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Service Manual - Kohler Engines

1. E Flywheel Cover F Radiator Drain Plug Clean all parts thoroughly as engine is disassembled Only clean parts can be accurately inspected and gauged for wear or damage There are many commercially available cleaners that will quickly remove grease oil and grime from engine parts When such a cleaner is used follow manufacturer s instructions and safety precautions carefully Make sure all traces of cleaner are removed before engine is reassembled and placed into operation Even small amounts of these cleaners can quickly break down lubricating properties of engine oil 42 KohlerEngines com Disconnect Spark Plug Leads NOTE Pull on boot only to prevent damage to spark plug lead 1 Disconnect leads from spark plugs 2 Shut off fuel supply Remove Muffler Remove exhaust system muffler and attaching hardware from engine 66 690 01 Rev A Remove Starter and Adapter Plate Disassembly Inspection and Service External Engine Components 1 Disconnect leads attached to starter solenoid terminals 2 Remove screws securing starter to adapter plate 3 Remove screws attaching adapter to crankcase Note orientation of cutout Upper screw may also secure a clamp for stator leads Drain Coolant from Cooling System Coolant Drain Plug Details owZ SE ei A Coolant Drain Plug 1 Loosen radiator cap then loosen radiator drain plug and allow system to d
2. KOHLER Acois LH630 LH640 LH685 LH690 LH750 LH755 Service Manual IMPORTANT Read all safety precautions and instructions carefully before operating equipment Refer to operating instruction of equipment that this engine powers Ensure engine is stopped and level before performing any maintenance or service 2 Safety 3 Maintenance 5 Specifications 12 Tools and Aids 15 Troubleshooting 19 Air Cleaner Intake 20 Fuel System 25 Governor System 26 Lubrication System 28 Electrical System 34 Starter System 38 Cooling System 42 Disassembly Inspection and Service 58 Reassembly 66 690 01 Rev A KohlerEngines com Safety SAFETY PRECAUTIONS A WARNING A hazard that could result in death serious injury or substantial property damage A CAUTION A hazard that could result in minor personal injury or property damage NOTE is used to notify people of important installation operation or maintenance information A WARNING Explosive Fuel can cause fires and severe burns GLU Do not fill fuel tank while engine is hot or running Gasoline is extremely flammable and its vapors can explode if ignited Store gasoline only in approved containers in well ventilated unoccupied buildings away from sparks or flames Spilled fuel could ignite if it comes in contact with hot parts or sparks from ignition Never use gasoline as a cleaning agent A WARNING Accidental S
3. Place stator leads within clamp and close loop 3 If violet B charge lead is separate from main harness secure it to wiring harness with a tie strap directly above clamp Install Starter Assembly NOTE Stator leads and rectifier regulator plug must be above starter 1 Mount starter to adapter plate using screws 2 Make sure starter is square to flywheel and torque screws to 15 3 N m 135 in Ib 3 Attach leads to appropriate starter solenoid terminals 4 To avoid damage or breakage do not over tighten nut when attaching positive battery cable Torque nut to 6 9 N m 53 79 in Ib Install Lower Flywheel Cover Rectifier Regulator and Mounting Plate 1 Install make sure small metal spacers are positioned in mounting holes of lower flywheel cover 2 Attach lower flywheel cover to cylinder 2 oil filter side lower radiator support bracket using M6 screws and flat washers Finger tighten only at this time 3 Align lower flywheel cover with cylinder 1 starter side lower radiator support bracket holes Position rectifier regulator mounting plate behind cover and install remaining two screws or nuts and flat washers Torque four fasteners to 9 9 N m 88 in lb If screws and Timmerman nuts clips are used torque to 2 2 2 8 N m 20 25 in Ib 4 If removed mount rectifier regulator to plate with two screws and attach connector plug Install Muffler 1 Install new exhaust gaskets and attach
4. Refer to equipment s operating instructions for specific battery requirements Battery Size Recommendations Temperature Battery Required Above 32 F 0 C 200 cca minimum 0 F to 32 F 18 C to 0 C 5 F to 0 F 21 C to 18 C 250 cca minimum 300 cca minimum 10 F 23 C or below 400 cca minimum If battery charge is insufficient to turn over engine recharge battery Battery Maintenance Regular maintenance is necessary to prolong battery life Battery Test To test battery follow manufacturer s instructions 66 690 01 Rev A Electrical System ELECTRONIC IGNITION SYSTEMS Ignition System Components Kill Switch A Off Position of Air Gap Key Switch C Flywheel Magnet E Spark Plug F Ignition Modules These engines are eguipped with a capacitive discharge CD coil This ignition system is designed to be trouble free for life of engine Other than periodically checking replacing spark plugs no maintenance or timing adjustments are necessary or possible Mechanical systems do occasionally fail or break down Refer to Troubleshooting to determine root of a reported problem Reported ignition problems are most often due to poor connections Before beginning test procedure check all external wiring Be certain all ignition related wires are connected including spark plug leads Be certain all terminal connections fit snugly Make sure ign
5. Rotate crankshaft to check for free operation of valve train Check clearance between valve spring coils at full lift Minimum allowable clearance is 0 25 mm 0 010 in Install Valve Covers 1 Make sure sealing surfaces of cylinder heads and valve covers are clean and free of all old gasket material 2 Install new valve cover gaskets onto valve covers 3 Install valve covers with gaskets in their original locations 4 Install lower mounting screws in each cover and finger tighten only Upper screws will be installed later Install Water Pump Drive Belt and Transfer Tube Assembly Water Pump Components O ring B Water Pump A C Water Pump Belt D Camshaft Pulley E Transfer Tube Water Pump Torque Sequence NOTE Amark or dot of paint applied to top of pulley indicating keyway location will make installation easier KohlerEngines com 63 Reassembly NOTE When installation is complete tangs of two hose clamps should face outward away from flywheel and slightly down 1 Remove seal protector and or protective tape if used from over keyway and make sure end of camshaft is clean and free of any nicks or damage Install and fully seat key squarely into keyway Be careful not to contact camshaft seal Test fit cam pulley onto shaft and key it must slide on without force or restriction Remove pulley 2 If water pump by pass hose fitting was removed prev
6. 0025 in Bore I D New Max Wear Limit 20 000 20 025 mm 0 7874 0 7884 in 20 038 mm 0 7889 in Camshaft Bearing Surface O D New Max Wear Limit 19 962 19 975 mm 0 7859 0 7864 in 19 959 mm 0 7858 in 3Values are in Metric units Values in parentheses are English equivalents 5 Lubricate threads with engine oil prior to assembly 66 690 01 Rev A KohlerEngines com 7 Specifications CLEARANCE SPECIFICATIONS LH630 LH640 LH685 LH690 LH750 LH755 Connecting Rod Connecting Rod to Crankpin Running Clearance New Max Wear Limit 0 043 0 068 mm 0 0016 0 0026 in 0 083 mm 0 0032 in Connecting Rod to Crankpin Side Clearance 0 26 0 63 mm 0 0102 0 0248 in Connecting Rod to Piston Pin Running Clearance 0 015 0 028 mm 0 0006 0 0011 in Crankcase Governor Cross Shaft Bore I D New Max Wear Limit 8 025 8 075 mm 0 3159 0 3179 in 8 088 mm 0 3184 in Crankshaft End Play free 0 070 0 590 mm 0 0028 0 0230 in Crankshaft Sleeve Bearing LD crankcase New Max Wear Limit 40 974 40 987 mm 1 6131 1 6136 in 41 000 mm 1 6141 in Crankshaft Bore in closure plate New Max Wear Limit 40 974 41 000 mm 1 6131 1 6141 in 41 038 mm 1 6156 in Crankshaft Bore in closure plate to Crankshaft Running Clearance Max Out of Round Crankshaft to Sleeve Bearing crankcase Running Clearance New 0 039 0 08
7. 1 Inspect fan for any cracks damaged missing fan blades and secure mounting 2 Bearings in hub of pulley should rotate smoothly without roughness binding or play wobble 3 V groove of each pulley upper and lower should not be bent nicked or damaged Pulley mounting areas and lower pulley shims should be free of any cracks or elongation 4 Drive belt is designed and constructed for this system Do not use a substitute belt Check overall condition and replace belt if cracked damaged or proper tension cannot be established by repositioning of lower pulley shims Use only Kohler Part No 66 203 02 S belt if replacement is necessary See a Kohler authorized dealer for any necessary service KohlerEngines com 39 Cooling System Checking Fan Belt and Tension Fan belt and belt tension should be checked daily or before each use Fan belt should not be cracked damaged or exhibit excessive wear Proper tension is 12 7 mm 3 8 1 2 in belt deflection per side under 10 Ibs applied tension If belt is cracked damaged or is worn that relocation of pulley shims cannot establish proper belt tension belt should be replaced Use only Kohler Part No 66 203 02 S belt DO NOT use a substitute belt For a new belt assemble lower pulley with all three shims between pulley halves For a used original belt being reinstalled assemble with two or one shim s between pulley halves and remaining shim s on outside fro
8. 10 2 cm 4 in of water If reading is below specification or if pressure is present check table below for possible causes and conclusions Conclusion Crankcase breather clogged or inoperative NOTE If breather is integral part of valve cover and cannot be serviced separately replace valve cover and recheck pressure Disassemble breather clean parts thoroughly check sealing surfaces for flatness reassemble and recheck pressure Seals and or gaskets leaking Loose or improperly torque fasteners Replace all worn or damaged seals and gaskets Make sure all fasteners are tightened securely Use appropriate torque valves and sequences when necessary Piston blow by or leaky valves confirm by inspecting components Restricted exhaust Recondition piston rings cylinder bore valves and valves guides Check exhaust screen spark arrestor if equipped Clean or replace as needed Repair or replace any other damaged restricted muffler or exhaust system parts 66 690 01 Rev A KohlerEngines com 17 Troubleshooting COMPRESSION TEST For Command Twins A compression test is best performed on a warm engine Clean any dirt or debris away from base of spark plug s before removing them Be sure choke is off and throttle is wide open during test Compression should be at least 160 psi and should not vary more than 15 between cylinders All other models These engines are equipped with
9. 7 165 9 16 12 101 7 75 169 5 125 237 3 175 9 16 18 135 6 100 223 7 165 311 9 230 5 8 11 149 5 110 244 1 180 352 6 260 5 8 18 189 8 140 311 9 230 447 5 330 3 4 10 199 3 147 332 2 245 474 6 350 3 4 16 271 2 200 440 7 325 637 3 470 Metric Fastener Torgue Recommendations for Standard Applications Property Class Noncritical Size ere Tightening Torque N m in Ib a 10 M4 1 2 11 7 15 2 9 26 4 1 36 5 0 44 2 0 18 M5 2 5 22 2 28 5 8 51 8 1 72 9 7 86 4 0 35 M6 4 3 38 7 50 9 9 88 14 0 124 16 5 146 6 8 60 M8 10 5 93 6 120 24 4 216 33 9 300 40 7 360 17 0 150 Tightening Torque N m ft Ib 10 M10 21 7 16 27 1 20 47 5 35 66 4 49 81 4 60 33 9 25 M12 36 6 27 47 5 35 82 7 61 116 6 86 139 7 103 61 0 45 M14 58 3 43 76 4 56 131 5 97 184 4 136 219 7 162 94 9 70 Torque Conversions N m in Ib x 0 113 in Ib N m x 8 85 N m ft Ib x 1 356 ft Ib N m x 0 737 66 690 01 Rev A KohlerEngines com 11 Tools and Aids Certain quality tools are designed to help you perform specific disassembly repair and reassembly procedures By using these tools you can properly service engines easier faster and safer In addition you ll increase your service capabilities and customer satisfaction by decreasing engine downtime Here is a list of tools and their source SEPARATE
10. Do not use wire or carburetor cleaner KohlerEngines com 66 690 01 Rev A GOVERNOR Engine is equipped with a centrifugal flyweight mechanical governor It is designed to hold engine speed constant under changing load conditions Governor gear flyweight mechanism is mounted inside closure plate and is driven off gear on camshaft Governor Components A Flyweight B Regulating Pin C Cross shaft D Governor Lever E Throttle Linkage F Throttle Lever e Centrifugal force acting on rotating governor gear assembly causes flyweights to move outward as speed increases Governor spring tension moves them inward as speed decreases As flyweights move outward they cause regulating pin to move outward Regulating pin contacts tab on cross shaft causing shaft to rotate One end of cross shaft protrudes through crankcase Rotating action of cross shaft is transmitted to throttle lever of carburetor through external linkage When engine is at rest and throttle is in fast position tension of governor spring holds throttle plate open When engine is operating governor gear assembly is rotating Force applied by regulating pin against cross shaft tends to close throttle plate Governor spring tension and force applied by regulating pin balance each other during operation to maintain engine speed When load is applied and engine speed and governor gear speed decreases governor spring tension moves gove
11. Kohler 25 455 12 S reamer Valve Guide Service Kit Courage Aegis Command OHC For servicing worn valve guides AIDS Description Kohler 25 455 12 S Design Technology Inc SE Tools KLR 82415 Source Part No Camshaft Lubricant Valspar ZZ613 Kohler 25 357 14 S Dielectric Grease GE Novaguard G661 Kohler 25 357 11 S Dielectric Grease Loctite 51360 Kohler Electric Starter Drive Lubricant Inertia Drive Kohler 52 357 01 S Kohler Electric Starter Drive Lubricant Solenoid Shift Kohler 52 357 02 S RTV Silicone Sealant Loctite 5900 Heavy Body in 4 oz aerosol dispenser Only oxime based oil resistant RTV sealants such as those listed are approved for use Loctite Nos 5900 or 5910 are recommended for best sealing characteristics Loctite Ultra Copper 5920 Kohler 25 597 07 S Loctite 5910 Loctite Ultra Black 598 Loctite Ultra Blue 587 Spline Drive Lubricant Kohler 25 357 12 S 66 690 01 Rev A KohlerEngines com 13 Tools and Aids FLYWHEEL HOLDING TOOL ROCKER ARM CRANKSHAFT TOOL A flywheel holding tool can be made out of an old junk A spanner wrench to lift rocker arms or turn crankshaft flywheel ring gear and used in place of a strap wrench may be made out of an old junk connecting rod 1 Using an abrasive cut off wheel cut out a six tooth 1 Find a used connecting rod from a 10 HP or larger segment of r
12. NOTE Make sure flywheel key is installed properly in keyway Flywheel can become cracked or damaged if key is improperly installed 1 Install woodruff key into keyway of crankshaft Make sure that key is properly seated and parallel with shaft 2 Thread starter mounting bolts into hub of flywheel or use flywheel puller to serve as a handle and set flywheel in place 3 Install screw and washer 4 Use a flywheel holding tool to hold flywheel and torque screw to 66 4 N m 49 ft Ib 5 Using a light visually check that sufficient clearance exists between cooling system components and bottom of flywheel e If clearance is OK continue with installation of ignition modules e If clearance is insufficient or contact is noted remove flywheel and adjust as required Reinstall flywheel and recheck for adequate clearance Install Ignition Modules 1 Rotate flywheel magnet away from ignition module mounting bosses 2 Install ignition modules with ground terminal out onto crankcase mounting bosses using screws Slide ignition modules away from flywheel as far as possible and tighten four screws 3 Rotate flywheel to position magnet directly under one of ignition modules A Insert a 0 25 mm 0 010 in flat feeler gauge or shim stock between magnet and ignition module Loosen screws enough to allow magnet to pull module against feeler gauge 5 Torque screws to 4 0 N m 35 in Ib Repeat steps 3 to 5 for other i
13. P D e oo q o EL TA L 36 50 28 575 Option 1 437 1 125 o y 155 58 E gt 6 125 J Q Y Y 9 Ee Engine Mounting Surface Z E Top View il i 89 00 gt 4 00 Pilot Oil Drain Plug 3 504 157 Mounting Holes IW 238 61 gt 9 394 Mounting Hole A Mounting Surface La 431 61 gt 16 992 66 690 01 Rev A KohlerEngines com Specifications ENGINE IDENTIFICATION NUMBERS Kohler engine identification numbers model specification and serial should be referenced for efficient repair ordering correct parts and engine replacement Model ce ee hae lee eed LH630 Liquid Cooled AT Horizontal Shaft Numerical Designation Specification LH630 0001 Seal oai PA a 3923500328 Year Manufactured Code Factory Code Code Year 39 2009 40 2010 41 2011 GENERAL SPECIFICATIONS LH630 LH640 LH685 LH690 LH750 LH755 Bore 77mm 80 mm 83 mm 3 3 in 3 03 in 3 15 in Stroke 67 mm 2 64 in 69 mm 2 7 in Displacement 624 cc 674 cc 747 cc 45 6 cu 38 1 cu in 41 1 cu in in Oil Capacity refill 1 6 1 8 L 1 7 1 9 U S at Maximum Angle of Operation full oil level 20 LH630 LH640 LH685 LH690 LH750 LH755 TORQUE SPECIFICATIONS Carburetor and Intake Manifold Intake Manifold Fastener torque in 2 increments first to 7 4 N m 66 in lb finally to 9 9 N m 88 in Ib Thermost
14. Radiator Drain Plug 1 Ensure engine is cool When radiator is cool to touch slowly loosen radiator cap to first stop and allow any pressure to bleed off Then loosen it fully and remove it Loosen remove radiator drain plug and allow coolant to drain 2 If equipped remove coolant drain plugs located on each side of engine block Drain coolant into a suitable container After coolant has drained completely apply pipe sealant with Teflon Loctite PST 592 or equivalent to threads and reinstall plugs Torque plugs to 36 7 N m 325 in lb 3 Remove overflow hose from reservoir Unhook inboard retainer and slide reservoir out of supports Pour out contents and wash or clean as required Dispose of all old coolant in accordance with local ordinances 4 Reinstall reservoir cap Do not kink pinch hose 5 Flush cooling system Flushing Cooling System NOTE To prevent engine damage do not pour water into a hot engine Do not operate engine without coolant With system properly drained 1 Fill cooling system with clean water and a cooling system cleaner recommended for aluminum engines Follow directions on container 2 Reinstall and tighten radiator cap 3 Start and run engine for five minutes or until it reaches operating temperature Stop engine and allow it to cool 66 690 01 Rev A Cooling System 4 Drain cooling system 5 Fill cooling system Filling Cooling System NOTE To
15. Remove anion Modules Inspect flywheel for cracks and flywheel keyway for 1 Disconnect kill leads from ignition modules damage Replace flywheel if cracked Replace flywheel 2 Rotate flywheel so magnet is away from ignition crankshaft and key if flywheel key is sheared or keyway modules is damaged 3 Remove mounting screws and take off each ignition Inspect ring gear for cracks or damage Kohler does module not provide ring gears as a serviceable part Replace flywheel if ring gear is damaged Remove Flywheel Check charging system magnets to be sure they are not NOTE Always use a flywheel puller to remove flywheel loose or cracked from crankshaft Do not strike crankshaft or flywheel as these parts could become cracked Remove Stator Assembly or damaged Remove mounting screws and pull stator with plug in 1 Use a flywheel strap wrench or holding tool to hold connector attached from engine flywheel Remove screw and flat washer 2 Use a puller to remove flywheel from crankshaft 3 Remove woodruff key from crankshaft keyway 66 690 01 Rev A KohlerEngines com 47 Disassembly Inspection and Service Remove Intake Manifold Thermostat Housing By pass Hose and Wiring Harness 1 Disconnect by pass hose from fitting on water pump 2 Remove six mounting screws and carefully separate intake manifold from cylinder heads with by pass hose and wiring harness attached 3 Remove intake manifold gaskets 4 Further disass
