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Engine Service manual

1. 0 0025 0 064 0 0038 0 097 Connecting Rod Journal Diameter 1 6252 41 28 1 6260 41 30 Crankshalt End ES 0 006 0 15 0 012 0 30 CONNECTING ROD Large Bore Diameter Rod boits properly torqued 1 6280 41 35 1 6285 41 36 Connecting Rod Side Clearance 0 0020 0 051 0 0160 0 406 Piston Pin Bushing Bore Finished bore 0 6879 17 47 0 6882 17 48 Bearing to Crankshaft Clearance Aluminum ROO EE 0 0020 0 051 0 0033 0 084 CAMSHAFT Bearing Journal Diameter 1 3740 34 90 1 3745 34 91 Bearing Clearan6e uos ei meo RAE 0 0015 0 038 0 0030 0 076 Play PE 0 0030 0 076 Camshaft Lift MAKE qui yea 0 286 7 26 0 295 7 49 Exhaust cios uis E S bana dU ads qi ui des eus 0 291 7 39 0 299 7 59 PISTON Clearance in Cylinder Measure 90 to pin 1 187 inch below top of piston 0 0033 0 084 0 0053 0 135 PISION PIT BOIS EV EE 0 68774 17 47 0 68814 17 48 Ring Groove Width Top 1 Compression 0 080 2 032 0 081 2 057 2 Compression 0 0 080 2 032 0 081 2 057 No 3 Ol Control RING 52542400405
2. 0 188 4 775 0 189 4 801 8 1 DESCRIPTION PISTON PIN Clearance in Piston 5 Clearance in Connecting Rod Aluminum Rod oo so ois ow eS eed ew REDE e Eo RN VE E PISTON RINGS Clearance ASA eade Ring End Gap in Cylinder INTAKE VALVE Stem Diameter OPERETUR Clearance Stem to Guide Valve Face INTAKE VALVE SEAT Seat Cylinder Bore Diameter Seat Outside Valve Seat Width vote ek DUE E FUE QS Vale Seat EXHAUST VALVE Stem DIBmeler 2 E Lnd MA Clearance Stem to Guide Valve Face OR cR COR E c De EXHAUST VALVE SEAT Seat Cylinder Head Bore Diameter Seat Outside P Valve Seat Width EE EE E S TS Valve VALVE GUIDE inside Diameter 2 ihe hk oe edie esses TAPPET BOGY DIAMO ias ctu coat aao Cs qu RE Bore Diameter Clearanc
3. 5 won Disconnected Governor Spring Sensitivity Too Great EL LL et Pl d i Edi ji f onem Binding Redistribution or publication of this document by any means is strictly prohibited Oil System CRANKCASE OIL Refer to engine nameplate or Periodic Maintenance Schedule located the Operators Manual for change interval If operating in extremely dusty high ambient or low ambient conditions change more often Run engine until thoroughly warm before draining oil Stop the engine piace a pan under the drain outlet and remove the oil drain plug After the oil is completely drained clean and replace the drain plug Fill crankcase with correct amount of oil Refer to SPECIFICATIONS for crankcase capacity Use oils meeting the classifi cation SF SF CC or SF CD Refer to chart to determine the proper viscosity grade of oil to use Straight weight oils are recommended for severe duty use and at temperatures above 32 F 0 C for minimum oil consumption AWARNING Crankcase pressure can blow out hot oil which can cause severe personal injury Do not check oil while the engine is running Hot crankcase oil can cause burns if AWARNING it comes in contact with skin Wear protective clothing and keep fingers and hands clear when draining oil ALWAYS REPLACE TIGHTLY OR OIL LEAKAGE MAY OCCUR FULL CAUTION DO NOT OVERFILL ADD ONE PINT 0 5 litre
4. 5 Install the remaining piston and rod in the same manner Crank the engine over by hand to see that all bearings are free 6 Install the oil base with a new gasket 7 Install the cylinder heads See Cylinder Head section for torques and torquing procedure 8 Replace and break in engine CYLINDER HEADS Remove the cylinder heads for carbon cleaning and gasket change at least every 200 hours or when poor engine performance is noticed For engines running on unleaded fuel this interval may be extended to 400 hours 1 Use a 1 2 inch 13 mm socket wrench to remove cylinder head bolts Lift heads off Torquing or removing cylinder ACAUTION heads when hot above 100 F 37 C will result in head damage Allow heads to cool to below 100 F 37 C before torquing or removing 2 After removing heads clean outall carbon deposits Be careful not to damage the outer sealing edges where gaskets fit The heads are made of aluminum and can be damaged by careless handling 3 Use new head gaskets and clean both the heads and the cylinder block thoroughly where the head gaskets rest 4 Place a head gasket on the cylinder head and align the stud holes in the gasket with the stud holes in the cylinder block While hoiding the gasket against the cylinder head carefully install the cylinder head on the engine Do not attempt to slide the head bolts through the gasket withoutthe cylinder block behind it or the gasket may
5. FIGURE 1 VALVE ASSEMBLY 10 2 Warpage occurs chiefly in the upper stem due to its exposure to intense heat Out of round wear follows when the seat is pounded by a valve whose head is not in line with the stem and guide If a valve face is burned or warped or if the stem is worn install a new valve Too much clearance in the intake guide admits air and oil into the combustion chamber upsetting carburetion increasing oil consumption and making heavy carbon deposits Carbon reduces heat dissi pation Clean metal is a good heat conductor but carbon insulates and retains heat This increases combustion chamber temperatures which causes warping and burning Unburned carbon residue gums valve stems and causes them to stick in the guide Deposits of hard carbon with sharp points projecting become white hot and cause pre ignition and pinging Refinish valves that are slightly pitted or burned onan accurate valve grinder valves are badly pitted or have a thin margin when refacing replace them VT 1020 FIGURE 2 VALVE STEM AND VALVE GUIDE INSPECTION Stems And Guides Always check valve stems and guides for wear Figure 2 Use hole gauge to measure the valve guide When clearance with stem exceeds that specified in DIMENSIONS AND CLEARANCES replace either valve or guide or both as may be necessary Always regrind seat to make concentric with the newly installed guide Worn valve stem guides can be replaced from i
6. Install all housings and air cleaner Fill crankcase with oil 12 13 Operation Start engine and check oil pressure Run for approxi mately 15 minutes to bring engine to operating temper ature Check for oil leaks fuel leaks and exhaust leaks Adjust carburetor and governor for speed and sensitivity Testing Compression The compression tester is used to determine the condition of valves pistons piston rings and cylinders To check compression 1 Run the engine until thoroughly warm 2 Stop engine and remove spark plugs 3 Remove air cleaner and place throttle and choke in the wide open position 4 insert the compression gauge in one spark plug hole 5 Crank the engine and note the reading Refer to SPECIFICATIONS section for compression pressures There may be variations due to equipment temperature atmospheric conditions and altitude These pressures are for a warm engine at cranking speed about 300 rpm Tappet Adjustment The engine is equipped with adjustable vaive tappets The valve tappet clearance should be checked and adjusted if necessary at least every 200 operating hours or when poor engine performance is noticed Adjust the valve clearance only when engine is at ambient temperature Proceed as follows 1 Remove ignition key to prevent accidental star ting 2 Remove all parts necessary to gain access to valve tappets 3 Remove spark plugs to ease tne task of turning the engine
7. LS 1077 FIGURE 1 CRANKCASE OIL FILL 6 1 ACAUTION 55 can cause high sumption high operating temper atures and oil foaming Do not overfill crankcase Oil level should be to the FULL mark of the dipstick Start engine and run for a short time to check for oil leaks around the drain plug USE THESE SAE VISCOSITY GRADES 20 0 20 40 60 80 100 30 20 10 0 10 20 30 40 TEMPERATURE RANGE YOU EXPECT SEFORE NEXT OIL CHANGE LS 1170 C 1001 FIGURE OU FILTER OIL FILTER CHANGE Refer to engine nameplate or Periodic Maintenance Schedule located in the Operator s Manual for oil filter change interval If operating in extremely dusty high ambient or low ambient conditions change oil filter more often Spin off oil filter element and discard it Thoroughly clean filter mounting surface and make sure new gasket is inserted in the element Apply a thin film of oil to the gasket Spin element down by hand until gasket just touches mounting pad and then turn down an additional 1 4 1 2 turn Do not overtighten With oil in crankcase start engine and check for leaks around filter element Retighten only as much as necessary to eliminate leaks do not overtighten CRANKCASE BREATHER The crankcase breather prevents pressure from building up in the crankcase It also prevents oil contamination by removing moisture or gasoline vapors and other harmful blow b
8. TEST VALUES 15A SYSTEM 20A SYSTEM 12 12 VDC 40 VAC minimum 60 VAC maximum 31 VAC minimum 51 VAC maximum Engine Wiring Diagram 9301513 Q3SHSINYNS 1691 53 3130 3959 719919373 GATIVISNI HAWOLSNO Sv 1 38 LSNW ISNA 1 e mim i AU311Vv8 9313915 45 vd 1VNOILdO 7 ME 1VNOlLdO 1 01140 d313AMWV HOLIMS HO LIMS T OXdO1 2 5222 LJ e E 1102 HOLIMS ASSY dvO NOILIN I NOILINSI L 9 HOLIMS 13915 YOLYNYSLIV 1114 1 38 LSNW GION310S NMOGLNHS NO 39YAIV3 VIN SZ SLVNINITA OL IVNOILdO PPS 10 15 NOILOSNNOO AYALLVG 5 19038 934 519310 4 SE 351 3 9 OV 1108 ONILNNOW HONOYHL OJONNOYD 38 LSNW 133HM H3MO l8 QNIH38 8 5 Redistribution or publication of this document by any means is strictly prohibited Starting System ELECTRIC STARTER Normaily the starter will require little or no service other than possible brush replacement However if through accident or misuse the starter requires service or overhaul the following information will provide the information necessary to perform this service Service When starting engine note starter motor action The pinion gear should
9. UNIT OF MEASURE in in mm in mm cu in KW Qts litre Qts litre in mm in mm in mm in mm BIDC psi kPa SERIES 3 3 0 005 0 13 0 013 0 33 0 025 0 635 0 021 0 53 21 75 to 115 517 to 793 48 2 3 250 82 55 2 875 73 02 47 7 782 6 7 to 1 18 13 4 1 7 1 6 3 3 0 005 0 13 0 013 0 33 0 025 0 635 0 021 0 53 21 75 to 115 517 to 793 Redistribution or publication of this document by any means Is strictly prohibited Dimensions and Clearances All clearances given at room temperature of 70 F 21 C All dimensions in inches approximate millimeter dimensions in parentheses unless otherwise specified DESCRIPTION MINIMUM MAXIMUM Inches mm Inches mm CYLINDER BLOCK Cylinder Bore Honed Diameter 3 2490 82 53 3 2500 82 55 Maximum Allowable jio fo 0 005 0 13 uio 0 003 0 08 Main Bearing Inside Diameter Without bearing 2 187 55 55 2 188 55 58 Main Bearing Inside Diameter Installed 2 0015 50 84 2 004 50 90 Camshaft Bearing Bore Bearing installed 1 3760 34 95 1 3770 34 98 CRANKSHAFT Main Bearing Journal 1 9992 50 78 2 0000 50 80 Main Bearing Clearance
10. 1 Inspect the pistons for fractures at the ring lands skirts and pin bosses Check for wear at the ring lands using a new ring and feeler gauge Figure 15 Replace the piston when the side clearance of the top compression ring reaches that specified in DIMENSIONS AND 0 0 CLEARANCES MEASURE CLEARANCE HERE gt 2 Replace pistons showing signs of scuffing Nw scoring worn ring lands fractures or damage from preignition Excessive piston wear near the edge of the top ring land indicates preignition 4 Connecting Rod Inspection 1 Replace connecting rod bolts and nuts with damaged threads Replace connecting rods FIGURE 16 MEASURING PISTON CLEARANCE 10 9 Fitting Piston Rings 1 Install the piston ring in the cylinder bore Invert the piston and push the ring to the end of ring travel about halfway into the bore which trues the ring end gap Check the gap with a feeler gauge Figure 17 2 The practice of filing ring ends to increase the end gap is not recommended If the ring end gap does not meet specifications check for the correct set of rings and the correct bore size A cylinder bore that is 0 001 inch 0 03 mm under size will reduce the end 0 003 inch 0 08 mm f Y 5 2 2 Z 2 72 FIGURE 17 POSITIONING OF PISTON RING AND MEASURING OF END GAP CYLINDER BLOCK The cylinder block is the main support for all other basic engine parts Crankshaft and camshaft are
