differs in operation The gaseous carburetor contains two major sections the idle circuit and the load circuit Fuel delivery depends on the demand created on the fuel inlet line A small vacuum on the inlet line opens the fuel regulator delivering fuel For no load operation the idle adjustment controls the quantity of fuel allowed through the idle port The throttle plate is al most closed so the increased vacuum on the engine side of the carburetor draws fuel through the idle passage When load increases the flow of air through the carburetor draws fuel from the main fuel port located at the venturi of the carburetor Adjustment Set the carburetor idle adjustment and then the load adjustment NOTE If the carburetor is completely out of adjustment so the engine won t run open the idle adjustment one or two turns then crank the engine while opening the main adjust ment until the engine starts Adjust the carburetor in the same manner as the gasoline carburetor Usually the idle adjustment will have little effect on operation becau
42. vw v 9 5 B 8 s 9 c9 9 9 9 9 3 4 44 4 5 a 9 9 9 4 9 o 9 s o o 9 c e 9 9 a e 9 9 4 vo 9 9 9 9 9 o 3 9 9 a 3 9 9 o9 9 9 o 9 4 8 8 9 t 9 9 Boe 3 9 9 9 8 9 9 c9 4 a 9 a 9 4 9 v San 5 9 9 3 8 5 5 ess 44 9 9 3 9 v 9 9 8 9 5 9 4 9 9 9 9 9 9 9 y wo t no o i 9 3 9 v 9 9 9 3 5 9 9 9 9 9 9 9 9 9 a 9 9 9 9 a 3 9 4 9 9 9 9 9 v SERIES JB 1 25 32 4690 4695 344 345 342 343 467 468 1 547 1 548 1 361 1 362 433 439 1 364 1 365 1 550 1 551 3 64 1
43. which follows closing of intake valve 2 Turn the flywheel until the TC top center mark on the flywheel lines up with the timing pointer on the gear cover Then turn the flywheel in a clockwise direction for an additional 10 to 45 degrees There is no timing mark for this position so it must be estimated With the piston located in this position the cylinder will be in EXHAUST WALVES FIGURE 55 ADJUSTING VALVE CLEARANCE its power stroke with both valves completely closed 3 Check the cylinder head bolt torque See Fig 60 4 Using feeler gauge check the clearance between the rocker arm and the valve see Fig 55 Increase or re duce the clearance until the proper gap is established adjusting with the locknut which secures the rocker arm to the cylinder head Refer to Table 3 for correct valve clearance setting for your particular engine Adjust valve clearance on the Four Cylinder J Series engine as follows 1 Adjust the valve clearance in the firing order 1 2 4 3 sequence After the cooling period set timing for the 1 cylinder and the valve clearance 2 To adjust the valve clearance for the number 2 cyli nder the flywheel in a clockwise direction 180 1 2 revolution from the position used in step 2 A The wheel position should be between 10 and 45 past the BC bottom center flywheel mark NOTE Early model four cylinder engines do not have BC mark on the f lywheel 3 Afte
44. AD TOP PIN PRIOR TO SPEC FUEL DLE THROTTLE ADJUSTMENT THIS DISTANCE 1 32 NO LOAD MAIN FUEL ADJUSTMENT A NYLON ROD EXTENDING DOWN THROUGH LOWER HROUD PAN FIGURE 15 NO LOAD ADJUSTMENT SPEC R ALTERNATE METHOD USE WHEN THERE IS NO LOAD ADJUSTMENT POSSIBLE 1 Start the plant and allow it to warm up Push in on the governor mechanism to slow the plant down to about 400 500 r pm 2 Set the idle adjustment screw for even operation so the engine is firing on all cylinders and running smoothly 3 Release the governor mechanism to allow the engine to accelerate engine should accelerate evenly and without a lag If not adjust the needle outward about 1 2 turn and again slow down the engine and release the mechanism Continue until the engine accelerates evenly and without a lag after releasing the governor With the carburetor and governor adjusted and the plant run ning with no load Fig 15 allow 1 32 clearance to the stop pin This prevents excessive hunting when a large load is suddenly removed Removal and Disassembly 1 Remove the air housing door and top panel fuel line governor linkage and electric choke wire 17 THIS DIMENSION SHOULD BE 11 64 PRIOR TO ADJUST DIMENSION SHOULD BE 3 16 FIGURE i6 FLOAT ADJUSTMENT 2 Remove the two carburetor mounting nuts and pull off the carburetor 3 Remove the air cleaner
45. AT T WHEN USED i EN RESISTOR ASS Y bow N 3O4A505 TANK FUEL SOLENOID ra WHEN USED E JS 7 T s r 1 E esti al STATOR IPHASE Z WIRE CAUTION 120 240 VOLT 3 i di NY OTHER T GROUND WITE Efe e 77 5 SERIOUS gp M s DAMAGE TO EXCITERL MEE 120 2 409 P M 3 WIR E 0 SLIP RINES cC CHARGING 2 07540 Y PH 3WIREISOC Ona WINDING Fr TT Blacasseg 7 LINDYID 34055384 110 801 ON 1 224s WYY9YIA 1031405 or 28 SWITCH N9308 PE ELECT Y HAND ESE START CRANK START 21 START ark gt DISCONNECT 1 IGNITION 1 IGNITION RELAY RELAY 1 59 N2 307B623 1 1 SPARK PLUG RESISTOR SUPPRESSORS DISTRIBUTOR RESISTOR SUPPRESSOR IGNITION OHM RESISTOR N 504A32 I 0HM 10WATT RESISTOR 23044217 JMFD COAD N S3IQAS2 TERMINAL BLOCK 332 706 MARKER STRIP 55247359 DISTRIBUTOR s 1 SWITCH TEMP CENTRIFUGAL RUE Swire mm WHEN USED a zx Zu STOR O START UE 1 i 2 li TERM BLOCK eee NE Z32A537 at LOW OL MARKER STRIP PRESS SWITCH N 332A566 E 1 WHEN
46. D NS 3078623 507 40 SUPPRESSORS 1 1 4 IGNITION 4 52 2 I DHM IO WAIT POINTS B t RESIS TOR 1 72 0H MES HME SOLAS 1 IGNITION 1 CaNDENSER T A TERMINAL BLOCK T ER 5324706 E MARKER STRIP NES NIZXEZATZIS Ld HIGH TEMP STIR 4 MARKEN STRAP M XORPISS j USED RN M METAZATIE START r 35 r TERMLBLOCK 1 STRIP 82 92332586 i CHARGING t BIENUIB PTT ewo ro 645 4 n ES n e t ENGINE WHEN USED AIC CUXAD CONNECTIONS a STARTER 9 LPHASEZWIRE EE EE 2 ELECTRIC FUEL JERYULI PUMP WHEN uSED n PHASE WIRE CAUTION i2 0 24Q0VDLT 3Rl 120 240V IPH 3W 60CY E3R 20 240V 1PM IW 50 7 6 1 664 f 29 113592 10 991 ON 8 9 312 24 lt 9 0 65 EI LE DERI E S ee RES 308 2 EN 4 5 d RELAY 3 i 43208164 REVERSE gt CURRENT RELAT N2367 SOLENOID 9307640
47. ER GROUND WILL t Ta E fU MARGE m E EXCITER 12 0 2 40v WINDING E Cede 61202 243 MIHIM 1041 a LINDY 34055344 110 AO or 1 2296 wo vg 98 0 amp 1295 55 H2 i5JgyC 5R SPEC IL SPEC Ic N2308 VIEW START START DISCONNECT fy IGNITION IGNITION RELAY RELAY i 423078 N2307B 623 SPARK PLUG RESISTOR SUPPRESSORS DISTRIBUTOR RESISTOR SUPPRESSOR L2 VOLT IGNITION le hire COND 3 52 O4M JOWATT RESISTOR 5504 2 TERMINAL BLOCK CHARGE 53254706 RECTIFIER MARKER STRIP 1 AP 2 SOSAZ 22 759 BATTERY i POLARITY t Truy Ri ESSERE T SWITUM 1 7 FUGAL z qu MARKER STRIP wasoariss iN 83284216 _ 51970 START _ 1 1 m ZSZZASAT i ks mcum opu MARKER STRIP 23532 566 1 1 GTA ELECTRIC 1 1 1 L j CHOKE WHEN USED VALVE CENOID NOTE ENGINE I WHEN USED i A C LOAD CONNECTIONS 1 2 WIRE J m IPHASE 2 WIRE r j20 v OLT 240 047 rr ELECTRIC FUEL MER USED CHAREE RESISTOR PUMP rT IMP HE 1 2 0HM 50 W
48. IL PRESSURE GAUGE The gauge is located on the lower front comer of the cylinder block If it is damaged replace it Before replacing check for a clogged oil passage behind the gauge OIL FILTER The full flow filter is mounted on the filter plate at the left front corner of the crankcase Replacement is normally every 200 hours of operation Remove the filter by turning counterclockwise Lubricate the gasket on the new filter with engine oil Install the filter until the gasket touches the base and tighten 1 2 turn do not overtighten If at any time the oil becomes so ditty that markings on the dipstick can t be seen change the oil filter and shorten the filter service interval accordingly CRANKCASE BREATHER The crankcase breather located in the rear left cornet of the crankcase maintains a partial vacuum in the crankcase 27 during operation to control oil loss and ventilate the crank case The older type includes a metal filter packed into the tube on the crankcase a rubber cap with flapper valve and hose connecting it to the engine air horn NOTE The JC does not use a flapper valve To disassemble remove the rubber cap from the crankcase tube and pry the valve out of the cap Wash the valve in fuel at regular intervals and if defective replace it Also pull the baffle out of the breather tube and clean it Install the valve with the perforated disk toward the engine Service the breather system at least every 200
49. NAL BLOCK 21524706 MARKER STRIP NEZZZA7TAS DISTRIBUTOR 115412 38055334 110 d 2945 uibeg ONIN 1041409 2 0HM 150 WATT L N 304A500 REF uU DAY TANK FUEL SOLENOID To MUST WHEN USED BE GROUNDED CENTRIFUGAL SWITCH ie SWITCH H 4 gt Tx CH HEN USED cpi 77 4 1 M TERM BLUCK NDS NS 332 557 4 MARKER STRIP VEN ELECTRIC 2552 566 1 CHOME 1 MP LS WHEN USED c2 16 1 SOLEWOID 4 env ro 5 t ENGINE WHEN 5 i 1 PRIMER SOLENOID ELECTRIC FUELI ae ee E I i STATIC Onan ONNO OF SUOMA CORONATION BERENS SORES 7R CONNECTION SLIP RINGS CHARGING WINDING of
50. ND BRUSH TEETH TEETH COMMUTATOR GRIND BLADE TO WIDTH OF MICA COMMUTATOR BARS WORN BELOW LEVEL OF MICA SEPARATORS CAUSE SPARKING JUMPING NOISY BRUSHES MICA PROPERLY HIGH MICA UNDERCUT FIGURE 89 CORRECTING HIGH MICA CONDITION Brush Rig Alignment Align the brush rig to the neutral position Normaily the neutral position is identified by a yellow mark extending from the brush rig to the endbell Fig 90 If the mark is lost or a new brush rig installed find the neutral position according to the following instruc tions 1 With the generator end cover and band removed to allow access to the rig connect a voltmeter across the DC terminals 2 Then start the unit and apply full rated load 3 Loosen the brush rig mounting screws and rotate the rig to get the highest voltage 4 Rotate the rig in one direction until the voltmeter read ing starts to decrease Mark this point Repeat in the other direction 5 Half the distance between the two marked points is the neutral position NOTE If a voltmeter isn t available use the above pro cedure but mark the point where arcing begins 62 LOCATION OF REFERENCE FIGURE 90 BRUSH RIG POSITION GENERATOR DISASSEMBLY 1 2 3 4 Remove the battery cables and leads to the engine Remove the endbell cover and band Remove the brush springs Fig 85 Loosen the thru armature stud nut in the center of the rear bearing Remove the thru g
51. OR SERVING AS STARTING MOTOR CRANKS ENGINE trol system Blow out accumulated dust with low pressure The breaker point gap of the engine mounted centrifugal switch will have to be checked at regular intervals This gap should be set at 020 NOTE This switch is not used on exciter cranked models except with optional low oil pressure cut off Because of the basic differences between the control systbm for the exciter cranked JB and the control system for the starting motor cranked JB and JC they are separated MANUAL STARTING MODELS JB M Manual starting models contain no sterting motor they must be started with the crank These models essentially contain no control system except a stop button ELECTRIC STARTING MODELS JB E and JC E These models are designed to be started at the plant only The control starting circuit consists of a heavy duty starting i LLOW NG 4 CURRENT 70 ENGINE IGNITION ENGINE STARTS FIGURE 92 STARTING SEQUENCE FOR REVOLVING ARMATURE 64 SURFACE TILTED REMOVE INNER NUT FIGURE 93 START SOLENOID switch and the stopping circuit simply of an ignition switch that contro s current to the ignition coil If battery charging or optional emergency shut off circuits are used refer to the appropriate sections under remote starting control circuits TESTING AND REPAIR MODELS 4JB R and 5JB R REV ARM These plants use the generator as a starting
52. OYLNOD S8 LOW UIL PRESSURE wr TOP YIEW MM IGNITION RELA 23078523 1 ELIG OHM FU WATT xo NERA LATE SPANK PLDGS A M XIAL FONM 1 CWATT RESISTOR Br 2554 217 TERMINAL BLOCH 552 706 MARKER STRIP M93232A7S5S SWITCH MARKER STRIP 3 3032 54 5 57060 START 5 STANT 2 i T TERM EBELJICK HE 1 332 5 37 MARKER STRIP a 332 56 NN CHOKE 5 RS 1 CE f 21 co te 1 t M t o nd i enp To NOTE 1 1 1 ENGINE 1 WHEN USED A C LO AD CONNECTIONS 4 STARTERA __ IPHASE 2WRE PHASE 2 WIRE 1 FUELI 120V0LT 240 04 RED SSO ENDID PUMP i 2 1 USED E DHMUEUWATT HEN USED 30 RESISTOR ASSY p NI 304A505 IY uim CDS TANK FT 1 SOLENOID t DES _ WHEN USED lg s 7 71 IPHASE S WIRE CAUTION 420 240 0 77 TZ MUSI BE t STATOR A stance tEXCTTER PO Taena GROUNDED ANY OTH
53. RQUE TEST Check the battery water level and charge condition about every 100 hours Every 500 hours inspect all starting system witing for loose or dirty connections especially connec tions to the battery terminals Inspect the generator com mutator and brushes for wear scoring or dirt For repair in structions refer to Generator Repaits Separate Starting Motor Every 500 hours check for loose or dirty connections Check the battery water level and charge condition every 100 hours Inspect the starter commutator and if it is dirty clean with 00 sandpaper Check the brushes for excessive wear and reduced seating on the armature TESTING Poor cranking performance can be caused by afaulty starting motor defective battery or high resistance in the starting circuit Battery Check battery condition with a hydrometer Specific Low Free Speed High Current Won t Operate High Current Won t Operate No Current CONDITION CHECK FOR Tight dirty worn bearings bent armature shaft or loose field power screws which would allow the armature to drag a shorted armature or a grounded armature or field Direct ground in switch terminal field or frozen shaft bearings gravity should be between 1 290 and 1 225 If not recharge the battery If the battery won t recharge replace it Wiring With the starting motor operating check the voltage drops 1 from the battery ground terminal post not the cable
54. START DISCONNECT RELAY N 30i AZR TERMINAL BLOCK 32 537 MARKEA STRIP Nf332A566 STOP RELAY 13076253 m Stor 153 SWITCH 42304 f 2245 mbeg ensse1d 10 31A TRIC TeRM BLOCK E HOME NS 332 AGI FUEL soLenorw IGNITION SUPPRESSORS DEED MARKER STRIP WHEN USED USED Coy LNG SAZA CIE SWITCH WITCH 309416 PANEL CONTROL BOX NPBaAcVosg CONTROL BOX 1130152008 COVER CONT AOL BOX 1 BRKT CONTROL BOX 5 84 220182218 BRKT CONTROL BOX MT CRM BERTHO WYTE RCO IGNITION 4 COVER RESISTOR 507 2012 RES 1 7 7 OMM 8 W T GENERATOR SCREEN N19 26 98 41144 4 A IGNITION CONDENSER i i e 4 i MPD CO CENTRIFUGAL Gt PRESSURE 6J8 3R SPEC 964 120 240 VOLT IPH 2 W cocY gro 1091909 5 5 RESISTOR 304 500 SJB 3R3 JIK amp GIB 3R tS REVERSE CURRENT RELAY NE3O7BIAO 730 0 5 RESISTOR MESOGAZSI ac no ae TART 2 SOLENOID etae a N2307 He3324537 STOP RELAY MARKER STRIP START 3324 556 DISCONNECT
55. SYSTEM Maintenance Periodic maintenance should include 1 Checking the ignition breaker point gap 2 Checking and cleaning spark plugs 3 Inspecting both the low and hi tension wiring 4 Checking the ignition timing To adjust the breaker gap rotate the crankshaft clockwise until the 55 ATC mark on the flywheel matches the timing pointer Fig 34 Check gap with a feeler gauge for 020 in Adjust the gap by loosening the adjustment screw and moving the stationary contact Tighten the screw and check the gap Fig 35 Check the points for cleanliness and pitting Clean the points with paper or gauze tape If they are defective or excessively pitted replace them NOTE Some early plants had no 550 ATC mark on the fly wheel On these models open the breaker box and rotate the flywheel until the breaker points reach maximum Timing 2 Cylinder The engine can be timed either stopped or running at rated speed With the engine stopped timing should be set for ignition at 5 ATC with the engine run ning at rated speed 25 BTC Adjust the breaker point gap before timing the ignition 1 TC S EX Top Center TIMING POINTER GEAR COVER 7 GOVERNOR FIGURE 34 TIMING MARK 29 Timing Procedure Plant Stopped 1 Remove the access door in the air housing Remove the breaker points cover disconnect the lead to the igni tion points and install a continuity test lamp and bat tery so the lamp lights w