16. S Kohler 25 761 05 S Kohler 25 761 06 S Kohler 25 761 41 S Digital Vacuum Pressure Tester For checking crankcase vacuum Individual component available Rubber Adapter Plug Design Technology Inc DTI 721 01 Design Technology Inc DTI 721 10 Electronic Fuel Injection EFI Diagnostic Software For Laptop or Desktop PC Kohler 25 761 23 S EFI Service Kit For troubleshooting and setting up an EFI engine Components of 24 761 01 S Fuel Pressure Tester Noid Light 90 Adapter In line T Fitting Code Plug Red Wire Code Plug Blue Wire Shrader Valve Adapter Hose Kohler 24 761 01 S Design Technology Inc DTI 019 DTI 021 DTI 023 DTI 035 DTI 027 DTI 029 DTI 037 Flywheel Holding Tool CS For holding flywheel of CS series engines SE Tools KLR 82407 Flywheel Puller For properly removing flywheel from engine SE Tools KLR 82408 Flywheel Strap Wrench For holding flywheel during removal SE Tools KLR 82409 12 KohlerEngines com 66 690 01 Rev A TOOLS Description Tools and Aids Source Part No Hydraulic Valve Lifter Tool For removing and installing hydraulic lifters Kohler 25 761 38 S Ignition System Tester For testing output on all systems including CD Kohler 25 455 01 S Inductive Tachometer Digital For checking operating speed RPM of an engine Design Technology Inc DTI 110 Offset Wrench K and M Series For removing and r
17. an automatic compression release ACR mechanism It is difficult to obtain an accurate compression reading because of ACR mechanism As an alternative use cylinder leakdown test described below CYLINDER LEAKDOWN TEST A cylinder leakdown test can be a valuable alternative to a compression test By pressurizing combustion chamber from an external air source you can determine if valves or rings are leaking and how badly Cylinder leakdown tester is a relatively simple inexpensive leakdown tester for small engines This tester includes a quick connect for attaching adapter hose and a holding tool 1 Run engine for 3 5 minutes to warm it up 2 Remove spark plug s and air filter from engine 3 Rotate crankshaft until piston of cylinder being tested is at top dead center TDC of compression stroke Hold engine in this position while testing Holding tool supplied with tester can be used if PTO end of crankshaft is accessible Lock holding tool onto crankshaft Install a 3 8 in breaker bar into hole slot of holding tool so it is perpendicular to both holding tool and crankshaft PTO If flywheel end is more accessible use a breaker bar and socket on flywheel nut screw to hold it in position An assistant may be needed to hold breaker bar during testing If engine is mounted in a piece of equipment it may be possible to hold it by clamping or wedging a driven component Just be certain that engine cannot rotate off of TDC in either directio
18. and lay assembly on top of crankcase to be removed with carburetor 44 KohlerEngines com Remove Carburetor and Adapter A WARNING j Do not fill fuel tank while engine is hot or running W Explosive Fuel can cause fires and severe burns HI Gasoline is extremely flammable and its vapors can explode if ignited Store gasoline only in approved containers in well ventilated unoccupied buildings away from sparks or flames Spilled fuel could ignite if it comes in contact with hot parts or sparks from ignition Never use gasoline as a cleaning agent 1 Disconnect lead to fuel shut off solenoid if equipped If a mechanical fuel pump is used disconnect fuel line from carburetor inlet 2 Disconnect breather hose from adapter fitting on carburetor 3 Remove carburetor mounting screws If a flexible tube and knob idle speed adjuster is used open retaining clamp and unhook 4 Remove carburetor throttle linkage and governor lever as an assembly 5 Remove carburetor gasket 6 Carburetor adapter throttle linkage and governor lever may be separated for individual component servicing as required If linkages are separated reattach bushings to linkages to prevent them from being lost 66 690 01 Rev A External Engine Components Disassembly Inspection and Service A Oil Sentry B Breather Cover C Gasket Fiber Filter Breather Reed Fan Mounting E Assem
19. idle progression transfer port chamber From idle progression chamber air fuel mixture is metered through idle port passage At low idle air fuel mixture is controlled by setting of idle fuel adjusting screws This mixture is then mixed with main body of air and delivered to engine As throttle plate opening increases greater amounts of air fuel mixture are drawn in through fixed and metered idle progression holes As throttle plate opens further vacuum signal becomes great enough at venturi so main circuit begins to work Main high speed At high speeds loads engine operates on main circuit As a metered amount of air is drawn through air jet fuel is drawn through main jet Air and fuel are mixed in main nozzles then enters main body of airflow where further mixing of fuel and air occurs This mixture is then delivered to combustion chamber Carburetor has a fixed main circuit no adjustment is possible Carburetor Adjustments NOTE Carburetor adjustments should be made only after engine has warmed up Carburetor is designed to deliver correct fuel to air mixture to engine under all operating conditions Main fuel jet is calibrated at factory and is not adjustable Idle fuel adjusting needles are also set at factory and normally do not need adjustment Low Idle Speed RPM Adjustment NOTE Actual low idle speed depends on application Refer to equipment manufacturer s recommendations Low idle speed for basic engines
20. indicating condition of part 66 690 01 Rev A Electrical System Condition Conclusion 20 25 amp 15 amp OK green light comes on and stays steady Disconnect tester black lead attached to 1 AC terminal and reconnect it to other AC terminal Repeat test If OK green light comes on again part is good and may be used Part is good and may be used a result of an inadequate ground lead connection Make certain connection location is clean and clamp is secure Other lights come on NOTE A flashing LOW light can also occur as Rectifier regulator is faulty and should not be used 15 20 25 Amp Battery Charging Systems NOTE Always zero ohmmeter on each scale before 3 With engine stopped measure resistance across testing to ensure accurate readings Voltage stator leads using an ohmmeter tests should be made with engine running at 3600 RPM with no load Battery must be good Condition Conclusion and fully charged Resistance is 0 064 0 2 Stator is OK When problems occur in keeping battery charged or ohms battery charges at high rate charging system or battery Resistance is 0 ohms Stator is shorted replace might be causing problems Resistance is infinity To test charging system for no charge to battery ohms Stator is open replace 1 Insert an ammeter in B lead from rectifier regulator With engine running at 3600 RPM and B at terminal on rectifier regul
21. lift complete assembly out of lower mounting bracket 6 Disconnect connector plug from rectifier regulator and remove mounting plate with rectifier regulator attached KohlerEngines com 43 Disassembly Inspection and Service 7 Remove four screws securing LH and RH side mounting brackets to crankcase Pull complete mount assembly forward to remove 8 Further disassembly for component servicing may be performed as required Remove Air Cleaner Assembly 1 Remove screws securing elbow adapter and gasket to carburetor 2 Remove upper valve cover mounting screws on each side which also secure main mounting bracket for air cleaner 3 Lift air cleaner mounting bracket assembly off engine Remove Throttle and Choke Controls Control Panel Details T N 6 b y A i lt a Ne a s d G NZ 4 e Y A ii Wf gt A Control Panel B Choke Lever o Governor Lever Nut D Governor Lever E Governor Spring 1 Remove screws securing main control bracket to cylinder heads 2 Mark hole location and disconnect governor spring from governor lever 3 Tilt main bracket and disconnect choke linkage from choke lever Remove main control bracket 4 Unhook choke linkage from actuator lever on carburetor Remove External Governor Controls Loosen nut of governor lever mounting screw Leave throttle linkage and spring connected to lever Lift governor lever off governor shaft
22. mounted position of this fitting at any time Contact factory service department for specific instructions if fitting is damaged or its mounting is affected in any way Inspection and Service Water Pump Details A Impeller B Drive Pulley Water coolant pump consists of a sealed impeller assembly which includes outer cover and a cogged drive pulley When pump is mounted to crankcase impeller fits into a cast recess and cover seals against an O ring outside perimeter of recess Impeller assembly is not serviceable but it should be inspected for wear or damage 1 Inspect impeller to make sure blades are in good condition and free of any cracks nicks or damage 2 Impeller shaft should rotate smoothly without binding or wobbling and there should be no sign that coolant has leaked past shaft to outer surface of cover 3 Check that drive pulley is not cracked or damaged in any way If your inspection causes you to doubt its reliability water pump assembly should be replaced Always use a new O ring whenever water pump is removed Do not reuse old O ring or try to use RTV in its place 66 690 01 Rev A Cylinder Head Components Disassembly Inspection and Service Remove Valve Covers 1 Remove screws from two lower valve cover mounting locations on each side 2 Remove valve covers and valve cover gaskets Note on which side oil fill or fuel
23. oil seal during installation 1 Lightly lubricate lips of crankshaft seal with grease 2 Carefully slide flywheel end of crankshaft into crankcase through oil seal Install Connecting Rods with Pistons and Rings Piston Connecting Rod Details A Cylinder 1 B Cylinder 2 NOTE Cylinders are numbered on crankcase Make sure to install piston connecting rod and end cap into its appropriate cylinder bore as previously marked at time of disassembly Do not mix end caps and connecting rods NOTE Proper orientation of piston connecting rod assemblies inside engine is extremely important Improper orientation can cause extensive wear or damage NOTE Make sure to align chamfer of connecting rod with chamfer of its mating end cap When installed flat faces of connecting rods should face each other Faces with raised rib should be toward outside 1 Stagger piston rings in grooves until end gaps are 120 apart Oil ring rails should also be staggered 2 Lubricate cylinder bore piston and piston rings with engine oil Compress rings of cylinder 1 piston using a piston ring compressor 66 690 01 Rev A Reassembly 3 Lubricate crankshaft journals and connecting rod bearing surfaces with engine oil 4 Make sure FLY stamping on pistons is facing towards flywheel side of engine Use a hammer with rubber grip and gently tap piston down into cylinder Be careful that oil ring rails do not spring free
24. pump for restrictions or faulty components as necessary 4 Make sure air cleaner base and carburetor are securely fastened to engine using gaskets in good condition 5 Make sure air cleaner element including precleaner if eguipped is clean and all air cleaner components are fastened securely 6 Make sure ignition system governor system exhaust system and throttle and choke controls are operating properly KohlerEngines com 21 Fuel System Troubleshooting Carburetor Related Causes Condition Possible Cause Conclusion Engine starts hard runs rough or stalls at idle speed Low idle fuel mixture some models speed improperly adjusted Adjust low idle speed tab then adjust low idle fuel needle Engine runs rich indicated by black sooty exhaust smoke misfiring loss of speed and power governor hunting or excessive throttle opening Clogged air cleaner Clean or replace air cleaner Choke partially closed during operation Check choke lever linkage to ensure choke is operating properly Low idle fuel mixture is improperly adjusted Adjust low idle fuel needle some models Float level is set too high Adjust float according to steps outlined in repair kit installation instructions Dirt under fuel inlet needle Remove needle clean needle and seat and blow with compressed air Bowl vent or air bleeds plugged Remove low idle fuel adjusting needl
25. pump is located for correct reassembly later Remove Spark Plugs Remove spark plugs from cylinder heads using a spark plug socket Remove Cylinder Heads and Valve Lifters NOTE Itis not necessary to remove cylinder studs from crankcase unless replacement is intended If studs are removed for any reason discard old stud s do not reuse reinstall Use new studs and refer to assembly sequence for proper installation 1 Rotate crankshaft of engine until valves of one cylinder are closed Loosen rocker arm screws until rocker arms can be pivoted to free push rods 66 690 01 Rev A A Valve B Head C Hydraulic Lifter D Push Rods E Valve Stem Seal F Valve Spring Cap G Spring H Valve Spring Retainers Valve Spring Keepers J Rocker Arms K Rocker Arm Pivot L Rocker Arm Screw M Valve Cover N Fuel Pump 2 Remove push rods and mark their location as either intake or exhaust and cylinder 1 or 2 Push rods should always be reinstalled in their original position 3 Repeat for opposite cylinder 4 Remove nuts and washers from cylinder head studs Carefully remove cylinder heads and head gaskets 5 Remove hydraulic lifters using a hydraulic lifter removing tool do not use a magnet Mark them similar to push rods intake or exhaust and cylinder 1 or 2 Hydraulic lifters should always be reinstalled in their original location Hydraulic Lifters Inspection Check base surface of hydraulic lifters for wear or damage If
26. retainer NOTE Do not soak armature or use solvent when cleaning Wipe clean using a soft cloth or use compressed air 1 Remove hex nut and disconnect positive brush lead bracket from solenoid terminal 2 Remove screws securing solenoid to starter 3 Unhook plunger pin from drive lever Remove gasket from recess in housing 4 Remove thru larger bolts 5 Remove commutator end plate assembly containing brush holder brushes springs and locking caps Remove thrust washer from inside commutator end 6 Remove frame from armature and drive end cap 7 Remove drive lever pivot bushing and backing plate if equipped from end cap 8 Take out drive lever and pull armature out of drive end cap 9 Remove thrust washer from armature shaft 10 Push stop collar down to expose retaining ring 11 Remove retainer from armature shaft Save stop collar 12 Remove drive pinion assembly from armature 13 Clean parts as required Inspection Drive Pinion Check and inspect following areas e Pinion teeth for abnormal wear or damage e Surface between pinion and clutch mechanism for nicks or irregularities which could cause seal damage e Check drive clutch by holding clutch housing and rotating pinion Pinion should rotate in only 1 direction Brushes and Springs Detail A Wear Limit Length Inspect both springs and brushes for wear fatigue or damage Measure length of each br
27. thermostat gasket on intake manifold 3 Install thermostat housing onto intake manifold Install and torque screws to 9 9 N m 88 in Ib 5 Reconnect radiator hose and secure with hose clamp if separated previously gt High Temperature Sensor A high temperature sensor may be mounted in intake manifold and is used to activate a warning light audible alarm or kill engine depending on application if safe operating temperature is exceeded Sensor is a normally open switch which completes a circuit when coolant temperature reaches rated temperature limit of switch For these engines temperature sensor limit is 123 8 C 255 F If warning device activates or engine kills indicating an excessive operating temperature check following 1 Make sure fan belt is in good condition and properly tensioned 2 Make sure cooling fan is properly secured not broken damaged or missing blades 3 Make sure all air intake and cooling surfaces are clean and free of debris accumulation 4 After engine has sufficiently cooled check coolant level in system to make sure it is not low or improperly mixed 5 Check cooling system for leaks 66 690 01 Rev A 6 Check thermostat and pressure test radiator cap 7 Make sure water pump and drive belt are operational 8 Check and inspect wiring from sensor for shorting or damage If none of those are found to be cause do following 1 Drain coolant from system
28. tolerances listed in Specifications 5 After installing new compression top and middle rings on piston check piston to ring side clearance Compare clearance to tolerance listed in Specifications If side clearance is greater than specified a new piston must be used Install New Piston Rings NOTE Rings must be installed correctly Ring installation instructions are usually included with new ring sets Follow instructions carefully Use a piston ring expander to install rings Install bottom oil control ring first and top compression ring last To install new piston rings proceed as follows 1 Oil control ring bottom groove Install expander and then rails Make sure ends of expander are not overlapped 2 Middle compression ring center groove Install center ring using a piston ring installation tool Make sure identification mark is up or dye colored stripe if contained is to left of end gap 66 690 01 Rev A Disassembly Inspection and Service 3 Top compression ring top groove Install top ring using a piston ring expender Make sure identification mark is up or dye colored stripe if contained left of end gap Remove Crankshaft Carefully pull crankshaft from crankcase Note thrust washer and shims if used Inspection and Service Crankshaft Components and Details Flat Washer Crankshaft A Self Tapping Screw B C Plug D E Fillet Must Ble
29. 7 048 mm 0 2775 in 0 25 mm O S 7 298 mm 0 2873 in Intake Valve Lift 8 88 mm 0 3496 in Exhaust Valve Lift 8 88 mm 0 3496 in Nominal Valve Seat Angle 45 3Values are in Metric units Values in parentheses are English equivalents 7 Measure 6 mm 0 236 in above bottom of piston skirt at right angles to piston pin 10 KohlerEngines com 66 690 01 Rev A Specifications GENERAL TORQUE VALUES English Fastener Torque Recommendations for Standard Applications Bolts Screws Nuts and Fasteners Assembled Into Cast Iron or Steel Grade 2 or 5 Fasteners E Into Aluminum Size Grade 2 Grade 5 Grade 8 O Tightening Torgue N m in Ib 20 8 32 2 3 20 2 8 25 2 3 20 10 24 3 6 32 4 5 40 3 6 32 10 32 3 6 32 4 5 40 1 4 20 7 9 70 13 0 115 18 7 165 7 9 70 1 4 28 9 6 85 15 8 140 22 6 200 5 16 18 17 0 150 28 3 250 39 6 350 17 0 150 5 16 24 18 7 165 30 5 270 3 8 16 29 4 260 3 8 24 33 9 300 Tightening Torque N m ft Ib 20 5 16 24 40 7 30 3 8 16 47 5 35 67 8 50 3 8 24 54 2 40 81 4 60 7 16 14 47 5 35 74 6 55 108 5 80 7 16 20 61 0 45 101 7 75 142 5 105 1 2 13 67 8 50 108 5 80 155 9 115 1 2 20 94 9 70 142 4 105 223