11. Service Manual BASMI BASMI Engine Te RASA NS 965 0754 B43M Spec C B48M Spec A 5 88 Pnnted in U S A d Safety Precautions It is recommended that you read your engine manual and become thoroughly acquainted with your equipment before you start the engine This symbol if used warns of imme SAGA diate hazards which will result in severe personal injury or death This symbol refers to a hazard or AWARNING unsafe practice which can result in severe personal injury or death This symbol refers to a hazard or ACAUTION unsafe practice which can result in personal injury or product or property damage Fuels electrical equipment batteries exhaust gases and moving parts present potential hazards that can result in serious personal injury Take care in following these recom mended procedures All local state and federal codes should be consulted and complied with This engine is not designed or in AWARNING tended for use in any type of aircraft Use of this engine in aircraft can result in engine failure and causes serious personal injury or death General Provide appropriate fire extinguishers and install them in convenient locations Use an extinguisher rated ABC by Make sure that all fasteners the engine are secure and accurately torqued Keep guards in position over fans driving belts etc 15 necessary to make adjustments while the engine is running
12. ment or misconnected fuel lines can result in leaking fuel creating a serious fire hazard Use extreme care when reassembling and reinstalling fuel pump PUMP DIAPHRAG DIAPHRAGM M AIR BLEED BASE PUMP PLATE 499 FIGURE 6 EXPLODED VIEW OF FACET FUEL PUMP GOVERNOR SENSITIVITY Engines equipped with variable speed governors Fig ure 8 are adapted for use where a wide range of speed settings are desired Engine speed is controlled at any given point between minimum and maximum by simply shifting the throttle lever on the control panel until the desired speed is reached Engines equipped with fixed speed governors Fig ure 7 are generally used where single constant speed is required Engine speed is controlled by adjusting governor spring tension The fixed and variable speed governor give an automatic decrease in sensitivity when the speed is increased The result is good stability at all speeds A reliable instrument for checking engine speed is required for accurate governor adjustment Engine speed can be checked with a tachometer Check the governor arm linkage throttle shaft and lever for binding condition or excessive slack and wear at connecting points A binding condition at any point will cause the governor to act slowly and regulation will be poor Excessive looseness may cause a hunting condition and regulation could be erratic Work the arm back and forth several times by hand while the engi
13. supported by the block assuring alignment of the crankshaft and cylinder bores Cleaning After removing pistons crankshaft cylinder heads etc inspect block for cracks and extreme wear If block is still serviceable prepare it for cleaning as follows 1 Scrape all old gasket material from block Remove oil by pass to allow cleaning solution to contact inside of oil passages 2 Remove grease and scale from cylinder block by agitating in a bath of commercial cleaning solution or hot soapy washing solution 3 Rinse block in clean hot water to remove cleaning solution Inspection When rebuilding the engine thoroughly inspect block for any condition that would make it unfit for further use This inspection must be made after all parts have been removed and block has been thoroughly cleaned and dried 1 Make a thorough check for cracks Minute cracks may be detected by coating the suspected area with a mixture of 25 percent kerosene and 75 percent light motor oil Wipe the part dry and immediately apply a coating of zinc oxide white lead dissolved in wood alcohol If cracks are present the white coating will become discolored at the defective area Always replace a cracked cylinder block 2 Inspect all machined surfaces and threaded holes Carefully remove any nicks or burrs from ma chined surfaces Clean out tapped holes and clean up any damaged threads 3 Check top of block for flatness with a straight e
14. use extreme caution when close to hot exhausts moving parts etc Protect Against Moving Parts e Donotwear loose clothing in the vicinity of moving parts such as PTO shafts 5 blowers couplings fans belts etc Keep your hands away from moving parts Batteries Before starting work on the engine disconnect batteries to prevent inadvertent starting of the engine DO NOT SMOKE while servicing batteries Lead acid batteries give off a highly explosive hydrogen gas which can be ignited by flame electrical arcing or by smoking Verify battery polarity before connecting battery cables Connect negative cable last Fuel System DO NOT fill fue tanks while engine is running DO NOT smoke or use an open flame in the vicinity of the engine or fuel tank Internal combustion engine fuels are highly flammable Fuel lines must be of steel piping adequately secured and free from leaks Piping at the engine should be approved flexible line Do not use copper piping for flexible lines as copper will work harden and become brittle enough to break Besure all fuel supplies have a positive shutoff valve Exhaust System e Exhaust products of any internal combustion engine are toxic and can cause injury or death if inhaled All engine applications especially those within a confined area should be equipped with an exhaust system to discharge gases to the outside atmosphere Donotuse ex
15. Nm Apply a thin film of grease to the commutator end of the armature shaft and to the portion ofthe shaft that contacts the bearings Apply a generous film of silicone base grease GE Versilube 322 L to the shaft threads Torque stop nut to a value of 20 to 25 ft Ibs 27 to 34 Nm Torque thru bolts to a value of 4 5 to 6 ft lbs 6 to 8 Nm Apply a small amount of silicone based grease GE Versilube 322 L to armature shaft spline Install dust cap pinion gear dust cover spacer anti drift spring stop nut washer and stop nut Push dust cover on until it snaps into position FLYWHEEL RING GEAR 0020 0010 051 0 25mm FLYWHEEL GEAR FREE TRAVEL WHEN ENGAGED WITH STARTER GEAR Starter Mounting Before installing starter motor make sure the starter mounting surface on the engine base is clean and free of oil 1 Install starter motor and tighten mounting cap screws just enough to hold starter in place 2 Remove spark plugs from the engine This allows free movement of the flywheel 3 Manually pull the starter pinion gear outward on its shaft until pinion gear teeth mesh completely with flywheel ring gear teeth 4 Measure the amount of free travel lash between the pinion gear teeth and the ring gear teeth Figure 5 If lash is too tight causing binding and slow starter operation or lash is greater than 0 035 inch 0 889 mm lash must be adjusted 5 Proper lash is 0 020 0
16. Standard torque values must not be used where those listed in Table 1 apply The engine assembly torques given here will assure proper tightness without danger of stripping threads All threads must be clean and lubricated with new engine oil before torquing Check all studs nuts and capscrews and tighten as required to keep them from working loose Refer to the PARTS MANUAL for the location of washers and capscrews TABLE 1 TORQUE TORQUE DESCRIPTION SPECIFICATION DESCRIPTION SPECIFICATION Ft Lb Nm Ft Lb Nm Gearcase 8 10 11 14 Other 1 4 Cylinder Block Cylinder Head Bolts Cold Stud and Nuts 1 9 10 12 Asbestos Gasket 16 18 22 24 Other 5 16 Cylinder Block Graphoil Gasket 14 16 19 22 Stud and Nuts 8 10 11 14 Rear Bearing Plate Screws 25 27 34 37 Oil 18 23 24 31 Starter Mounting Bolts 24 26 33 35 Intake Manifold Mounting Connecting Rod Bolt 14 19 Ay ioo vale i 6 10 8 14 Flywheel Cap Screw 50 55 67 75 OIL PUMD 7 9 10 12 Valve 1 2 1 3 Exhaust Manifold Mounting 9 11 12 15 Special Tools The following special tools are available from Onan For further information see TOOL CATALOG 900 0019 Valve Seat Driver Valve Guide Driver Oil Guide and Driver Combination Bearing Remover Main and Ca
17. THROTTLE STOP ON SCREW PLATE 5 1440 NIKKI CARBURETOR MARVEL SHEBLER CARBURETOR FIGURE 1 CARBURETOR ASSEMBLY 1 2 Reassembly and installation All other carburetors 1 BEND FLOAT TANG HERE Jo Aut 0 028 0 028 MINIMUM 0 712 0 712 mm FLOAT DROP D 0 213 5 41 mm Install needle valve and seat main jet and float assembly Make sure that float pivot pin is properly placed and that float moves freely without binding Gently push float tang down until needle just seats Measure float level Figures 2 3 4 Adjust float level if necessary Release float tang and measure float drop Figures 2 3 4 This is the distance from top of carburetor body to top of float When checking float level and float drop measure to float body not seam Position gasket on carburetor and attach carburetor sections together with screws Slide in throttle shaft and install plate using new screws Before tightening the screws the plate must be centered in the bore To do so back off the throttle stop screw as necessary and completely close the throttle lever Seat the plate by tapping with a small screwdriver then tighten screws Install the choke shaft and plate in the same manner Install idle adjustment screw throttle stop screw and fixed main jet plug or optional main fuel adjustment needle Mount carburetor on intake manifold and install assembly on engine Mount
18. air cleaner assembly Connect air intake hose breather hose fuel line vacuum line and throttle linkage Adjust carburetor and governor according to direc tions given in this section CARBURETOR BODY FIGURE 2 MARVEL SCHEBLER FLOAT LEVEL BEND FLOAT WALBRO TANG HERE 0 02 0 02 INCH TO ADJUST j NEEDLE AND SEAT CARBURETOR BODY FLOAT LEVEL ADJUSTMENT BEND FLOAT ARM MINIMUM HERE TO ADJUST FLOAT DROP NO FUEL FUEL LEVEL 0 25 INCH E WITH FUEL FS 1524 FIGURE 3 WALBRO FLOAT LEVEL ADJUSTMENT 0 394 10 0 mm NEEDLE BEND FLOAT ARM AND SEAT HERE TO ADJUST FLOAT LEVEL ADJUSTMENT NO FUEL WITH FUEL FIGURE 4 NIKKI FLOAT ADJUSTMENT NEEDLE AND SEAT BEND FLOAT TANG HERE TO ADJUST FUEL LEVEL 472 12 0 mm 0512 028 1 3 71 mm FLOAT LEVEL ADJUSTMENT WITH FUEL BEND FLOAT ARM HERE TO ADJUST MINIMUM FLOAT DROP 2913 7 4 mm NO FUEL FIGURE 5 NIKKI FLOAT LEVEL ADJUSTMENT WITH SEMI AUTOMATIC CHOKE AND LIMITED IDLE ADJUSTMENT SCREW PULSATING DIAPHRAGM FUEL PUMP Pulsating diaphragm fuel pumps or pulse pumps rely on changes in crankcase vacuum to create a pulsating movement of the pump diaphragm As the engine s pistons move outward a vacuum is created This vacuum is transmitted to the pump diaphragm causing it to pull back and suck fuel into the pump As the engine s pistons move inward crankcase vacuum
19. element will result engine damage Do not run engine without air cleaner element installed WING NUT COVER POLYURETHANE PRECLEANER PAPER AIR ELEMENT INTAKE BASE TUBE BREATHER TUBE M 1318 1 WASH 2 SQUEEZE DRY 3 COAT WITH OIL 4 INSTALL OVER PAPER ELEMENT FIGURE 11 AIR CLEANER ASSEMBLY 1 8 Ignition and Battery Charging IGNITION SYSTEM DESCRIPTION The engine is equipped with an automotive type battery ignition system Both spark plugs fire simultaneously thus the need for a distributor is eliminated IGNITION TIMING The timing is preset atthe factory Slight timing changes can be made by adjusting the points BREAKER POINTS The timing is adjusted during initial engine assembly and is fixed by the point gap adjustment To maintain maximum engine efficiency change the breaker points every 200 hours of operation Replacement and Adjustment Top Adjust Points 1 Remove spark plugs 2 Remove breaker box cover Rotate crankshaft clockwise facing flywheel until points are fully open 3 Remove condenser screw A and detach condenser lead and coil lead screw B See Figure 1 4 Remove two Allen screws C and lift breaker assembly from engine 5 Replace condenser and point assembly with new parts and reinstall using above procedure in reverse order of removal 6 Adjust point gap by rotating crankshaft clockwise facing flywheel by hand until the points are fully