56. VER i BREAKER ARM AT CONTACT FIGURE 42 MEASURING POINT TENSION causes contact bounce To adjust tension refer to Distributor Assembly Removal and Disassembly 1 Remove the distributor cap by releasirig the clips on the distributor Remove the primary lead from the distrib utor terminal 2 Record the distributor body position and the rotor posi tion for easier assembly 3 Remove the distributor hold down capscrew and pul the distributor out of the crankcase 4 Remove the 3 screws holding the breaker plate to the distributor housing and loosen the primary lead mounting terminal Lift the breaker arm off its hinge Rotate the breaker plate countercleckwise about 45 and pull it out of the distributor body Remove the two centrifugal advance springs 6 Remove the spring clip cam retaining spring holding the cam to the drive shaft and lift out the cam The weights are now free and can be lifted out 7 To remove the drive shaft grind or file off the peened over end of the pin holding the drive gear to the shaft Drive out the pin then remove the gear and pull the shaft out through the distributor body CAM RETAINING CENTRIFUGAL 4 ADVANGE SPRING N CAM AND STOP PLATE CENTRIFUGAL ADV ANGE WEIGHTS PRESS DOWN FEELER GAUGE BETWEEN GEAR AND THRUST WASHER FIGURE 44 CHECKING END PLAY 8 If necessary press the two bronze bearings out of the distributor body
57. Valve Seat Bore Diameter Intake Exhaust Depth From Cylinder Head Face Seat Insert Outside Diameter Exhaust Intake Seat Width Seat Angle Available Oversizes VALVE SPRINGS Load Valve Closed Load Valve Load Valve SPARK PLUGS Spark Plug Gap n CENTRIFUGAL SWITCH Breaker Point Adjustment MAGNETO Pole Shoe BREAKER POINT SETTING 237197942 a E Rome SORIA RR Suet es Distributor Dwell Angle If Using Dwellmeter TAPPETS Gasoline Intake Exhaust Gas and Gas Gasoline Intake Exhaust IGNITION TIMING SPARK ADVANCE Running Gas Fuel Stopped Gas Fuel Running Gasoline Fuel Flywheel Magneto Battery Stopped Gasoline Fuel Flywheel Magneto Battery 20 BTC for units with shielded distributor 10 BTC for units with shielded distributor e 9 9 m9 8 os ane o y 9 9 9 9 9 v 5 of o9 o 9 o9 9 9 o V o9 9 c9 4 9 nA 9 9 9 5 n 9 OR 9 9 o9 9 nao nane o P so 9 9 d 39 9 124 44 4 144 09 o9 3 vo oc 9 9 9 4 9 5 8 c
58. WINDING Revolving Field 5DR 120 240 Volts Delta Wound 4 wire 3 Phase 73 vL 625A429 CONTROL WIND NG EFE TURN CONTROL WINDING WHEN MOUNTED ON GEN THE POLARITY DOTS WILL BE ON TOP OF EACH REACTOR PICTORIAL GATE WINDING SCHEMATIC 120 60 CY SWITCH RESIDUAL RESET 14 WIRE 275 LG RECTIFIER FIELD NEG RECTIFIER CONTROL RECTIFIER FIELD POS REACTOR CONTROL RESISTOR VOLT CONTROL RESISTOR DAMPING L3 REACTOR GATE DESCRIPTION DIVISION OF STUDEBAKER INDUSTRIES INC Minneapolis Minnesota 2 2 5 5 EXCITER WIRING DIAGRAM 120 MODEL O4SXINIB VAC 60 DWG NO 625A429 WVYOVIC SNIWUIA JUa LIOXs gINIXSPO ANO 8f GL 625461 PICTORIAL 5 amy ee tee CONTROL WINDING 2 250 14 WIRE 27 LG 2 RECTIFIER FIELD NEG 7 4 PRECTIFIER CONTROL 1 RESISTOR STABILIZING 5 j 3 lRECTiFIER FIELD POS LM 3 RESISTOR VOLT CCNTROL COMPOUND WINDING 2 j RESISTOR CAMPING 1 TURN j 2 WREACTOR GATE 5 QTY PESE RE CONTROL i Qn DIVISION OF STUDEBAKER INDUSTRIES INC WINDING ATE pL J iemeapoia Minnesota WHEN MOUNTED ON WINDING GEN THE POLARITY DOTS NAME 5 EXCITER WIRING DIAGRAM WILL BE ON TOP OF 120 VAC 60 CY EACH REACTOR wwe 625063 Wvu5VIG
59. adapter and choke from the carburetor 4 Remove the main fuel adjustment needle begin Spec R and the float bowl nut and pull off the bowl Re move the float pin float 5 Lift out the float valve and unscrew its seat 6 Remove the no load adjusting needle the load adjusting needle Prior to Spec R and spring 7 Remove the throttle plate screws and the plate and pull out the throttle shaft 8 Remove the choke plate screws and plate and pull out the choke shaft Cleaning and Repair Soak all components thoroughly in a good carburetor cleaner following the cleaner manufacturer s instructions Clean all carbon from the carburetor bore especially in the area of the throttle valve Blow out the passages with compressed air If possible avoid using wire to clean the passages Check the adjusting needles and nozzle for damage If the float is loaded with fuel or damaged replace it The float should fit freely on its pin without binding Invert the car buretor body and measure the float level Fig 16 18 GAS MAIN ADJUSTMEN GAS DLE ADJUSTMENT GAS INLET 4 p E al i CLAMP GAS HOSE TO REGULATOR PRIOR TO SPEC R GAS MAIN GAS IDLE ADJUSTMENT ADJUSTMENT FIGURE 17 GASEOUS FUEL ADJUSTMENTS To adjust float level bend the small lip that the intake valve rides on Check the choke and throttle shafts for excessive side play and replace if necessary Don t remove
60. ans for prying the stator loose Be careful not to let the stator touch or drag on the rotor 7 Remove baffle ring from adapter Turn rotor through stud nut to the end of the through stud While pulling the rotor outward with one hand strike a sharp blow to the nut in the direction of the through stud Not Vertically with a heavy soft faced hammer to loosen the rotor from its tapered shaft fit If the rotor does not come loose strike it with a sharp downward blow in the center of the lamination stack with a lead or plastic hammer Rotate the rotor and repeat until it comes loose Be careful not to hit the collector rings bearing or windings 8 After disassembly all parts should be wiped clean and visually inspected GENERATOR ASSEMBLY 1 Clean and inspect all mating surfaces 2 Coat the mating area between the generator shaft and the engine crankshaft with a thin film of lubricating oil Moly Coat or equal 3 Install the rotor through stud in the engine crankshaft 4 Install the key in the crankshaft 5 Slide the rotor over the through stud and onto the crank shaft Be careful not to let the weight of the rotor rest on the through stud 6 Install the baffle ring 7 Install generator through studs in the adapter INSERT PRY BEHIND BLOWER WHEEL THROUGH AIR OUTLET OPENING 8 Install the stator and bearing support end bell Tighten the nuts on through studs NOTE Make certain the B1 lead is pla
61. are defective Remove the leads and check resistance of the coil between the hi tension terminals Check the terminals for corrosion Check the leads for resistance replace any that show a high resistance If resistance is low the coil is probably shorted and should be replaced 3 Check for shorting between the primary and secondary coils by checking for continuity between a primary terminal and secondary terminal IMPORTANT Test this coil using a six volt tester only MAGNETO IGNITION JB Manual Start This ignition system is similar to the JB battery ignition except that it uses magneto as a source of power The magneto is behind the flywheel and consists of both stator and secondary windings energized by permanent magnets on the flywheel For maintenance timing condenser repair and for breaker repair refer to the applicable section in battery ignition Magneto Coil The magneto coil is located behind the en gine flywheel and reached by removing the flywheel If igni tion spark at the spark plugs is defective first inspect the breaker points To test the coil remove both spark plug leads ground one to bare engine metal Hold the other about 3 8 away from bare metal and crank the engine a good spatk should occur between the lead and engine If not the coil flywheel magnets or high tension leads are defective Test the coil as follows 1 With an ohmmeter check resistance between the lead to the breaker points
62. ase BY PASS VAL VE The by pass valve located on the outside of the rear bearing plate controls oil pressure by allowing excess oil to flow directly back to the crankcase Normally the valve begins to open about 25 psi It is non adjustable and normally needs no maintenance To determine if abnormal high or low oil pres sure is caused by a sticking plunger clean and inspect the valve REAR BEARING PLATE OIL BY PASS SPRING OIL BY PASS FIGURE 30 OIL BY PASS VALVE 694 Rev FLUSH ROCKER BOX OIL LINE WITH FUEL CLEAN HOLES WITH FINE WIRE FIGURE 31 ROCKER BOX OIL LINE remove the valve first remove generator assembly see Generator Repair Section Unscrew the recessed plug in the tear bearing plate and lift out the spring and plunger as sembly Fig 30 Determine proper valve operation by checking the spring and plunger according to the following Plunger Diameter 3365 to 3380 Free Length 2 5 16 1 16 2 225 Ib 11 Ib at 1 3 16 OIL LINES The rocker box oil line Fig 31 should be flushed with approved solvent and the small holes cleaned with fine wire every 1000 hours Clean other oil lines and drillings with compressed air whenever the engine is disassembled or overhauled Remove the oil mounting plate to reach the oil gauge passage external oil lines the rocker box oil line and the in ternal oil line to the rear bearing are replaceable O
63. ase must be replaced or returned to the factory to have a new housing fitted AC GENERATOR MAINTENANCE STATOR OUTPUT 4 So RESIDUALMAGNETISM IN ROTOR STARTS PROCESS MAGNECITER AND VOLTAGE REGULATOR ROTATING FIELD BRUSHES FIGURE 76 EXCITATION SCHEMATIC This section covers the revolving field generator and static exciter Magneciter and the revolving armature generator GENERATOR REVOLVING FIELD 7 5 B JC and 50Cycle 6JB plants use 4 pole revolv BRUSH HOLDER GENERATOR ing field generator with static exciter Magneciter to excite the field and regulate the plant s AC output Fig 76 The generator is mounted to the engine crankcase through the engine to generator adapter The rotor connects directly through a tapered fit with key to the engine crankshaft A ball bearing housed in the generator endbell supports the outboard collector ring end of the rotor The endbell is supported by studs through the stator assembly to the adap ter The generator can t be removed from the engine as a complete unit Fig 77 The generator s AC output comes from the stator windings which also supply 120volts to the static exciter This 120 volts is from either a 120 volt winding or special 120 volt tap on high voltage winding 480volt An additional stator winding supplies power for the plant s battery charging system To aid servicing and repair all output leads
64. ble 002 005 010 and 025 Otherwise install new standard size seat inserts CROWD METAL OF HEAD AGAINST VAL VE SEATS BY PEENING AREA BE TWEEN MACH NE ROLL MARKS sate PEENED AREA VALVE SEAT p A74 FIGURE 58 PEENING HEAD MATERIAL MACHINE ROLL Drive the new valve seat inserts into place Each seat must rest solidly on the bottom of the counterbore at all points To ease installation heat the cylinder head in an oven at at 325 F for about 1 2 hour and cool the valve seats in dry 1ce After installation and before facing the new seats peen the head material against the valve seat in the 3 areas between the machine roll marks Fig 58 Face each new seat to 459 angle and width of approxi mately 3 64 The finished seat face should contact approximately center of the valve face Use Prussian Blue on each valve face to check this Make corrections to the seat not the valve face Check the valve springs on an accurate compression scale Replace any spring that is weak cracked or pitted or has SHIELD THIS END GOES INTO BLOCK RING SHIELD SPRING Co WASHER 1 RI NG ends out of square See Dimension end Clearance Section for valve spring data INSTALLATION 1 Push a new valve stem oil seal onto each intake valve guide and clamp in place Then oil the inside surface of each seal NOTE Plants built before June 1962 had no valve seals
65. ced through the grommet in the baffle ring and out the air discharge opening in the adapter 9 Now torque down the rotor through stud nut 55 60 ft 1 Because the stator and bearing support were tight ened before tightening the rotor the rotor and stator are automatically aligned 10 Tap the bearing support to the horizontal and vertical plane with a lead hammer to relieve stresses on the components recheck torque 11 Reconnect the leads to the preheater centrifugal switch and governor solenoid 12 Install lead B1 on the adjustable resistor Check this lead to see that it is short and is kept away from the blow er If necessary when installing a new stator or leads cut it shorter and reinstall the connector 13 Install the brushes and brush holders 14 Close the Magneciter secure with four capscrews and install the end cover REVOLVING ARMATURE GENERATOR The revolving armature used on 4 0JB 5 0 7 6 B and 60 cycle 6 0JB plants is a 4pole self excited generator with inherent regulation The generator serves as a starting motor and furnishes DC current to recharge the batteries during operation The generator field contains shunt windings and series windings a few turns of heavy wire wound on the same forms as the shunt windings The series windings act as the start ing motor field The shunt windings produce the magnetic field in which the armature turns to produce useful output The generator s armature
66. cessary on the generator it should be performed by a competent electrician who is familiar with operation of electric generating equipment TROUBLESHOOTING In the event of abnormal generator output voltage observe the following procedures No Voltage Buildup Remove the exciter cover and with the plant running operate the residual reset button on the Magneciter NOTE Early 04SX and 06SX models had no reset button On reset button On these models place jumpers momentarily from G1 to G2 of each reactor simultaneously with the plant running On the 02SX exciter the buildup relay automatically performs this function Plants beginning Spec P have a volt age tap at terminal 35 which allows automatic field flashing during plant cranking to assure voltage buildup If output voltage won t buildup after pushing the reset button flash the field Fig 81 Connect a voltmeter across the AC output the plant and momentarily touch the leads of a six volt lantern battery to the exciter to brush leads positive to F1 and negative to F2 While viewing the voltmeter 1 If voltage builds up to normal trouble was due to lost residual in the field 2 If voltage is low the Magneciter is probably defective See Magneciter Troubleshooting Chart 3 If there is no voltage output with battery connected to F1 and F2 trouble is in alternator Over Voltage or Fluctuating Voltage If the engine is oper ating at the co
67. d open the valve An audible hiss indicates that the regulator is opening 19 GASOLINE IDLE GAS MAIN ADJUSTMENT ADJUSTMENT GAS IDLE ADJUSTMENT f GAS HOSE To REGULATOR PRIOR TO SPEC GAS MAIN ADJUSTMENT GAS IDLE GAS HOSE TO REGULATOR GASOLINE CHOKE MAIN ADJUSTMENT LOCK WIRE FIGURE 19 GASEOUS FUEL CARBURETOR TABLE 1 MODIFICATION TO GASOLINE TO GASEOUS FUEL eee AA M ET S ivi Carburetor float and needle valve Replace if removed for gas Remove if for extended operation on gas reduces wear Spark plug gap Set at 025 Set at 025 podido edid pice 20 Di APHRAGM PUSH ROD AND VAL VE SEAT ASSEMBLY r SOLENOID PRIMER ALGAS GAS REGULATOR FIGURE 20 ALGAS GAS REGULATOR A water manometer Fig 21 is the standard tool for test ing regulator inlet pressure which must be within the limits specified for your regulator Use the chart in Fig 21 to convert the difference in water level between the 2 tubes to pressure in ounces Gas Regulator Garretson The maximum allowable inlet pressure is 8 oz minimum 2 oz If gas line pressure is greater than 8 oz install a primary regulator to reduce the pressure The regulator has an adjustment to control the maximum pressure at which the regulator shuts off when there is no demand To obtain maximum regulator sensi tivity adjust it to just shut off at your line pressure when th