30. 7 mm 0 0015 0 0034 in Main Bearing Journals O D New 40 913 40 935 mm 1 6107 1 6116 in O D Max Wear Limit 40 84 mm 1 608 in Max Taper 0 022 mm 0 0009 in 0 025 mm 0 0010 in Max Out of Round New 0 039 0 074 mm 0 0015 0 0029 in Connecting Rod Journal O D New 35 955 35 973 mm 1 4156 1 4163 in O D Max Wear Limit 35 94 mm 1 415 in Max Taper 0 018 mm 0 0007 in 0 025 mm 0 0010 in Crankshaft T I R PTO End Crank in Engine Entire Crank in V Blocks 0 15 mm 0 0059 in 0 10 mm 0 0039 in Cylinder Bore Cylinder Bore I D New Max Wear Limit 77 000 80 000 83 006 83 031 mm 77 025 mm 80 025 mm 3 2679 3 2689 in 3 0315 3 1496 3 0325 in 3 1506 in 77 063 mm 80 065 mm 83 069 mm 3 0340 in 3 1522 in 3 2704 in Max Taper Max Out of Round 0 12 mm 0 0047 in 0 05 mm 0 0020 in Cylinder Head Max Out of Flatness 0 076 mm 0 003 in 3Values are in Metric units Values in parentheses are English equivalents 8 KohlerEngines com 66 690 01 Rev A CLEARANCE SPECIFICATIONS Specifications LH630 LH640 LH685 LH690 LH750 LH755 Governor Governor Cross Shaft to Crankcase Running Clearance 0 025 0 126 mm 0 0009 0 0049 in Governor Cross Shaft O D New Max Wear Limit 7 949 8 000 mm 0 3129 0 3149 in 7 936 mm 0 3124 in Governor Gear Shaft O D New Max Wear Limit 5
31. 990 6 000 mm 0 2358 0 2362 in 5 977 mm 0 2353 in Governor Gear Shaft to Governor Gear Running Clearance 0 090 0 160 mm 0 0035 0 0063 in Ignition Spark Plug Gap 0 76 mm 0 030 in Ignition Module Air Gap 0 203 0 305 mm 0 008 0 012 in Piston Piston Rings and Piston Pin Piston to Piston Pin 0 006 0 018 mm 0 0002 0 0007 in Piston Pin Bore D Max Wear Limit New 17 006 17 013 mm 0 6695 0 6698 in Max Wear Limit 17 025 mm 0 6703 in Piston Pin O D New 16 995 17 000 mm 0 6691 0 6693 in 16 994 mm 0 6691 in Top Compression Ring to Groove Side Clearance 0 040 0 050 0 014 0 041 mm 0 086 mm 0 096 mm 0 0005 0 0016 in 0 0016 0 0020 0 0034 in 0 0038 in Middle Compression Ring to Groove Side Clearance 0 040 0 030 0 012 0 039 mm 0 086 mm 0 076 mm 0 0004 0 0015 in 0 0016 0 0012 0 0034 in 0 0030 in Oil Control Ring to Groove Side Clearance 0 046 0 046 0 026 0 176 mm 0 196 mm 0 196 mm 0 0010 0 0070 in 0 0018 0 0018 0 0077 in 0 0077 in Top and Middle Compression Ring End Gap New Bore 0 250 0 56 mm Top Ring 0 180 0 180 0 0098 0 022 in 0 380 mm 0 430 mm 0 007 1 0 0071 0 0150 in 0 0169 in Middle Ring 0 250 0 250 0 450 mm 0 460 mm 0 0098 0 0098 7s 0 0177 in 0 0181 in Used Bore Max 0 77 mm 0 80 mm 0 94 mm 0 037 0 030 in 0 0315 in in Piston Thrust Face
32. AP Coolant Temp Gauge AQ Over heat Alarm AR Blue AS aaa a Electronic Ignition Systems Tests Special Tools Required NOTE Ignition tester must be used to test ignition on these engines Use of any other tester can result in inaccurate findings Battery on unit must be fully charged and properly connected before performing tests a battery that is hooked up or charged backward will crank engine but it won t have spark Be certain drive is in neutral and all external loads are disconnected e Hand tachometer e Ignition tester e Automotive timing light e Multi meter digital Specifications Required e 0 76 mm 0 03 in Test Ignition Systems NOTE If engine starts or runs during testing you may need to ground kill lead to shut it down Because you have interrupted kill circuit it may not stop using switch Isolate and verify trouble is within engine 1 Locate connectors where wiring harnesses from engine and equipment are joined Separate connectors and remove white kill lead from engine connector Rejoin connectors and position or insulate kill lead terminal so it cannot touch ground Try to start engine to verify whether reported problem is still present Conclusion Condition Possible Cause Problem goes away Electrical System Check key switch wires connections safety interlocks etc Leave kill lead isolated until all testing is completed Identify white kill lead of engine wiring harnes
33. Change oil and oil filter Lubrication System Every 200 Hours e Replace fuel filter Every 250 Hours e Replace air cleaner element and check inner element Air Cleaner Intake Every 500 Hours e Replace air cleaner inner element Air Cleaner Intake Every 500 Hours e Replace spark plugs and set gap Electrical System Every 1000 Hours e Change engine coolant Cooling System 1 Perform these procedures more frequently under severe dusty dirty conditions REPAIRS SERVICE PARTS Kohler genuine service parts can be purchased from Kohler authorized dealers Find your local Kohler Engines dealer at KohlerEngines com or call 1 800 544 2444 U S A and Canada 66 690 01 Rev A KohlerEngines com 3 Maintenance OIL RECOMMENDATIONS We recommend use of Kohler oils for best performance Other high quality detergent oils including synthetic of API American Petroleum Institute service class SJ or higher are acceptable Select viscosity based on air temperature at time of operation as shown in table below F 20 0 20 32 40 50 60 80 100 C 30 20 10 0 10 20 30 40 FUEL RECOMMENDATIONS A WARNING Explosive Fuel can cause fires and severe 3 burns 4 4 Do not fill fuel tank while engine is hot or running Gasoline is extremely flammable and its vapors can explode if ignited Store gasoline only in approved containers in well ventilated unoccupi
34. If these items were noted during disassembly make sure they were reinstalled in proper sequence as illustrated A different procedure must be followed to check and adjust crankshaft end play on these models Race for thrust bearing presses loosely into closure plate If it is not already installed push it into crankshaft bore inside closure plate Pack thrust bearing with heavy grease and stick bearing into race Wipe some grease on face of thrust washer and stick it onto thrust bearing Wipe some grease on face of original shim and stick it onto thrust washer Install closure plate onto crankcase without applying RTV sealant and secure it with only two or three fasteners at this time Use a dial indicator to check crankshaft end play End play should be 0 070 0 590 mm 0 0027 0 0232 in Shims are available in five color coded thicknesses listed below if adjustment is needed Crankshaft End Play Shims Remove closure plate If end play requires adjustment remove original shim and install appropriate size replacement BLUE 0 48 0 52 mm 0 050 mm Nominal 0 019 in BLACK 0 667 0 705 mm 0 686 mm Nominal 0 27 in GREEN 0 8366 0 9127 mm 0 8750 mm Nominal 0 34 in YELLOW 1 9652 1 1414 mm 1 1033 mm Nominal 0 043 in RED 1 2938 1 3700 mm 1 3319 mm Nominal 0 052 in 60 KohlerEngines com A Oil Seal B 8 0 mm 0 315 in C Closure Plate 1 Check to make sure th
35. O D New 76 968 79 963 82 973 76 986 mm 79 981 mm 82 991 mm 3 0302 3 1481 3 2666 3 0309 in 3 1488 in 3 2673 in Max Wear Limit 76 840 mm 79 831 mm 82 841 mm 3 0252 in 3 1430 in 3 3136 in 3Values are in Metric units Values in parentheses are English equivalents 7 Measure 6 mm 0 236 in above bottom of piston skirt at right angles to piston pin 66 690 01 Rev A KohlerEngines com Specifications CLEARANCE SPECIFICATIONS LH630 LH640 LH685 LH690 LH750 LH755 Piston Piston Rings and Piston Pin cont Piston Thrust Face to Cylinder Bore Running 0 014 0 019 0 015 Clearance 0 057 mm 0 062 mm 0 058 mm 0 0005 0 0007 0 005 0 0022 in 0 0024 in 0 0022 in Valves and Valve Lifters Hydraulic Valve Lift er to Crankcase Running Clearance 0 0124 0 0501 mm 0 0005 0 0020 in Intake Valve Stem to Valve Guide Running Clearance 0 038 0 076 mm 0 0015 0 0030 in Exhaust Valve Stem to Valve Guide Running Clearance 0 050 0 088 mm 0 0020 0 0035 in Intake Valve Guide I D New Max Wear Limit 7 038 7 058 mm 0 2771 0 2779 in 7 134 mm 0 2809 in Intake Valve Stem Diameter Max Wear Limit New 6 982 7 000 mm 0 2749 0 2756 in Exhaust Valve Guide I D New 7 038 7 058 mm 0 2771 0 2779 in 7 159 mm 0 2819 in Exhaust Valve Stem Diameter New 6 970 6 988 mm 0 2744 0 2751 in Valve Guide Reamer Size Standard
36. TOOL SUPPLIERS Kohler Tools SE Tools Design Technology Inc Contact your local Kohler source of 415 Howard St 768 Burr Oak Drive supply Lapeer MI 48446 Westmont IL 60559 Phone 810 664 2981 Phone 630 920 1300 Toll Free 800 664 2981 Fax 630 920 0011 Fax 810 664 8181 TOOLS Description Source Part No Alcohol Content Tester For testing alcohol content in reformulated oxygenated fuels Kohler 25 455 11 S Camshaft Endplay Plate For checking camshaft endplay SE Tools KLR 82405 Camshaft Seal Protector Aegis For protecting seal during camshaft installation SE Tools KLR 82417 Cylinder Leakdown Tester Individual component available Adapter 12 mm x 14 mm Required for leakdown test on XT 6 engines For checking combustion retention and if cylinder piston rings or valves are worn Kohler 25 761 05 S Design Technology Inc DTI 731 03 Dealer Tool Kit Domestic Complete kit of Kohler required tools Components of 25 761 39 S Ignition System Tester Cylinder Leakdown Tester Oil Pressure Test Kit Rectifier Regulator Tester 120 V AC 60Hz Kohler 25 761 39 S Kohler 25 455 01 S Kohler 25 761 05 S Kohler 25 761 06 S Kohler 25 761 20 S Dealer Tool Kit International Complete kit of Kohler required tools Components of 25 761 42 S Ignition System Tester Cylinder Leakdown Tester Oil Pressure Test Kit Rectifier Regulator Tester 240 V AC 50Hz Kohler 25 761 42 S Kohler 25 455 01
37. a brush holder with a protective sleeve that will also serve as an installation tool Perform steps 10 13 in Starter Reassembly sequence If starter has been disassembled installation must be done after armature drive lever and frame are installed KohlerEngines com Starter Reassembly NOTE Always use a new retainer Do not reuse old retainers that have been removed NOTE Correctly installed center pivot section of drive lever will be flush or below machined surface of housing Apply drive lubricant to armature shaft splines Install drive pinion onto armature shaft Install and assemble stop collar retainer assembly a Install stop collar down onto armature shaft with counter bore recess up b Install a new retainer in larger rear groove of armature shaft Squeeze with a pliers to compress it in groove c Slide stop collar up and lock it into place so recess surrounds retainer in groove If necessary rotate pinion outward on armature splines against retainer to help seat collar around retainer Install offset thrust stop washer so smaller offset of washer faces retainer collar Apply a small amount of oil to bearing in drive end cap and install armature with drive pinion Lubricate fork end and center pivot of drive lever with drive lubricant Position fork end into space between captured washer and rear of pinion Slide armature into drive end cap and at same time seat drive lever into hou
38. afe use Never use gasoline as a cleaning agent After inspecting external condition of engine clean engine thoroughly before disassembly Clean individual components as engine is disassembled Only clean parts can be accurately inspected and gauged for wear or damage There are many commercially available cleaners that will quickly remove grease oil and grime from engine parts When such a cleaner is used follow manufacturer s instructions and safety precautions carefully Make sure all traces of cleaner are removed before engine is reassembled and placed into operation Even small amounts of these cleaners can quickly break down lubricating properties of engine oil 66 690 01 Rev A CRANKCASE VACUUM TEST Troubleshooting A WARNING Carbon Monoxide can cause severe nausea fainting or death Avoid inhaling exhaust fumes A WARNING Rotating Parts can cause severe injury Stay away while engine is in operation Engine exhaust gases contain poisonous carbon monoxide Carbon monoxide is odorless colorless and can cause death if inhaled Keep hands feet hair and clothing away from all moving parts to prevent injury Never operate engine with covers shrouds or guards removed A partial vacuum should be present in crankcase when engine is operating Pressure in crankcase normally caused by a clogged or improperly assembled breather can cause oil to be forced out at
39. ages which could cause severe engine damage Removing crankpin plug when crankshaft is ground provides easy access for removing any grinding deposits that may collect in oil passages Use following procedure to remove and replace plug Remove Crankshaft Plug 1 Drill a 3 16 in hole through plug in crankshaft 2 Thread a 3 4 in or 1 in long self tapping screw with a flat washer into drilled hole Flat washer must be large enough to seat against shoulder of plug bore 3 Tighten self tapping screw until it draws plug out of crankshaft Install New Crankshaft Plug Use 1 single cylinder camshaft pin as a driver and tap plug into plug bore until it seats at bottom of bore Make sure plug is tapped in evenly to prevent leakage Remove Governor Cross Shaft Governor Cross Shaft Oil Seal Cross Shaft Oil Seal Details A 2 0 mm 0 0787 in NOTE Always use a new retaining ring when reassembling Do not reuse old retaining ring 1 Remove retaining ring and nylon washer from governor cross shaft 2 Remove cross shaft and small washer out through inside of crankcase 56 KohlerEngines com B Governor Cross Shaft Seal Remove governor cross shaft oil seal from crankcase and replace it with a new one if seal is damaged and or leaks Install new seal to depth shown using a seal installer Remove Flywheel End Oil Seals Remove flywheel end crankshaft and camshaft oil seals from crankcase C
40. ality of fuel dirt water stale mixture KohlerEngines com 15 Troubleshooting Engine Loses Power e Dirty air cleaner element e Engine overheated e Excessive engine load e Restricted exhaust e Faulty spark plug s e High crankcase oil level e Incorrect governor setting e Low battery e Low compression e Low crankcase oil level e Quality of fuel dirt water stale mixture Engine Uses Excessive Amount of Oil e Loose or improperly torqued fasteners e Blown head gasket overheated e Breather reed broken e Clogged broken or inoperative crankcase breather e Crankcase overfilled e Incorrect oil viscosity type e Worn cylinder bore e Worn or broken piston rings e Worn valve stems valve guides Oil Leaks from Oil Seals Gaskets e Breather reed broken e Clogged broken or inoperative crankcase breather e Loose or improperly torqued fasteners e Piston blow by or leaky valves e Restricted exhaust 16 KohlerEngines com EXTERNAL ENGINE INSPECTION NOTE It is good practice to drain oil at a location away from workbench Be sure to allow ample time for complete drainage Before cleaning or disassembling engine make a thorough inspection of its external appearance and condition This inspection can give clues to what might be found inside engines and cause when it is disassembled e Check for buildup of dirt and debris on crankcase cooling fins grass screen and o
41. ant level and clean away any debris accumulation daily or before each use Simultaneously inspect hoses and all system connections for signs of leakage Make sure cooling fan is not cracked or missing any blades Check that fan belt and two drive pulleys are in good condition and proper belt tension is present Service Lift screen vertically to remove for cleaning servicing Clean screen and cooling fins of radiator with a soft brush or blow out using clean compressed air To avoid damage to screen and cooling fins do not use a high pressure washer to clean Checking Coolant Level Overflow Reservoir Details A Full B Add NOTE Do not operate engine without coolant in system Do not remove radiator cap when hot Engine coolant is hot and under pressure and can cause severe burns To prevent engine overheating and damage do not exceed more than 70 antifreeze in cooling system Coolant level should be checked at overflow reservoir located behind radiator on fan shroud 1 Check coolant level within overflow reservoir Coolant level should be between FULL and ADD marks on reservoir Do not operate engine with 38 KohlerEngines com 66 690 01 Rev A coolant level below ADD mark Add coolant to overflow reservoir as required which is a 50 50 mixture of ethylene glycol and water distilled or deionized water is recommended Drain Cooling System Radiator Drain Plug Details A L A
42. ap Removal MOHU AECS O OHV UGUD COOED 673 70 26 524 622 54 Overall 24 509 Overall without Rain Cap 2X 184 20 7 252 127 90 Mounting Hole 5 035 g Mounting Hole Dimensions in millimeters Inch eguivalents shown in Oil Filter Side Optional Oil Fill 175 41 6 906 Mounting Hole A 4 458 49 PTO Side 18 051 Overall Flywheel End 2X 297 47 142 88 Bolt Circle 1 711 6 625 Exhaust Ports 119 78 4 716 K 15 70 Oil Filter Removal 0 618 Starter Side EI gt Bolt Circle 197 00 oder S 4X 3 8 16 UNC 2B Inch 7 756 Overflow Oil Fill le 299 00 Oil Filter 4x 7 16 14 UNC 2B Inch Air Intake Optional Orientation Fill oon 11 77 le 235 19 Yeon i 9 259 Wa Mounting Hole A Ge EE gg o I 583 30 Z ORY 22 965 101 60 d s 4 000 Option 4 Inch Square Key 490 74 19 320 112 92 8 18 UNF Thread Center of Air Intake o m k 4 446 i 7 16 20 Thread Option V
43. at Housing Mounting Fastener 6 2 7 3 N m 55 65 in Ib Carburetor Mounting Fastener Closure Plate 9 9 N m 88 in lb Closure Plate Fastener 24 4 N m 216 in lb Connecting Rod Cap Fastener torque in increments 11 3 N m 100 in Ib Crankcase Breather Cover Fastener 10 7 N m 95 in Ib into new hole 7 3 N m 65 in Ib into used hole Oil Drain Plug Cylinder Head 13 6 N m 10 ft Ib Cylinder Head Fastener torque in 2 increments first to 16 9 N m 150 in lb finally to 33 9 N m 300 in Ib Rocker Pivot Fastener 11 3 N m 100 in lb 3Values are in Metric units Values in parentheses are English equivalents 4 Exceeding maximum angle of operation may cause engine damage from insufficient lubrication 5 Lubricate threads with engine oil prior to assembly S Any and all horsepower hp references by Kohler are Certified Power Ratings and per SAE J1940 amp J1995 hp standards Details on Certified Power Ratings can be found at KohlerEngines com 6 KohlerEngines com 66 690 01 Rev A TORQUE SPECIFICATIONS Specifications LH630 LH640 LH685 LH690 LH750 LH755 Electric Starter Starter Thru Bolt 5 6 9 0 N m 49 79 in Ib Starter Mounting Screw 15 3 N m 135 in Ib Starter Brush Holder Fastener 2 5 3 3 N m 22 29 in Ib Starter Solenoid Fastener 4 0 6 0 N m 35 53 in Ib Starter Solenoid Positive Br
44. at there are no nicks or burrs in crankshaft bore of closure plate 2 Apply a light coat of engine oil to outside diameter of oil seal 3 Drive oil seal into closure plate using a seal driver Make sure oil seal is installed straight and true in bore to depth shown 66 690 01 Rev A Install Closure Plate Assembly Closure Plate Sealant Pattern A Plated Screw Location RTV silicone sealant is used as a gasket between closure plate and crankcase Always use fresh sealant Using outdated sealant can result in leakage 1 Be sure sealing surfaces have been cleaned and prepared 2 Check to make sure that there are no nicks or burrs on sealing surfaces of closure plate or crankcase 3 Apply a 1 16 bead of sealant to sealing surface of closure plate 4 Make sure end of governor cross shaft is lying against bottom of cylinder 1 inside of crankcase 5 If alignment pins were removed previously install them in their respective locations in crankcase 66 690 01 Rev A Reassembly Install closure plate on crankcase Carefully seat camshaft and crankshaft into their mating bearings Rotate crankshaft to help engage oil pump and governor gear meshes Install screws securing closure plate to crankcase If a thick flat washer was used on one of screws install it in number 10 location Install silver plated ground screw in its original location normally number 4 or 6 loca