20. end of the bearing bore Front cam bearing oil hole must line up with oiling hole in cylinder block Figure 20 Press in the rear camshaft bearing until pastthe ignition plunger hole Lubricate bearing surfaces with oil after installing New crankshaft main bearings are precision type which do not require line reaming or line boring after installation Use a press or a suitable driver to remove bearings Support casting to avoid distortion and to avoid damaging the bearing bore during removal and installation Before installing main bearings expand bearing bore by placing the casting in an oven heated to 200 F 94 C If practical cool the precision bearing to shrink it Before installing the front main bearing use the towelette included with the bearing kit to clean the outside of the bearing and bearing bore in the block Breathing vapor from towelette and AWARNING prolonged contact with skin can be harmful Use only well ventilated area and avoid prolonged contact with skin After allowing three to four minutes for drying apply the Locktite from the small tube to the mating surfaces of the bearing and the bearing bore Align the oil holes in the bearing with the oil holes in the bearing bore Figure 22 The oil passage should be at least half open Install the bearing flush with the block using the combination driver Wipe off excess Locktite around the bearing Allow at least one hour for hardening at room tempera
21. is shorted replace with a new one Figure 3 9 1 inspecting for an Open Circuit in Armature The most likely place to check for an open circuit is at the commutator riser bars Inspectfor loose connections on the points where the conductors are joined to the commutator bars COMMUTATOR BARS ES 1001 FIGURE 2 TESTING ARMATURE FOR GROUNDS HACK SAW BLADE p a a ES 1002 FIGURE 3 TESTING ARMATURE FOR SHORT CIRCUITS Housing Inspection Magnets are glued to inside of housing Magnets must be secure and free of cracks Brush Inspection brushes are worn shorter than 1 4 inch 6 35 mm replace them Check to see that brushes move smoothly in the brush holders Figure 4 0 25 INCH 635mm Bx WEAR LIMIT FIGURE 4 BRUSH WEAR LIMIT Pinion Gear If pinion gear is badly worn has broken teeth or pinion splined sleeve is damaged replace pinion gear and dust cover assembly If pinion gear is in good condition wipe armature shaft spline and pinion clean Starter Assembly 3 10 Before reassembling the starter wipe any dirt from parts with a clean cloth or blow with filtered compressed air Assemble brushes so that the chamfered side is away from the brush springs Make sure brush wires do not rub against the commutator or end cap Torque brush screws to a value of to 3 1 2 ft lbs 4 to 5 Nm Torque input stud to a value of 4 to 5 ft lbs 5 to 7
22. mesh quickly with flywheel ring gear and spin engine Once engine starts and solenoid opens the starter should disengage and stop If starter cranks engine slow or not at all check start circuit components Failure to crank is normally caused by low battery charge defective battery cables corroded or poor connections or low temperatures If after checking these variables starter continues to crank slowly starter must be removed and repaired Starter Disassembly 1 Remove the through bolts and separate the end cap the housing and the armature Figure 1 2 Disassemble the drive assembly and the drive end cap by loosening the self locking nut THROUGH BOLT PINION GEAR SEAL ARMATURE gt DUST STOP COVER NUT gt 3 oF HOUSING BRUSH SCREWS ES 1334 INPUT STUD NUT STARTER DISASSEMBLY END CAP FIGURE 1 inspection of Parts Testing Armature for Grounds Touch armature shaft or core and the end of each commutator bar with a pair of ohmmeter leads Figure 2 the ohmmeter reading is low itindicates a grounded armature Replace grounded armature Testing Armature for a Short Circuit Use a growler for locating shorts in the armature Place armature in growler and hold a thin steel blade e g hacksaw blade parallel to the core and just above it while slowly rotating armature in growler A shorted armature will cause the blade to vibrate and be attracted to the core If armature
23. of the cylindner regularly during honing A dia bore gauge is the easiest method but a telescoping gauge can be used Check size at six places in bore measure twice at top middle and bottom at 90 degree angles 6 Crosshatch formed by the stones shouid form an included angle of 23 degrees This can be achieved by moving the rotating hone 250 to 450 rpm up and down in cylinder bore about 40 times per minute 7 Clean cylinder bores thoroughly with soap water and clean rags A clean white rag should not become soiled on wail after cleaning is complete Do not use a solvent or gasoline since they wash oil from the walls but leave the metal particles 8 Dry crankcase and coat it with oil PRODUCE CROSS MATCH SCRATCHES Deglazing Cylinder Bores Degiaze the cylinder bores if there are no scuff marks and no wear or out of round beyond specifications before installing new rings Deglazing gives a fine finish but does not enlarge cylinder diameter so the original pistons with new rings may still be used The reason for deglazing a cylinder is to provide cavities to hold oil during piston ring break in 1 Wipe cylinder bores with a clean cloth which has been dipped in clean light engine oil 2 Use a brush type deglazing tool with coated bristie tips to produce crosshatch pattern in the cylinder bore 3 Use a slow speed drill to drive the deglazing tool Move deglazing 100 up and down in cylinder 10 to 12 complete stro
24. open Set the point gap using flat feeler gauge at 0 021 inch 0 53 mm by adjusting the Allen screw D inward or outward Figure 1 0 021 inch point gap is equivalent to 21 BTC Make sure feeler gauge is clean and free of any grease oil or dirt 7 Replace breaker box cover coil wire spark plugs and spark plug cables Replacement and Adjustment Side Adjust Points 1 Remove spark plugs 2 Remove breaker box cover Rotate crankshaft clockwise facing flywheel until points are fully open 3 Referto Figure 1 Remove mounting nut E and pull points from box just far enough so screw B can be removed and leads disconnected 8 1 4 Remove screw F replace condenser 5 Replace points with a new set but do not com pletely tighten mounting nut E 6 Insert a screwdriver in notch G on right side of points Set point gap using flat feeler gauge at 0 021 inch 0 53 mm by moving points up or down Figure 1 A 0 021 inch point gap is equivalent to 21 BTC Tighten mounting nut and recheck gap Make sure feeler gauge is clean and free of any grease oil or dirt 7 Replace breaker cover spark plugs and spark plug cables 9 2 cM NE 021 INCH GAP 0 53 mm ONE Cif 14 4 ED o MOUNTING SCREWS p TOP ADJUST POINTS D ew SIDE ADJUST POINTS FIGURE 1 SETTING POINT GAP Continuity Test As a check for
25. over by hand 4 Place socket wrench on the flywheel capscrew and rotatethe crankshaft in a clockwise direction until the left intake valve viewed from flywheel end opens and closes Continue turning the crankshaft until the TC mark on the flywheel is lined up with the TC mark on the gear cover This should place the left piston 1 at the top of its compression stroke Verify that the left intake and exhaust valves are closed and there is no pressure on the valve lifters 5 The correct feeler gauge for the valve adjustment see SPECIFICATIONS should pass freely between valve stem and tappet a 0 002 inch 0 05 mm thicker gauge should not Figure 1 6 To correct the valve clearance use a 7 16 inch open end wrench to turn the adjusting screw to obtain the correct clearance The screw is self locking and will stay where it is set A 9 16 inch 14 mm open end wrench is required to hold the tappet while turning the adjusting screw 7 To adjust valves on the right hand cylinder turn engine one complete revolution and again line up mark the flywheel and the TC mark on the gear cover Then follow adjustment procedure given for left hand cylinder 8 Replace all parts removed in Step 2 Tighten all screws securely Torque manifold bolts to spec ified torque NOTE USEASTANDARD AUTOMOTIVE TYPE WRENCH TO ADJUST THE TAPPETS VALVE SEAT VALVE SPRING INSERT VALVE GUIDE A VALVE CLEARANCE VALVE RETA
26. overhauling a carburetor consists of disas sembly a thorough cleaning and replacement of worn parts Carburetor overhaul kits are available General instructions for overhauling a carburetor are given below Carefully note the position of all parts while removing to assure correct placement when reassem bling Read through all the instructions before beginning for a better understanding of the procedures involved Carburetor components are shown in Figure 1 AWARNING Ignition of fuel can result in severe personal injury or death Do not smoke or allow any spark pilot light or arcing equip ment near the fuel system Removal 1 Remove air cleaner and hose 2 Disconnect governor and throttle linkage choke control and fuel line from carburetor 3 Remove the four intake manifold cap screws and lift complete manifold assembly from engine 4 Remove carburetor from intake manifoid Disassembly Nikki limited idle adjustment 1 Remove main jet and idle adjustment needle 2 Remove attaching screws and separate upper and lower carburetor sections 3 Carefully note position of float assembly parts then puli out retaining pin and float assembly 4 Remove needle valve Disassembly All other carburetors 1 Remove throttle and choke plate retaining screws and plates Pull out throttle and choke shafts 2 Remove main adjustment and idle adjustment needles 3 Remove attaching screws and separate upper and lower
27. to damage the gear cover oil seal Figure 9 OVERNOR ARM AOLE TUN GOVERNOR SHAFT ROTATE GOVERNOR CUP SO THAT ROLL PIN FITS INTO THE METAL LINED HOLE OR PLASTIC BUSHING IN THE CUP GOVERNOR SHAFT YOKE Smooth Side Toward Cup IF FEELER WILL ENTER HOLE 1 2 BALL HAS FALLEN OUT FIGURE 9 GEAR COYER ASSEMBLY WHEN GOVERNOR IS PROPERLY ASSEMBLED THE DIMENSION SHOWN ON DRAWING WILL BE AS INDICATED CUP GOVERNOR FLYBALL 5 BALL GOVERNOR C 1107 6 BALL GOVERNOR 8 BALL GOVERNOR 5 1238 FLYBALL LOCATIONS FIGURE 10 GOVERNOR CUP DETAILS GOVERNOR CUP With the gear cover removed the governor cup can be taken off after removing the snap ring from the camshaft center pin Catch the flyballs while sliding the cup off Figure 10 Replace with a new part any flyball which is grooved or has a flat spot the ball spacer if its arms are worn or otherwise damaged the gear spacer assembly if loose on gear hub and the governor cup if the race surface is grooved or rough The governor cup must be a free spinning fit on the camshaft center pin but without any excessive play If replacing the ball spacer be sure to position it so an arm is lined up with the space on the camshaft gear if your camshaft gear does not have a space in it disregard this paragraph the ball spacer arm is not lined up with the space in the camshaft gear a flyball can slip into the space and cau
28. 010 inches 0 51 0 25 Loosen and adjust the starter motor as necessary to obtain the correct setting 6 Remove flywheel and torque starter mounting capscrews to 24 to 26 ft lbs 33 to 35 Nm Failure to torque starter bolts ACAUTIO properly can cause starter failure and ring gear damage Torque starter bolts to correct values when installing 7 Install flywheel spark plugs blower housing and cylinder air housings For correct cylinder air housing installation required on some models refer to Cylinder Air Housing Clearance STARTER MOTOR PINION GEAR ES 1003 FIGURE 5 CHECKING STARTER GEAR LASH 9 2 Engine Disassembly DISASSEMBLY ASSEMBLY When complete engine disassembly is necessary first remove all complete assemblies Individual assem blies such as fuel pump and carburetor can be disassembled and repaired at another time Suggested Disassembly Order 1 Drain crankcase 2 Disconnect all exhaust lines and electrical lines 3 Remove engine from its mountings and place on a suitable bench or work stand 4 Remove all housings shrouds blower housings etc 5 Remove flywheel using a puller 6 Remove the gear cover being careful to protect the seal from keyway damage 7 Remove the crank gear using a gear puller and ring 8 Remove all accessories such as oil filter starter intake manifold fuel lines spark plugs etc 9 Remove breaker point box 10 Remove oil base oil pum