68. disconnected from the points and a good ground on the engine Resistance should be about 0 6 ohms 2 Remove both spark plug leads from the plugs and meas ure resistance between the leads Resistance should be 31 IGNITION L HIGH TENSION LEADS 1 FLY WHEEL 100 eee MAGNETO COIL i AND a POLE SHOE LEAD TO IGNITION BREAKER gt POINTS SEE INSET FIGURE 39 MAGNETO IGNITION about 11 000 ohms If it is greater either the leads or circuits by measuring resistance from the breaker lead magneto high tension coils contain a high resistance or to a spark plug lead Any continuity indicates a defec are open circuited The magneto should be removed to tive coil test resistances of the coil and leads separately In spect the high tension terminals on the coil for cor rosion If the resistance is low the secondary winding is probably shorted and the coil must be replaced Flywheel Magnets Permanent magnets mounted on the fly wheel provide a magnetic field for the magneto coils Never remove these magnets from the flywheel it may destroy their 3 Check for shorting between the primary and secondary alignment and seriously weaken the magnets P IGNITION COIL DISTRIBUTOR LEAD TO CONTROL BOX FIGURE 40 JC IGNITION SYSTEM 32 A piece of steel held on the magnets must be strongly attracted to the magnets magnets shouldn t loose strength with age or b
69. ds Clean each connecting rod and check for defects Check the upper comnecting rod bushings for proper piston pin clearance Clearance should be 0002 to 0007 Press out excessively worn bushings and install new bush ings Press the new bushings in until they are centered in the connecting rod Fig 63 After installation drill the bushings with a 3 16 drill through the counterbored hole the connecting rod top Be sure the connecting rod oil spray hole is open 3 16 DRILL IS BE THROUGH BUSHING AFTER ASSEMBLY IN ROD BUT BEFORE BUSHING IS FINISHED REAMED BUSHING TO BE ASSEMBLED WITH SPLIT IN THIS ONE CROSS SECTION PRECISION TYPE BEARING MEASURE CLE ARANCE IN DIRECTION INDICATED BY ARROW FIGURE 63 CONNECTING ROD BUSHING TOP OF PISTON THIS NOT CH TOWARD FRONT OF ENGINE FIGURE 64 PROPER PISTON ALIGNMENT Connecting Rod Bearings Inspect the connecting rod bear ings for burrs breaks pitts and wear Measure the clearance between bearings and the crankshaft journal The clearance should be 001 to 003 If necessary replace with new standard or oversize precisian bearings Refet to dimensions and clearances for journal size 1 Install the connecting rods on each piston with pins and retaining pins Install so the connecting rod oil spray hole is the same side as the notch in each piston 2 Install all rings on each piston Tapered type rings a
70. e Control System Governor To remove the governor cup remove the snap ring from the camshaft center pin and slide the cup off Catch the ten flyballs that will fall out when the cup is removed Replace any flyballs that have flat spots or grooves Replace the cup if the race surface is grooved or rough The governor cup must be a free spinning fit on the camshaft center pin but should be replaced if excessively loose or wobbly PRESS BEARING FLUSH WITH FRONT CRANK CASE SURFACE ALIGN OIL HOLES FIGURE 69 CAMSHAFT BEARING ALIGNMENT 49 The distance the center extends from the camshaft gear must be 25 32 to give the proper travel distance fot the cup If less the engine may race if more the cup won t hold the balls properly If the distance is too great drive or press the center pin in If it is too small replace the pin it can t be removed without damaging the surface In some cases if the distance is too small the head of the governor cup be ground to give the necessary 7 32 travel distance To install the governor assembly tip the front of the plant upward Set the flyballs in their recesses and position the governor cup on its shaft Install the snap ringon the center pin Camshaft camshaft is one piece machined casting driven through gears by the crankshaft It rides on sleeve bearings pressed into the crankcase addition to opening and closing the valves the camsha
71. e affected by dropping the flywheel If the magnetism is lost return the flywheel to the factory for r charging Some flywheel magnet chargers in the field can recharge the magnets but makeshift equipment will probably reduce the magnetism further To recharge the magnet it must have the correct polarity The north seeking end of a compass needle must be attracted toward the leading magnet pole JC IGNITION SYSTEM The JC electtic plant uses a battery ignition system with automotive distributor to produce and distribute spark Fig 40 The system includes ignition coil distributor with spark advance and breaker points and spark plugs Maintenance Periodic maintenance of the system should include oiling the distributor cleaning and adjusting the breaker points checking ignition timing cleaning and ad justing the spark plugs and general inspection of the igni tion system wiring At regular intervals add 3 to 5 drops of medium engine oil to the oiler on the distributor Add 1 drop of light engine oil to the breaker arm hinge pin and 3 to 5 drops to the felt in the top of the breaker cam and to the governor weight pivots Wipe grease lightly on each lobe of the breaker arm Don t over lubricate the distributor To adjust the breaker points remove the distributor cap and rotor Rotate the crankshaft to get maximum breaker gap The gap should be between 018 in and 022 in At the same time inspect the points f
72. e breather cleaning rocker box oil lines and replacing the oil filter Use good quality heavy duty detergent oil that meets the API American Petroleum Institute service designations MS MS DG or MS DM Recommended SAE oil numbers for FIGURE 29 OIL SYSTEM 26 expected ambient temperatures are as follows 30 F and Above SAE 30 309F and Below SAE 5W 20 OIL PUMP The oil pump is mounted on the front of the crankcase behind the gear cover and is driven by the crankshaft gear Removal 1 Remove the gear cover and oil base Refer to Engine Repair Section Unscrew the intake cup from the pump 2 Remove the crankshaft lock ring and gear retaining washer 3 Loosen the two capscrews holding the pump and remove the pump Repair Except for the gaskets component parts of the pump are not individually available If the pump is defective or worn replace it Disassemble the pump by removing the two capscrews holding the pump cover to the body Inspect for excessive wear in gears and shafts To improve pump per formance adjust the gear end clearance by using the thinnest gasket that permits free movement of the pump shaft Oil all parts when reassembling the pump Installation Before installing fill the pump intake and out let with oil Mount the pump on the engine and adjust for 005 lash between the pump gear and the crankshaft gear Mount the intake cup on the pump so it is parallel with the bottom of the crankc
73. e cylinder builds up pressure Continue rotating until the TC mark of the flywheel aligns with the timing pointer 2 Install the rotor on the distributor shaft and the ting on the body 3 While holding the distributor in the position shown in Fig 45 the rotor 1 8 turn counterclockwise from the position shown push the distributor into its mount POSITION OF DISTRIBUTOR WHEN NO CYLINDER IS TOP CENTER COM PRESSION STROKE FIGURE 45 DISTRIBUTOR POSITION AT TOP CENTER 35 ing hole If necessary turn the rotor slightly to align teeth of gear If the rotor is not in the position shown repeat the procedure changing the gear alignment 4 Install the distributor clamp screw If the spark plug leads were removed from the distributor cap reinstall them in the propet order see Fig 40 Time the ignition system Ignition Coil The JC plant uses a standard automotive igni tion coil mounted on the air shroud near the engine access door Inspect and tighten the primary terminals Inspect the secondary terminal and clean it if necessary Test the coil either on a standard automotive tester or by checking primaty and secondary winding resistances Re sistance from the high tension terminal to the ground tetminal should be 7 000 to 10 000 ohms resistance between the primary terminals about 1 ohm A quick coil check can be made by simply disconnecting the high tension lead between coil and distribu
74. egulator rating Maximum inlet pressure is 5 psi and minimum 6 ounces NOTE The standard ONAN supplied solenoid shut off valve 307P312 locks off at gas inlet pressure of slightly over 1 pound optional valve is a vailable with pressure rating to 5 psi GAS HOSE ADJUSTING 8 PIPE PLUG FIGURE 21 TESTING INLET REGULATOR PRESSURE 21 TO STARTER SIDE OF START SOLENOID TO GROUND 4 SOLENOID PRIMER CL REGULATOR FIGURE 23 SOLENOID PRIMER If the regulator doesn t deliver fuel check the inlet pressure If pressute is over 5 psi 1 psi with optional solenoid valve a primary regulator is required to reduce the inlet pressure If the inlet pressure is within the required limits and the regulator won t deliver fuel or leaks disassemble it for repait To disassemble the regulator carefully remove the cover and separate the diaphragm from the cover and body kit is available from ONAN to repair the regulator Solenoid Primer Algas regulator only Algas regulators use an optional solenoid primer to provide quick engine starting The primer Fig 23 holds the regulator open during plant cranking It can be adjusted for a rich or lean mixture by loosening the lock nut and turning the primer in or out Clock wise tichens the mixture To adjust for proper priming of a cold engine set the primer So a hot engine one with gas in the regulator carburetor hose and the carburetor sounds slightly roug
75. enerator stud nuts on the endbell Slide the endbell brush rig and frame off as one assem bly Be careful not to drag the frame on the armature Remove the screws holding the blower baffle to the engine to generator adapter and remove the baffle Slide the armature and blower assembly off the stud To loosen the assembly from the crankshaft tap the thread ed end of the stud several times with a soft hammerto avoid damaging the threads NOTE If the above procedure doesn t loosen the arma ture assembly tap downwards on the outboard end of the armature shaft rotate it 1 2 turn and repeat Don t hit the commutator collector rings or bearing If necessary to remove field coils remove the pole shoes by removing the capscrews holding each to the frame GENERATOR ASSEMBLY 1 2 3 Reinstall any pole shoes and field coils removed Install the armature and blower assembly and install the stud nut Check for armature runout Fig 91 Runout should be less than 002 Excessive runout may be caused by dirt or a nick on the taper of either the rotor or crankshaft not correct by tapping the high side of the shaft near the ball bearing Don t hit the ball bearing commutator or collector rings FIGURE 91 ARMATURE RUNOUT Install the blower and secure with screws Install the bearing stop on the ball bearing Install the field frame and endbell assembly and secure Be sure generator output wires feed throu
76. er 15 20 Intake Manifold 13 15 Oil Base Mounting Screws 45 50 Oil Filter Hand Tight Plus 1 4 to 1 2 Turn Oil Pump Mounting Screws 15 20 Rear Bearing 40 45 Rocker Arm 4 10 Rocker Arm 35 40 Through Stud Nut Revolving Armature 30 40 Revolving 55 60 This torque is from friction between the threads only and locks the nuts in place The rocker arm nuts are for adjusting valve lash Caution Tighten nuts evenly to avoid manifold damage SPECIAL TOOLS AND EQUIPMENT These tools are available from Onan to aid service and repair work Connecting Rod Aligning Set 420P173 Crankshaft Gear Pulling Ring 420A275 Driver Front Camshaft Bearing 420A252 Driver Rear Camshaft Bearing 420B251 Driver Center Camshaft Bearing 4 420B254 Driver Main Bearing Front and Rear 4 cyl 420B269 Driver Valve Seat 420B270 Rear Seal Guide and Driver 420B250 Front Oil Seal Guide and Driver 420B281 Replacement Blades for 4208272 420B274 Ridge Reamer 420P260 Compressor 420 214 Valve Spring Compressor Tool 420A210 Valve Seat Remover 420A272 Replacement Blade
77. er housing The larger bearing sur face acts as a spacer bushing and must be on the inside of the housing 11 FUEL SYSTEM CARBURETOR Air cleaner removed BREATHER TUBE THERMO MAGNE TIC FUEL LINE CHOKE FUEL PUMP FUEL PUMP PRIMING LEVER 27 FUEL FILTER FIGURE 4 GASOLINE FUEL SYSTEM Standard JB and JC engines use a gasoline carbureted fuel system to deliver a mixture of fuel and air to the combus tion chamber The system draws fuel a tank delivers it through a filter and fuel pump to the carburetor float ALGAS REGULATOR CARBURETOR GAS REGULATOR TO CONTROL TERM SED GROUND TO CONTROL TERM 4 PARALLEL WITH IGNITION COIL SUPPORT GAS SOLENOID VALVE py TO STARTER SIDE OF START SOLENOID chamber Air passing through the carburetor venturi section draws fuel from the float chamber Options combination gasoline gaseous fuel carburetor or straight gaseous fuel carburetors are available far use with gaseous fuels gaseous fuel system uses a fuel regulator Fig 5 to control the flow of gas from the lines to the carburetor At the carburetor the gaseous fuel is mixed with the incoming air fuel system components are described in the following paragraphs Select the components that apply to your plant FUELS Use regular grade gasoline Premium fuels contain more Tetra Ethyl lead than regular the lead quantity also varies between fuel brands In
78. er must contact the shutter roll pin at room temperature To adjust loosen the power element mounting screws and slide the assembly until it touches the roll pin with the shutter closed Fig 3 REPAIR If the shutter won t open check the power ele ment for defects binding of the plunger and the shutter for binding against the housing SLOWER HOUSING FIGURE 2 SHUTTER ASSEMBLY LATE MODELS ADJUST THE VERNATHERM UPPER SHUTTER POWER ELEMENT TO REST ON THE ROLL PIN WITH SHUTTER CLOSED AT AMBIENT TEMPERATURE SHUTTERS VERNATHERM BRACKET TON H 4 ADJUSTING AND MOUNTING SCREWS IN SLOTTED HOLES VERNATHERN POWER ELEMENT LOWER SHUTTER ACTUATING ROD VERNATHERM BRACKET ADJUSTING AND MOUNTING SCREWS IN SLOTTED HOLES SHUTTER ACTUATING ADJUST THE VERNATHERM POWER ELEMENT TO REST ON THE ROLL PIN WITH SHUTTER CLOSED AT AMBIENT TEMPERATURE 4 EARLY MODELS FIGURE 3 SHUTTER MECHANISM 10 To test the power element remove it from the assembly and apply heat When the element reaches about 120 F the plunger should start to move out Total movement should be at least 13 64 in If the shutter won t close check for a weak return spring binding in the nylon bearings or dirt in the power element plunger If the nylon bearings are worn or bind replace them Remove the shutters and pull out the stub shafts Push out the old bearings and push in new bearings from the inside of the shutt
79. ere is no demand Adjust the regulator for shut off when there is no demand to prevent gas leaks The factory ad justed shut off between 2 and 4 oz If gas line pressure is between 4 and 8 oz readjust the screw Fig 22 To adjust the regulator the gas line should be connected and the outlet hose removed Make a coarse adjustment by turn ing the adjusting screw inward until the hissing of escaping INCHES OF O 0 INDICATES EQUIVALENT OF WATER LEVEL DIF FERENCE IN OUNCES SUPPLYLINE HOSE TO CARBURETOR GARRETSON GAS REGULATOR FIGURE 22 GARRETSON GAS REGULATOR gas at the outlet stops Install a water manometer on the in let side of the regulator to make the fine adjustment With the gas on cover the regulator outlet for a few seconds and then open If the regulator is leaking the pressure shown on the manometer will drop slightly waver indicating that the valve is opening Turn the screw inward slightly and repeat the test Continue until the manometer holds steady as the outlet is closed for a few seconds and then opened If this regulator appears defective either won t open won t close or delivers insufficient fuel check the shut off pres sure adjustment kit is available from ONAN to replace both the diaphragm and valve Gas Regulator Algas The Algas regulator has no adjust ments and features a positive lock off if pressure increases above the r