45. ator to ground using a DC 4 With engine stopped measure resistance from each stator lead to ground using an ohmmeter voltmeter If voltage is 13 8 volts or more place a minimum Condition Conclusion load of 5 amps turn on lights if 60 watts or more or Resistance is infinity ohms Stator is OK not shorted place a 2 5 ohm 100 watt resistor across battery no continuity to ground terminals on battery to reduce voltage Observe ammeter Resistance or continuity Stator leads are shorted to measured ground replace Condition Conclusion To test charging system for battery continuously charging Charge rate increases Charging system is OK at high rate when load is applied and battery was fully 1 With engine running at 3600 RPM measure voltage charged from B lead to ground using a DC voltmeter Charge rate does not Test stator and rectifier Si increase when load is regulator steps 2 and 3 Condition Conclusion applied Voltage is 14 7 volts or Charging system is OK less Battery is unable to hold 2 Remove connector from rectifier regulator With charge sence or EE engine running at 3600 RPM measure AC voltage otage is more than 14 7 Paro rectifier regulator across stator leads using an AC voltmeter VOIIS e Condition Conclusion Voltage is 28 volts or Stator is OK Rectifier more regulator is faulty replace Voltage is less than 28 Stator is faulty replace vo
46. ator is installed External Engine Components Position upper radiator support brackets on top of air cleaner mounting bracket Install and finger tighten four mounting screws Connect upper and lower radiator hoses to inlets of radiator and water pump Secure with hose clamps Make sure tangs of upper clamp face away from fan Check for adequate clearance between fan and shroud Adjust lower radiator supports as required then torque four mounting screws to 9 9 N m 88 in Ib Hold radiator assembly in position then torgue screws securing two upper radiator supports to 9 9 N m 88 in Ib A Dipstick B Electric Starter Adapter Plate D Oil Drain Plug E Flywheel Cover F Radiator Drain Plug 70 KohlerEngines com 66 690 01 Rev A 8 If securing upper brackets to top radiator mounts were loosened torque to 9 9 N m 88 in Ib 9 Ifa pulse style fuel pump is used install it to tapped holes in cylinder 2 side upper radiator support bracket and torque two screws to 6 8 7 3 N m 60 65 in Ib Connect outlet line between pump and carburetor and vacuum line to crankcase fitting Secure with clamps Install Starter Adapter 1 Install starter adapter to crankcase so cutout is offset down and facing away from flywheel side Install mounting screws and position clamp for stator leads on upper screw Torque screws to 15 3 N m 135 in Ib 2
47. between bottom of ring compressor and top of cylinder 5 Guide lower end of connecting rod and rotate crankshaft to join two Install rod cap to connecting rod using screws and torque in increments to 11 3 N m 100 in Ib 6 Repeat above procedure for other connecting rod and piston assembly Install Camshaft 1 Inspect edges of camshaft keyway make sure they are not nicked or burred Use a seal protector 11 16 to prevent damaging seal lips or dislodging inner spring when camshaft is installed Cellophane tape over keyway is also recommended 2 Lubricate camshaft bearing surfaces of crankcase and camshaft with engine oil Apply a small amount of grease to lips of oil seal 3 Rotate crankshaft and position timing mark of crankshaft gear at 12 o clock position 4 Turn governor cross shaft clockwise until lower end of shaft contacts crankcase cylinder 1 side Make sure cross shaft remains in this position while installing camshaft 5 Slide camshaft into bearing surface of crankcase positioning timing mark of camshaft gear at 6 o clock position Make sure that camshaft gear and crankshaft gear mesh and timing marks are aligned Checking Setting Camshaft End Play 1 Install shim removed during disassembly onto camshaft 2 Position end play tool on camshaft 3 Apply pressure on end play checking tool pushing camshaft toward crankshaft Use a feeler gauge to measure end play between shim and end play to
48. bly F Adapter Plate G Carburetor Bracket l Fan J Fan Belt K Bearing Pulley M Pulley Half N Spacer Shims o Adapter 66 690 01 Rev A KohlerEngines com 45 Disassembly Inspection and Service Remove Oil Sentry if equipped Disconnect wire lead from Oil Sentry switch and remove switch from breather cover Remove Breather Cover 1 2 Remove screws securing breather cover to crankcase Carefully pry under protruding edge of breather cover to separate and remove cover from gasket Do not pry on sealing surfaces as it could cause damage resulting in leaks Remove breather gasket and fiber filter from breather chamber Remove screw breather reed retainer and breather reed from breather chamber Remove Lower Drive Pulley and Fan Belt 1 2 Remove four screws attaching lower drive pulley assembly to pulley adapter and flywheel Remove pulley halves with spacer shims from adapter and take fan belt off upper pulley fan assembly Note number of shims between pulley halves and on front side of pulley especially if same belt will be reinstalled Remove Fan Assembly Mounting Bracket and Fan Shaft NOTE Further disassembly of fan hub and pulley 46 assembly is not necessary unless a problem exists see If disassembly is performed note assembly order and position of parts 1 Remove front nut and washer securing fan assembly to fan shaft Remove fan and pulley asse
49. carburetor fl oat bowl and is drawn into carburetor body and mixed with air This fuel air mixture is then burned in engine combustion chamber FUEL RECOMMENDATIONS Refer to Maintenance FUEL LINE Low permeation fuel line must be installed on carbureted Kohler Co engines to maintain EPA and CARB regulatory compliance FUEL SYSTEM TESTS FUEL PUMP These engines use either a mechanical fuel pump or optional remote mounted electric fuel pump assembly Operation of mechanical fuel pump occurs by direct lever pump actuation off rocker arm movement Pumping action causes diaphragm on inside of pump to pull fuel in on its downward stroke and to push it into carburetor on its upward stroke internal check valves prevent fuel from going backward through pump Fuel Pump Replacement Mechanical fuel pump is an integral part of valve cover assembly and not serviced separately 1 Disconnect fuel lines from inlet and outlet fittings Note orientation 2 Follow procedure for replacing valve cover Refer to Disassembly and Reassembly 3 Reconnect fuel lines to inlet and outlet fittings and secure with clamps When engine starts hard or turns over but will not start fuel system might be causing problems Test fuel system by performing following tests 1 Check for fuel in combustion chamber a Disconnect and ground spark plug leads b Close choke on carburetor c Crank engine several times d Remove spark plug and check
50. case Components pr Neen A V oe oo A Oil Seal B Governor Gear Shaft C m Vlk D Governor Gear E Regulating Pin F Camshaft G Gerotor H Oil Pump Assembly I Nipple J Oil Filter K Crankshaft L Governor Cross Shaft M Piston Pin Retainer N Piston Pin o Connecting Rod P Piston Q Piston Ring Set Remove Closure Plate Inspection 1 Remove screws securing closure plate to crankcase 2 Locate three splitting tabs which are cast into perimeter of closure plate Insert drive end of a 1 2 breaker bar between top splitting tab and crankcase Hold handle horizontal and pull it toward you to break RTV seal If necessary pry at bottom splitting tabs also Do not pry on sealing surfaces as this could cause leaks Note assembly and orientation of parts Carefully pull closure plate from crankcase 52 KohlerEngines com Inspect oil seal in closure plate and remove it if it is worn or damaged Inspect main bearing surface for wear or damage Replace closure plate assembly if required 66 690 01 Rev A Governor Gear Assembly Disassembly Inspection and Service Oil Pump Assembly Governor Shaft Press Depth Details Oil Pump Torque Sequence A Gear Shaft B 19 40 mm 0 7638 in C 34 0 mm 1 3386 in 33 5 mm 1 3189 in Governor gear assembly is located inside closure plate If service is reguired refer to these procedures Inspection Inspect governor gear
51. ctifier regulator tester To test 20 25 amp rectifier regulators 1 Connect single lead adapter in between B center terminal of rectifier regulator being tested and squared single end of tandem adapter lead 2 Connect tester ground lead with spring clamp to body of rectifier regulator 3 Connect red lead and 1 black lead to terminals on open end of tandem adapter lead connections are not location specific 4 Connect remaining black lead from tester to 1 outer AC terminal on rectifier regulator 32 KohlerEngines com 5 Plug tester into proper AC outlet power for tester being used Turn on power switch POWER light should be illuminated and 1 of 4 status lights may be on as well This does not represent condition of part 6 Press TEST button until a click is heard and then release Momentarily 1 of 4 lights will illuminate indicating partial condition of part To test 15 amp rectifier regulators 1 Connect tester ground lead with spring clamp to body of rectifier regulator being tested 2 Connect tester red lead to B terminal of rectifier regulator and 2 black tester leads to 2 AC terminals 3 Plug tester into proper AC outlet power for tester being used Turn on power switch POWER light should be illuminated and 1 of 4 status lights may be on as well This does not represent condition of part 4 Press TEST button until a click is heard and then release Momentarily 1 of 4 status lights will illuminate
52. ctions that intermittently ground ignition kill circuit e Quality of fuel dirt water stale mixture e Restricted fuel tank cap vent Engine Starts Hard e Engine overheated e Faulty spark plug s e Idle fuel adjusting needle s improperly set e Idle speed adjusting screw improperly set e Inadequate fuel supply e Low compression e Quality of fuel dirt water stale mixture e Restricted fuel tank cap vent Engine Overheats e Clogged fuel line or fuel filter e Engine overheated e Faulty ACR mechanism e Faulty or misadjusted choke or throttle controls e Faulty spark plug s e Flywheel key sheared e Fuel pump malfunction vacuum hose clogged or leaking e Interlock switch is engaged or faulty e Loose wires or connections that intermittently ground ignition kill circuit e Low compression e Quality of fuel dirt water stale mixture e Weak spark 66 690 01 Rev A e Cooling fan broken e Excessive engine load e Fan belt failed off e Faulty carburetor e High crankcase oil level e Lean fuel mixture e Low cooling system fluid level e Low crankcase oil level e Radiator and or cooling system components clogged restricted or leaking e Water pump belt failed broken e Water pump malfunction Engine Knocks e Excessive engine load e Hydraulic lifter malfunction e Incorrect oil viscosity type e Internal wear or damage e Low crankcase oil level e Qu
53. cupied buildings away from sparks or flames Spilled fuel could ignite if it comes in contact with hot parts or sparks from ignition Never use gasoline as a cleaning agent NOTE Main and slow jets are fixed and size specific and can be removed if required Fixed jets for high altitudes are available e Inspect carburetor body for cracks holes and other wear or damage e Inspect float for cracks holes and missing or damaged float tabs Check float hinge and shaft for wear or damage e Inspect fuel inlet needle and seat for wear or damage e Inspect spring loaded choke plate to make sure it moves freely on shaft 1 Perform removal procedures for appropriate air cleaner and carburetor outlined in Disassembly 2 Clean exterior surfaces of dirt or foreign material before disassembling carburetor Remove bowl retaining screws or solenoid assembly on most single cylinder engines and carefully separate fuel bowl from carburetor Do not damage fuel bowl O rings Transfer any remaining fuel into an approved container Save all parts Fuel can also be drained prior to bowl removal by loosening removing bowl drain screw 3 Remove float pin some carburetors may have a screw which requires removal and inlet needle Seat for inlet needle is not serviceable and should not be removed 4 Clean carburetor bowl and inlet seat areas as required 5 Carefully remove main jets from carburetor For two barrel carbur
54. d This switch is designed to prevent engine from starting in a low oil or no oil condition Oil Sentry may not shut down a running engine before damage occurs In some applications this switch may activate a warning signal Read your equipment manuals for more information Oil Sentry pressure switch is installed in breather cover On engines not equipped with Oil Sentry installation hole is sealed with a 1 8 27 N P T F pipe plug Installation 1 Apply pipe sealant with Teflon Loctite PST 592 Thread Sealant or equivalent to threads of switch 2 Install switch into tapped hole in closure plate 3 Torque switch to 4 5 N m 40 in Ib Testing Compressed air a pressure regulator pressure gauge and a continuity tester are required to test switch 1 Connect continuity tester across blade terminal and metal case of switch With O psi pressure applied to switch tester should indicate continuity switch closed 2 Gradually increase pressure to switch As pressure increases through range of 3 5 psi tester should indicate a change to no continuity switch open Switch should remain open as pressure is increased to 90 psi maximum 3 Gradually decrease pressure through range of 3 5 psi Tester should indicate a change to continuity switch closed down to 0 psi 4 Replace switch if it does not operate as specified 66 690 01 Rev A KohlerEngines com Lubrication System 27 Electrical Syst
55. dure for other cylinder head Do not interchange parts from 1 cylinder head to other EXHAUST VALVE Sy INTAKE VALVE S EXHAUST INSERT INTAKE INSERT Dimension Intake Exhaust A Seat Angle 89 89 B Insert O D 36 987 37 013 mm 1 4562 1 4572 in 32 987 33 013 mm 1 2987 1 2997 in C Guide Depth 4 mm 0 1575 in 6 5 mm 0 2559 in D Guide I D 7 038 7 058 mm 0 2771 0 2779 in 7 038 7 058 mm 0 2771 0 2779 in E Valve Head Diameter 33 37 33 63 mm 1 3138 1 3240 in 29 37 29 63 mm 1 1563 1 1665 in E Valve Face Angle 45 45 G Valve Margin Min 1 5 mm 0 0591 in 1 5 mm 0 0591 in H Valve Stem Diameter 6 982 7 000 mm 0 2749 0 2756 in 6 970 6 988 mm 0 2744 0 2751 in 50 KohlerEngines com 66 690 01 Rev A After cleaning check flatness of cylinder head and corresponding top surface of crankcase using a surface plate or piece of glass and feeler gauge Maximum allowable out of flatness is 0 076 mm 0 003 in Carefully inspect valve mechanism parts Inspect valve springs and related hardware for excessive wear or distortion Check valves and valve seat area or inserts for evidence of deep pitting cracks or distortion Check clearance of valve stems in guides Hard starting or loss of power accompanied by high fuel consumption may be symptoms of faulty valves Although these symptoms could also be attributed to worn rings remove and check valves first After
56. e Clean vent ports and air bleeds Blow out all passages with compressed air Leaky cracked or damaged float Submerge float to check for leaks Engine runs lean indicated by misfiring loss of speed and power governor hunting or excessive throttle opening Low idle fuel mixture is improperly adjusted Adjust low idle fuel needle some models Float level is set too low Adjust float according to steps outlined in repair kit installation instructions Idle holes plugged dirt in fuel delivery channels Remove low idle fuel adjusting needle Clean main fuel jet and all passages blow out with compressed air Fuel leaks from carburetor Float level set too high Adjust float according to steps outlined in repair kit installation instructions Dirt under fuel inlet needle Remove needle clean needle and seat and blow with compressed air Bowl vents plugged Blow out with compressed air Carburetor bowl gasket leaks Replace gasket Fuel Shut off Solenoid Most carburetors are equipped with a fuel shut off solenoid Solenoid is attached to fuel bowl Solenoid has a spring loaded pin that retracts when 12 volts is applied to lead allowing fuel flow to main jet When current is removed pin extends blocking fuel flow Below is a simple test performed with engine off that can determine if solenoid is functioning properly 1 Shut off fuel and rem
57. e an inside micrometer telescoping gauge or bore gauge and measure cylinder bore Take measurement approximately 63 5 mm 2 5 in below top of bore and perpendicular to piston pin 3 Piston to bore clearance is difference between bore diameter and piston diameter step 2 minus step 1 KohlerEngines com 57 Reassembly Crankcase Components NOTE Make sure engine is assembled using all specified torque values tightening sequences and clearances Failure to observe specifications could cause severe engine wear or damage Always use new gaskets Apply a small amount of oil to threads of critical fasteners before assembly unless a sealant or Loctite is specified or preapplied Make sure all traces of any cleaner are removed before engine is assembled and placed into operation Even small amounts of these cleaners can quickly break down lubricating properties of engine oil Check closure plate crankcase cylinder heads and valve covers to be certain that all old sealing material has been removed Use gasket remover lacquer thinner or paint remover to remove any remaining traces Clean surfaces with isopropyl alcohol acetone lacquer thinner or electrical contact cleaner A Oil Seal B Governor Gear Shaft C a D Governor Gear E Regulating Pin F Camshaft G Gerotor H Oil Pump Assembly l Nipple J Oil Filter K Crankshaft L Governor Cross Shaft M Piston Pin Retainer N Piston Pin o Co
58. ed buildings away from sparks or flames Spilled fuel could ignite if it comes in contact with hot parts or sparks from ignition Never use gasoline as a cleaning agent NOTE E15 E20 and E85 are NOT approved and should NOT be used effects of old stale or contaminated fuel are not warrantable Fuel must meet these requirements e Clean fresh unleaded gasoline e Octane rating of 87 R M 2 or higher e Research Octane Number RON 90 octane minimum e Gasoline up to 10 ethyl alcohol 90 unleaded is acceptable e Methyl Tertiary Butyl Ether MTBE and unleaded gasoline blend max 15 MTBE by volume are approved e Do not add oil to gasoline e Do not overfill fuel tank e Do not use gasoline older than 30 days KohlerEngines com STORAGE If engine will be out of service for 2 months or more follow procedure below 1 Add Kohler PRO Series fuel treatment or equivalent to fuel tank Run engine 2 3 minutes to get stabilized fuel into fuel system failures due to untreated fuel are not warrantable 2 Change oil while engine is still warm from operation Remove spark plug s and pour about 1 oz of engine oil into cylinder s Replace spark plug s and crank engine slowly to distribute oil 3 Disconnect negative battery cable 4 Store engine in a clean dry place 66 690 01 Rev A Engine Dimensions Specifications Fuel Pump N 440 00 17 323 6005 Rain C