29. 3 Disconnect plug from regulator rectifier and test the AC voltage atthe plug with engine running near 3600 rpm If AC voltage reads more or less than specified in Table 1 proceed to step 4 If AC voltage is as specified but DC voltage is low replace regulator rectifier 4 Use the Rx1 scale on the ohmmeter for detecting opens in the stator unit not running Disconnect plug from regulator rectifier Connect ohmmeter test leads to wires coming from stator Refer to Table 1 for resistance specifications If resistance is not as specified replace stator If stator resistance readings are as specified and windings are not shorted to ground low AC voltage may be due to loss of magnetism If so blower wheel assembly must be replaced Check for magnetism with steel too blade Next connect one ohmmeter test lead to stator wire connect the other test lead to ground If the ohmmeter reading is low the stator is grounded and must be replaced TABLE 1 TESTING 15 AND 20 AMPERE SYSTEMS 1 4 Alternator and Wiring BASIC TEST PROCEDURE 2 Battery Voltage after unit is running 3 to 5 minutes 13 6 to 14 7 VDC 13 6 to 14 7 VDC 3 Alternator Stator Ohmmeter reading from stator and Wiring output unit not running 0 1 to 0 2 Ohms 0 3 to 0 5 Ohms Measure AC open circuit stator voltage with unit running Measure between iwo stator leads with plug disconnected and unit running at approximately 3600 rpm
30. CE identify your model by referring to the MODEL and SPEC specification NO as shown on the unit nameplate Always use this number and the engine serial number when making reference to your engine How to interpret MODEL and SPEC NO 018 1 W 8 a 0 wn gt Factory code for general identification of basic engine series Cubic inch displacement Engine duty cycle Fuel required G gasoline Cooling system description A air cooling pressure BHP rating 7 Factory code for designated optional equipment if any 8 Specification spec letter which advances with factory production modifications gt Oo INCORRECT SERVICE OR REPLACMENT OF PARTS CAN RESULT IN SEVERE PERSONAL INJURY AND OR EQUIPMENT DAMAGE SERVICE PERSONNEL MUST BE QUALIFIED TO PERFORM ELECTRICAL AND OR MECHANICAL SERVICE Redistribution or publication of this document by any means is strictly prohibited Specifications This manual contains SI metric equivalents that follow immediately in parentheses SPECIFICATION Number of Cylinders Bore Stroke Displacement Compression Ratio Power at Rated Speed 3600 rpm Oil Capacity Without Filter Oil Filter Capacity Valve Clearance Cold intake Exhaust Spark Plug Gap Breaker Point Gap Ignition Timing static setting Cylinder Compression after the U S customary units of measure
31. INER em VALVE SYSTEM A properly functioning valve system is essential for good engine performance All engines utilize an L head type valve design as shown in Figure 1 Access to the valve system can be obtained by removing the cylinder heads and the valve covers on top of the engine valve spring compressor must be used to remove valves from the cylinder block A valve stem seal is sometimes used on the intake valve guides of some engines This seal must be replaced each time the valve is removed Place valves springs retainers and tappets in a rack as they are removed from cylinder block so they can be identified and reinstalled in their original locations Discard old valve stem seals and replace with new ones during assembly Use the following procedures to inspectand service the valve system Inspection Clean carbon from the valves valve seats valve guides and cylinder block Valves Check the valve face for evidence of burning warpage out of round and carbon deposits Burning and pitting are caused by the valve failing to seat tightly This condition is often caused by hard carbon particles on the seat It may also be due to weak valve springs insufficient tappet clearance warpage and misalignment gt M uu CLEARANCE VT 1000 VALVE ADJUSTING SCR VALVE qr VALVE WASHER LOCK 4 Bd eh O RING VALVE 2 INTAKE VALVE STEM _ ONLY SEAL VALVE ROTATOR OPTIONAL VT 1005
32. S rebore and hone cylinder to the next oversize F Reading A compared to reading C and reading B compared to reading D indicate whether or not cylinder is out of round If out of round exceeds that specified in DIMENSIONS AND CLEARANCES the cylinders must be rebored and honed to the next oversize reboring machine is used when going to oversize pistons The following repair data covers honing to oversize by use of a hone Reboring the Cylinder Rebore and hone engine whenever cylinder bore is worn damaged out of round or if cylinder taper exceeds specifications A worn cylinder bore should be resized to the smallest standard oversize diameter at which it will clean up The final finish and bore diameters should then be obtained by honing Final bore diameter should equal the standard diameter added to the oversize ACAUTION mproper boring will result in engine damage Boring must be done by qualified mechanics 10 11 TOP END OF CYLINDER annm tm BOTTOM OF RING TRAVEL FIGURE 18 METHODS OF MEASURING THE DIAMETER OF A CYLINDER BORE After boring to the correct oversize cylinder bore dimension piston and ring clearance should be appropriate There is no need to adjust or fit pistons and rings When reboring cylinders take the following pre cautions 1 Make sure cutting tool is properly ground before using it 2 Besur
33. ULL GOVERNOR SHAFT YOKE FIGURE 8 GOVERNOR ADJUSTMENTS On side pull governors the governor spring is set by the factory in the third hole of the governor arm Third hole from pivot On front pull governors the governor spring is set by the factory in the second hole of the governor arm adapter Second hole from pivot To increase sensitivity move spring loop into a hole closer to the pivot To decrease sensitivity move spring loop into a hole farther away from the pivot After sensitivity has been set recheck the low Speed rpm setting Adjust mecessary CARBURETOR ADJUSTMENTS The carburetor idle and main mixture were set for maximum efficiency at the factory and should normally not be disturbed If adjustments seem necessary first be sure the ignition system is working properly and governor sensitivity is properly adjusted If adjustmentis needed proceed as follows and refer to Figures 9 and 10 A CAUTION Overtightening the mixture adjustment screw will cause carburetor damage Turn mixture adjustment screw in only until light tension can be felt 1 These initial adjustments will permit engine to start and warm up prior to final adjustment A Marvel Schebler carburetor mixture screw settings Turn both mixture screws in until lightly seated then back the idle mixture screw out 1 turn and the main mixture screw out 1 1 4 turns B Walbro carburetor mixture screw settings Turn idle mixture screw in until lig
34. ation needed by engine mechanics for troubleshooting servicing repairing or over hauling the engine If a major repair or an overhaul is necessary Onan recommends that a competent mechanic either do the job or supervise and check the work of the mechanic assigned to do the job to ensure that all dimensions clearances and torque values are within the specified tolerances Use the table of contents for a quick reference to the separate engine system sections The troubleshooting guide is provided as a quick reference for locating and correcting engine trouble The illustrations and procedures presented in each section apply to the engine listed on the cover The flywheel blower end of the engine is the front end so right and left sides are determined by viewing the engine from the front The disassembly section contains major overhaul procedures for step by step removal disassembly inspection repair and assembly of the engine components The wiring diagram shows how the engine electrical components are interconnected A parts catalog contains detailed exploded views of each assembly and the individual piece part numbers and their proper names for ordering replacement parts Use only Genuine Onan replacement parts to ensure quality and the best possible repair and overhaul results When ordering parts always use the complete Model and Spec number as well as the Serial number shown on the nameplate ENGINE MODEL REFEREN
35. azard Table of Contents TITLE PAGE General 1 1 Specifications 2 1 Dimensions and Clearances 3 1 Assembly Torques and Special Tools 4 1 Engine Troubleshooting 5 1 Oil System 6 1 Fuel 7 1 Ignition and Battery Charging 8 1 Starting 9 1 Engine 10 1 Redistribution or publication of this document by any means is strictly prohibited General Information KNOW YOUR ENGINE Read this manual carefully observing all WARNINGS and CAUTIONS Operating instructions adjustments and periodic maintenance procedures are given so you the owner can keep your unit running like new and expect many years of dependable service from it Remember any machine regardless of design or type will perform only in relation to the service it receives Regularly scheduled maintenance lowers operating costs INTRODUCTION This manual deals with specific mechanical and electrical inform
36. be used when valve is reinstalled Removing a valve after installing valve ACAUTION stem seal can cause seal damage Do not allow valve stem groove to come in contact with valve stem seal after installation Valve Spring Check valve springs for cracks worn ends distortion and tension If spring ends are worn check valve spring retainer for wear Check forspring distortion by placing spring ona flat surface nexttoa square Measure height of spring and rotate it against square edge to measure distortion If distortion exceeds 0 06 inch 1 5 mm replace spring Check spring tension at the installed height for both the valve open and closed position using an accurate valve spring tester Replace any valve spring that is weak cracked worn or distorted Valve Rotators Positive type valve rotators prolong valve life and decrease valve repairs When func tioning properly the vaive is rotated a fraction of a turn each time it opens While at open position the valve must rotate freely There is no easy way to determine if a valve rotator is good or bad Onan recommends that valve rotators be replaced at each major overhaul or if a build up of carbon is noted on valve face and valve seat Valve Seats Inspect valve seat inserts If seats are loose cracked or severely pitted new ones must be installed Remove valve seat inserts using a valve seat removal tool If valve seat insert bores in cylinder block are damaged or worn so that a pre
37. buretor section 4 install idle adjustment screw throttle stop screw and fixed main jet plug 5 Mount carburetor on intake manifold and install assembly on engine 6 Mount air cleaner assembly Connect air intake hose breather hose fuel line vacuum line and throttle linkage 7 Adjust carburetor and governor according to direc tions given in this section 2 CHOKE SHAFT FLOAT ASSEMBLY FLOAT ASSEMBEY FUEL INLET VALVE THROTTLE SHAFT NEEDLE VALVE b 25 MAIN JET MAIN FUEL ADJUSTMENT IDLE ADJUSTMENT THROTTLE STOP THROTTLE NEEDLE SCREW ANE SHAFT 9 AND LEVER CAP IDLE ADJUSTMENT me 4 A NEEDLE THROTTLE PLATE THROTTLE STOP CREW FS 1440 3 NIKKi CARBURETOR WITH SEMI AUTOMATIC CHOKE AND LIMITED IDLE ADJUSTMENT SCREW WALBRO CARBURETOR i PLATE CHOKE VALVE CHOKE SHAFT __ CHOKE SHAFT OS f SLEEVE ASSEMBLY FLOAT GM FLOAT VALVE ASSEMBLY 8 ASSEMBLY FLOAT AND LEVER d ASSEMBLY Sa EC 2 MAIN ADJUSTING OPTIONAL MAIN vut 7 FUEL ADJUSTMENT AM E Ue BRE e 3 M FIXED E IDLE ADJUSTING MAIN JET ea a 7 NEEDLE gt Mn gt AA vo REUS THROTTLE STOP ens 474 SCREW eL ie E IDLE ADJUSTMENT CARBURETOR THROTTLE SHAFT a NEEDLE INLET PLATE AND LEVER gt FUEL INLET THROTTLE VALVE C2
38. carburetor sections 4 Carefully note position of float assembly parts then pull out retaining pin and float assembly 5 Remove needle and unscrew needle valve seat Cleaning and Repair 1 Soak all metal components not replaced in car buretor cleaner Do not soak non metal floats or other non metal parts Follow the cleaning manu facturer s recommendations 2 Cleanall carbon from the carburetor bore especially where the throttle and choke plates seat Be careful not to plug the idle or main fuel ports 3 Dry outall passages with low pressure air 35 PSI Avoid using wire or other objects for cleaning which may increase the size of critical passages 4 Check the condition of the adjustment needle replace if damaged Replace float if loaded with fuel or damaged 5 Check the choke and throttle shafts for excessive play in their bore This condition may necessitate replacement of the carburetor 6 Replace old components with new parts Reassembly and Installation Nikki limited idle adjustment 1 Install needle valve main jet and float assembly Make sure float pivot pin is properly placed and float moves freely without binding 2 Turn carburetor on its side and measure float level Figure 5 Adjust float level only if necessary Measure float drop the distance from the top of carburetor body to top of float Adjust only if necessary 3 Position gasket on lower carburetor section and install upper car