80. fference between the highest and lowest cylinder taken at the same cranking rpm Exces sively high readings indicate catboned combustion chambers Compression readings will change because of differences in cranking speed altitude and ambient temperature conditions There the limits are given only as a guide The best indica tion of leakage is the pressure difference between cylinders or a compression increase when oil is added to the cylinder Disassembly NOTE Valves tappets rocker atms and pushrods should be kept in order and returned in same otder 1 Remove the rocker box cover spark plugs and connect ing oil lines to the cylinder heads Remove tlie intake and exhaust manifold 2 Remove the capscrews holding each cylinder head to the cylinder block 3 Remove each head If it sticks rap it sharply with a soft hammer Don t use a pry 4 Remove the rocker arms end pushrods 5 Using a valve spring compressor disassemble the valve assemblies 44 DRILL PRESS Be sure y 4 3 oil pilot of tool After cutting FIGURE 57 REMOVING VALVE SEAT Repair Thoroughly clean all components of the cylinder assemblies Remove all the carbon deposits from the com bustion chambers and clean all gasket surfaces Remove all carbon and check each valve for burning pitting ot warped stem Valves that are slightly pitted or burned refinish on an accurate valve grinder to a 45 angle But if t
81. flywheel slowly until the test lamp goes out indicating that the breaker points have opened If the TC mark on the flywheel and the ignition timing pointer ate aligned timing is correct otherwise adjust the distributor 4 To adjust timing align the flywheel TC mark and the timing pointer Loosen the distributor body and rotate it clockwise if ignition occured early and counter clockwise if late until the light goes out Tighten the distributor body in the new position and check the timing step 3 If timing still doesn t occur at the cor rect point repeat step 4 Timing Engine Running 1 Remove the access door and install an automotive timing light on the spark plug for cylinder 1 Run the plant at rated speed Aim the flashing timing light in through the access door opening and toward the fly wheel Don t run the engine for more than a min 4 ute or two with the access door removed The engine overheats rapidly and could damage itself Run without load 2 The timing pointer on the gear cover must indicate 25 To adjust timing loosen the distributor body clamp and rotate the distributor body If timing is early 259 mark to the right of the pointer rotate the distrib utor clockwise to retard the ignition point Tighten the distributor in its mount and recheck timin g NOTE If the relative position of the timing marks doesn t remain steady the distributor may be defective This ca
82. ft operates the fuel pump and on JC plants the distributor Remove the camshaft as follows 1 Remove the rocker arms and pushrods from the valve chambers 2 Remove fuel pump from the engine Remove the distrib utor JC only 3 Remove the crankshaft gear retaining washer by remov ing the lock ring on the crankshaft 4 Lay the engine on side to avoid dropping tappets and remove the camshaft assembly as a group If neces sary pry it out with a screwdriver between the cam shaft gear and crankcase Be sure the camshaft lobes don t catch on pushrod tappets during removals 5 Remove the tappets from the camshaft end of the push rod holes CAMSHAFT PRESSED IN WASHER i PULLED OUT FIGURE 70 CAMSHAFT END PLAY 50 Hf a lobe is slightly scored dress it smooth with a fine stone If the camshaft is badly worn or scored replace it The camshaft gear pressed fit on the camshaft and drives it at 1 2 the crankshaft speed The gear drives the ignition timing start disconnect switch on 4 cylinder gear on 2 cylinder models To remove use a hollow tool or pipe that will fit inside the gear bore and over the center pin Press the camshaft out of the gear careful not to damage the center pin The camshaft bearings should be replaced if the clearance to the camshaft is greater than specified or if the bearings show cracks breaks burrs excessive wear ot other defects T
83. ful not to lose any shims that might be behind the flange FiELD COIL POLE SHOE COMMUTATOR n aom ae ARMATURE SOLENOID PLUNGER STARTING MOTOR 3 Remove the link pin holding the shift lever to the sole noid plunger and remove the shift lever pivot pin 4 Remove the thru bolts from the commutator end of the motor Pull off the end cover and lift the brushes off their seats Pull the cast housing from the front end of the motor and lift the armature and clutch out of the motor frame 5 To remove the over running clutch from the armature drive the retainer away from lockring near the front end of the shaft remove the lockring and pull the assembly off Don t attempt to disassemble the clutch assembly 6 If necessary to service the solenoid remove the four capscrews and electrical connection holding it to the motor frame Remove the two screws on the rear of the solenoid to reach the switch contacts STARTING MOTOR REPAIR Armature Inspect armature for mechanical defects before testing for grounds or shorted coils Test for grounds with a 120volt test lamp Check between each commutator segment and the shaft If commutator is grounded lamp will light and will require replacement See Figure 50 Don t touch probes to commutator brush surfaces it will burn them Use a growler to test for shorted coils Place armature in growler and run a steel strip over the armature surface If coil is shorting the steel s
84. gear assembly sticks replace the complete assembly Inspect the weight springs and compare them with Fig 36 If the cam is loose on the gear shaft replace the complete assembly Clean and inspect the bearing surfaces in the breaker plate and gear case clean the oil trickle holes into these bearings Check the oil spray hole in the gear case to be sure it is open If the breaker points won t maintain the proper gap check for excess wear in both the cam and the ignition breaker plunger Assembly 1 Install springs on the weight assemblies Install the cam on the gear shaft being sure to align the timing marks Fig 37 and install the cam spring Weights should snap outward between 1000 and 1075 rpm If necessary adjust by lightly bending one or both spring anchor pins toward center of gear 2 Install the spacer and thrust washer on the gear shaft assembly and install the assembly into the gearcase matching the timing marks on the timing gear and cam shaft gear Fig 37 o MARK TIMING GEAR THESE MARKS ALIGNED 8 ON IGNITION TIMING GEAR SHAFT THESE MARKS MUST BE ALIGN ED 0 MARK ON TIMING WEIGHT FIGURE 37 TIMING GEAR MARKS 3 Install the spring and plunger on the end of the shaft 4 Install the breaker plate Install the ignition plunger and diaphragm and diagram cup Fig 38 5 Install the start disconnect when used diaphragm and plunger and install the s
85. gear or camshaft gear is incorrectly instal TO ADSUST RETARD IGNITION TIMING SLOT FOR ADJUSTING WITH SCREWDRIVER SET IGNITION BREAK ER POINT GAP 0 020 KEEP THIS OIL HOLE d lt d 224 CLEAR f b 7 SET DISCONNECT BACK SIDE IGNITION BREAKER PLATE SWITCH GAP AT 0 020 FIGURE 35 ADJUSTING IGNITION TIMING 30 A TENSION IN POUNDS DIMENSION A FIGURE 36 SPRING TENSION led or the centrifugal advance mechanism is defective Dis assemble the breaker mechanism for repair Breaker Points The breaker points operate from a cam lo cated on the timing or start disconnect gear This gear is driven by the camshaft gear Disassembly 1 Disconnect the battery to prevent accidental shorts 2 Remove the point set cover and disconnect the wires from the start disconnect switch if used and the igni tion breaker points 3 Remove the two capscrews holding the breaker plate assembly and pull off the plate 4 Pull out the cam and weight assembly Be careful not to lose the spacer mounted the gear shaft 5 To disassemble the breaker plate assembly remove the condenser and points and out the plunger and plunger diaphragm Repair Thoroughly clean the gear and cam assembly The weights should move freely in and out without catching in either end position Inspect the gear ramp for notches or other defects If any part of the cam weight and
86. gh the slot in the front of the frame Tighten the thru armature stud nut to 30 40 Ib ft Connect leads to the engine Install the battery cables Align the brush rig 63 CONTROL SYSTEM The plant control system controls starting stopping battery recharging and provides a means of emergency automatic stopping The control system and control system defects should be analyzed with the aid of the proper wiring diagram The views shown ONAN witing diagrams are modified pic torials Components are shown in their actual positions and normally the top view of each component is shown for ter minal location Dotted lines show the edges of the control box and indicate the direction from which it is being viewed i e View relays are shown in the de energized position Plant control systems are divided into two main types re volving armature plants and revolving field plants Each of these types is divided into three different control systems Manual start M Electric start E and Remote start R MAINTENANCE Periodically check all connections and contacts in the con START SWITCH START SOLEN 0 START DISCONNECT MM MAT CIRCUIT Ap GENERATOR VOLTAGE BUILDS UP CLOSES START 0 5 START SOLENOID DROPS OUT ENG NE RUNNING STARTING CYCLE ENDED A750 CONNECT RELAY CURRENT THROUGH CHARGE RESISTOR JO AMP RESISTOR PULLS IN STOP RELAY GENERAT
87. h and produces slightly dark exhaust after the engine first starts firing For a course adjustment 1 Remove the regulator carburetor hose at the regulator and apply battery voltage across the primer 2 Turn the primer clockwise richer until you can hear a small flow of gas at the outlet 3 Remove the voltage connect the hose and attempt to start the engine If the plant starts within three seconds the primer is cor rectly adjusted If not remove the hose at the regulator and crank the engine for a few seconds to empty the hose and carburetor of gas and readjust the primer slightly Connect the hose and attempt to start Continue until the engine starts within three seconds from an empty hose and carbu retor When the primer is properly adjusted be sure the regu lator locks off whenthe unit is stopped To test the primer remove it from the regulator noting the number of turns necessary to unscrew it and operate the start switch The plunger must extend out The wiring 22 SHAKE OUT DIRT EVERY 50 HOURS OF OPERATION REPLACE AT LEAST EVERY 500 HOURS FIGURE 24 PAPER AIR CLEANER primer solenoid may be defective or the plunger is stuck in the primer body AIR CLEANER Three types of air cleaners are used The dry paper type folded paper moistened foam type synthetic sponge and the oil bath type Dry Paper Type early JB plants only Remove and clean either by shaking or blowing out with c
88. have slack CARBURETOR AIR PRE HEATER Optional Fig 27 Heated air supplied to the air cleaner during cold weather prevents carburetor icing The air source is automatically selected by the Vernatherm thermo static element which opetates a shutter in the induction air stream The shutter is fully closed at 80 F just touches bottom is half open at 90 F and is fully open to ambient air at 100 F Flange of hose adapter where used is positioned inside of plenum and one sheet metal screw first mounts shield where used next to vertical exhaust Check shutter for binding Tee nut aligns plunger for binding Mounting depth of Verna therm adjusts plunger to just touch shutter at 70 F Grease points of contact NOTE Gaseous fuels natural gas do not require preheated air 23 GOVERNOR SYSTEM The governor system controls engine speed with and without load The system consists of a govertior cup with steel fly balls on the camshaft a yoke shaft and arm governor spring and adjusting screw and linkage to the carburetor GOVERNOR ARM GOVERNOR CAM GEAR OC CUP GOVERNOR FLYBALLS GOVERNOR SPEED ADJUSTING NUT SENSITIVITY A DJUSTING RATCHET GOV ERNOR ARM GOVERNOR SPRING SENSITIVITY ADSUSTING RATCHET DECREASE SENSITIVITY INCREASE SENSITIVITY Vatiations in engine speed changes the positionof the gover nor cup on its shaft This change is transmitted by the shaft arm and linkage
89. he camshaft to bearing clearance should be 0012 to 0037 To check the rear bearing remove the expansion plug at the rear of the crankcase Press new bearings into place Fig 69 using bearing driving tool Press the reat bearing flush with the bottom of expansion plug recess Press the front bearing in flush with the crankcase front surface so the crankcase and bearing oil passages align After the rear bearing is installed in sert new expansion plug in the recess using sealing com pound and expand it into place with sharp blows at its center The bearings are precision type and do not require reaming Install the camshaft assembly as follows l Install the key and press the camshaft gear on its shaft Mount the governor components 2 Slide the thrust washer onto the shaft 3 Lay the engine on side or end and insert the pushrod tappets 4 Install the camshaft assembly in the engine Align the timing marks on the camshaft gear and crankshaft gear Fig 71 5 Replace the pushrods and fuel pump Install and retime the distributor JC only Crankshaft The engines use a counterbalanced ductile iron Oixeo PULLER THESE MARKS MUST COINCIDE WHEN INSTALLING TIMING GEARS FIGURE 71 TIMING GEAR MARKS CRANKSHAFT FIGURE 72 REMOVING CRANKSHAFT GEAR crankshaft The two cylinder crankshafts ride on a two lead bronze bearings the front one housed in the crankcase and the rear one in the bearing plate
90. hen the points are closed 2 Rotate the flywheel clockwise until the TC mark on the flywheel approaches the timing indicator Fig 34 Then slowly rotate the flywheel clockwise until the light goes out indicating that the points have opened This is the ignition point If timing is correct igni nition will occur at 59 3 If ignition timing isn t correct align the 5 ATC mark and the timing pointer then loosen the breaker plate capscrews and rotate the plate so the light goes out Rotating clockwise advances timing countetclockwise retards it Fig 35 4 Tighten the plate and check timing step 2 If timing ism t correct readjust the plate Otherwise connect the ignition lead and install the cover Timing Procedure Plant Running l Remove the access door and install an automotive timing light on either of the spark plug leads 2 Run the engine at rated speed and check timing with the light If timing is incorrect loosen the breaker plate mounting screws and correct it by rotating the plate Rotating clockwise advances timing counter clockwise retards it Tighten the plate and recheck the timing point See Figure 35 CAUTION With the access door open the engine will over heat rapidly Run it only a few minutes and only without load 3 Adjust the timing tighten the breaker plate and then re check the ignition point gap If the breaker points can t be adjusted to specifications either the timing
91. hey are badly pitted or will have a thin edge when tefaced teplace them Check refinished valves for a tight seat to the valve seat with an air pressure type testing tool or by applying Prus sian Blue on the valve face and rotating it against the seat Check valve guide to valve clearance If the proper clear ances can t be obtained by replacing the valves replace the valve guides Drive the old valve guides into the valve cham bers Drive new guides in until they protrude 11 32 the rocker box side of the head Ream the new valve guide to obtain the proper clearance see Dimensions and Clear ances Section If the valve seats are pitted refinish them Using conven tional seat grinding equipment reface each seat to a 45 angle and a seat width of 3 64 to 1 16 You should be able to reface each seat several times before it becomes necessaty to replace it If however the valve seats are loose or cannot be refaced replace them Use Onan 420A272 in a drill press Fig 57 to remove each valve seat Adjust the tool to cut 1 64 from the edge of the seat Oil the pilot to prevent seizing in the valve guide Cut each seat down to a narrow rind on edges and bottom and break it out with a sharp tool Be careful not to cut into the counter bore bottom Thoroughly clean the valve seat counterbore and remove any burrs from the edges If the counterbore is damaged machine for an oversize seat Oversize seats are availa