59. einstalling cylinder barrel retaining nuts Kohler 52 455 04 S Oil Pressure Test Kit For testing verifying oil pressure on pressure lubricated engines Kohler 25 761 06 S Radiator Tester For pressure testing radiator and cap on Aegis liquid cooled engines Kohler 25 455 10 S Rectifier Regulator Tester 120 volt current Rectifier Regulator Tester 240 volt current For testing rectifier regulators Components of 25 761 20 S and 25 761 41 S CS PRO Regulator Test Harness Special Regulator Test Harness with Diode Spark Advance Module SAM Tester For testing SAM ASAM and DSAM on engines with SMART SPARK Starter Servicing Kit All Starters For removing and reinstalling drive retaining rings and brushes Individual component available Starter Brush Holding Tool Solenoid Shift Kohler 25 761 20 S Kohler 25 761 41 S Design Technology Inc DTI 031 DTI 033 Kohler 25 761 40 S SE Tools KLR 82411 SE Tools KLR 82416 Triad OHC Timing Tool Set For holding cam gears and crankshaft in timed position while installing timing belt Kohler 28 761 01 S Valve Guide Reamer K and M Series For properly sizing valve guides after installation Design Technology Inc DTI K828 Valve Guide Reamer O S Command Series For reaming worn valve guides to accept replacement oversize valves Can be used in low speed drill press or with handle below for hand reaming Reamer Handle For hand reaming using
60. em SPARK PLUGS A CAUTION E Electrical Shock can cause injury Do not touch wires while engine is running Spark Plug Component and Details o Bo A Wire Gauge B Spark Plug C Ground Electrode D Gap NOTE Do not clean spark plug in a machine using abrasive grit Some grit could remain in spark plug and enter engine causing extensive wear and damage Engine misfire or starting problems are often caused by a spark plug that has improper gap or is in poor condition Engine is equipped with following spark plugs Gap 0 76 mm 0 03 in Thread Size 14 mm Reach 19 1 mm 3 4 in Hex Size 15 9 mm 5 8 in Refer to Maintenance for Repairs Service Parts Service Clean out spark plug recess Remove plug and replace 1 Check gap using wire feeler gauge Adjust gap to 0 76 mm 0 03 in 2 Install plug into cylinder head 3 Torque plug to 27 N m 20 ft Ib Inspection Inspect each spark plug as it is removed from cylinder head Deposits on tip are an indication of general condition of piston rings valves and carburetor Normal and fouled plugs are shown in following photos 28 KohlerEngines com Normal Plug taken from an engine operating under normal conditions will have light tan or gray colored deposits If center electrode is not worn plug can be set to proper gap and reused Worn e On a
61. embly of intake manifold components may be performed as necessary If thermostat is to be removed loosen and remove screws securing thermostat housing to intake manifold Separate housing and remove thermostat discard old gasket Water Pump Components eo A e A it Me A 3 LU O ring B Water Pump Camshaft Pulley A C Water Pump Belt D E Transfer Tube Remove Camshaft Pulley and Water Pump Belt 1 Remove screw and flat washer securing cogged drive pulley to camshaft 2 Carefully lift pulley off camshaft and remove belt from water pump pulley 3 Remove camshaft key from keyway Remove Water Pump and Transfer Tube 1 Loosen and unscrew hex cap section securing transfer tube to 90 fitting in crankcase Support fitting with a wrench when loosening hex cap section 2 Remove screws securing water pump to crankcase 3 Lift water pump up and carefully work ferruled end of transfer tube out of fitting Remove water pump with transfer tube and hose section attached Remove and discard O ring from within channel of pump housing 48 KohlerEngines com 4 Inspect and if necessary separate transfer tube and hose section from water pump Remove hose clamps noting their size differences and position of tangs IMPORTANT 90 fitting in crankcase which transfer tube is connected to is sealed and installed at factory in a specific position Do not loosen remove or alter
62. end housing and carefully place tool with extension and assembled original brush holder assembly onto end of armature shaft Slide brush holder assembly down into place around commutator install positive brush lead grommet in cutout of frame Install end cap onto armature and frame aligning thin raised rib in end cap with corresponding slot in grommet of positive brush lead Solenoid Tests Starter System 12 Install thru bolts and brush holder mounting screws Torque bolts to 5 6 9 0 N m 49 79 in Ib and brush holder mounting screws to 2 5 3 3 N m 22 29 in Ib 13 Hook plunger behind upper end of drive lever and install spring into solenoid Insert mounting screws through holes in drive end cap Use these to hold solenoid gasket in position then mount solenoid Torque screws to 4 0 6 0 N m 35 53 in bi 14 Connect positive brush lead bracket to solenoid and secure with nut Torque nut to 8 11 N m 71 97 in Ib Do not overtighten NOTE DO NOT leave 12 volt test leads connected to solenoid for any time over what is necessary for performing each of individual tests Internal damage to solenoid may occur Disconnect all leads from solenoid including positive brush lead attached to lower stud terminal Remove mounting hardware and separate solenoid from starter for testing To test solenoid pull in coil plunger Actuation 1 2 Use a 12 volt power supply and 2 test leads Connect 1 lead to f
63. er energizes but turns Battery Check specific gravity of battery If low recharge or replace slowly battery as necessary Brushes Check for excessively dirty or worn brushes and commutator Clean using a coarse cloth not emery cloth Replace brushes if excessively or unevenly worn Transmission or Engine Make sure clutch or transmission is disengaged or placed in neutral This is especially important on equipment with hydrostatic drive Transmission must be exactly in neutral to prevent resistance which could keep engine from starting Check for seized engine components such as bearings connecting rod and piston 34 KohlerEngines com 66 690 01 Rev A Solenoid Shift Starter Components A Tube B Washer C Armature D Drive E Stop F Retaining Ring G Collar H Drive End Cap l Screw J Plunger K Spring L Lever M Plate N Plug O Solenoid P Frame and Field Q Brush Holder R Nut s So End T Scrawl U Bolt When power is applied to starter electric solenoid moves drive pinion out onto drive shaft and into mesh with flywheel ring gear When pinion reaches end of drive shaft it rotates flywheel and cranks engine When engine starts and start switch is released starter solenoid is deactivated drive lever moves back and drive pinion moves out of mesh with ring gear into retracted position 66 690 01 Rev A Starter System Starter Disassembly NOTE Do not reuse old
64. es in contact with hot parts or sparks from ignition Never use gasoline as a cleaning agent Keihin One Barrel Carburetor Components Carburetor Upper alia A Body Choke B Self relieving Choke Body Gasket Formed C Rubber D Slow Speed Jet E Inlet Needle Valve F Clip G Float Pin H Float Assembly Carburetor Lower Body Throttle Maner K Idle ene cueing L Solenoid Seat 3 Idle Speed Adjusting M Fuel Shut off Solenoid N Screw o Jet Accelerator Pump P Accelerator Pump Carburetor only Cover Q Diaphragm R Diaphragm Spring S O ring T Rubber Boot U Bushing V Return Spring W Accelerator Pump 66 690 01 Rev A Fuel System Engines in this series are equipped with emission compliant fixed main jet carburetors manufactured by Keihin All have self relieving chokes for efficient operation Depending on specifications and application involved most will also contain a fuel shut off solenoid and an accelerator pump Troubleshooting Checklist When engine starts hard runs rough or stalls at low idle speed check these areas before adjusting or disassembling carburetor 1 Make sure fuel tank is filled with clean fresh gasoline 2 Make sure fuel tank cap vent is not blocked and is operating properly 3 Make sure fuel is reaching carburetor This includes checking fuel shut off valve fuel tank filter screen in line fuel filter fuel lines and fuel
65. etors note and mark jets by location for proper reassembly Main jets may be size side specific After main jets are removed on some carburetors main nozzles can be removed through bottom of main towers Note orientation direction of nozzles End with 2 raised shoulders should be out down adjacent to main jets Save parts for cleaning and reuse 6 Position of slow jet varies and is removable only on some styles of carburetors See correct illustration for corresponding style of carburetor showing Carburetor is now disassembled for appropriate cleaning and installation of parts in overhaul kit See instructions provided with repair kits for more detailed information High Altitude Operation Engines may require a high altitude carburetor kit to ensure correct engine operation at altitudes above 1219 meters 4000 ft To obtain high altitude kit information or to find a Kohler authorized dealer visit KohlerEngines com or call1 800 544 2444 U S and Canada This engine should be operated in its original configuration below 1219 meters 4000 ft as damage may occur if high altitude carburetor kit is installed and operated below 1219 meters 4000 ft 24 location On two barrel carburetors slow jets may be sized to specific side Mark or tag jets for proper reassembly Note small O ring on bottom of each jet Save parts for cleaning and reuse unless a jet kit is also being installed Clean slow jets using compressed air
66. ew to secure pulley in place Torque screw to 9 9 N m 88 in Ib 66 690 01 Rev A Flywheel ignition Intake Manifold Components Reassembly AAS H d N Ge L N G AG AL A L 4 A Des im 3 s 1 i AN g fe FF gt o ee KX ji a lt S 6 ei f 3 be A A k d y Ns GS A AN Lei A A X f ZV LL Ne LM yA f oe Re Ke g POZA WX fal CO lt ng 1 OG gt lt lt Gei 2 BO ary Ort LA x x P lt 9 AJ VW Ww gt Le LJ A EN Ze s V X 7 H 4 o gt A D f gt tS Sa f d A Thermostat Housing B Intake Manifold C Thermostat D Ignition Module E Flywheel F Stator G Torque Sequence 4 Install and tighten pipe plug or temperature warning installintake Mannole switch if removed previously from threaded port of 1 Check that gasket surfaces of intake manifold and intake manifold Use pipe sealant with Teflon cylinder heads are clean and free of any nicks or Loctite 592 or equivalent on threads Torque to damage 22 6 N m 200 in Ib 2 Install new intake manifold gaskets onto port 5 Connect wire leads to temperature warning switch surfaces of cylinder heads audible alarm and or Oil Sentry switch as 3 Set intake manifold with by pass hose and wiring equipped harness attached down into position onto gaskets and cylinder heads Install and finger tighten screws in their appropriate loca
67. f a low speed drill press is preferred as it facilitates more accurate alignment of bore in relation to crankshaft crossbore Honing is best accomplished at a drill speed of about 250 RPM and 60 strokes per minute After installing coarse stones in hone proceed as follows 1 Lower hone into bore and after centering adjust so that stones are in contact with cylinder wall Use of a commercial cutting cooling agent is recommended 2 With lower edge of each stone positioned even with lowest edge of bore start drill and honing process Move hone up and down while resizing to prevent formation of cutting ridges Check size frequently 3 When bore is within 0 064 mm 0 0025 in of desired size remove coarse stones and replace with burnishing stones Continue with burnishing stones until within 0 013 mm 0 0005 in of desired size and then use finish stones 220 280 grit and polish to final size A crosshatch should be observed if honing is done correctly Crosshatch should intersect at approximately 23 33 off horizontal Too flat an angle could cause rings to skip and wear excessively too steep an angle will result in high oil consumption 4 After resizing check bore for roundness taper and size Use an inside micrometer telescoping gauge or bore gauge to take measurements These measurements should be taken at three locations in cylinder at top middle and bottom Two measurements should be taken perpendicular to each othe
68. f ignition switch and shorted kill lead BATTERY CHARGING SYSTEM NOTE Observe following guidelines to avoid damage to electrical system and components e Make sure battery polarity is correct A negative ground system is used e Disconnect rectifier regulator plug and or wiring harness plug before doing any electric welding on equipment powered by engine Disconnect all other electrical accessories in common ground with engine e Prevent stator AC leads from touching or shorting while engine is running This could damage stator NOTE 20 amp charging systems use a 15 amp stator with a 25 amp rectifier regulator Most engines are equipped with a 15 20 or 25 amp regulated charging system 15 20 25 Amp Regulated Charging System Stator Stator is mounted on crankcase behind flywheel Follow procedures in Disassembly and Reassembly if stator replacement is necessary Rectifier Regulator NOTE When installing rectifier regulator take note of terminal positions and install plug correctly NOTE Disconnect all electrical connections attached to rectifier regulator Testing may be performed with rectifier regulator mounted or loose Repeat applicable test procedure 2 or 3 times to determine condition of part Rectifier regulator is mounted on backing shroud assembly To replace it disconnect plug remove mounting screws and ground lead Testing rectifier regulator may be performed as follows using appropriate re
69. for fuel at tip Condition Fuel at tip of spark plug 2 Check for fuel flow from tank to fuel pump a Remove fuel line from inlet fitting of fuel pump b Hold line below bottom of tank Open shut off valve if equipped and observe flow 3 Check operation of fuel pump a Remove fuel line from inlet fitting of carburetor b Crank engine several times and observe flow Conclusion Fuel is reaching combustion chamber No fuel at tip of spark plug Check fuel flow from fuel tank step 2 Fuel flows from fuel line Check for faulty fuel pump step 3 If fuel pump is working check for faulty carburetor Refer to Carburetor No fuel flow from fuel line Fuel line condition Check fuel tank cap vent fuel pickup screen in line filter shut off valve and fuel line Correct any observed problem and reconnect line Check for a clogged fuel line If fuel line is unobstructed check for overfilled crankcase and or oil in pulse line If checks don t reveal cause of problem replace pump 20 KohlerEngines com 66 690 01 Rev A CARBURETOR A WARNING W Explosive Fuel can cause fires and severe burns g d Do not fill fuel tank while engine is hot or running Gasoline is extremely flammable and its vapors can explode if ignited Store gasoline only in approved containers in well ventilated unoccupied buildings away from sparks or flames Spilled fuel could ignite if it com
70. formed within limits allowed by cap Do not attempt to remove limiter caps 1 Place throttle control into idle or slow position Adjust low idle speed to 1200 RPM Follow Low Idle Speed RPM Adjustment 2 Low idle fuel needle s setting place throttle into idle or slow position a Turn 1 low idle fuel adjusting needle out counterclockwise from preliminary setting until engine speed decreases rich Note position of needle Now turn adjusting needle in clockwise Engine speed may increase then it will decrease as needle is turned in lean Note position of needle Set adjusting needle midway between rich and lean settings b Repeat procedure on other low idle adjustment needle two barrel carburetor only 3 Recheck adjust Low Idle Speed RPM to specified setting High Speed RPM Adjustment 1 With engine running move throttle control to fast 2 Turn inner adjustment screw outward to decrease or inward to increase RPM speed Courage singles require loosening screws on speed control bracket and sliding towards carburetor to lower and away from carburetor to increase speed KohlerEngines com 23 Fuel System Carburetor Servicing A WARNING Explosive Fuel can cause fires and severe burns M 4 Do not fill fuel tank while engine is hot or running Gasoline is extremely flammable and its vapors can explode if ignited Store gasoline only in approved containers in well ventilated unoc
71. gnition module 7 Rotate flywheel back and forth checking for clearance between magnet and ignition modules Make sure magnet does not strike modules Recheck gap with a feeler gauge and readjust if necessary Final air gap 0 203 0 305 mm 0 008 0 012 in 8 Connect kill leads to ignition modules Push bend loop portion of clamp on cylinder 1 side back as far as possible for maximum clearance from fan D 66 690 01 Rev A External Engine Components Reassembly A Oil Sentry B Breather Cover C Gasket D Fiber Filter Breather Reed Fan Mounting E Assembly F Adapter Plate G Carburetor H Bracket I Fan J Fan Belt K Bearing L Pulley M Pulley Half N Spacer Shims o Adapter P Torgue Seguence Install Spark Plugs Install Reed and Breather Cover Assembly 1 Check gap using wire feeler gauge Adjust gap to 0 76 mm 0 03 in 2 Install plug into cylinder head 3 Torque plug to 27 N m 20 ft Ib 66 690 01 Rev A 1 Make sure sealing surfaces of crankcase and breather cover are clean and free of all old gasket material Clean with an aerosol type gasket remover or cleaning solvent DO NOT scrape surfaces as this can result in leakage 2 Check to make sure there are no nicks or burrs on sealing surfaces KohlerEngines com 67 Reassembly 3 Install breather reed and breather reed retainer onto crankcase and secure with
72. h oil level below or above operating range indicator on dipstick Ensure engine is cool Clean oil fill dipstick areas of any debris 1 Remove dipstick wipe oil off 2 Reinsert dipstick into tube press completely down 3 Remove dipstick check oil level Level should be at top of indicator on dipstick 4 If oil is low on indicator add oil up to top of indicator mark 5 Reinstall and secure dipstick CHANGE OIL AND FILTER Change oil while engine is warm 1 Clean area around oil fill cap dipstick drain plug oil drain valve Remove drain plug and oil fill cap dipstick Allow oil to drain completely Clean area around oil filter Place a container under filter to catch any oil and remove filter Wipe off mounting surface Reinstall drain plug Torque to 13 6 N m 10 ft Ib Place new filter in shallow pan with open end up Fill with new oil until oil reaches bottom of threads Allow 2 minutes for oil to be absorbed by filter material Apply a thin film of clean oil to rubber gasket on new filter Refer to instructions on oil filter for proper installation Fill crankcase with new oil Level should be at top of indicator on dipstick Reinstall oil fill cap dipstick and tighten securely Start engine check for oil leaks Stop engine correct leaks Recheck oil level 26 KohlerEngines com 66 690 01 Rev A 9 Dispose of used oil and filter in accordance with local ordinances OIL SENTRY if equippe
73. heck all components and connections for signs of leakage Check condition of radiator hoses If they swell excessively while testing system they may be weak and should be replaced Gauge Needle Drops Quickly A steady drop or loss of pressure indicates serious leakage is occurring within system which must be located and corrected before engine is returned to service If a pressure loss is noted 1 With pressure on system apply a soap water solution and check all joint connections hoses and cooling system components for external leakage Repair or replace as required 66 690 01 Rev A Cooling System Remove dipstick and check appearance of oil in crankcase Another method would be to remove an oil drain plug and drain a small amount of oil for inspection A milky or an opaque color similar to chocolate milk indicates presence of engine coolant in oil Check for a blown head gasket step 3 below or a possible crack or internal leakage from water jacket Remove spark plugs Apply 14 15 lbs of pressure and listen inspect for internal coolant leakage into cylinder combustion chambers This can denote a head gasket failure leak If required further test by performing a Cylinder Leakdown Test as described in Troubleshooting KohlerEngines com 41 Disassembly Inspection and Service External Engine Components A Dipstick B Electric Starter C Adapter Plate D Oil Drain Plug