39. d of the crankshaft Line up notches of thrust washer with lock pins before tightening end plate or lock pins will be damaged CRANKSHAFT ENDPLAY After the rear bearing end plate has been tightened using the torque recommended in ASSEMBLY TOR QUES check the crankshaft endplay Figure 23 If there is too much endplay see DIMENSIONS AND CLEARANCES for minimum and maximum endplay remove the rear bearing end plate and add a shim Figure 21 between the thrust washer and plate Reinstall the end plate making sure the thrust washer and shim notches line up with the lock pins Torque and recheck endplay of the crankshaft MEASURE ENDPLAY HERE REFER TO DIMENSIONS ANO CLEARANCES FIGURE 23 CRANKSHAFT ENDPLAY 10 14 CHECKING CONNECTING ROD BEARING CLEARANCE WITH PLASTIGAUGE 1 Make certain that all parts are marked or identified so that they are reinstalled in their original positions 2 Place a piece of correct size Plastigauge in the bearing cap the full width of the crankshaft rod surface and about 1 4 inch 6 35 mm off center Figure 24 3 Rotate the crank about 30 degrees from bottom dead center and reinstall the bearing cap tighten the bolts to the torque specified in ASSEMBLY FOR SC act Mug TORQUES AND SPECIAL TOOLS Do not turn the M sen crankshaft 4 Remove bearing cap The flattened Plastigauge will be found adhering to either the bearing cap or crankshaft 5 Compare flatten
40. dge and a feeler gauge Cylinder Bore Inspection inspect cylinder bores for scuffing scratches wear and scoring If cylinder bores are scuffed scratched scored or worn they must be rebored and honed for the next oversize piston When the appearance of cylinder bores is good and there are no scuff marks check cylinder bore for wear or out of roundness as follows 1 Check cylinder bore for taper out of round and wear with a cylinder bore gauge telescope gauge or inside micrometer These measurements should be taken at four places top and bottom of piston ring travel parallel and perpendicular to axis of crankshaft 2 Record measurements taken at top and bottom of piston travel as follows Figure 18 10 10 A Measure and record as A the cylinder bore diameter parallel to crankshaft near the top of cylinder bore where greatest amount of wear OCCUIS B Also measure and record as B cylinder bore diameter parallel to crankshaft at the bottom of piston travel C Measure and record as C cylinder bore diameter perpendicular to crankshaft near the top of cylinder bore where greatest amount of wear occurs D Also measure and record as D cylinder bore diameter perpendicular to crankshaft at the bottom of piston travel E Reading A subtracted from reading B and reading C subtracted from reading D indicates cylinder taper If cylinder taper exceeds that specified in DIMENSIONS AND CLEARANCE
41. e VALVE SPRINGS INTAKE AND EXHAUST Valve Spring Free Length Approx Valve Spring Length Valve EM Valve S be En COS RUN Spring Load 9 1 375 inch Valve Closed Spring Load 1 125 inch Valve Open GEAR BACKLASH TNO dc MC LTD Oil Pump GEN VR EAE ACE 3 2 MINIMUM inches mm 0 00004 0 001 0 0002 0 005 0 6875 17 46 0 003 0 076 0 010 0 254 0 3425 8 70 0 0010 0 025 1 4395 36 56 1 470 37 34 0 031 0 787 0 3410 8 661 0 0025 0 064 1 189 30 20 1 192 30 28 0 031 0 787 0 344 8 74 0 7475 18 99 0 7500 19 05 0 0015 0 038 1 662 1 125 1 375 38 Ib 17 kg 71 Ib 32 kg 0 002 0 051 0 002 0 051 MAXIMUM Inches 0 00064 0 0007 0 6877 0 008 0 020 0 3430 0 0025 1 4405 1 471 0 047 0 3415 0 040 1 190 1 193 0 047 0 345 0 7480 0 7515 0 003 42 21 28 58 34 93 42 16 79 ib 0 003 0 005 mm 0 016 0 018 17 47 0 203 0 508 8 71 0 064 36 59 37 36 1 194 8 674 0 102 30 23 30 30 1 194 8 76 19 00 19 09 0 076 19 kg 36 kg 0 076 0 127 Assembly Torques The torque values given in Table 1 have been deter mined for specific applications
42. ed Plastigauge with the graduations on Plastigauge envelope to determine clearance The number within the matching graduation on the envelope indicates total clearance in millimetres or thousandths of an inch FIGURE 24 MEASURING BEARING CLEARANCE REAR BEARING PLATE MOUNTING FACE THIS SURFACE SHOULD BE OIL SEAL OF GEAR COVER CLEANED OF ALL OLD SEALING COMPOUND BEFORE INSTALUNG SEAL 645 INCH 16 4 mm THIS GEAR COVER SURFACE 740077 DRIVE OR PRESS OIL SHOULD BE CLEANED OF ALL SEAL TO SHOULDER OLD SEALING COMPOUND OF THE PLATE BORE BEFORE INSTALLING SEAL GEAR COVER GEAR COVER SEAL REAR BEARING PLATE OIL SEAL LS 1163 FIGURE 25 GEAR COVER AND REAR BEARING PLATE OIL SEALS 10 15 OIL SEALS The bearing plate must be removed to replace the oil seal Figure 25 Drive the oil seal out from the inside Before installing seals fill the space between lips with a multi purpose grease This will improve sealing When installing the gear cover oil seal tap the seal inward until itis 645 inch 16 4 mm from the front of the gear cover When installing the bearing plate oil seal tap the seal into the bearing plate bore to bottom against the shoulder in the plate bore Use a seal expander or place a piece of heavy paper around the end of the crankshaft when replacing the bearing plate to avoid damaging the seal Remove the paper as soon as the plate is in place PISTON ASSEMBLY 1 Lubricate all parts wi
43. essure gauge level with pump outlet record pressure gauge reading 11 Shut engine off and remove pressure gauge hose from fuel pump outlet Connect fuel outlet line to fue pump Repair or replace the fuel pump if test readings are not within the values specified in TABLE 1 TABLE 1 PULSE PUMP TEST SPECIFICATIONS Engine Pump inlet Pump Outlet Speed Vacuum Pressure Minimum Minimum Low Idle 2 6 inches 1 7 psi of mercury High Idle 2 6 inches 1 7 psi of mercury Fuel Pump Repair 1 Remove the vacuum and fuel lines Inspect the lines for wear cracking or brittleness Replace as necessary 2 To insure correct alignment when reassembling scribe a line across the outer pump parts on each end of the pump PUMP COVER GASKET ASSEMBLY SCREWS 3 Holding the pump carefully remove the assembly screws Figure 6 4 Carefully pull apart the pump sections and check for worn or damaged parts Replace with new parts where necessary or install pump repair kit 5 Check and unclog if necessary the small diaphragm air bleed hole located behind the pump diaphragm in the pump base ACAUTION A clogged diaphragm air bleed E hth hole can cause diaphragm wear and seal damage Be sure air bleed hole is unclogged Replace gaskets and reassemble pump Reinstall assembly screws checking the scribe marks for proper alignment Reinstall fue and vacuum lines and clamps A WARNING improper fuel pump parts align
44. etop of engine block is smooth and deposit free 3 Clean base of boring bar before bar is set up Deposits under boring bar will cause it to tilt and the cytinder will be distorted after boring 4 Make an initial rough cut followed by a finish cut Then hone cylinder bore to the specified oversize Honing Cylinders Using Precision Hones Refer to hone manufacturer s recommended grit size to produce specified surface finish of 20 to 40 RMS Too rough of a finish will wear out the rings and too smooth of a finish can retard piston ring seating 1 Position block solidly for either vertical or hori zontal honing Use either a drill press or heavy duty drill which operates at approximately 250 to 450 rpm 2 Follow hone manufacturer s instructions for the use of oil or lubricant on stones Do not use lubricants with a dry hone 3 Insert hone bore and adjust stones to fit snugly to the narrowest section When adjusted cor rectly the hone should not shake or chatter tn cylinder bore but will drag freely up and down when hone 15 not running 4 Connect drill to hone and start drill Feel out bore for high spots which cause an increased drag on stones Move hone up and down in bore with short overlapping strokes about 40 times per minute Usually bottom of cylinder must be worked out first because it is smaller As cylinder takes a uniform diameter move hone up and down all the way through cylinder bore 5 Check diameter
45. haust gases to heat a compartment Make sure that your exhaust system is free of leaks Ensure that exhaust manifolds are secure and are not warped by bolts unevenly torqued Exhaust Gas is Deadly Exhaust gases contain carbon monoxide a poisonous gas that can cause unconsciousness and death It is an odorless and colorless gas formed during combustion of hydrocarbon fuels Symptoms of carbon monoxide poisoning are Vomiting Muscular Twitching Throbbing in Temples e Dizziness Headache Weakness and Sleepiness If you experience any of these symptoms get out into fresh air immediately shut down the unit and do not use until it has been inspected The best protection against carbon monoxide inhalation is proper installation and regular frequent inspections of the complete exhaust system If you notice a change in the sound or appearance of exhaust system shut the unit down immediately and have it inspected and repaired at once by a competent mechanic Cooling System Coolants under pressure have a higher boiling point than water DO NOT open a radiator pressure cap when coolant temperature is above 212 F 100 C or while engine is running Keep the Unit and Surrounding Area Clean Makesurethatoily rags are notlefton or near the engine Remove all unnecessary grease and oil from the unit Accumulated grease and oil can cause overheating and subsequent engine damage and present a potential fire h
46. htly seated then back idle mixture screw out 1 1 8 turns On engines equipped with main fue adjustment turn main mixture screw in until lightly seated then back the main mixture screw out 1 1 2 turns Nikki carburetor mixture screw settings Turn idle mixture screw in until lightly seated then back idle mixture screw out 3 4 turn On MAIN FUEL HIGH SPEED ADJUSTMENT THROTTLE IDLE FUEL STOP ADJUSTMENT SCREW SIDE VIEW REAR VIEW MARVEL SCHEBLER CARBURETOR THROTTLE STOP SCREW N IDLE FUEL MAIN FUEL ADJUSTMENT ADSUSTMENT FS 1002 WALBRO CARBURETOR engines equipped with main fuel adjustment main mixture screw in until lightly seated then back the main mixture screw out 1 1 4 to 1 1 2 turns D Nikki carburetor with semi automatic choke and limited idie adjustment screw No initial mixture adjustments are required When replacing idle mixture screw turn in until lightly seated then turn screw back out 1 1 4 turns Replace limiter cap with the plastic stop approximately centered Start the engine and allow it to warm up thoroughly at least 10 minutes Some equipment manufacturers may require higher throttle stop speed and governor low speed rpm settings Refer to equipment manufacturer s Opera tors Manual for the correct rpm settings When rpm settings are not specified by the equipment manu facturer use the rpm settings listed in steps 3 through 7 Movetheengine speed control t
47. ing on ohmmeter Place ohmmeter leads inside of spark plug cable holes Figure 6 Secondary resistance should read 12 500 15 400 ohms 4 if any of the above conditions are not met replace coil OHMMETER FIGURE 6 COIL TEST STATOR FLYWHEEL VOLTAGE REGULATOR ES 1333 B AC B AC RE 15 AMP 20 AMP VOLTAGE REGULATOR CONNECTIONS TO STARTER AND IGNITION TO BATTERY BATTERY JUMP STARTING Occasionally it may be necessary to jump start charge a weak battery using charged booster battery If jump starting is necessary the following procedure 1 recom mended to prevent starter damage battery damage and personal injuries Overcranking the engine can cause ACAUTION starter damage Allow 5 minutes for starter to cool if engaged for longer than 30 seconds 1 Disconnect engine load 2 Use a battery of the same voltage 12V as is used with your engine 3 Attach one end ofthe positive booster cable red to the positive terminal of the booster battery Attach the other end of the positive cable to the positive terminal of your engine battery 4 Attach one end of the negative booster cable black to negative terminal of booster battery Attach other end of negative cable to solid chassis ground on your engine A WARNING Electrical arcing can cause severe personal injury Do not allow positive and negative cable ends to touch 5 Jump starting in any o