92. his opens the ignition circuits and stops the plant To re start plant wait one minute and push reset button Fig 98 To check relay energize the heater circuit in series with the 1 resistor from the 12 volt battery Reset button should pop out 15 20 seconds WIRING DIAGRAMS The wiring diagrams in this section are typical and apply only to standard electric generating plants Wiring diagrams for special models are available upon request from the factory Send complete generator model number and specification letter with the request The first table is for locating wiring connection diagrams for your particular unit the second table is for locating internal exciter diagrams the third table is for locating internal control diagrams WIRING CONNECTIONS SPECS REVOLVING REVOLVING VOLTAGE INCLUDED ARMATURE FIELD 120 240 120 240 120 240 120 240 120 208 220 380 277 480 240 416 240 120 240 120 240 120 208 277 480 240 416 120 240 7 5 B 60 Cycle 6 0 B 50 Cycle 7 5 60 Cycle 6 0 B 50 Cycle 6 0 B 6 0JB 7 5 B 60 Cycle 6 0 50 Cycle 7 5 60 Cycle 6 0 B 50 Cycle 6 01 6 0 B MAGNECITER CONNECTIONS JB JC JC Penn State Only 611C664 611C668 611C661 611C656 611C805 611C804 611C797 611C790 612C2243 612C2239 612C2658 612C2657 EXCITER NO 045 045 O6SXINIB O6SXIN3B O6SXIN3B 74 75 76 76 76
93. hours See Figure 32 JB BEGIN SPEC 5 BREATHER HOSE NI BREATHER HOSE INSULATOR CAP AND HOSE CLAMP RING INSULATOR CRANKCASE BREATHER BEGIN 5 5 Remove hose clamp breather hose breather cap clamp and insulator halves to release breather cap and valve assembly Wash valve assembly and the baffle suitable solvent and reinstall BEGIN SPEC Beginning with Spec S the JB uses the new style breather shown in Figure 32 The JC prior to Spec T retains the older breather system without the valve Beginning with Spec T the JC uses a PCV Positive Crankcase Ventilation valve mounted under the rocker boxes See Figure 32 Every 500 hours remove the PCV valve wash in diesel fuel or kerosene and inspect for carbon residue If the valve appears to be unusually gummy it may have to be disassembled for cleaning Replacement with a new valve is preferable under these conditions JB PRIOR TO SPEC BREATHER TUBE FLAPPER 555 VALVE m TUBE FROM ASSEMBLY AIR E CLE ANER BREATHER aN TUBE BAFFLE t CRANKCASE BREATHER Remove breather cap Remove valve from cap Wash valve in fuel Dry and install with perforated disc toward engine faulty install new valve JC PRIOR TO SPEC M TUBE FROM CLEANER q BREATHER TUBE SAFFLE FIGURE 32 CRANKCASE BREATHER SYSTEMS 28 Three different types of ignition systems cover the manual
94. hrod shields to the block and install the cap screws but don t tighten b Install the intake manifold to the heads and tighten the nuts to 13 15 Ibs ft c Tighten the cylinder head capscrews following the sequence in Fig 60 8 Install the exhaust manifold oil lines spark plugs and carburetor Install the valve stem caps Install the push rods rocker arms and rocker arm nuts 9 Set the valve clearance according to Table 3 NOTE After the first 50 hours of operation retighten the cylinder head bolts and recheck valve clearance 10 Reinstall the rocker box cover air housing and access door PISTONS CONNECTING RODS CYLINDERS Each cam ground aluminum piston is tapered and fitted with two compression rings and an oil control ring Full floating piston pins held in place with snap rings connect the piston to its connecting rod The lower end of each connect ing rod contains half steel precision bearings and the upper end semi finished bushings 2 HEAVIEST COMPRESSION 4 RING IN TOP GROOVE 55522 lt lt 4 RS RAIL EXPANDER RAILS ARE NOT USED ON TWO CYLINDER ENGINES FIGURE 61 PISTON RINGS 46 NOTE Plants marked with an E following the plant serial number are fittedwith 005 in oversize pistons at the factory Use standard rings for these pistons Removal and Disassembly Connecting rods and caps are stamped with numbers for installation in the proper cylinder When remo
95. htly within the range shown in Table 6 adjust the governor This will also change the plant output frequency Be sure the frequency stays within the maximum and minimum limits shown in Table 6 for Revolving Armature generators Adjust the governor sensitivity to change the voltage drop from no load to full load within the range shown in Table 6 TESTING AND REPAIR Most of the following tests can be performed without dis assembling the generator Armature Testing Before testing remove all brushes from their holders Fig 85 1 Using a test lamp or ohmmeter check the AC winding for an open circuit between the slip rings If an open circuit is found replace the armature 2 Test both the slip rings and commutator for grounding to the shaft Minimum Preferred Voltage At Full Load Maximum Voltage At No Load Nominal 120 240 120 208 216 200 Drop No Load To Full Load 122 114 64 5 57 Cycles 61 59 246 236 64 Cycles 57 Cycles 61 59 246 236 57 Cycles 61 59 INSTALL BRUSHES WITH BEVELLED TOP SLANTING DOWN TOWARD SPRING HOLD ER TO REMOVE BRUSH SPRING PRESS SPRING HOL DER DOWN AND OUT AS SHOWN IN BROKEN LINES FIGURE 85 BRUSH REMOVAL If the commutator is grooved out of round or otherwise damaged refinish it Turn it in a lathe and then undercut the mica as described above Shield the ball bearing during refinishing Collector Rings If the collector rings are grooved out of round
96. ified CONTROL REACTOR IS DEFECTIVE if no continuity is indicated between the common lead C and the numbered lead indicating the presence of an open circuit STEP 4 CHECKING RESISTORS The resistors must be checked with a multimeter adjusted to appropriate range of resistances See wiring diagram for correct values Results 1 RESISTOR IS SERVICEABLE if the measured resistance falls within 20 percent of the value specified in the wiring diagram 2 RESISTOR IS DEFECTIVE if there is indication of continuity through the resistor If the measured resistance exceeds the percent limits either way the stabilizing resistor can be adjusted to bring the resistance within the required limits MAGNE TER RECTIFIER ASSEMBLY HEAT SINK RECTIFIERS FIGURE 83 CHECKING RECTIFIERS WITH OHMMETER 58 GENERATOR DISASSEMBLY 1 Disconnect the battery to prevent accidental starting of the plant 2 Remove the exciter cover and open the exciter This will reveal the rotor thru stud nut 3 Remove the four machine screws on the end bell near the bearing and lift out the brush holders Fig 79 4 Remove the lead from the tapped adjustable resistor in the generator air outlet opening 5 Remove the leads from the control box to the ignition system choke start disconnect switch etc on the engine 6 Remove generator through stud nuts remove the end bell and stator assembly Screwdriver slots in the adapter provide a me
97. ion makes this replacement necessary If the bearing becomes noisy worn or otherwise defective replace it Remove the old ballbearing with a gear puller and press a new one into place See Fig 80 COLLECTOR RINGS The collector rings must beclean and free of burrs scratches and marks If necessary use No 00 sandpaper to clean the surface Never use emery cloth or other conducting abrasives ROTOR SHAFT FIGURE 80 INSTALLING BALL BEARING Collector rings may have a dark brown or black appearance This is a thin lubricating film and aids the life of the brush es and slip rings Do not remove film If the collector rings are grooved out of round pitted or rough so that good brush seating can t be maintained remove the rotor and refinish the rings in a lathe Remove or shield the ballbearing during refinishing The collector rings should have a Total Indicated Reading T LR of 002 EXCITER The exciter contains no moving parts except for the 02SX Periodically blow out any dust and make certain that all components and connections are secure A buildup relay was used on the 025 models Early models had open relays and later model relays were enclosed in metal shields The relay contacts should be cleaned regular ly Carefully wipe the relay contacts with paper to remove any non conducting film or dirt TOUCH MOMENTARILY TO RESTORE RESIDUAL 6 VOLT DRY CELL BATTERY TESTING AND REPAIR If repair work is ne
98. ions OVERHEATING Overheating in an air cooled engine is difficult to discover The first sign is usually a vapor lock in the fuel system and the second scored pistons The usual causes of overheating dirty cooling surfaces operating without the engine air housing and incorrect instal lation The air housing including the door must be on when operating the engine Over ACCESS heating and permanent damage could result from as little as one minute of full load operation without it The most common installation problems leading to over heating are 1 Installation with duct size too small so air flow is insufficient 2 Installation in small room with no ducts and insufficient air ventilation in the room 3 Installation of air inlet and outlet ducts so air outlet feeds back to the inlet AIR SHUTTER Optional The shutter assembly mounts on the engine air outlet on the right side of the cylinder shroud Fig 2 thermostatic element Fig 3 controls the shutter closing which limits air flow when the engine is cold When the air temperature reaches 120 F the element plunger begins to move outward opening the shutters The shutters are completely open by 140 F BLOWER BLOWER WHEEL FIGURE COOLING AIR FLOW NOTE On early models a high temperature cut off switch mounts on the air shutter assembly AIR SHUTTER The shutter opening temperature isn t adjustable The power element plung
99. ires a spring scale and torque arm voltmeter ammeter and variable resistance to apply the voltage specified by the test characteristics The voltage drop across the solenoid on the starting motor should be less than 1 50 volts If not remove it for repair BATTERY Plants with a separate cranking motor normally use a single 12volt battery of at least 72amp hour capacity Exciter cranked plants use 2 six volt batteries in series Each bat tery must be at least 105amp hour capacity Do not use undersize batteries on revolving armature plants as serious armature damage may occur The plant battery charging system maintains the batteries at or near full charge at all times Inspect the battery charging system and adjust the charge rate if batteries appear t be continually discharged NOTE Adding accessories that draw battery current requires an adjustment of the charge rate If discharging or failure to charge can t be traced to the bat tery charging system thoroughly inspect and test the bat tery and replace it if necessaty REMOVAL AND DISASSEMBLY STAR TING MOTOR 1 Remove electrical connections to control box and bat tery at the shifting solenoid Remove engine front air housing and remove the flywheel 2 Remove the nut holding the starterrear mounting bracket to the engine Remove the three capscrews holding the starting motor mounting flange to the crankcase Then pull the starting motor off the engine Be care
100. ke should be warm to the touch within a minute or two of plant starting To disassemble choke refer to Fig 11 Electric Choke If the choke will not heat properly check for a broken heating coil or high resistance electrical con INSERT INNER END OF SPRING IN SLOT IN OF SPRING IN SPRING SLOT IN COVER TAB WASHER 17 64 V D x 5 8 x 1 16 d 7 CHOKE SPRING BODY CHOKE PLATE CHOKE WASHER INSULATOR RING RETAINING 4 ARMATURE E ASSY SOLENOID BIMETAL AND SOLENOID 3 HEATER ASSY FRAME SOLENOID 1 294 GROUND THERMO MAGNETIC CHOKE m LEAD GROUND WASHER SHAKEPROOF E p WASHER 24 64 1 0 x 9 16 O D x 16 New NUT 5 16 18 FIGURE EXPLODED VIEW ELECTRIC CHOKE 15 nections Check the coil resistance with an ohmmeter With the element at room temperature resistance should be about 5 6 ohms for 12 volt models about 25 ohms for 24 volt models and about 16 ohms for 22 volt models If the coil is defective replace the thermostat cover Thermo Magnetic Choke If choke will not heat properly check for broken heater wire high resistance connections or broken lead wires to the bi metal and heater assembly With the element at room temperature check the heater resist ance with an ohmmeter The resistance should be about 30 6 to 37 4 ohms for a 12 volt system If the heater is defective replace it with a new one When the start button is engaged
101. lenoid in the control box controls starting Revolving field generators use a separate starting motor Fig 47 The starting motor mounts on the right side of the engine and drives the flywheel for starting It is a standard automotive starting motor with solenoid shift and over running clutch controlled by a start solenoid in the control box When the control box solenoid energizes the solenoid on the motor operates shifting the starter pinion to engage the fly wheel ring gear and closing the circuit to the starting motor The starting motor remains engaged until after the engine starts when the control circuit centrifugal switch closes completing the starting cycle The over running clutch pro tects the starter armature from overspeeds NOTE ONAN doesn t stock parts for the starting motor See an authorized dealer MAINTENANCE Revolving Armature Models Poor starter performance may damage the generator If the starter wouldn t crank over the engine compression stroke high currents passing through the armature may burn out the commutator The battery cables and generator must be in good operating condition TO START SOLENOID V IN CONTROL BOX M GROUND CONNECTION TO ENGINE FIGURE 47 STARTING SYSTEM REVOLVING FIELD GENERATORS 37 GROUND ON MOTOR AT POINT FREE OF GREASE AND PAINT _ POSITION OF BRAKE ARM 12 KNIFE SWITCH VARI ree RESISTANCE STORAGE BATTERY FIGURE 48 STARTER TO
102. ly resistance will be very high in one direction and low in other direction The Adjustable Resistor is located in the generator blower outlet and has a total resistance of 2 ohms It includes both a fixed section and an adjustable section The fixed section determines the maximum charging current and must always be in the circuit to protect the components Automatic Emergency Stopping There are two parts to the emergency automatic stopping system a high temperature cut off switch and an optional low pressure cut off circuit When the generating plant is used with Line Transfer Automatic Demand Control and one of the emergency stop ping devices opetates the plant will stop and then crank until the control s cranking limiter operates The High Temperature Cut off Optional located in the op tional shutter assembly is in series with the ignition circuit Normally closed it opens at 240 F 6 breaking the circuit to the ignition system stopping the engine The switch closes again at about 195 F The Low Oil Pressure Circuit Optional has a non adjustable low oil pressure switch Early model circuits also have a latching relay and bridge rectifier later models have an emergency relay If relay on either model becomes latched a reset button must be pushed before the plant can be started NOTE On early models the low oil pressure circuit may prevent starting after installing new oil filter or after an idle