74. id coolant can get extremely hot from operation Turning radiator cap when engine is hot can allow steam and scalding liquid to blow out and burn you severely Shut off machine Only remove radiator cap when cool enough to touch with bare hands Slowly loosen cap to first stop to relieve pressure before removing completely When it is necessary to open cooling system at radiator cap shut off engine and remove filler cap only when cool enough to touch with bare hands Slowly loosen cap to first stop to relieve pressure before removing completely This section covers operation and servicing of liquid cooling system Cooling System Components Cooling system consists of these following components e Radiator with removable screen e Hoses e Coolant Pump and Belt e Thermostat e Intake Manifold with Thermostat Housing e Radiator Cap e Cooling Fan Belt and Drive Pulleys e Overflow Reservoir e Crankcase and Heads with Integral Cooling Passages Operation Engine coolant is pumped through cooling system by a pump belt driven off camshaft Coolant coming out of pump is divided and moves simultaneously through separate circuits within each head and corresponding sides of crankcase As coolant moves through these passages it absorbs heat from engine parts After traveling through engine coolant from two separate circuits merges and moves through intake manifold to lower side of thermostat During warm up thermostat
75. if disconnected previously then install carburetor onto intake manifold Install and torque mounting screws to 6 2 7 3 N m 55 65 in Ib 4 If adapter was separated from carburetor install a new gasket and mount adapter with breather hose connection port facing rear Install and torque mounting screws to 7 3 N m 65 in Ib 68 KohlerEngines com 5 Connect upper end of breather hose to fitting on rear of adapter 6 Connect long end of choke linkage to carburetor 7 Ifa mechanical fuel pump is used install fuel line between outlet of fuel pump and carburetor inlet and secure with clamps Install External Governor Controls and Main Control Bracket Control Panel Details 6 s gt gt F in A Control Panel B Choke Lever C Governor Lever Nut D E Governor Spring Governor Lever 1 Install governor lever onto governor cross shaft If separated connect throttle link to governor lever with plastic bushing Hook dampening spring into small middle hole 2 Move governor lever TOWARDS carburetor as far as it will go wide open throttle and hold in this position 3 Insert a nail into hole in cross shaft and rotate shaft COUNTERCLOCKWISE as far as it will turn Then torque nut to 6 8 N m 60 in lb 4 Connect choke lever of main control bracket to choke linkage from carburetor Mount main control bracket to cylinder heads with four screws Torque screws to 10 7 N
76. ing gear as shown engine Remove and discard rod cap 2 Grind off any burrs or sharp edges 2 Remove studs of a Posi Lock rod or grind off 3 Invert segment and place it between ignition bosses aiming steps of a Command rod so joint surface is on crankcase so tool teeth engage flywheel ring ale gear teeth Bosses will lock tool and flywheel in 3 Finda 1 in long capscrew with correct thread size to position for loosening tightening or removing with a match threads in connecting rod puller 4 Use a flat washer with correct I D to slip on capscrew and approximately 1 in O D Assemble capscrew and washer to joint surface of rod 14 KohlerEngines com 66 690 01 Rev A TROUBLESHOOTING GUIDE Troubleshooting When troubles occur be sure to check simple causes which at first may seem too obvious to be considered For example a starting problem could be caused by an empty fuel tank Some general common causes of engine troubles are listed below and vary by engine specification Use these to locate causing factors Engine Cranks But Will Not Start Engine Will Not Crank e Battery connected backwards e Blown fuse e Carburetor solenoid malfunction e Choke not closing e Clogged fuel line or fuel filter e Diode in wiring harness failed in open circuit mode e DSAI or DSAM malfunction e Empty fuel tank e Faulty electronic control unit e Faulty ignition coil s e Faulty spark plug s e Fuel pump malfuncti
77. ing of crankcase 2 Start hex cap onto threaded section of fitting 90 fitting in crankcase is installed and sealed at factory in a specific position Special tools and procedures are involved Do not loosen remove or alter mounting position of this fitting at any time 64 KohlerEngines com 10 1 Carefully push water pump down from raised position thereby rotating tube 90 within end connections Guide pump into position over O ring aligning two mounting pins and five screw hole locations Start screws with longer screw nearest pump outlet Torque screws to 9 9 N m 88 in Ib in sequence shown Push down on formed tube and hold in this position to prevent it from pivoting upward when tightening hex cap Torque hex cap to 22 6 N m 200 in Ib to secure joint connection Support fitting with a wrench while torquing if possible to prevent applying unnecessary pressure on fitting and joint Check that formed tube and hose section have not been pulled up Install drive belt onto cogged pulley of water pump then around cam pulley Slide cam pulley with belt attached down onto keyway end of camshaft Be careful not to push key out of keyway and or into seal when installing pulley Check or use a feeler gauge to see that there is at least 3 17 mm 0 125 in clearance between underside of pulley and hose tube and clamps Remove pulley and reposition tube or clamps if required Install flat washer and scr
78. ioned within cutout in intake manifold Be careful not to pinch harness wires between bracket and intake manifold when tightening 5 If disassembled reassemble fan and pulley assembly Make sure one flat washer is placed between bearings in hub Other washer is located under front nut Torque fan pulley hub mounting screws to 6 8 N m 60 in Ib 6 If fan shaft was removed from upper mounting bracket apply Loctite 242 to rear threads Install and torque rear nut to 15 8 N m 140 in Ib Install fan and pulley assembly onto fan shaft and upper mounting bracket 7 Apply Loctite 242 to front threads of fan shaft Install flat washer and nut to secure Torque nut to 15 8 N m 140 in lb 8 Carefully work belt into place on pulleys Check belt tension There should be no more than 9 53 12 7 mm 3 8 1 2 belt deflection per side with 10 Ibs of applied tension If belt tension is low remove belt and relocate a shim from between pulley halves to outside front Reinstall belt and recheck tension Repeat procedure until correct tension is reached if shims have all been moved to outside and belt is still too loose replace belt 66 690 01 Rev A Reassembly When proper tension is obtained individually remove each capscrew apply Loctite 242 to threads of lower pulley and reinstall Torque four bolts in a criss cross sequence to 24 3 N m 215 in Ib Mount RH and LH lower radiator supports with cr
79. iously apply pipe sealant with Teflon Loctite 592 or equivalent on threads and tighten it into pump Orient fitting so outlet points in 11 o clock position as shown 3 Check sealing surfaces of water pump and crankcase They must be clean and free of any nicks or damage 4 Apply asmall amount of grease in several locations to hold new water pump O ring in place Install a new O ring in groove of crankcase Do not use RTV sealant in place of O ring or attempt to reinstall a used O ring 5 Apply rubber lubricant to inner surfaces of short hose section Assemble hose to outlet of water pump and secure with larger diameter clamp Orient clamp so tangs extend out in 3 to 4 o clock position 6 Slide smaller diameter clamp onto extruded end of formed metal tube and insert this end of tube into hose section Position tube so its formed offset leads down and away from outlet perpendicular to pump Install clamp onto hose and position tangs of clamp parallel to those of first clamp 7 Holding pump assembly elevated assemble transfer tube to 90 fitting in crankcase as follows a For new first time tube installation 1 Place a new ferrule compression ring in 90 fitting of crankcase and loosely install hex cap onto threads of fitting 2 Insert plain end of transfer tube through hex and compression ring b For reinstallation of an existing tube 1 Insert end of transfer tube with compression ring into 90 fitt
80. is closed preventing circulation through radiator Coolant circulates through engine only and is returned to pump via bypass hose When engine heat brings coolant up to a temperature of 79 4 C 175 F thermostat will begin to open allowing coolant to circulate through upper hose to radiator Thermostat is completely open at 90 5 C 195 F allowing full coolant flow through radiator where it is cooled After getting cooled in radiator coolant is drawn into pump through lower radiator hose and circulation starts all over again A cooling fan driven off flywheel by a belt draws ambient air through radiator to maintain cooling process Coolant will provide protection from 37 C 34 F to 108 C 226 F For protection and use outside indicated temperature limits follow antifreeze manufacturer s instructions on container but do not exceed 70 antifreeze DO NOT use antifreeze with stop leak additive s or put any other additives in cooling system Cooling System Maintenance and Service Maintenance Maintaining correct coolant level cleaning any debris accumulation from radiator surfaces and insuring all parts are in proper operating condition is critical to ensuring long life proper system performance and preventing overheating To ensure proper air circulation make sure radiator cooling fan drive belt pulleys cooling fins and external surfaces of engine are kept clean and in good condition at all times Check cool
81. is 1200 RPM Place throttle control into idle or slow position Turn low idle speed adjusting screw in or out to obtain allow idle speed of 1200 RPM 75 RPM not setba Idle Speed Adjustment If equipped Hold governor lever away from carburetor so throttle lever is against idle speed RPM adjustment screw of carburetor Start engine and allow to warm up then adjust screw to set approximately 1200 RPM Check speed using a tachometer Turn adjustment screw inner clockwise in to increase or counterclockwise out to decrease speed 2 Release governor lever and check that throttle lever is in idle position Turn governed idle adjustment screw to obtain equipment manufacturer s recommended idle speed 1500 1800 RPM Some engines have a bendable tab that is used to set this speed A pliers should be used to bend this tab to achieve recommended speed Governed idle speed RPM is typically 300 RPM approximate higher than low idle speed 3 Move throttle lever to wide open full throttle position and hold in this position Turn high speed screw to obtain intended high speed no load RPM Governed idle speed must be set before making this adjustment 66 690 01 Rev A Fuel System Low Idle Fuel Adjustment Optimum Low Idle Fuel Setting X A Rich B Lean C Midpoint D Left Side E Right Side NOTE Engines will have fixed low idle or limiter caps on idle fuel adjusting needles Step 2 can only be per
82. ition as before disassembly 1 Lubricate lifters and lifter bores in crankcase with engine oil 2 Install lifters into their respective lifter bores according to location and cylinder number marked during assembly Valve Stem Seals These engines use valve stem seals on intake and exhaust valves Always use a new seal before valves are installed in cylinder head Also replace seals if they are deteriorated or damaged in any way Never reuse an old seal 62 KohlerEngines com Prior to installation lubricate all components with engine oil paying particular attention to lip of valve stem seal valve stems and valve guides Install following items in order listed below using a valve spring compressor e Valve stem seals e Intake and exhaust valves e Valve spring caps e Valve springs e Valve spring retainers e Valve spring keepers 66 690 01 Rev A Install Cylinder Heads Cylinder Head Torque Sequence NOTE Match numbers embossed on cylinder heads and crankcase 1 Check to make sure there are no nicks or burrs on sealing surfaces of cylinder head or crankcase 2 Rotate crankshaft to position piston in cylinder 1 to top dead center TDC on compression stroke 3 Install a new cylinder head gasket 4 Install cylinder 1 head onto number 1 side mounting studs 5 Install a plain washer onto each stud and secure with a nut 6 Torque nuts in two steps first
83. ition switch is in run position Ignition timing and spark remains constant regardless of engine speed Timing of spark is controlled by location of flywheel magnet group as referenced to engine TDC A typical fixed ignition system consists of e 1 magnet assembly which is permanently affixed to flywheel e 2 electronic capacitive discharge ignition modules which mount on engine crankcase e 1 kill switch or key switch which grounds modules to stop engine e 2 spark plugs KohlerEngines com 29 Electrical System Wiring Diagram 15 20 25 Amp Regulated Battery Charging System with Fixed Timing E 66 690 01 Rev A KohlerEngines com 30 Electrical System A Accessory Yellow B Battery Red C Starter Blue Red D Run Red E Ignition Kill White F Key SC Geh G Ground H Starter l Battery J Accessory K Key Switch L Ignition Kill M Run N Yellow O Connector P Starter Solenoid Stud Starter Solenoid Tang R Starter Assembly S Fuse T Red Intake Manifold U Black V White W Carburetor X Screw Y Ground Black Z Oil Sentry Light AA Carburetor Solenoid AB Ee 15 AC Regulator Connector AD AC AE B AF Stator AC White Regulator Rectifier Blower Housing AG Purple AH 25 Amp Al Safety Switch AJ Spark Plug s AK Ignition Module s AL ma AM Coolant Temp Switch AN Oil Pressure Switch Coolant Temp AO Orange
84. lat spade S start terminal on solenoid Momentarily connect other lead to lower large post terminal When connection is made solenoid should energize audible click and plunger retract Repeat test several times Continuity 1 2 Use an ohmmeter set to audible or Rx2K scale and connect 2 ohmmeter leads to 2 large post terminals Perform solenoid pull in coil plunger actuation test and check for continuity Ohmmeter should indicate continuity Repeat test several times Condition To test solenoid hold in coil Function 1 Connect a 12 volt test lead to flat spade S start terminal on solenoid and other lead to body or mounting surface of solenoid 2 Manually push plunger IN and check if coil holds plunger retracted Do not allow test leads to remain connected to solenoid for a prolonged period of time Continuity 1 Use an ohmmeter set to audible or Rx2K scale and connect 2 ohmmeter leads to 2 large post terminals 2 Perform preceding solenoid hold in coil function test and check for continuity Meter should indicate continuity Repeat test several times Conclusion Solenoid fails to activate No continuity is indicated Plunger fails to stay retracted Replace solenoid 66 690 01 Rev A KohlerEngines com 37 Cooling System A WARNING Hot liquid can cause severe burns Do not loosen radiator cap while engine is operating or warm to touch Liqu
85. lifters need to be replaced apply a liberal coating of Kohler lubricant to base of each new lifter before it is installed Bleeding Lifters To prevent a possible bent push rod or broken rocker arm it is important to bleed any excess oil out of lifters before they are installed 1 Cut a 50 75 mm 2 3 in piece from end of an old push rod and chuck it in a drill press KohlerEngines com 49 Disassembly Inspection and Service 2 Lay a rag or shop towel on table of drill press and 1 place lifter open end up on towel 3 Lower chucked push rod until it contacts plunger in 2 lifter Slowly pump plunger two or three times to force oil out of feed hole in side of lifter Disassemble Cylinder Heads NOTE These engines use a valve stem seal on intake and exhaust valves Serial No 3422000010 and lower used a seal on intake side only Always use new seals when valves are removed from cylinder head Replace seals if they are deteriorated or damaged in any way Never reuse an old seal 4 Inspection and Service Valve Details Remove screws rocker arms pivots and rocker arms from cylinder head s Compress valve springs using a valve spring compressor and remove valve spring keepers Remove compressor With keepers taken out following items can be removed e Valve spring retainers e Valve springs e Valve spring caps e Intake and exhaust valves e Valve stem seals intake valve only Repeat above proce
86. lts Test stator further using an ohmmeter steps 3 and 4 66 690 01 Rev A KohlerEngines com 33 Starter System NOTE Do not crank engine continuously for more than 10 seconds Allow a 60 second cool down period between starting attempts Failure to follow these guidelines can burn out starter motor NOTE If engine develops sufficient speed to disengage starter but does not keep running a false start engine rotation must be allowed to come to a complete stop before attempting to restart engine If starter is engaged while flywheel is rotating starter pinion and flywheel ring gear may clash and damage starter NOTE If starter does not crank engine shut off starter immediately Do not make further attempts to start engine until condition is corrected NOTE Do not drop starter or strike starter frame Doing so can damage starter Engines in this series use solenoid shift starters Troubleshooting Starting Difficulties Condition Possible Cause Conclusion Starter does not energize Battery Check specific gravity of battery If low recharge or replace battery as necessary Wiring Clean corroded connections and tighten loose connections Replace wires in poor condition and with frayed or broken insulation Starter Switch By pass switch or solenoid with a jumper wire If starter cranks or Solenoid normally replace faulty components Remove and perform individual solenoid test procedure Start
87. m 95 in Ib into new holes or 7 3 N m 65 in Ib into used holes 5 Connect dampening spring to throttle lever Hook governor spring from throttle control bracket in appropriate governor lever hole as indicated in chart below Note that hole positions are counted from pivot point of governor lever Install Lower Crankshaft Pulley Pulley Adapter and Cooling Fan Assembly NOTE Do not assemble lower pulley with belt between pulley halves as pinching of belt or damage to pulley can occur 66 690 01 Rev A 1 Make sure shoulder of flywheel hub and adjacent face surface are clean and free of any nicks or damage 2 Install crankshaft pulley adapter onto flywheel hub so offset for pulley is out and holes are aligned Make sure adapter rests squarely on face of flywheel 3 Assemble front and rear pulley halves placing shims as indicated a For a new belt Assemble with 2 or 3 shims between pulley halves and remaining shim if any on outside front of outer pulley half b For a used belt Assemble with 2 shims between pulley halves and remaining shim s on outside front of outer pulley half Install and snug pulley assembly Final belt tension and pulley assembly will be made after fan upper pulley assembly is installed 4 Install upper fan mounting bracket to intake manifold with screws Torque M6 Screws to 7 3 N m 65 in Ib M8 Screws to 24 4 N m 216 in lb By pass hose and wires must be posit