48. is reduced and the diaphragm return spring pushes the pump diaphragm forward forcing fuel through the pump outlet Fuel Pump Test Procedure Before testing make certain that fuel pump vacuum line connections are tight and free of leaks 1 Operate engine at an idle for five minutes to ensure that carburetor is full of fuel 2 Shut engine off and remove fuel inlet line from fuel pump Ignition of fuel can result in severe personal injury or death Thoroughly clean up any spilled fuel 3 10 1 4 Connect a vacuum gauge to fuel pump inlet using a piece of fuel hose with clamps Start engine and allow to idle for at least five seconds Record vacuum gauge reading Move throttle control to high idle position Wait at least five seconds and record vacuum gauge reading Shut engine off and remove vacuum gauge hose from fuel pump inlet Connect fuel inlet line to fuel pump Remove fuel outlet line from fuel pump ignition of fuel can result in A WARNING bs severe personal injury or death Thoroughly clean up any spilled fuel Connecta pressure gauge to fuel pump outlet using a piece of fuel hose with clamps Start engine and allow to idle for at least five seconds While holding pressure gauge level with pump outlet record pressure gauge reading Move throttle control to high idle position and allow engine to run for at least five seconds While holding pr
49. kes rapidly enough to obtain a crosshatch pattern Figure 19 AVOID THIS FINISH FOR FAST RING SEATING FIGURE 19 CROSS HATCHING improper cylinder cleaning will ACAUTION result in engine damage Do not use gasoline solvents or commercial cleaners to clean cylinder bores 4 Clean cylinder bore thoroughly with soap water and clean rags Continue cleaning until a clean white rag shows no discoloring when wiped through cylinder bore CRANKSHAFT Clean crankshaft thoroughly and inspect journals for scoring chipping cracking or signs of overheating If crankshaft has overheated is scored or excessively worn reconditioning or replacement will be required Examine bearing journals for cracks if overheating has occurred Measure crankshaft main bearing and connecting rod journals at several places on their diameter to check for roundness and taper The only recommended method of reconditioning the crankshaft is regrinding as required to accommodate undersize bearings Metalizing of bearing journals is not recommended If regrinding of crankshaft journals is necessary the work should be done by a reputable machine shop that has suitable equipment to handle precision work of this type Undersize main bearings are available in sizes of 0 010 0 020 and 0 030 inch Undersize connecting rods are available in sizes of 0 010 0 020 0 030 and 0 040 inch Whenever making major repairs on the engine always inspect the d
50. m Combination Bearing Driver Main and Cam Fiywheel Puller Redistribution or publication of this document by any means Is strictly prohibited Engine Troubleshooting GASOLINE ENGINE TROUBLESHOOTING GUIDE CAUSE STARTING SYSTEM gt IGNITION SYSTEM Wrong Spark Piug Gap Worn Poin s or Improper Gap Setting Bad Ipnition Coi Consense Fauity Spark Plug Wires FUEL SYSTEM Dirty Carbureto Dirty Air Cleaner fe fet O A fol BONES el Jet peo 81 1 LH ejeje je jei lef iej ENED ENAN Lidii eleje INTERNAL ENGINE jet f lejo a 114141110 101111 Tej je I1 wong Bear p COOLING SYSTEM AIR COOLED ee ee eer LLL LT A or 0 15 5 111111 4 1 je Biown Head LUBRICATION SYSTEM Defecsive Gauge Too Li prt or 19 91 Li 141 1 Dirty Crankcase Breathe Va ve THROTTLE AND GOVERNOR tt tT LLL LE dee 11 vintage Out of Aciostmen TEIL DELL
51. n rings from the piston with a piston ring spreader Figure 13 Remove the piston pin retainer and push the piston pin out FIGURE 13 REMOVING PISTON RINGS 7 Remove dirt and deposits from the piston surfaces with an approved cleaning solvent Clean the piston ring grooves with a groove cleaner or the end of a piston ring filed to a sharp point Figure 14 Care must be taken not to remove metal from the groove sides A CAUTION Improper piston cleaning can cause piston damage Do not use caustic cleaning solvent or wire brush for cleaning pistons When cleaning the connecting rods in solvent be sure to include the rod bore Blow out all passages with compressed air FIGURE 15 CHECKING RING SIDE CLEARANCE with deep nicks signs of fractures scored bores or bores out of round more than 0 002 inch 2 Use anew piston pin to check connecting rod for wear A push fit clearance ts required and varies from engine to engine If a new piston pin falls through a dry rod pin bore as a result of its own weight replace the rod 82 FIGURE 14 PISTON GROOVE CLEANING Fitting Pistons Inspection 1 Proper piston tolerances must be maintained l for satisfactory operation Follow the procedures given below when inspecting pistons gno connecting Tods 2 Refer to DIMENSIONS AND CLEARANCES SECTION to determine where to measure piston to be sure the total clearance follows speci fications Piston Inspection
52. nd eliminate the danger of seat loosening in the bore valve seat must be staked insert valve seat staker into valve seat or guide in cylinder block Using a lead hammer strike the staking tool a sharp blow to wedge new valve securely in place It will be necessary to refinish valve seat inserts before installing valves TAPPETS Very little wear takes place on tappet diameters or in tappet bores If the clearance between tappet and bore in cylinder block exceeds specifications replace the tappet Inspect the tappet faces which contact camshaft lobes for roughness scuffing or concave wear Replace any worn tappets If tappets are worn inspect camshaft for wear VALVE FACE AND SEAT GRINDING Some engines are equipped with a premium valve package aluminized intake valves if the aluminized valve face does not clean up using a wire brush the valve face may be refinished This removes the aluminized coating from the valve face An aluminized vaive that has been refinished will normally have a life expectancy equal to a standard valve If longer valve life is required worn or damaged valves should be replaced with new premium vaives Before installing new valves or previously used valves inspect valve seats for proper valve seating If used valves are reinstalled the valve stems should be cleaned and valve faces ground to their specified angles of 44 Refinish valve seats to a 45 angle When refacing valves and seats remo
53. ne is idling to check for above conditions Ifthe variable speed governor is hunting or notoperating properly adjust as follows Figure 8 1 Disconnect linkage A from one of holes C 2 Push linkage A and governor arm B as far back toward carburetor as they will go 3 Holding linkage and governor arm toward direction of carburetor insert end of linkage into whichever hole C in governor arm lines up the closest If between two holes insert in next hole out To adjust fixed speed governor Figure 7 Adjust governor link length so that with the engine stopped and tension on the governor spring the stop on the throttle shaft assembly almost touches the stop on the side of the carburetor Ku GOVERNOR SPRING ph Lad pe di T SPRING TENSION ADJUSTMENT 0 b a Q Ys GOVERNOR EINS 5 1490 FIXED SPEED GOVERNOR FIGURE 7 GOVERNOR ADJUSTMENTS THROTTLE STOP SCREW CARBURETOR THROTTLE PLATE GOVERNOR CONTROL LINKAGE GOVERNOR eae We GOVERNOR ARM p ADAPTER al GOVERNOR SHAFT YOKE GOVERNOR SPRING VARIABLE SPEED FRONT PULL GOVERNOR SCREW THROTTLE STOP A CARBURETOR THROTTLE PLATE GOVERNOR CONTROL LINKAGE GOVERNOR GOVERNOR SPRING STOP ADJUSTMENT PIVOT VARIABLE SPEED SIDE P
54. nside the valve chamber a seal is provided behind the intake valve guides only The smaller diameter of the tapered valve guides must facetoward the valve head Tappets are also repiaceable from the valve chamber after first removing the valve assemblies Valve Guide Removal Before removing valve guides use an electric drill with a wire brush to remove carbon and other foreign material from top surface of guides Failure to perform this operation may result in damage to the guide bores Drive the guides out with a hammer and valve guide driver 10 3 ACAUTION Driving out old valve guides can cause guide and tappet bore damage Do not strike guide or tappet bores with driver during removal Valve Guide Installation Run a small polishing rod covered with crocus cloth through valve guide holes to clean out carbon and other foreign materials Place a new gasket on the intake valve guide and coatthe outer edge of each new guide with oil Place guide notch up in cylinder block and press in until guide stops or protrudes 11 32 inch 8 7 mm from rocker box side of block suggested method of installation is shown in Figure 3 5 16 18 HEX NUT 178 om Zp 7 5 16 FLAT WASHER 2 REQUIRED 2 REQUIRED 32 mm nw 1 1 4 Se mm 4 3 4 5 8 16 mm FIGURE 3 VALVE GUIDE INSTALLATION Valve Stem Seals Do not reuse valve stem seals Each time the valves are removed from cylinder block a new seal must
55. ny parts are worn Oil By Pass Valve The by pass valve located to the right and behind gear cover controls oil pressure by allowing excess oil to flow directly back to the crankcase Normally the valve begins to open about 20 psi 138 kPa The valve is non adjustable and normally does not need maintenance Determine if valve is operating normally by inspecting plunger action as follows 1 Remove the 3 8 x 24 x 7 8 cap screw located behind gear cover and under governor arm 2 Remove spring and plunger with a magnet tool Determine proper valve operation by checking the spring and plunger according to the following measurements 0 3105 to 0 3125 in 7 89 to 7 94 mm Plunger Diameter Spring Free Length 1 00 inch 25 4 mm vocc eese 2 6 0 2 Ibs 11 6 0 9 when compressed to 0 5 inch 12 7 mm Checkthe valve seat and clean away any accumu lation of metal particles which could cause erratic valve action Verify thatthe valve seatis concentric with the larger diameter valve bore 5 Clean plunger and spring in parts cleaning solvent and install Redistribution or publication of this document by any means is strictly prohibited Fuel System CARBURETOR OVERHAUL Carburetion problems that are not corrected by mixture adjustments are usually a result of gummed up fuel passages or worn internal parts The most effective solution is a carburetor overhaul In general
56. o the slow position Bend or turn the low speed stop on the governor so the throttle stop screw on the carburetor controls engine speed Adiust throttle stop screw to obtain the following rpm A Marvel carburetor without governor low speed adjustment screw 1200 rpm with governor low speed adjustment screw 1100 rpm B Walbro and Nikki carburetor 1000 rpm THROTTLE STOP SCREW d LOCATION OF OPTIONAL MAIN ADJUSTMENT FS 1406 NIKKI CARBURETOR THROTTLE STOP SCREW IDLE FUEL m LIMITER CAP QUT FS 1406 2 NIKKI CARBURETOR WITH SEMI AUTOMATIC CHOKE AND LIMITED IDLE ADJUSTMENT SCREW FIGURE 9 CARBURETOR ADJUSTMENTS Ifyour engine is equipped with Nikki carburetor with limited idle adjustment screw skip steps 5 and 6 if your engine is not equipped with limited adjustment Nikki proceed with step 5 Determine the best idle mixture setting by first turning the idle adjustment screw in until engine speed drops and then outward until engine speed drops again Over a narrow range between these two settings engine speed remains at its highest Set the adjustment screw about 1 8 turn outward rich from the midpoint of this range Readjust throttle stop screw to obtain the RPM specified in step 3 and release the governor arm Adjust governor low speed stop for 1100 100 rpm idle Move the engine speed control to the fast position Bend the high speed sto