103. motor The con trol system includes the starting circuit a battery charging circuit with reverse current relay and optional high temper ature and low oil pressute cut offs If any component of the control system fails replace it Nor mally relays cannot be repaired Starting and Stopping System The revolving armature starting system includes the start solenoid stop relay and start disconnect relay Fig 92 shows a starting cycle To stop the engine the stop switch grounds the stop relay breaking the circuit to the ignition coil The starting solenoid controls the heavy currents required by the exciter starting motor The Stop Relay controls voltage to the ignition coil When energized it closes the ignition coil circuit During starting the stop relay pulls in at the same time as the start solenoid The generator s DC output maintains it energized throughout operation To stop the stop button grounds the relay which de energizes opening the ignition coil circuit NOTE This is a 6 volt relay and must be used in series with the 30 ohm voltage dropping resistor Check the coil resistance it should be about 30 ohms in spect the contacts and check contact operation when volt age is applied to the coil If the contacts are dirty they can be cleaned with hard paper or gauze moistened with carbon tetrachloride The Start Disconnect Relay is energized by the generator DC output so it pulls in when the output builds
104. n t in good condition replace it Check clearance by inserting each piston in its cylinder Check the clearance 90 from the axis of the piston pin and 3 8 below the oil control ring Clearance should be 0012 0032 If it isn t within the limit replace the piston and check the cylinder bore size Piston Pins Each pin should be a thumb push fit into its piston at room temperatures If the pin is excessively loose install a new pin or the next oversize pin If the piston is wom so that the oversize pin won t fit replace the piston Rings Inspect each ring carefully for fit in the piston grooves and seating on the cylinder wall Fit each ring to the cylinder wall at the bottom of its travel using a piston to square the ring in the bore Check the end gap with a feeler gauge Fig 62 It should be 010 to 020 If the gap is too small file the butt ends of the rings Don t use rings that need a lot of filing they won t seat right on the PISTON RING IN CYLINDER BORE FIGURE 62 CHECKING RINGS cylinder walls If oversize pistons are used use the correct oversize rings During piston ring replacement de glaze the cylinder walls with either de glazing hone or emery paper Don t change the diameter of the cylinder bore Create a cross hatch pat tern on the cylinder walls After de glazing be sure to com pletely clean the cylinder walls and the rest of the engine to remove all residue Connecting Ro
105. new seal from the inside with rubber lip toward outside of gear cover open side of seal inward and drive it flush with the outside surface Fig 67 During geat cover installation reverse the driver to protect the oil seal Lubticate lips with heavy grease 1 Operate the governor shaft to check for binding and see that governor shaft end thrust ball is in place Fig 66 2 Turn governor yoke so the smooth side is toward gov cup Set the governor cup so the stop pin in the S4 PRESS BEARING FLUSH WITH BOTTOM OF RECESS REAR 3 BEARING BEARING WHEN GOVERNOR IS PROPERLY ASSEMBLED THE DIMENSION SHOWN ON DRAWING WILL BE AS INDICATED CENTER PIN SNAP RING GOVERNOR CUP GOVERNOR FLYBALL FIGURE 68 GOVERNOR CUP gear cover will fit into one of the holes in the cup sur face Fig 66 Measure the distance from the end of the stop pin to the mounting face of the cover It should be 25 32 If not replace the pin Position open edge of pin toward crankshaft seal to avoid governor cup drag 3 Use an oil seal driver or a piece of shim stock over the crankshaft keyway to protect the oil seal and install the gear cover Tighten the mounting sctews to speci fied torque Before tightening the screws be sure the stop pin is in the governor cup hole Fig 66 4 Install and time the ignition points on JB see Ignition System Install and gap the centrifugal switch on JC Se
106. olled by the adjusting needle To prevent a power if VAPORI ZED GASOLINE F A METERING PRIOR TO 23 j NOTE VENT EXTENDS __ E METERING THROUGH AIR 2 WELL CLEANER ADAPTER ON LATER MODELS IDLE JET OPERATING METERING WELL AIN JET IDLE JET OPERATING FIGURE i4 IDLE OPERATION lag when load is increased a metering well around the out side of the nozzle delivers fuel until the main jet can catch up with the increased demand Adjustment Gasoline Carburetor The carburetor should be adjusted in two steps first the idle adjustment and then the load adjustment NOTE Jf the carburetor is completely out of adjustment so the engine won t run open both needle valves 1 to 1 1 2 turns off their seats to permit starting Don t force the needle valves against their seats This vill bend the needle Before adjusting the carburetor be sure the ignition system is working properly and the governor is adjusted Then allow the engine to warm up 1 With no generator load turn the idle adjustment out until the engine speed drops slightly below normal Then turn the needle in until speed returns to normal 2 Apply a full load to the generator Carefully turn the main adjustment in until speed drops slightly below normal Then turn the needle out until speed returns to normal MAIN FUEL ADJUSTMENT THROTTLE STOP SCREW B FUEL IDLE ADJUSTMENT THIS DISTANCE 1 32 AT NO LO
107. oltage and gives the highest voltage At the factory the connection was made to C2 On the 04SX and 065 Magneciter an adjustable tapped resistor controls the voltage output It is adjustable over a range of about 5 percent with the highest voltage when the tap is moved to the top of the resistor GENERATOR END BELL FIGURE 79 BRUSH REMOVAL 54 MAINTENANCE The generator normally needs little care other than periodic inspection of the exciter ballbearing collector rings and brushes every 1000 hours However 02SX exciters require build up relay cleaning every 500hours BRUSHES To examine the brushes brush springs and slip rings remove the exciter cover at the rear end of the generator The exciter mounts on a hinged plate Remove the screws from the right side of the plate and swing the assembly outward To remove the brush holders unscrew the four machine screws on the endbell near the ballbearing Fig 79 Replace the brushes when they wear to about 5 16 long Don t use a substitute brush that may look identical It might have entirely different electrical characteristics GENERATOR BEARING The generator ballbearing is prelubricated and doublesealed Inspect every 1000 hours with the plant running If the plant is used for standby power replace bearing every five years If used as prime power replace bearing every 10 000 hours or two years Deterioration of the bearing grease due to oxidat
108. ompressed air at least every 100 hours Don t wash it When using compressed air hold the nozzle far enough from the cartridge so it won t rupture Replace the cartridge at least every 500 hours If the paper cartridge has a foam wrapper remove the wrapper before cleaning wash itin clean fuel dry and install on the cartridge AFTER WASHING ELEMENT DIP IN ENGINE AND SQUEEZE AS DRY AS POSSIBLE e FIGURE 25 MOISTENED FOAM AIR CLEANER MOUNTING BRACKET FIGURE 26 OIL BATH AIR CLEANER Foam Type Cleaner This cleaner consists of a foam element over a metal retainer Approximately every 200hrs remove the foam element and wash it thoroughly in gasoline Then dip it in crankcase grade oil and squeeze as dry as possible The eiement should be replaced only if damaged Oil Bath Air Cleaner Optional Fig 26 Clean and Re fill the oil cup at regular intervals depending on the ambient operating conditions In some conditions service the cleaner daily Establish a regular cleaning interval so the operator can correctly service clean the cup befote the dirt accumu lates in the bottom to a depth of 1 2 in or the oil appears too heavy to spray or circulate properly Use same crankcase grade oil When changing oil inspect the wire screen filter ing element and remove any accumulation of lint etc Air AIR CLEANER CONTROL FIGURE 27 CARBURETOR AIR PRE HEATER cleaner mounts remotely flexible hose must
109. operation Two and four cylinder electric generating plants are included in this manual because of the similarity be tween them Unless otherwise specified all instructions and procedures apply to both If possible use a parts cetalog with the service manual The parts catalog will give a good picture of assembly and disassembly and help in identifying plant compon ents Since the first and most important part of repair work is correct diagnosis of the trouble a troubleshoot ing chart is included to help find the fauit list of special tools is included in the manual These are available from Onan and will make it easier to work on the plant ON When discussing left side and right side in this manual view the plant from the engine end of the plant which is designated the front end HOW TO INTERPRET MODEL AND SPEC NO 15 0JC 3CR 96T i 1 3 45 1 Indicates kilowatt rating 2 Factory code for general identification purposes 3 Combines with 1 and 2 to indicate Model No 43 indicates voltage 120 240 indicates reconnectible R indicates remote starting 4 Factory code for specific optional equipment sup plied 5 Specification Spec Letter Advances with factory production modifications SPECIFICATIONS NOMINAL DIMENSIONS OF PLANT INCHES 5 018 6 1JB 6 0 6 0 10 0 12 5 7 5 8 12 5 C 15 01 Remote Remote 295 25 7 51
110. or dirt pitting Dirty points can be cleaned with tape and carbon tetrachloride But if the points are excessively pitted they must be replaced Check the distributor cap for cracks carbon runners toded high tension terminals or excessively burned inserts STATIONARY CONTACT BREAKER ARM RUBBING BLOCK ON HIGH POINT OF CAM FIGURE 4l POINT ADJUSTMENT After normal use the vertical surfaces of the cap inserts become slightly burned They can be cleaned with carbon tetrachloride but don t file the inserts If vertical or hori zontal faces of inserts are burned replace the distributor cap Inspect the rotor for cracks or for burning on the top of the metal strip If the vertical surface is slightly burned clean it with carbon tetrachloride But if the top is burned replace the rotor Timing The JC ignition system may be timed either with the engine stopped or running But before timing the ignition be sure the breaker points are clean and properly adjusted Set the timing at 259 of each compression stroke EXCEPTION Advance 10 more for gas fuel Timing Procedure Engine Stopped 1 Disconnect the low voltage lead to the distributor and connect a test lamp and battery so the lamp lights when the breaker points ate closed 2 Remove the spark plug from 41 cylinder and rotate the flywheel clockwise until air is forced out of the spark plug hole 3 Continue rotating the
111. ove maximum the diaphragm is probably too tight or the diaphragm spring too strong This can also be caused by fuel seeping under the diaphragm retainer nut and between the diaphragm layers causing a bulge in the dia phragm Overhaul the pump and replace the defective parts Low pressure with little or no pressure leak after pumping stops indicates a weak or broken spring or worn linkage and in most cases the pump should be replaced Removal and Disassembly Fig 8 1 Remove the pump inlet and outlet Remove the two cap screws holding the pump to the engine and lift it off 2 Notch the pump cover and body with a file for assembly in the same relative position and remove the six screws holding them together 3 Tap the body with screwdriver to separate the two parts Don t pry them apart this may damage the diaphragm 4 Lift out the diaphragm assembly and diaphragm spring Repair Fuel pump failure is usually due to a leaking dia phragm valve or valve gasket A kit is available for replace ment of these parts Because the extent of wear cannot easily be detected replace all parts in the kit If the dia phragm is broken or leaks check for diluted crankcase oil SPEC C R LOOSEN THIS SCREW AND ROTATE THE ENTIRE COVER ASSEMBLY AMBIENT TEMP F CHOKE OPENING Inches TO MANUAL CHOKE CONTROL KNOB ON OUTSIDE OF BLOWER HOUSING FIGURE 9 MANUAL CHOKE Occasionally failure is due to a broken o
112. ow voltage drop actoss the connection Overrunning Clutch Clean the clutch thoroughly but don t dip in solvent It can t be repacked with grease It should slide easily on the armature shaft with no binding Turn the pinion it should rotate smoothly but not necessarily freely Reverse the direction a few times and it should instantly lock and unlock Replace the clutch if operation is defective or pinion is worn or damaged 40 FIGURE 51 TESTING ARMATURE FOR SHORTS Shifting Solenoid Check that the plunger m ves freely in coil Check pull in coil continuity between the solenoid con trol terminal and the solenoid connection to the motor Check the hold in coil continuity between the solenoid control terminal and ground on the motor ASSEMBLY STARTING MOTOR Starter motor assembly includes soaking the bronze bear ings in oil These beatings are designed to absorb 25 of their own weight in oil Be sure the felt oil pad is in the outer end of the commutator end bearing After assembly check the armature end play It should be 005 to 030 Adjust end play by add ing or removing wash ers at the commutator end Check pinion clearance Figure 52 to ensure engagement Press solenoid core to shift pinion into f ll mesh Measure clearance between pinion and pinion stop It should be 09 02 try to get 07 7 Adjust solenoid plunger link screw for proper clearance PLUNGER FEELER GAGE 0 07
113. period Plant will not run long enough to fill filter and build up oil pressure To avoid this switch to manual for starting Emergency relay on later models allows time for oil pressure build up The Low Oil Pressure Switch mounts on oil filter adapter Switch contacts open when plant oil pressure builds up and close if oil pressure drops below 9 psi on early models and 14 psi on later models Closed switch contacts energize relay Test switch by checking continuity with plant stopped and running The latching relay early models latches in the energized position Push the reset button to release it The relay oper ates when the oil pressure switch closes and energizes Coil A Fig 97 which opens the engine ignition circuit and stops the plant Energizing Coil allows current flow to Coil B which keeps the relay in a latched position and Coil A de energizes Pushing the reset button opens Coil B circuit and the relay unlatches 67 EARLY MODELS FIGURE 97 EMERGENCY LATCH RELAY To test relay operate plant and short oil pressure switch to ground If relay does not energize and stop plant check both coils with an ohmmeter for a resistance of 50 ohms each If it does not latch check contacts in series with Coil B The Emergency Relay Late Models will operate in 15 to 20 seconds after the oil pressure switch has closed after loss of oil pressure 68 LATE MODEL S FIGURE 98 EMERGENCY LATCH RELAY T
114. r timing the number 2 cylinder adjust the valve clearance refer to two cylinder adjustment 4 To adjust the valve clearance for the number 4 cylinder the flywheel in a clockwise direction 1809 1 2 revolution The flywheel should be between 10 and 45 past the TC flywheel mark 5 After timing the number 4 cylinder adjust the valve clearance 6 To adjust the valve clearance for the number 3 cylinder turn the flywheel in a clockwise direction 180 1 2 revolution The flywheel should be between 109 and 45 past the BC flywheel mark GASOLINE BEGIN PRIOR SPEC D TO SPEC TABLE 3 VALVE CLEARANCE FOR JB JC GAS COMBINATION GAS GASOLINE 43 ROCKER ADJUST VALVE CLEARANCE HERE VALVE SPRING RETAINER VALVE SPRING INTAKE VALVE ONLY SHORT SLEEVE DOWN VALVE SEAT FIGURE 56 VALVE TRAIN 7 After timing the number 3 cylinder adjust the valve clearance Testing Run the engine until thoroughly warm Stop and re move all spark plugs Insert the compression gauge in a spark plug hole crank the engine and note the reading To check for piston blow by squirt a small amount of SAE 50 oil into the cylinder and repeat the check n increase in compres sion with oil in the cylinder indicates piston blow by Compression of a standard new engine cranking at about 300 rpm is about 110 psi Compression should be fairly uniform normally with less than 10 psi di