88. mbly from upper mounting bracket 2 Remove screws and take off mounting bracket with fan shaft attached 3 Fan shaft may be removed from mounting bracket by removing rear nut if individual servicing of either part is required Inspection and Service Cooling fan assembly consists of a fan attached to a v pulley and bearing carrier hub rotating on a dual ball bearing fan shaft arbor Assembly is mounted with a bracket to intake manifold and driven via a split pulley off flywheel Inspect components carefully for signs of wear or damage 1 Inspect fan to make sure blades are in good condition and free of any cracks nicks or damage Area around fan mounting holes must also be free of any cracks or damage 2 Fanand hub assembly when mounted to center arbor shaft must rotate smoothly without noticeable bearing play wobble or binding 3 Check v belt for excessive wear cracking or damage If proper belt tension cannot be obtained or condition of belt is suspect replace it with Kohler Part No 66 203 02 S Do not use a substitute belt KohlerEngines com 66 690 01 Rev A Disassembly Inspection and Service Flywheel ignition Intake Manifold Components CO e LY QQ WW 4 FV EP Y LP A VY A d C NS o D G ch A Thermostat Housing B Intake Manifold C Thermostat D Ignition Module E Flywheel F Stator PF Inspection
89. muffler and mounting hardware Torque screws to 9 9 N m 88 in Ib 2 Install nuts to exhaust studs Torque nuts to 24 4 N m 216 in lb 66 690 01 Rev A Reassembly Install Oil Filter and Fill Crankcase with Oil NOTE Make sure both oil drain plugs are installed and torqued to specifications to prevent oil leakage 1 Install oil drain plug s Torque plug s to 13 6 N m 10 ft Ib If oil drain valve is used make sure valve body is closed and cap is on 2 Place new filter in shallow pan with open end up Fill with new oil until oil reaches bottom of threads Allow 2 minutes for oil to be absorbed by filter material 3 Apply a thin film of clean oil to rubber gasket on oil filter 4 Refer to instructions on oil filter for proper installation 5 Fill crankcase with new oil Level should be at top of indicator on dipstick 6 Reinstall oil fill cap dipstick and tighten securely Install Coolant 1 Use equal parts of ethylene glycol antifreeze and water only Distilled or deionized water is recommended especially in areas where water contains a high mineral content Propylene glycol based antifreeze is not recommended 2 Fill cooling system through radiator with coolant mix Allow coolant to drain into lower areas Fill overflow reservoir midway between FULL and ADD marks then install radiator and reservoir caps Reconnect Battery and Spark Plug Leads Connect leads to spark plugs Reconnec
90. n 4 Install adapter into spark plug hole but do not attach it to tester at this time 5 Turn regulator knob completely counterclockwise 6 Connect an air source of at least 50 psi to tester 7 Turn regulator knob clockwise increase direction until gauge needle is in yellow set area at low end of scale 8 Connect tester quick connect to adapter hose While firmly holding engine at TDC gradually open tester valve Note gauge reading and listen for escaping air at combustion air intake exhaust outlet and crankcase breather Condition Conclusion Air escaping from crankcase breather Ring or cylinder worn Air escaping from exhaust system Defective exhaust valve improper seating Air escaping from intake Defective intake valve improper seating Gauge reading in low green zone Piston rings and cylinder in good condition Gauge reading in moderate yellow zone Engine is still usable but there is some wear present Customer should start planning for overhaul or replacement Gauge reading in high red zone Rings and or cylinder have considerable wear Engine should be reconditioned or replaced 18 KohlerEngines com 66 690 01 Rev A Air Cleaner Intake AIR CLEANER BREATHER TUBE These systems are CARB EPA certified and components Ensure both ends of breather tube are properly should not be altered or modified in any way connected Heavy Duty Air Cleaner Components AIR COOLING A WARNING zt Ho
91. nd Smoothly with Bearing Journal Surface F High Point from Fillet Intersections G 45 Minimum H This Fillet Area Must Be Completely Smooth Inspect gear teeth of crankshaft If teeth are badly worn chipped or some are missing replacement of crankshaft will be necessary Inspect crankshaft bearing surfaces for scoring grooving etc Replaceable bearing is used in crankshaft bore of closure plate and or crankcase Do not replace bearing unless they show signs of damage or are out of running clearance 0 039 0 074 mm 0 0015 0 0029 in If crankshaft turns easily without noise and there is no evidence of scoring grooving etc on races or bearing surfaces bearing can be reused KohlerEngines com 55 Disassembly Inspection and Service Inspect crankshaft keyways If they are worn or chipped replacement of crankshaft will be necessary Inspect crankpin for score marks or metallic pickup Slight score marks can be cleaned with crocus cloth soaked in oil If wear limits as stated in Clearance Specifications are exceeded it will be necessary to replace crankshaft or regrind crankpin to 0 25 mm 0 010 in undersize If reground a 0 25 mm 0 010 in undersize connecting rod big end must then be used to achieve proper running clearance Measure crankpin for size taper and out of round Connecting rod journal can be ground 1 size under When grinding a crankshaft grinding stone deposits can get caught in oil pass
92. nnecting Rod P Piston Q Piston Ring Set Install Flywheel End Oil Seal and Camshaft Oil Seal 1 2 Check to make sure that there are no nicks or burrs in crankshaft and camshaft seal bores of crankcase Apply a light coat of engine oil to outside diameter of flywheel end oil seal Install oil seal into crankcase using a seal driver Make sure oil seal is installed straight and true in bore until tool bottoms against crankcase Apply a light coat of engine oil to outside diameter of camshaft oil seal Install camshaft oil seal to a depth of 1 0 1 5 mm 0 039 0 059 in below top of seal bore Do not bottom seal in bore or oil passage may be obstructed 58 KohlerEngines com 66 690 01 Rev A Install Governor Cross Shaft 1 Lubricate governor cross shaft bearing surfaces in crankcase with engine oil Apply a small amount of grease to lips of oil seal 2 Slide small lower washer onto governor cross shaft and install cross shaft from inside of crankcase 3 Install nylon washer onto governor cross shaft then start push on retaining ring Hold governor shaft up in position then place a 0 25 mm 0 010 in feeler gauge on top of nylon washer and push retaining ring down shaft to secure Remove feeler gauge which will have established proper end play 4 Pivot governor cross shaft so bottom end faces cylinder 1 side Install Crankshaft NOTE Apply cellophane tape over crankshaft keyway to prevent cutting
93. nt of outer pulley half Check belt tension as described above When proper tension is obtained individually remove each capscrew of lower pulley apply Loctite 242 to threads and reinstall Torque each capscrew in a criss cross sequence to 24 5 N m 215 in Ib Hoses and Tubes Hoses and tubes are used to connect components within cooling system To guard against coolant loss and hose failure hoses tubes and their connections should be checked regularly for leaks or damage Loss of coolant can result in serious engine damage Over time engine vibration can affect hose joint connections and hoses themselves can be affected by heat and coolant Swelling hardening and or deterioration can occur depending on operating environment Deterioration usually takes place more rapidly from inside making outside inspections incomplete and not always dependable Regular outside inspection and careful inside inspection whenever connections are opened can minimize a possible in service problem Use new clamps whenever a hose is replaced or a joint connection is opened When making hose connections a light coating of rubber lubricant will make assembly easier Thermostat Testing and Servicing Temperature Sensor Details 40 KohlerEngines com Thermostat is mounted in intake manifold beneath thermostat housing It controls rapid warm up and operating temperature of engine If a problem is enco
94. ntrol cables are routed side by side especially under a single clamp there must be a small gap between cables to prevent internal binding After high speed setting has been complete check that there is gap of at least 0 5 mm 0 020 in between control cables 1 With engine running move throttle control to fast Use a tachometer to check RPM speed 2 Loosen lock nut on high speed adjusting screw Turn screw outward to decrease or inward to increase RPM speed Check RPM with a tachometer 3 When desired RPM speed is obtained retighten lock nut KohlerEngines com 25 Lubrication System This engine uses a full pressure lubrication system This system delivers oil under pressure to crankshaft camshaft and connecting rod bearing surfaces In addition to lubricating bearing surfaces lubrication system supplies oil to hydraulic valve lifters A high efficiency gerotor pump is located in closure plate Oil pump maintains high oil flow and oil pressure even at low speeds and high operating temperatures A pressure relief valve in closure plate limits maximum pressure of system Lubrication Components CR po u N AN x h V Oho C AGRO d d s A Dipstick B Oil Fill Cap C Oil Filter D Oil Sentry E Oil Drain Plug OIL RECOMMENDATIONS Refer to Maintenance CHECK OIL LEVEL NOTE To prevent extensive engine wear or damage never run engine wit
95. ocedures If relief valve is a one piece style staked to oil pump housing removal should not be attempted nor is internal servicing possible If a problem with relief valve is encountered oil pump should be replaced Inspection Inspect oil pump housing gear and rotors for nicks burrs wear or any visible damage If any parts are worn or damaged replace oil pump Inspect oil pressure relief valve piston It should be free of nicks or burrs Check spring for wear or distortion Free length of spring should be approximately 47 4 mm 1 8 in Replace spring if it is distorted or worn Reassembly 1 Install pressure relief valve piston and spring 2 Install oil pickup to oil pump body Lubricate O ring with oil and make sure it remains in groove as pickup is being installed 3 Install rotor 4 Install oil pump body to closure plate and secure with screws Torque screws as follows a Install fastener into screw location 1 and lightly tighten to position pump b Install fastener into screw location 2 and fully torque to recommended value c Torque fastener in screw location 1 to 10 7 N m 95 in Ib into new holes or 6 7 N m 60 in Ib into used holes KohlerEngines com 53 Disassembly Inspection and Service 5 After torquing rotate gear and check for freedom of movement Make sure there is no binding If binding occurs loosen screws reposition pump retorque screws and recheck movement Remove Cam
96. oil seals gaskets or other available spots Crankcase vacuum is best measured with either a water manometer or a vacuum gauge Complete instructions are provided in kits To test crankcase vacuum with manometer 1 Insert rubber stopper into oil fill hole Be sure pinch clamp is installed on hose and use tapered adapters to connect hose between stopper and one manometer tube Leave other tube open to atmosphere Check that water level in manometer is at 0 line Make sure pinch clamp is closed 2 Start engine and run no load high speed 3 Open clamp and note water level in tube Level in engine side should be a minimum of 10 2 cm 4 in above level in open side If level in engine side is less than specified low no vacuum or level in engine side is lower than level in open side pressure check for conditions in table below 4 Close pinch clamp before stopping engine Condition To test crankcase vacuum with vacuum pressure gauge 1 Remove dipstick or oil fill plug cap 2 Install adapter into oil fill dipstick tube opening upside down over end of a small diameter dipstick tube or directly into engine if a tube is not used Insert barbed gauge fitting into hole in stopper 3 Run engine and observe gauge reading Analog tester needle movement to left of 0 is a vacuum and movement to right indicates a pressure Digital tester depress test button on top of tester Crankcase vacuum should be a minimum of
97. ol Camshaft end play should be 0 076 0 127 mm 0 003 0 005 in 4 If camshaft end play is not within specified range remove original shim and reinstall end play tool Use a feeler gauge to determine clearance between camshaft and tool Subtract 0 100 mm 0 004 in from measured clearance to obtain required shim thickness Refer to table below and install shim that matches calculated thickness Repeat steps 1 3 to verify that correct end play exists Camshaft Shims White 0 69215 0 73025 mm 0 02725 0 02875 in Blue 0 74295 0 78105 mm 0 02925 0 03075 in Red 0 79375 0 83185 mm 0 03125 0 03275 in Yellow 0 84455 0 88265 mm 0 03325 0 03475 in Green 0 89535 0 99345 mm 0 03525 0 03675 in Gray 0 94615 0 98425 mm 0 03725 0 03875 in Black 0 99695 1 03505 mm 0 03925 0 04075 in KohlerEngines com 59 Reassembly Oil Pump Assembly Install Closure Plate Oil Seal Oil pump is mounted to inside of closure plate If service was required and oil pump was removed refer to assembly procedures under Oil Pump Assembly in Reassembly Governor Assembly Cylinder Head Torque Sequence Governor assembly is located inside closure plate If service was required and governor was removed refer to assembly procedures under Governor Assembly in Reassembly Thrust Bearing Washer and Shim Some specifications use a thrust bearing thrust washer and shim to control end play of crankshaft
98. on vacuum hose clogged or leaking e Fuel shut off valve closed e Ignition module s faulty or improperly gapped e Insufficient voltage to electronic control unit e Interlock switch is engaged or faulty e Key switch or kill switch in OFF position e Low oil level e Quality of fuel dirt water stale mixture e SMART SPARK malfunction e Spark plug lead s disconnected Engine Starts But Does Not Keep Running e Battery is discharged e Faulty electric starter or solenoid e Faulty key switch or ignition switch e Interlock switch is engaged or faulty e Loose wires or connections that intermittently ground ignition kill circuit e Pawls not engaging in drive cup e Seized internal engine components Engine Runs But Misses e Carburetor adjusted incorrectly e Engine overheated e Faulty spark plug s e Ignition module s faulty or improperly gapped e Incorrect crankshaft position sensor air gap e Interlock switch is engaged or faulty e Loose wires or connections that intermittently ground ignition kill circuit e Quality of fuel dirt water stale mixture e Spark plug lead s disconnected e Spark plug lead boot loose on plug e Spark plug lead loose Engine Will Not Idle e Faulty carburetor e Faulty cylinder head gasket e Faulty or misadjusted choke or throttle controls e Fuel pump malfunction vacuum hose clogged or leaking e Intake system leak e Loose wires or conne
99. onto threads and tighten so fitting faces points toward 2 side long intake manifold screw 2 Attach coolant by pass hose to fittings in water pump and intake manifold Secure with clamps 3 Connect wire leads to temperature warning switch audible alarm and or Oil Sentry switch as equipped Install Stator Assembly 1 Place a small amount of pipe sealant with Teflon Loctite 592 or equivalent into holes for stator mounting screws Position stator assembly onto mounting studs so leads are at bottom and directed out toward cylinder 1 side in 3 o clock position Align mounting holes and install screws Torque each screw to 6 2 N m 55 in lb Install Flywheel A cAUTION Damaging Crankshaft and Flywheel can cause personal injury I Using improper procedures can lead to broken fragments Broken fragments could be thrown from engine Always observe and use precautions and procedures when installing flywheel NOTE Before installing flywheel make sure crankshaft taper and flywheel hub are clean dry and completely free of lubricants Presence of lubricants can cause flywheel to be overstressed and damaged when screw is torqued to specifications 66 KohlerEngines com NOTE Always use a flywheel strap wrench or holding tool to hold flywheel when tightening flywheel fastener Do not use any type of bar or wedge to hold flywheel as component damage and personal injury could result
100. ored Stripe Inspection Scuffing and scoring of pistons and cylinder walls occurs when internal engine temperatures approach welding point of piston Temperatures high enough to do this are created by friction which is usually attributed to improper lubrication and or overheating of engine Normally very little wear takes place in piston boss piston pin area If original piston and connecting rod can be reused after new rings are installed original pin can also be reused but new piston pin retainers are required Piston pin is included as part of piston assembly if pin boss in piston or pin are worn or damaged a new piston assembly is required Ring failure is usually indicated by excessive oil consumption and blue exhaust smoke When rings fail oil is allowed to enter combustion chamber where it is burned along with fuel High oil consumption can also occur when piston ring end gap is incorrect because ring cannot properly conform to cylinder wall under this condition Oil control is also lost when ring gaps are not staggered during installation 66 690 01 Rev A When cylinder temperatures get too high lacquer and varnish collect on pistons causing rings to stick which results in rapid wear A worn ring usually takes on a shiny or bright appearance Scratches on rings and pistons are caused by abrasive material such as carbon dirt or pieces of hard metal Detonation damage occurs when a portion of fuel charge ignites s
101. oss support bracket attached to crankcase using screws Snug screws only at this time o Install Air Cleaner Assembly External Engine Components RO A A Radiator Assembly B C Air Cleaner Assembly D Mounting Bracket Torque Sequence 1 Install a new elbow adapter gasket onto carburetor adapter 2 Set air cleaner mounting bracket assembly with hose and elbow attached in position on engine Align all of mounting holes Start and finger tighten each of mounting screws Make sure fuel line is outside of main bracket when installed 3 Torque elbow mounting screws to 7 3 N m 65 in lb Then torque eight valve cover mounting screws to 6 2 N m 55 in lb in sequence shown 4 lf removed install rain cap and secure with clamp Check position of dust ejector it should face downward Adjust end cap position as required 5 Connect wires for audible alarm if used KohlerEngines com 69 Reassembly Install Radiator Assembly 1 Reassemble components of radiator assembly including upper and lower radiator hoses Rubber lubricant may be applied to inner surfaces of hoses to make installation easier Secure with hose clamps Radiator subassembly should look as shown Tighten radiator drain plug Carefully set radiator assembly into place guiding lower radiator hose inside RH support bracket Make sure that cooling fins do not come in contact with fan blades as radi