57. od heat dissipation Knife edges lead to breakage burning and pre ignition due to heat localizing on the edge Replace any valve that cannot be entirely refaced while keeping a good valve margin Figure 7 or is warped worn or damaged in any way The amount of grinding necessary totrue a vave indicates whether valve head is worn or warped WARPED VALVE WITH KNIFE EDGE KNIFE EDGE UC M al 1 16 INCH 16 mm MINIMUM GOOD MARGIN M 1184 FIGURE 7 VALVE HEAD MARGIN When new valve seats are installed or previously used seats reground refinishing must be done with a valve seat grinder used according to the manufac turer s directions Valve seats should be ground with a 45 degree stone and the width of the seat band should be 1 32 inch to 3 64 inch 0 79 to 1 2 mm wide Grind only enough to assure proper seating Place each valve in its proper location Check each valve for a tight seat Make several marks at regular intervals across the valve face using machinist s bluing Observe if the marks rub off uniformly when the valve is rotated part of a turn against the seat The valve seat should contact the valve face evenly at all points The line of contact should be at the center of the valve face FLYWHEEL Removing the flywheel is a relatively simple process but the following procedure must be followed to avoid damage to the gear case and possible injury to the operator 1 Turn the flywheel mounting screw
58. outward about two turns AWARNING Incorrect flywheel removal can A result in severe personal injury Do not remove flywheel screw completely when using flywheel puller 2 Install a puller bar on the flywheel Figure 8 FLYWHEEL FLYWHEEL PULLER FLYWHEEL MOUNTING SCREW FIGURE 8 BLOWER WHEEL PULLEY 3 Turn the puller bar bolts in alternately until the wheel snaps loose on the shaft ACAUTION improper flywheel removal can cause gear case damage Do not use any tools to pry against gear cover when removing flywheel 4 Unscrew the puller from the flywheel remove the flywheel mounting screw and washer and pull the flywheel off the shaft Take care not to drop the wheel A bent or broken fin will destroy the balance Always use a steel key for mounting the flywheel 10 6 GEAR COVER After removing the mounting screws tap the gear cover gently with a soft faced hammer to loosen it When installing the gear cover make sure thatthe pin in the gear cover engages the nylon lined smooth holein the governor cup Turn the governor cup so that the nylon lined hole is at the three o clock position Use small amount of grease to assist in holding governor cup in position The smooth side of the governor yoke must ride against the governor cup Turn the governor arm and shaft clockwise as far as possible and hold in this position until the gear cover is installed flush against the crankcase Be careful not
59. p and cylinder heads 11 Remove valves springs lifters etc 12 Remove camshaft and gear assembly 13 Remove connecting rods and pistons 14 Remove rear bearing plate crankshaft and front bearing Keep all parts in their respective orders Keep valve assemblies together Return rod caps to their respec tive pistons Analyze the reasons for parts failure Suggested Assembly Procedure Engine assembly is normally the reverse of the disassembly procedure observing proper clearances and torques Use a torque wrench to assure proper tightness Coat the internal engine parts with oil as they are assembled After the internal engine parts are assembled the engine should turn over by hand freely Use only genuine Onan parts and special tools when reassembling your engine 10 1 10 11 1 Usethe proper bearing driver to install front main bearing after coating it with a light film of oil 2 Insert rear main bearing in rear bearing plate 3 Insert crankshaft rear bearing plate and crank shaft gear 4 Install piston and connecting rods 5 Install camshaft and gear assembly align crank gear mark with cam gear mark 6 Install valve assemblies oil pump oil base and cylinder heads 7 Install breaker point box 8 Install all accessories such as oil filter starter fuel lines and spark plugs 9 Install gear cover with oil sea and flywheel Set breaker points to obtain proper timing Check valve clearance
60. p on the governor so the engine runs at the equipment manufacturer s recommended speed Check the main mixture adjustment optional on some carburetors by rapidly accelerating the engine from idle to full speed The engine should accelerate evenly and without hesitation If it does not turn the main adjustment screw out in 1 8 turn increments until the engine accelerates smoothly but do not turn it out more than 1 2 turn beyond the original setting HIGH SPEED STOP LOW SPEEO ADJUSTMENT SCREW FRONT PULL GOVERNOR ASSEMBLY FIGURE 10 GOVERNOR SPEED ADJUSTMENT FS 1512 AIR CLEANER A dirly air cleaner element can cause ACAUTION engine damage Ensure air cleaner element is kept clean and free of excess debris Engine is equipped with a paper element If the engine is equipped with polyurethane precleaner it must be removed cleaned and oiled every 25 hours of operation more often under extremely dusty conditions 1 To clean precieaner wash in water and detergent Figure 11 Remove excess water by squeezing like a sponge and allow to dry thoroughly Distribute two tablespoons of SAE 30 engine oil evenly around the precleaner Knead into the precieaner to dis tribute evenly Wring out excess oil Depending on conditions in which the engine is operating the inner paper element should be replaced whenever it becomes excessively dirty or oily ACAUTION Running engine without air cleaner
61. proper ignition timing a continuity test may be performed 1 Adjust breaker points 2 Remove blower housing to expose timing marks on top of gearcase cover and flywheel Fig re 2 FLYWHEEL TIMING MARK GEARCASE TIMING 4 MARKS A M 1397 FIGURE 2 TIMING MARKS 3 Rotate flywheel clockwise until timing mark is aligned with the proper number of timing degrees Figure 2 stamped on the top of gearcase cover Refer to SPECIFICATIONS for proper number of timing degrees 4 Connect an ohmmeter or a continuity test lamp set across the ignition breaker points Touch one test prod to the coil lead terminal screw B Figure 1 5 Touch the other test prod to a good ground on the engine 6 Turn crankshaft against rotation counterclockwise until the points close Then slowly turn the crankshaft with rotation clockwise 7 The lamp should go out or continuity lost just as the points break which is where ignition occurs If timing is early advanced the point gap Is too large If timing is late retarded the point gap is too small Adjust point gap accordingly SPARK PLUGS Check and regap spark plugs every 100 hours of operation Figure 3 Replace spark plugs that show signs of fouling or electrode erosion FIGURE 3 SPARK PLUG GAP 8 2 BATTERY INSPECTION A WARNING Ignition of explosive battery gases can result in severe personal injury Do not smoke or allow any ignition source near the ba
62. rilled passages of the crankshaft Clean them to remove any foreign material and to assure proper lubrication of the connecting rods BEARINGS With camshaft and crankshaft removed use a micro meter to measure diameter of bearing journals Use a dial bore gauge or a telescopic gauge and micrometer to measure inside diameter of bearings Refer to Dimension and Clearance Section to determine if clearances are within specifications Any bearing that is scored chipped pitted or worn beyond the specified limits must be replaced Removal of the camshaft bearings requires complete disassembly of the engine Use a press or a suitable driver to remove bearings Support casting to avoid distortion and to avoid damaging the bearing bore during removal and installation Replacement camshaft bearings are precision type which do not require line reaming or line boring after installation Clean outside of the bearing and bearing bore in the block Before installing cam bearings use Locktite Bearing Mount on outside diameter of bearing Use a combination bearing driver to instal bearings Place the bearing on the crankcase over the bearing AL 18 13 IGN HOLE IN BEARING T 32 5 6 mm FROM OUTSIDE WITH HOLE IN BEARING BORE CAMSHAFT BEARING FIGURE 20 FRONT CAMSHAFT BEARING bore with the lubricating hole front only in the proper position Be sure to start the bearing straight Press in the front bearing flush with the outside
63. se engine racing and governing problems Figure 10 When installing the governor cup tilt the engine so the gear is up put the flyballs in place Figure 10 and install the cup and snap ring on the center pin The camshaft center pin extends out 3 4 inch 19 mm from the end of the camshaft This distance provides an in and out travel distance of 7 32 inch 5 6 mm for the governor cup as illustrated Hold the cup against the flyballs when measuring The camshaft center pin 10 7 cannot be pulled outward or removed without damage If the center pin extends out too far the cup will not hold the flyballs properly If the distance is less than 7 32 5 6 mm the engine will race especially at no load remove the center pin and press in a new pin TIMING GEARS If replacement of either the crankshaft gear or the camshaft gear becomes necessary always install both gears new The camshaft and gear must be replaced as an assembly Before removing the camshaft and gear assembly remove the cylinder head and valve assemblies Then remove the operating plunger for the breaker points and tappets To remove the crankshaft gear first remove the snap ring and retainer washer then attach the gear pulling ring using two No 10 32 screws Figure 11 Tighten the screws alternately until both are tight Attach a gear puller tothe puller ring and proceed to remove the gear Each timing gear is stamped with O nearthe edge The gear tee
64. ss fit cannot be obtained when installing new standard size valve seat inserts the bores must be machined for an oversize seat USE NEW VALVE SEAT TO ADJUST PULLER DEPTH PULLER JAWS C 1104 FIGURE 4 VALVE SEAT REMOVAL V lve Seat Removal Remove carbon and combustion deposits from valve seat Select proper puller size determined by inside diameter of valve seat On some pullers use a new seat as a guide to adjust puller depth Figure 4 Puller jaws must expand into cylinder block at the point where bottom of valve seat insert rests on cylinder block Position puller on valve seat and tighten hex nut Clamp cylinder block to a solid bench Attach slide hammer to puller Tighten hex nut between each blow with the slide hammer VALVE SEAT INSERT DRIVER USE PROPER TOOL CHECK THIS SURFACE VALVE SEAT FOR BURRS BE FORE icc INSERTING SEAT E Py za e x h eS m 3 b a Ed 4 FIGURE 5 INSERTING NEW VALVE SEAT Valve Seat Installation After the old seat has been removed clean out any carbon or metal burrs from the seat insert recess Use a valve seat insert driver and hammer to install the insert Figure 5 Drive the valve seat insert in so the insert enters the recess evenly Make certain that the valve seat insert rests solidly on the bottom of the recess all the way around its circumference To assure a tight valve seat fit a
65. st enough to recharge battery after each start Charging system tests require a full charged battery Alternator output is reduced in direct proportion to engine rpm Also power required for accessories reduces power available to recharge battery 2 Make sure alternator stator leads are not shorted together 3 Be sure regulator rectifier output control has a good ground connection Mating surface for moun ting must be clean and fasteners tightened properly 4 Never reverse the battery leads With the engine running between 1800 to 2600 rpm observe the panel ammeter if not already equipped connect a test ammeter If no charging is evident proceed with the Alternator Output Test ALTERNATOR OUTPUT TEST Use a volt ohmmeter such as the Simpson 270 when testing the charging system 1 With the engine running check the battery terminal voltage regulator output using a DC voltmeter Voltage output should be within the values specified in Table 1 If voltage is greater than specified replace regulator rectifier assembly If voltage is less than specified proceed to step 2 2 Examine all wires for loose corroded broken connections short circuits etc Check fuses Repair as needed to assure complete circuits from regulator rectifier B terminal to battery positive terminal and from battery negative terminal to regulator rectifier case If battery voltage remains low with engine running proceed to step 3