115. r weak spring or wear in the linkage In this case install a new pump Assembly 1 Before installing a new diaphragm soak it in fuel In sert the diaphragm spring and soaked diaphragm into the pump body 2 Compress the rocker spring and install between the body and rocker arm 3 Assembie the cover to the body with notch marks lined up Install the screws but don t tighten Push the rocker arm in full stroke and hold in this position to flex the diaphragm NOTE The diaphragm must flexed or it will deliver too much fuel pressure 4 Tighten the cover screws altetnately and securely then release the rocker arm BEGIN SPEC 5 w f o J s e FIGURE 10 CHOKE ADJUSTMENTS 14 5 Install the pump on the engine and repeat the pressure test CHOKE Gasoline fuel system Remote starting plants use an automatic electric choke Fig 4 manual starting plants use a hand choke Fig 9 electric element controls the automatic electric choke Be fore the plant starts the choke is partially closed When the plant has started the generator supplies current to the heat ing element which heats the bi metal coii opening the choke plate Adjustment Electric Choke Under normal operation adjust the choke so the distance measured between the choke plate and carburetor throat Fig 10 is as shown in the table with the engine cold Use the straight shank end of a drill bit to measure the gap The up
116. rclockwise gives more sensitivity less speed drop If the governor is ioo sensitive a hunting condition occurs alternate increas ing and decreasing speed Adjust for maximum sensitivity without hunting see Table 2 After sensitivity adjustment the speed may require readjustment Speed Adjustment Begin Spec R Adjust engine speed RPM by turning governor speed adjusting nut Fig 28 Turn nut clockwise to increase speed counterclockwise to decrease speed Sensitivity Adjustment Begin Spec R Sensitivity no load to full load speed droop is adjusted by tuming the sensi tivity adjusting rachet nut accessible through hole in side of blower housing If speed drops too much when full load is applied turn the rachet nut counterclockwise to increase spring tension and compensate for reduced rpm An over sensitive adjustment apptoaching no speed drop when load is applied may result in hunting condition alternate increase and decrease in speed After adjusting speed and sensitivity replace dot button in blower housing air cooled units only and secure speed stud lock nut the governor is either too sensitive or not sensitive enough and can t be adjusted with the stud or ratchet the sensitivity can be coarsely adjusted by changing spring attachment on the governor arm Moving this point further from the governor shaft decreases the governor s sensitivity TABLE 2 Nominal Output Frequency cps Revolving Armatu
117. re Revolving Field Maximum Allowable Frequency cps Preferred Frequency Spread No Load To Ful Load Minimum Allowable Frequency cps 64 57 3 1920 1710 90 63 59 3 1890 1770 90 52 48 3 1560 1440 90 NOTE Numbers in parentheses are plant speed in rpm 50 54 47 3 1620 1410 90 25 OIL SYSTEM J series electric generating plants have pressure lubrication to all working parts of the engine The oil system includes an oil intake cup gear type oil pump by pass valve oil pressure gauge fuli flow oil filter and crankcase passages and drillings to deliver oil throughout the engine Oil is held in the oil base drawn by the pump and delivered through the oil filter Lines leading to the rocker housing drillings through the crankcase to the crankshaft bearings and camshaft front bearing crankshaft passages to con necting rod bearings and connecting tod passages to piston pin bushings complete the oil system plumbing Because it aids oil consumption control the crankcase breather is in cluded in this system 9 CRANKCASE BREATHER O BY PASS VALVE Normal oil pressure should be 25 psi or higher when the en gine is at operating temperature If pressure drops below 20 psi at governed speed inspect the oil system for faulty com ponents MAINT EN ANCE Petiodic oil system maintenance should include changing crankcase oil cleaning the crankcas
118. re marked or identified in some other manner Place this mark toward the closed end of the piston Space the ring gaps 1 3 of the way around the piston from one another No gap should be in line with the piston pin Oil the rings and pistons 3 Position a bearing half in each connecting rod Be sure there is no dirt under the bearing This could cause high spots and early bearing failure BE SURE THAT CONNECTING ROD WITNESS MARKS ARE FIGURE 65 INSTALLING ROD 47 4 Oil the cylinder walls and pistons Install each piston in the proper cylinder using a suitable installer Each assembly should be installed with the V mark on the piston toward the front of the engine 5 Position each connecting rod on the crankshaft oil the journal and install its rod cap with bearing half When installing the rod cap position so the raised witness mark on the forging matches the mark on the connecting rod Fig 65 6 Tighten the connecting rod capscrews to the specified torque 7 Crank the engine over by hand to see that all bearings are free 8 Install the eil base with a new gasket Install the cylinder heads Break In Period Whenever new rings or pistons are instal led or the cylinder refinished the engine must be run in before regular operation Run the engine for 15 20 minutes at no load about 1 2 hour at 1 3 load and 2 3 hours at 2 3 load Then resume regular operation Avoid light
119. rrect speed see Magneciter Troubleshooting Chart FIGURE 81 FLASHING THE FIELD 55 ALTERNATOR TESTING Most alternator testing can be performed without disassem bling the generator Test Rotor Continvity 5 Follows Remove the brushes so none touch the collector rings 1 Using an ohmmeter t st for grounding between each slip ring and the rotor shaft 2 Test for a short or open circuit in rotor winding by measuring resistance of winding It should measure between 3 5 and 4 8 ohms for the JB and between 2 and 3 ohms for the JC at 70 F If an accurate ohmmeter isn t available check the rotor for open circuit or ground ing with an AC test lamp Fig 82 Replace the rotor if it is grounded or has an open circuit or short Test Stator Continuity Follows 1 Disconnect the generator output leads in the control box Use the wiring diagrams to determine the output leads in the control box Use the wiring diagrams to determine the output lead coding Using either the test lamp or an ohmmet r check each winding of the stator for grounding to the laminations or frame NOTE Some generators have ground connections to the frame Check the wiring diagrams 2 Using an accurate ohmmeter test the resistance of each stator winding Compare the resistances obtained All windings of equal output voltage should indicate about the same resistance An unusually low reading indicates a short a high reading an open
120. s 420A274 PERIODIC SERVICE GUIDE AFTER EACH CYCLE OF INDICATED HOURS SERVICE THESE ITEMS inspect Plant Generally Check Governor Linkage Change Crankcase Oil Check Breaker Points Empty Fuel Sediment Bow Complete Reconditioning Service more often under extreme dust conditions T Tighten head bolts and adjust valve clearance after first 50 hours on new or overhauled engine ENGINE TROUBLESHOOTING Sues MOIS 31635 03 pau ng uoisseaduio 4003 043402 JOUIBAOH ON s y aulgug sjunH 40uJ8 Aot Ajpayadxaun 54015 8 84135138 54011 gt aly 3 44 0 enssSad Speo ily sa issip 9urdua peo 59445 ouiBuz 40391nq4e 2 ONAN GASOLINE ENGINE TROUBLE SHOOTING uondunsuo SAISSADXy July pue Puo 2091514 peo 34314 seausiw 58 ssui Faulty Ignition Clean Adjust Points Plug Out of Fuel Check Battery Low or Discharged Lean Fuel Mixture Adjust Carburetor alal sisi Te MC intake le Poor Quality Fuel Keep Fuel Fresh 1111 1 E elei e feof eejo er Joje
121. s Battery Charge Rate 2 2 2 Ventilation Required at 1800 RPM Engine Pressure 520 520 890 Engine Vacu Flo 610 610 1600 Generator ous Uum ded om dea 75 126 126 Combustion Air 32 32 64 Output Rated at Unity Power Factor Load 1 Phase 1 Output Rated at 0 8 Power Factor Load No 3 Phase 3 Phase AC Voltage Regulation in 5 5 3 3 AC Frequency Regulation 5 5 5 Revolving Armature Yes No No Revolving Field Generator 2 No Yes Yes 120 240 Volt Singie Phase Model Reconnectible No Yes Yes Rotating EXCEL 22252 ee go oh oe a Yes No No Static Exciter No Yes Yes Basic 50cycle model Basic 60cycle model Plus quart for filter 3 DIMENSIONS AND CLEARANCES values in inches unless otherwise specified CAMSHAFT Bearing Journal Diameter Front Bearing Journal Diameter Rear Bearing Journal Diameter Center Bearing Clearance Limit End Play Camshaft Cam Tappet Diameter Cam Tappet Hole Diameter Cam Tappet Diameter Cam Tappet Hole Diameter CONNECTING RODS Large Bore Diameter Small Bore Diameter Clearence Bearing to Crankshaft CYLINDER Cylinder Bore
122. se of the high plant speed Removal and Disassembly 1 Remove the air housing door and top panel the fuel hose and governor linkage 2 Remove the 2 carburetor mounting nuts and pull off the carburetor 3 Remove the float bowl and main adjustment screw begin Spec R 4 Remove the idle adjustment screw and the main adjust ment screw Prior to Spec R 5 Remove the throttle plate screws and the plate and pull out the throttle shaft Repair and Assembly Clean in a suitable carburetor cleaner and blow out the idle passage Check the idle needle for wear or damage and the main adjustment for worn threads For assembly reverse the disassembly procedure CARBURE TOR COMBINATION GAS GAS OLINE This carbutetor operates on either gasoline or gaseous fuels To switch operating fuels make adjustments according to Table 1 The combination carburetor consists of both the gasoline and gaseous fuel carburetors on a single casting Refer to the gasoline and gaseous fuel carburetors for descriptions of operation GASEOUS FUEL REGULATOR The demand type regulator opens upon a small vacuum from the carburetor It supplies fuel on demand and shuts off fuel flow when the engine is stopped The regulator is simply a diaphragm with linkage connecting it to a valve in the gas line A small vacuum from the engine moves the diaphragm opening the delivery valve Testing Blow into the diaphragm vent hole on the regulator cover this shoul
123. ssure UNITS OF MEASUREMENT INCHES OF WATER INCHES OF MERCURY OUNCES FIGURE 54 EXHAUST BACK PRESSURE MEASUREMENT 42 ENGINE DISASSEMBLY This section covers various assemblies and parts of the engine repairs should be accomplished by a competent mechanic Maintain factory limits and clearances see Dimen sion and Clearance Section CYLINDER HEADS AND VALVES Each cylinder head assembly contains valves valve seat in serts and guides tocker arms and spark plugs The valve assemblies are operated by pushrods running through the cylinder head and push rod shields to the camshaft Exhaust valves are hardened chrome alloy faced and ride on hardened chrome alloy seat inserts all valves have release type rotaters Check the valve clearances at regular intervals In addition scrape the combustion chambers clean and inspect the valves and valve seats regularly If the combustion chambers show excessive carbon build up reduce the interval between clean ing Adjustment After engine has reached a stable temperature condition the valve clearances may be adjusted It is recom mended that the valve clearance is set with engine at room temperature approximately 75 F Allow at least two hours cooling time after engine operation Adjust valve clearance on the Two Cylinder J Series engines as follows 1 Turn the flywheel until the cylinder which is to have its valve adjusted on its compression st oke
124. t IGNITION RELAY START RELAY i MES 5 ir SOLENOID N232758625 307840 SUPPRESSORS IGNITION D uc COND Iz N23IQAS I IGNITION 15 0HM WATT BREAKER RESIS OR POINTS HYTEMCO IGN LIE TI RESISTOR e i 1 72 08 MAS W 20 60 y t t CHARGE RECTIFIER N 305A235 IGNITION x CONDENSER 1 TERMINAL BLOCK 4706 MARKER STRIP 5324753 SWITCH C CENTRIFUGAL STOP START SWITCH HIGH TEMP E WHEN USED SWITCH WHEN YSED r i TERM BLOCK 27324537 1 MARKER STRIP M ELECTRIC N 232A566 CHOKE 1 t SILK SCREEN 988 589 GAS SOLENOID TO VACVE E NOTE ENGINE 1 WHEN USED C LOAD CONNECTIONS 1PHASE 2WIRE IPHASE 2 WIRE i ELECTRIC FUEL 20 VOLT 240VOLT PUMP CHARGE RESISTOR 4 ASST 5044505 WHEN USED d 2 159 W Ii LS Sar i N9 204A500 REF 1 ez gs TERM T3 5 STATIC EXCITER 3 WIRE CAUTION 120 240 VOLT T2 MUST BE GROUNDED ANY OTHER GROUND WILE CAUSE SER OUS Bi DAMAGE EXCITER C CHARGING B2 WINDING BR1120 2404_ 1PH 3 VA 69 CY SIRI26 240V 104 FW f CC Y 6
125. tart disconnect breaker points 6 Adjust the start disconnect breaker point gap to 020 7 Install the ignition breaker points and adjust the gap Time the ignition Condenser The 3 mfd condenser mounted on the breaker plate aids primary field breakdown when the points open and prolongs the life of the breaker points by reducing the arc across them A defective condenser causes a weak spark and rapid breaker point wear Use a standard commercial condenser checker to test the cond nser for leakage open ings grounding If no tester is available check for shorts or defective leads and teplace the condenser if you suspect it of defects Coil If spark is weak there is no spark and the breaker points clean and properly adjusted test the coil for possible defects Disconnect both spark plug leads ground one and hold the other about 3 8 from the engine Crank the engine If there is a good spark the coil is operating Also test the coil as follows 1 Disconnect the breaker point lead at the breaker points 9 IGNITION BREAKER PLATE IGNITION BREAKER PLUNGER t DIAPH RAGM CUP FIGURE 38 DIAPHRAGM amp CUP and measure resistance from that lead to ground It should be about 1 ohm 2 Disconnect both spark plug leads at the plugs and measure resistance between them Resistance should be between 7000 and 10 000 ohms If it is higher either the high tension terminals or spark plug leads
126. the gear teeth The ring will contract rapidly and may shrink to the flywheel before it is in place If this occurs a new ring gear may be required DON T HEAT WITH A TORCH Gear Cover To remove the gear cover detach the upper governor ball joint and remove the ignition breaker points start disconnect switch plate and gear Remove the screws holding the gear cover to the crankcase To loosen the gear cover tap it with a soft hammer Governor Shaft Two sets of needle bearings support the governor shaft To remove the shaft from the gear cover remove the governor yoke and pull the shaft from the gear CUP OIL SEAL IF FEELER WILL ENTER HOLE 1 2 BALL HAS FALLEN OUT Late models have larger ball which won t fall out FIGURE 66 GEAR COVER AND GOVERNOR SHAFT 48 INSTALL OIL SEAL FLUSH WITH THIS SURFACE OIL SEAL THIS SURFACE MUST BE CLEAN BEFORE INSTALLING SEAL FIGURE 67 GEAR COVER OIL SEAL cover If the shaft binds during operation clean the bear ings if loose replace the bearings To remove the larger beating drive both bearing and oil seal out from the outside of the gear cover Remove the smaller bearing with an Easy Out or similar tool Press new bearings and oil seal into place Gear Cover Oil Seal Replace the oil seal if damaged wom Drive the old seal out from inside the gear cover Lay the coveron a board so the seal boss is supported Using an oil seal driver insert the
127. the gearcover back plate with the ignition breaker points and operates directly off the camshaft gear Normally open the switch closes when engine speed builds up about 900 rpm For correct operation maintain the switch contact gap at 020 Fig 95 Check the contacts for dirt or pitting when adjusting the gap Clean the contacts with paper or replace it if badly pitted In an emergency if the centrifugal switch won t operate the engine can be run by shorting the switch leads when the en gine starts For disassembly and repair of the timing gear and switch operating mechanism see Ignition System Section SOLENOID STARTING MOTOR CLOSES CRANKS ENGINE N E EUG Y gt v gt START 1 SWITCH CURRENT TO START IGNITION IGNITION COIL ENGINE CENTRIFUGAL RELAV ENERGIZED AND STARTS SWITCH CLOSES ENGINE RUNS STARTING CYCLE ENDED A748 OPENS START NE PISO START IGNITION RELAY IGNITION RELAY PULLS IN ANO MAINTAINS CURRENT 6 SYSTEM REVOLVING FIELD REMOTE STARTING FIGURE 94 STARTING CIRCUIT FOR REVOLVING FIELD GENERATORS 66 CENTRIFUGAL SWITCH BREAKER POINTS SET GAP AT 020 FIGURE 95 CENTRIGUGAL SWITCH Battery Charging Circuit This circuit includes the adjust able charge resistor rectifier and ammeter It converts AC current supplied by the generator charging winding to DC and delivers it through the ammeter to the battery
128. the solenoid should cause the spring loaded armature to con tact the solenoid core Jf this does not occur check for broken lead wires or a defective solenoid coil There must be slack in the lead wires between the choke body and the bi metal and heater assembly The solenoid coil resistance should be 2 09 to 2 31 ohms in a 12 volt system Assembly Fig 11 When assembling electric choke be sure the fork in the plate straddles and holds the outer end of the coil and that the spring winds in a clockwise direction from center When assembling the thermo magnetic choke connect the bi metal and heater assembly as follows 1 Lead tagged to ground terminal on coil solenoid 2 Lead tagged H to either of the H1 terminals on the sole noid core CARBURETOR GASOLINE The gasoline carburetor is a horizontal draft type It consists of three major sections the bowl and float idle circuit and load circuit Fuel enters the carburetor through the intake valve Fig 12 and pesses into the float chamber The float controls fuel level in the bowl by closing the intake valve when fuel reaches a certain height and opens it when the fuel level drops The idle circuit Fig supplies fuel during no load operation and for small loads The throttle plate is nearly FUEL INLET rl VALVE SEAT E LES p gt CARBURETOR FUEL INLET FIGURE 12 FUEL INLET VALVE 16 FLOAT BOWL VENT CHOKE VAPORIZED GASOLIN
129. to the carburetor throttle lever Engine speed is determined by the tension on the governor spring Sensitivity speed drop from no load to full load is con TURN TO INCREASE R P M q HOLD SPRING STUD iN POSITION GOVERNOR SPRING TURN FOR MINIMUM GOVERNOR SPEED OROP THEN SPRING STUD ADJUST NUT GOVERNOR SPRING NUT PRIOR TO SPEC GOVERNOR STUD p 7 S SPEED N 72 SPEED ADJUSTING NUT FIGURE 28 GOVERNOR ADJUSTMENTS 24 trolled by the number of spring coils used More coils give less speed drop from no loadto full load greater sensitivity MAINTENANCE Periodically lubricate the governor linkage with lubricating graphite or light non gumming oil Also inspect the governor linkage for binding or excessive slack or wear ADJUSTMENTS Prior to Spec R both the governed speed and the governor sensitivity are adjusted with the stud and nut on the front of the engine air housing Fig 28 Beginning Spec R the sensitivity is adjusted with an adjusting ratchet Speed Adjustment Prior to Spec R To adjust the governed speed hold the governor spting stud in position and turn the governor spring nut with a wrench For accurate speed ad justment use a teed type frequency meter on the generator s AC output mechanical tachometer can be used but is not as accurate Set speed according to Table 2 Sensitivity Adjustment Prior to Spec 8 To adjust the sensitivity turn the governor spring stud counte
130. tor at the distrib 36 utor holding the end about 1 4 from bare engine metal and ctanking the engine spark between the lead and engine indicates the coil is operating although it might be weak No spark indicates that the coil points or control circuit to the coil are defective Check for voltage between the coil negative terminal and ground while cranking the plant and inspect the breaker points Ignition Condenser The condenser is mounted on the outside side of the distributor Refer to JB Battery Ignition Section for test procedure Capacitance should be 25 to 28 mfd SPARK PLUGS JB and JC generating plants use standard automotive spark plugs Champion H 8 or equivalent Clean and inspect the plugs at regular intervals Clean on a commercial plug cleaner and gap For gasoline operation the spark plug gap should be set at 025 When spark plug electrodes become worn or if the plugs are damaged replace them When in stalling spark plugs always use new gaskets CONTROL BOX BRUSHES SERIES Sq WINDING 2 6 VOLT BATTERIES FIGURE 46 REVOLVING ARMATURE STARTING ONAN electric generating plants use one of two types of starting systems Plants with revolving armature generators use the generator as a starting motor Fig 46 The battery supplies the starting current through a series field winding STARTING MOTOR SOLENOID STARTING SYSTEM and the DC section of the armature A start so
131. trip becomes magnetized and vibrates Rotate armature slightly and repeat test for one complete revolution of the armature If armature is defective replace it See Figure 51 39 120 VOLT TEST LAMP FIGURE 50 TESTING FOR GROUNDS Clean commutator with 00 or 00 sandpaper Blow the sand out of motor after cleaning If heavily scored or worn turn it down in a lathe Field Coils Using a 120vok test lamp and probes check the field coils for grounding to the motor frame or open cir cuit Inspect all connections to be sure they are properly clinched and soldered Inspect the insulation for evidences of damage The only way to check for field coi shorts is to use the starting motor test Bearings If either the front or rear bearings show excessive wear replace them Drive the old bearings out and using an arbor press and the proper arbor press new bearings into place Brushes Check the brushes for wear or improper seating They should slide freely in their holders Check the brush spring tension with a spring scale To change spririg tension twist the spring at the holder with long nosed pliers If brushes are excessively worn replace them Some brushes are soldered to the field lead To remove these brushes unsolder the lead and open the loop in the field coil lead Insert the new brush pigtail completely into the loop and clinch before resoldering good soldering job is neces sary to ensure good contact and l
132. ts in the DC armature wind rate the windings and check each ing 2 Check the field winding resistance from the negative commutator brushes from F2 when used to the con This test can only be performed with the generator dis nection on the generator is connected to the posi assembled and requires a growler Place the armature in tive brushes with all commutator brushes lifted off the Un pus the 2 nol ass Pas their seats See Resistance Table 7 for correct values back and fort over above the armature windings Fig If the windings are warm from running the resistance 87 If the strip is magnetically attracted to the armature m PRU M will be slightly higher than specified the resistence at any point a short is indicated After testing in one Nd LADO 22 is high check for an open circuit in one of the parallel position rotate the armature slightly and repeat the Ms windings step 3 otherwise go directly to step 4 uo TT 3 Separate the parallel field windings at F and check If the test indicates a short circuit in the DC windings each for open circuit be sure the commutator is clean Carbon dust dirt and 4 Check for open circuit in the series winding with ohm grease between the bars or slip rings could cause a meter Touch probes to lead S1 and connection If short there is an open circuit isolate each coil and check it If any of thetests above show that the
133. turned ait cleaner must be removed for choke adjustment To adjust the choke loosen the two screws on the endplate and rotate the cover assembly Operation and Adjustment Thermo Magnetic Choke This choke uses a strip heating element and a heat sensitive bi metai spring to control the choke blade position solenoid actuated during engine cranking closes the choke all or part way depending on ambient temperature The bimetal is calibrated to position the choke to the proper opening under any ambient condition The choke is adjusted at the factory If for any reason readjustment is required use the following procedure Adjustment must be made with the bimetal at ambient tem perature Do not attempt adjustments until the engine has been shut down for at least one hour Remove the air cleaner to expose the carburetor throat Loosen the screw which secures the choke body assembly Refer to Fig 10 for correct choke setting according to temperature Use bit to measure the choke opening Rotating the choke body clockwise richens and counterclockwise leans the choking effect Tighten screw that secures choke body Disassembly and Repair Electric and Thermo Magnetic Choke If the choke does not operate or will not maintain its adjustment disassemble it for repair If it will not close check for binding incorrect adjustment or incorrect assembly of the coil If it will not open after plant starts check for heating The cho
134. up to 10 or 11 volts and remains energized throughout plant operation When the relay pulls in it opens the circuit to the start sole noid coil opening that solenoid to break the starting circuit To test this relay inspect the contacts check the coil re sistance it should be 20 to 24 ohms and check contact operation when the plant starts Battery Charging Circuit The generator DC windings supply current for the battery charging circuit The current flows through the reverse current relay charge ammeter and the adjustable charge rate resistor located outside the control box The battery charge rate can be adjusted between 2 and 5 amps by moving the slider on the charge resistor The Reverse Current Relay allows current flow only from the generator to the battery and opens when current attempts to flow in the other direction To test the relay isolate it by removing the generator connection GEN Check for con tinuity between the battery and generator terminals Conti nuity here indicates that the relay contacts welded together Measure the resistance from the generator terminal to ground This shouid be approximately 112 ohms Automatic Emergency Stopping optional emergency stopping system includes two separate devices the high temperature cut off and low oil pressure cut off Both devices are optional equipment NOTE When the generating plant is used with Line Trans fer or Automatic Demand Controls and one
135. used by pitted or misaligned breaker 33 SPRING points incorrect breaker point spring tension or loose breaker plate or distributor shaft or bushing Distributor The distributor contains and opens the breaker points at the proper time contains an automatic spark ad vance mechanism and distributes the spark to the proper cylinder Testing Remove the distributor and test it on a commercial tester Following the equipment manufacturer s instructions check the centrifugal advance mechanism and cam dwell angle The cam dwell angle should be 51 30 Do not set breaker gap by cam dwell With the proper point gap if cam dwell is outside the above limits check for worn distributor cam If a distributor tester isn t available test as follows To check the spark advance mechanism remove the distrib utor cap and rotate the rotor sevetal degrees clockwise If the advance mechanism is operating properly the rotor will return to its original position not overhaul the distributor Thoroughly inspect the breaker points and check to be sure the movable contact turns freely on its pivot Using a spring scale Fig 42 measure the tension of the points as they break contact Tension should be 17 to 20 ounces If it is greater it causes excess wear if less it PRIMARY TERMINAL DISTRIBUTOR SHAFT AND WEIGHT MOUNTING PLATE DISTRIBUTOR FIGURE 43 JC DISTRIBUTOR DISASSEMBLY 34 HOOK O
136. ut voltage slow to build up Open in one field rectifier and 10 to 20 percent above rated voltage after build up Open circuit in gate winding G1 G2 of reactor A or B Shorted winding in control reactor Test control reactor and replace Output voltage builds up normally if defective but less than rated voltage after build p Compound winding 51 52 in Check wiring diagram for polarity with slightly less than rated stalled backward or has open of compound windings through voltage at no load and low circuit reactors and B and test for voltage at full load continuity Output voltage builds up normally Check wiring diagram for polarity of compound winding through reactor or B Output voltage builds up normally but 20 percent above rated voltage after build up Voltage regulation poor Compound winding 51 52 in stalled backward through one reactor or B Check continuity from the junc tion of control rectifiers Z and Y to the junction of control recti fiers X and W Open circuit in control rectifier bridge Output voltage builds up normally but is 25 percent above rated voltage after build up Shorted turn in gate winding Test reactors and B for shorted Output voltage builds up normally 61 62 of reactor A or B turns and replace if defective but 125 to 150 percent above rated voltage after build up
137. ving piston assemblies check marking so each can be re installed in the proper cylinder Keep all com ponents of each piston assembly together 1 Drain the crankcase oil and remove the oil base air housing and cylinder heads 2 Scrape off the carbon ring and ridge at the top of each cylinder to prevent damaging rings or pistons Onan stocks a ridge reamer for this purpose 3 Remove the connecting rod cap and push the assembly through the top of the cylinder bore If the ridge at the top of the cylinder interferes with piston removal cut it down with a ridge remover befote taking the piston assembly out 4 Using ring expander remove the rings from each piston 5 Remove the two retaining rings and push the piston pin from each piston Cylinders The cylinder walls should be free of scratches pitting and evidence of wear Check with inside reading micrometer for excessive out of round or taper New cylinder dimensions are 3 2495 to 3 2505 If necessary rebore the cylinder to fit the next oversize piston Pistons and ring sets are available in 1010 0207 and 030 oversize refinishing is not required remove any ridges from the top of the wall with a ridge cut ter or if the ridge is small a de glazing stone Pistons Clean the carbon from the ring grooves and be sure all oil holes are open If any piston is badly scored or burred loose in the cylinders has badly worn ring grooves or other wise is
138. ween G and 62 cannot be read with accuracy on the multimeter a Set the resistance range selector on the meter to the resistance range b Isolate one gate winding by disconnecting either end of gate winding 61 062 from its point of connection for example disconnect G1 at E2 Measure the resistance in the gate winding across G1 G2 Refer to Table 5 c Isolate one control winding by disconnecting either lead C1 or C2 from the terminal block Measure the resistance in the control winding across C1 C2 Refer to Table 5 d Connect one meter lead to the disconnected gate winding lead and the other meter lead to the disconnected control winding lead and check for continuity Results 1 REACTOR IS SERVICABLE if resistance is within 20 percent either way of the value listed and there is no continuity between the control and gate windings 2 REACTOR IS DEFECTIVE if there is an open circuit in either the gate or the control windings Continuity between the gate and the control windings is also an indication of a defective reactor either case the reactor should be replaced STEP 3 CHECKING CONTROL REACTOR a Isolate the control reactor by disconnecting common lead from its point of connection and carefully measure the resistance from this leed to the number lead on the control reactor Refer to Table 5 Results 1 CONTROL REACTOR IS SERVICEABLE if resistance is within 10 percent of the value spec

Onan JB-JC Service Manual 967-500

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