66. tear 10 17 5 Follow the head torque sequence shown in Fig ure 28 A Graphoil head gasket torque procedure Tighten all bolts to 5 ft lbs 7 Nm then 10 ft lbs 14 Nm and then torque all bolts to 14 to 16 165 19 22 Nm Recheck all head bolts for correct torque B Asbestos head gasket torque procedure Tighten all bolts to 5 ft lbs 7 Nm then 10 ft lbs 14 Nm and then torque all bolts to 16 to 18 ft lbs 22 24 Nm Recheck all head bolts for correct torque NO 1 CYLINDER NO 2 CYLINDER FIGURE 28 CYLINDER HEAD TORQUE SEQUENCE Redistribution or publication of this document by any means is strictly prohibited Redistribution or publication of this document by any means is strictly prohibited Onon Cummins Power Generation 1400 73rd Avenue N E Minneapolis MN 55432 763 574 5000 Fax 763 574 8087 Cummins and Onan are registered trademarks of Cummins Inc
67. th engine oil 2 Position piston on its respective rod and install the pin 3 Install the rings on the pistons starting with the oil control ring Figure 26 Use a piston ring spreader to prevent twisting or excessive expansion of the ring Compression rings have a dot or the word top on one side of the ring to indicate which side faces the top of the piston Unmarked piston rings can be installed either way oil control ring has an expander install the expander first and then close until the expander ends butt The joint should be 180 degrees from the gap of that ring CT 1047 FIGURE 26 PISTON RINGS INSTALLATION OF PISTON IN CYLINDER 1 Turn the crankshaft to position the number one rod bearing journal at the bottom of its stroke Lubricate the number one piston assembly and inside ofthe cylinder Compress the rings with a ring compressor Figure 27 Position the piston and rod assembly in the cylinder block Notched side of connecting rod must face camshaft rod bolts must be off set toward outside of block NOTCH TOWARD CAMSHAFT FIGURE 27 INSTALLING PISTON AND CONNECTING ROD 4 the piston down into the bore with the handle end of a hammer unti the connecting rod is seated on the journal Figure 27 install the bearing cap on the rod Install one fastener and tighten to 5 ft Ibs 7 Nm Repeat this for the other fastener Tighten both fasteners down to 14 ft lbs 19 Nm
68. th must mesh so that these marks exactly coincide when the gears are installed in the engine When installing the camshaft gear and shaft assembly be sure that the thrust washer is properly in place behind the camshaft gear Then install the crankshaft retaining washer and tock ring 4 ef THESE MARKS MUST ALIGN WHEN INSTALLING TIMING Ww FIGURE 11 TIMING GEAR REMOVAL AND INSTALLATION v aS PISTONS AND CONNECTING RODS Observe the following procedure when removing pistons and connecting rods from the engine 1 Drain oil 2 Remove the cylinder head and oil base pan from the engine 3 Remove the ridge from the top of each cylinder with a ridge reamer before attempting piston removal Figure 12 improper piston removal can ACAUTION cause piston damage Use ridge reamer to remove cylinder ridge before removing piston FIGURE 12 REMOVING RIDGE FROM CYLINDER 10 8 4 Turn the crankshaft until the piston is at the bottom of its stroke and remove the connecting rod nuts Lift the rod bearing cap from the rod and push the rod and piston assembly out through the top of the cylinder using a hammer handle Avoid scratching the crankpin and cylinder wal when removing the piston and rod 5 Mark each piston and rod assembly so they can be returned to their respective cylinders after overhaul Keep connecting rod bearing caps with their respective rods 6 Remove the pisto
69. ther manner may result in damage to the battery or the electrical system 6 Turn ignition switch to ON to start engine Jump starting a battery incor AWARNING rectly can cause battery to explode resulting in severe personal injury or death Do not smoke or allow any ignition source near the battery and do not jump Start a frozen battery MOUNTED ON CYLINDER COVER MOUNTED BEHIND BLOWER WHEEL ALT STATOR AC B AC CAUTION REGULATOR MUST BE GROUNDED THROUGH MOUNTING BOLTS 5 1332 FIGURE 7 FLYWHEEL ALTERNATOR SYSTEM FLYWHEEL ALTERNATOR This unit is equipped with a permanent magnet flywheel alternator and solid state voltage requlator rectifier output control See Figure 7 As with all solid state electrical units precautions are necessary when ser vicing Observe the following ACAUTION ACAUTION Reversing positive and negative bat i connections or allowing engine to run without being connected to the alternator will result in engine electrical system damage Do not switch battery connections or allow engine to run without being connected fo the alternator Weak ignition spark or a discharged battery indicates trouble in the charging system But before testing the engine s charging system always check the battery for serviceability Keep these points in mind when testing or servicing the alternator 1 Be sure engine is being run long enough and fa
70. tis picked up by the oil pump pick up cup by pass valve is used to control oil pressure Drain oil before removing oil base and always use a new gasket when replacing the oil base Pump The oil pump Figure 4 is mounted behind the gear cover and is driven by the crankshaft gear Inlet pipe and screen assembly are attached directly to the pump body A discharge passage in pump cover registers with a drilled passage in the crankcase Parallel passages distribute oil to the front main bearing rear main bearing and pressure control bypass valve OIL PUMP PICK UP CUP OIL PUMP ASSEMBLY CRANKCASE TURNED ON LEFT SIDE LS 1109 FIGURE 4 OIL PUMP ASSEMBLY Circumferential grooves in the main bearings supply oil to connecting rod bearings through drilled pas sages from each main journal A drilled passage connects the front main bearing oil supply to the front camshaft bearing rear cam bearing is splash lubrica ted Cil overflow from the bypass valve furnishings lubrication to the camshaft drive gears Normal oil pressure should be 30 psi 207 kPa or higher when the engine is at normal operating temperature If pressure drops below this value at governed speed inspect oil system for faulty components 6 3 Check oil pump thoroughly for worn parts Oil pump to prime it before reinstalling Except for gaskets and pick up cup component parts of the pump are not available individually Install a new pump assembly if a
71. ttery Check battery celis with a hydrometer Figure 4 The specific gravity reading should be approximately 1 260 at 77 F 25 C If one or more celis are low on water add distilled water and recharge Keep the battery case clean and dry An accumulation of moisture will lead to a more rapid discharge and battery failure SPECIFIC GRAVITY READING SHOULD BE 1 260 at 77 F 25 C FIGURE 4 SPECIFIC GRAVITY TEST Keep the battery terminals clean and tight Push the cable terminal down flush with or slightly below the top ofthe battery post Figure 5 After making connections coat the terminals with a light application of petroleum jelly or grease to retard corrosion Poor contact at the battery cable connections is often a source of trouble Make sure battery cables are in good condition and that contacting surfaces are clean and tightly connected Do not reverse battery leads Use recommended battery tools when disconnecting leads to avoid mechanical battery damage BATTERY POST CABLE TERMINAL FIGURE 5 BATTERY CABLE CONNECTION IGNITION COIL To test primary and secondary windings within the ignition coil first make sure the ignition power is off and coil is at room temperature of 70 F 21 C 1 Use a Simpson 260 VOM or equivalent 2 Place a black lead on negative terminal of coil and red lead to positive coil terminal Primary resistance should read between 3 87 4 73 ohms 3 Change resistance sett
72. ture REAR BEARING END PLATE LOCK PIN ALIGN BEARING OIL HOLES WITH OIL HOLES IN BEARING BORE THRUST WASHER FIGURE 21 BEARINGS FOR REAR BEARING PLATE Engines shipped from the factory have separate thrust washers and main bearings for both front and rear of engine Front bearing replacement part is a one piece bearing with attached thrust washer as shown in Figure 22 Do notadd an additional thrust washer to this front bearing FRONT MAIN BEARING BORE ALIGN BEARING NOTCHES WITH 5 OIL HOLES B49 Re REPLACEMENT FRONT MAIN BEARING FIGURE 22 FRONT BEARING INSTALLATION in the rear bearing plate install the bearing flush to 1 64 inch 0 40 mm below the end of the bore Be sure to align the oil holes in the bearing with the oil holes in the bearing bore Figure 21 The oil passage must be at least half open Lubricate bearing after installation If head of lock pin is damaged use side cutters or Easy Out tool to remove and install new pin Oil grooves in thrust washers must face the crankshaft and washers must be flat not bent The two notches on each washer must fit over the two lock pins to prevent riding on the crankshaft Figure 21 Lubricate the front main bearing lightly with oil and insert the crankshaft With the rear bearing plate gasket in place and the rear plate bearing lubricated slide the thrust washer grooves toward crankshaft and plate over the en
73. ve all evidence of pitting and grooving If end of valve stem is pitted or worn trueitandcleanitup on the refacer wheel very light grind is usually enough to square stem and remove any pits or burrs The valve guide should be thoroughly cleaned If valve guide is worn or valve is warped the necessary parts must be replaced By grinding the valve face and seat at slightly different angles a fine line of contact on face and seat is obtained eliminating the need to lap the seating surfaces The one degree difference in angles is defined as the interference angle Figure 6 The seat angle is greater than that of the valve face This assures contact at the maximum diameter on valve seat seating surface VT 1021 FIGURE 6 VALVE INTERFERENCE ANGLE 10 5 Refinish valve faces to a 44 angle on a valve refacing machine The first cut from valve face must be a light grinding Check if there is an unevenness of metal being removed If only part of valve s face has been touched check to see if valve is properly seated in machine or if valve is warped worn or distorted When cut is even around the whole valve face keep grinding until complete face is ground clean Be sure the correct valve face angle is maintained When valve head is warped a knife edge will be ground Figure 7 on part or all ofthe head due to the large amount of metal that must be removed to completely reface valve Heavy valve heads are required for strength and go
74. y materials from the crankcase These vapors are routed to the carburetor where they are mixed with incoming air and burned in the combustion chamber sticky breather valve can cause leaks high oil consumption rough idle reduced engine power and a rapid formation of sludge and varnish within the engine Crankcase Breather Service If the crankcase becomes pressurized as evidenced by oil leaks at the seals use the following procedure to service Remove the breather tube from the valve cover Fig ure 3 Remove the valve cover pack spring washer reed valve and breather baffle Discard gasket and clean all parts in part cleaning solvent A WARNING Most parts cleaning solvents are flammable and can cause severe personal injury or death if used improperly Follow the manufacturer s recommendations when cleaning parts BREATHER TUBE PLASTIC TIE HEX HEAD CAPSCREW FLAT WASHER GASKET SPRING OF w FLAT WASHER REED VALVE p BREATHER zu BAFFLE C 1003 FIGURE 3 CRANKCASE BREATHER The reed valve must be flat with no sign of a crease Assemble using a new gasket Do not overtighten valve Cover capscrew Overtightening the valve cover can LA CAUTION cause engine damage Do over tighten valve cover PRESSURE LUBRICATION Allengines use an oil pump to provide aconstant flow of oil to the engine parts The oil supply collects the oil base where i

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