102. ove solenoid from carburetor When solenoid is loosened and removed gas will leak out of carburetor Have a container ready to catch fuel 2 Wipe tip of solenoid with a shop towel or blow with compressed air to remove any remaining fuel Take solenoid to a location with good ventilation and no fuel vapors present You will also need a 12 volt power source that can be switched on and off 3 Be sure power source is switched OFF Connect positive power source lead to red lead of solenoid Connect negative power source lead to solenoid body original position with power OFF Test several times to verify operation Carburetor Circuits Turn power source ON and observe pin in center of solenoid Pin should retract with power ON and return to its Float Fuel level in bowl is maintained by float and fuel inlet needle Buoyant force of float stops fuel flow when engine is at rest When fuel is being consumed float will drop and fuel pressure will push inlet needle away from seat allowing more fuel to enter bowl When demand ceases buoyant force of float will again overcome fuel pressure rising to predetermined setting and stop flow 22 KohlerEngines com 66 690 01 Rev A Slow and Mid Range At low speeds engine operates only on slow circuit As a metered amount of air is drawn through slow air bleed jets fuel is drawn through main jet and further metered through slow jet Air and fuel are mixed in body of slow jet and exit to
103. pontaneously from heat and pressure shortly after ignition This creates two flame fronts which meet and explode to create extreme hammering pressures on a specific area of piston Detonation generally occurs from using low octane fuels Preignition or ignition of fuel charge before timed spark can cause damage similar to detonation Preignition damage is often more severe than detonation damage Preignition is caused by a hot spot in combustion chamber from sources such as glowing carbon deposits blocked cooling fins an improperly seated valve or wrong spark plug s Replacement pistons are available in STD bore size and in 0 25 mm 0 010 in and 0 50 mm 0 020 in oversize Replacement pistons include new piston ring sets and new piston pins Replacement ring sets are also available separately for STD 0 25 mm 0 010 in and 0 50 mm 0 020 in oversize pistons Always use new piston rings when installing pistons Never use old rings Some important points to remember when servicing piston rings 1 Cylinder bore must be deglazed before service ring sets are used 2 If cylinder bore does not need reboring and if old piston is within wear limits and free of score or scuff marks old piston may be reused 3 Remove old rings and clean up grooves Never reuse old rings 4 Before installing new rings on piston place top two rings each in turn in its running area in cylinder bore and check end gap Compare ring gap to
104. prevent engine damage do not use antifreeze mixture greater than 70 ethylene glycol in cooling system Do not use antifreeze with stop leak additive s or mix add other additives to cooling system Use only ethylene glycol antifreeze Cooling system capacity is approximately 2 liters 2 18 qt 1 Check condition of cooling system hoses clamps and associated components Replace as required 2 Fill with 2 0 L 2 1 U S qt equal parts of ethylene glycol anti freeze and water only Distilled or deionized water is recommended especially in areas where water contains a high mineral content Propylene glycol based anti freeze is not recommended 3 Fill radiator with coolant mixture Allow coolant to drain into lower areas Fill overflow reservoir to a level between FULL and ADD marks Reinstall radiator and reservoir caps 4 Start and run engine for five minutes Stop engine and allow to cool 5 Recheck coolant level in reservoir Coolant level should be between FULL and ADD marks Add coolant to reservoir if required Inspection Cooling Fan Assembly Belt and Drive Pulleys Cooling fan assembly used to draw air through radiator is attached to a hub and pulley assembly with sealed ball bearings This assembly is belt driven off flywheel via a lower split pulley and requires very little service or maintenance DO NOT operate engine without fan and properly functioning cooling system or engine damage will occur
105. r at each three locations Clean Cylinder Bore After Honing Proper cleaning of cylinder walls following boring and or honing is very critical to a successful overhaul Machining grit left in cylinder bore can destroy an engine in less than one hour of operation after a rebuild 66 690 01 Rev A Disassembly Inspection and Service Final cleaning operation should always be a thorough scrubbing with a brush and hot soapy water Use a strong detergent that is capable of breaking down machining oil while maintaining a good level of suds If suds break down during cleaning discard dirty water and start again with more hot water and detergent Following scrubbing rinse cylinder with very hot clear water dry it completely and apply a light coating of engine oil to prevent rusting Measuring Piston to Bore Clearance Piston Detail wll E A 6 mm 0 24 in NOTE Do not use a feeler gauge to measure piston to bore clearance it will yield inaccurate measurements Always use a micrometer Before installing piston into cylinder bore it is necessary that clearance be accurately checked This step is often overlooked and if clearances are not within specifications engine failure will usually result Use following procedure to accurately measure piston to bore clearance 1 Use a micrometer and measure diameter of piston 6 mm 0 24 in above bottom of piston skirt and perpendicular to piston pin 2 Us
106. rain Use a suitable container to catch coolant 2 If equipped remove coolant drain plugs on each side of block Allow any remaining coolant to drain out Dispose of coolant properly according to local regulations Drain Oil from Crankcase and Remove Oil Filter A Radiator Assembly B Mounting Bracket A Oil Filter Nipple B Oil Filter 1 Remove oil fill cap and dipstick and one or both drain plugs Allow sufficient time for oil to drain out 2 Remove and discard oil filter 66 690 01 Rev A C Air Cleaner Assembly Remove Flywheel Cover Radiator Assembly Mounting Brackets and Attached Components NOTE Do not allow cooling fins of radiator to contact fan blades 1 Remove screws or nuts and flat washers 2 on each side securing lower flywheel cover to LH and RH radiator support brackets Mounting plate for rectifier regulator will become detached when LH screws are removed Do not lose small spacers located within holes of lower cover Clips are used on some models instead of nuts 2 Ifa pulse style fuel pump is used disconnect fuel line from pump outlet and disconnect pulse line from fuel pump fitting 3 Disconnect upper radiator hose from radiator and lower radiator hose from inlet of water pump 4 Remove screws securing two upper radiator supports to air cleaner mounting bracket 5 Carefully tilt pull radiator forward slightly to clear fan and
107. rankcase Inspection and Service NOTE If bore is beyond wear limit a new miniblock or short block will be required Check all gasket surfaces to make sure they are free of gasket fragments Gasket surfaces must also be free of deep scratches or nicks Inspect main bearing if equipped for wear or damage Replace crankcase using a mini block or short block if required Check cylinder bore for scoring In severe cases unburned fuel can cause scuffing and scoring of cylinder wall It washes necessary lubricating oils off piston and cylinder wall As raw fuel seeps down cylinder wall piston rings make metal to metal contact with wall Scoring of cylinder wall can also be caused by localized hot spots resulting from a cooling system problem or from inadequate or contaminated lubrication If cylinder bore is badly scored excessively worn tapered or out of round resizing is necessary Use an inside micrometer to determine amount of wear then select nearest suitable oversize of either 0 08 mm 0 003 in 0 25 mm 0 010 in or 0 50 mm 0 020 in Resizing to one of these oversizes will allow usage of available oversize piston and ring assemblies Initially resize using a boring bar then use following procedures for honing cylinder 66 690 01 Rev A Honing Detail f A 23 33 Crosshatch While most commercially available cylinder hones can be used with either portable drills or drill presses use o
108. removal clean valve heads faces and stems with a power wire brush Then carefully inspect each valve for defects such as a warped head excessive corrosion or a worn stem end Replace valves found to be in bad condition Valve Guides If a valve guide is worn beyond specifications it will not guide valve in a straight line This may result in burnt valve faces or seats loss of compression and excessive oil consumption To check valve guide to valve stem clearance thoroughly clean valve guide and using a split ball gauge measure inside diameter of guide Then using an outside micrometer measure diameter of valve stem at several points on stem where it moves in valve guide Use largest stem diameter to calculate clearance by subtracting stem diameter from guide diameter If intake clearance exceeds 0 038 0 076 mm 0 0015 0 0030 in or exhaust clearance exceeds 0 050 0 088 mm 0 0020 0 0035 in determine whether valve stem or guide is responsible for excessive clearance Maximum I D wear on intake valve guide is 7 134 mm 0 2809 in while 7 159 mm 0 2819 in is maximum allowed on exhaust guide Guides are not removable but can be reamed 0 25 mm 0 010 in oversize Valves with 0 25 mm oversize stems must then be used If guides are within limits but valve stems are worn beyond limits install new valves 66 690 01 Rev A Disassembly Inspection and Service Valve Seat Inserts Hardened steel alloy intake and e
109. rnor arm to open throttle plate wider This allows more fuel into engine increasing engine speed As speed reaches governed setting governor spring tension and force applied by regulating pin will again offset each other to hold a steady engine speed 66 690 01 Rev A Governor System Governor Adjustments NOTE Do not tamper with governor setting Overspeed is hazardous and could cause personal injury Initial Adjustment Procedure Make this adjustment whenever governor lever is loosened or removed from cross shaft 1 Make sure throttle linkage is connected to governor lever and throttle lever on carburetor 2 Loosen hex nut holding governor lever to cross shaft 3 Move governor lever towards carburetor as far as it will move wide open throttle and hold in position 4 Insert a nail into hole on cross shaft and rotate shaft counterclockwise as far as it will turn then torque hex nut to 6 8 N m 60 in Ib Sensitivity Adjustment Governor sensitivity is adjusted by repositioning governor spring in holes on governor lever If speed surging occurs with a change in engine load governor is set too sensitive If a big drop in speed occurs when normal load is applied governor should be set for greater sensitivity 1 To increase sensitivity move spring closer to governor cross shaft 2 To decrease sensitivity move spring away from governor cross shaft High Speed RPM Adjustment NOTE When throttle and choke co
110. s connector Establish a connection to a known good ground location Engine should kill completely If not or only one cylinder is affected test ignition modules and white kill lead connection Problem persists Ignition or Electrical System 66 690 01 Rev A KohlerEngines com 31 Electrical System Test for Spark NOTE If 2 testers are available testing can be performed simultaneously for both cylinders However if only 1 tester is available 2 individual tests must be performed Side not being tested must have spark plug lead connected or grounded Do not crank engine or perform tests with 1 spark plug lead disconnected and not grounded or permanent system damage may occur 1 With engine stopped disconnect 1 spark plug lead Connect spark plug lead to post terminal of spark tester and attach tester clip to a good engine ground 2 Crank engine over establishing a minimum of 550 600 RPM and observe tester s for spark 3 Repeat spark test on opposite cylinder if cylinders are being tested individually Condition Possible Cause Conclusion Both cylinders have good spark but Spark Plug s Install new spark plug s and retest engine runs poorly or existing plug engine performance condition is questionable 1 cylinder has good spark and other Ignition Test ignition modules and cylinder has no or intermittent spark connections No spark at either cylinder Ignition Switch Recheck position o
111. screw Hold assembly in line when tightening Torque screw to 3 9 N m 35 in Ib 4 Install breather filter into cavity in crankcase 5 Carefully install breather cover gasket and breather cover onto crankcase 6 Install and torque four breather cover screws to 7 3 N m 65 in Ib in sequence shown 7 Install pipe plug or Oil Sentry switch as equipped into tapped breather port if removed earlier Apply pipe sealant with Teflon Loctite 592 or equivalent to threads Torque to 4 5 N m 40 in Ib If Oil Sentry switch is mounted to side of crankcase torque switch to 12 4 N m 110 in Ib 8 If vacuum fitting was removed from crankcase vacuum fuel pump apply pipe sealant with Teflon Loctite 592 or equivalent to threads of fitting and install With crankcase upright fitting must point to 1 30 position Reinstall Coolant Drain Plugs Coolant Drain Plug Details C3 ONE L wh A Coolant Drain Plug Reinstall brass coolant drain plugs in sides of crankcase and also cylinder head plugs if removed during head servicing Apply pipe sealant with Teflon Loctite 592 or equivalent to threads and reinstall plugs Torque plugs to 36 7 N m 325 in Ib Install Carburetor and Adapter 1 If separated install breather tube to breather cover 2 Install carburetor gasket on intake manifold 3 Attach longer ends of throttle linkage and spring to carburetor
112. shaft Remove camshaft and shims Remove Connecting Rods with Pistons and Rings NOTE If a carbon ridge is present at top of either cylinder bore use a ridge reamer tool to remove it before attempting to remove piston NOTE Cylinders are numbered on crankcase Use numbers to mark each end cap and connecting rod piston assembly for reassembly later Do not mix end caps and connecting rods 1 Remove screws securing closest connecting rod end cap Remove end cap 2 Carefully remove connecting rod and piston assembly from cylinder bore 3 Repeat above procedure for other connecting rod and piston assembly Connecting Rods Offset stepped cap connecting rods are used in all these engines Inspection and Service Check bearing area big end for excessive wear score marks running and side clearances Replace rod and cap if scored or excessively worn Service replacement connecting rods are available in STD crankpin size and 0 25 mm 0 010 in undersize An 0 25 mm 0 010 in undersized rod can be identified by a drilled hole located in lower end of rod shank Always refer to appropriate parts information to ensure correct replacements are used 54 KohlerEngines com Piston and Rings Components and Details Se A Piston Ring B End Gap C Identification Mark D Piston E Top Compression F Center Compression Ring Ring G Rails H Expander Oil trol Ri I Piece Ing J Dye Col
113. sing Install rubber grommet into matching recess of drive end cap Molded recesses in grommet should be out matching and aligned with those in end cap Install frame with small notch forward onto armature and drive end cap Align notch with corresponding section in rubber grommet Install drain tube in rear cutout if it was removed previously Install flat thrust washer onto commutator end of armature shaft Starter reassembly when replacing brushes brush holder assembly a Hold starter assembly vertically on end housing and carefully position assembled brush holder assembly with supplied protective tube against end of commutator armature Mounting screw holes in metal clips must be up out Slide brush holder assembly down into place around commutator and install positive brush lead grommet in cutout of frame Protective tube may be saved and used for future servicing Starter reassembly when not replacing brushes brush holder assembly a Carefully unhook retaining caps from brush assemblies Do not lose springs b Position brushes back in their slots so they are flush with I D of brush holder assembly Insert brush installation tool with extension or use tube described above from a prior brush installation through brush holder assembly so holes in metal mounting clips are up out 66 690 01 Rev A 11 c Install brush springs and snap on retainer caps d Hold starter assembly vertically on
114. so level is lower than installed position of temperature sensor 2 Remove and replace temperature sensor Use pipe sealant with Teflon on threads Cooling System Leakage Test A pressure test of cooling system can be performed as a relatively simple means of determining whether cooling system may contain a leak A pump pressure type cooling system tester with appropriate 45 mm adapter may be used to check cooling system and radiator cap Test Instructions 1 With engine cool carefully remove radiator cap see Pressure Radiator Cap Make sure all parts of cap and adapter are clean Install cap on corresponding adapter and make sure it is completely seated Install adapter onto tester and lock in place 2 Pressurize tester to 15 psi 3 Observe indicated pressure It should hold steady and not decrease or leak down If leakage is detected cap should be replaced If tester pressure is increased to 16 psi or above cap should then bleed off this excess pressure 4 Install and lock system adapter and tester onto neck of cooling system Pressurize tester to 14 15 psi 5 Observe system pressure on gauge Gauge Needle Holds Steady If gauge needle holds steady there should be no serious leaks in system It is however recommended that all connections be checked for overall condition anyway using a flashlight Gauge Needle Drops Slowly If gauge needle drops slowly it indicates presence of a small leak or seepage C
115. t Parts can cause severe burns t Do not touch engine while operating or just after stopping Never operate engine with heat shields or guards removed Proper cooling is essential To prevent over heating clean screens cooling fins and other external surfaces of engine Avoid spraying water at wiring harness or any A Air Cleaner Housing B Inner Element electrical components Refer to Maintenance Schedule C Retaining Clip D Element E End Cap F Dust Ejector Valve NOTE Operating engine with loose or damaged air cleaner components could cause premature wear and failure Replace all bent or damaged components NOTE Paper element cannot be blown out with compressed air 1 Unhook retaining clips and remove end cap s 2 Check and clean inlet screen if equipped 3 Pull air cleaner element out of housing and replace Check condition of inner element replace when dirty 4 Check all parts for wear cracks or damage and that ejector area is clean 5 Install new element s 6 Reinstall end cap s with dust ejector valve screen down secure with retaining clips 66 690 01 Rev A KohlerEngines com 19 Fuel System Typical carbureted fuel system and related components include following e Fuel tank e In line fuel filter e Fuel pump e Carburetor e Fuel lines Fuel from tank is moved through in line filter and fuel lines by fuel pump Fuel then enters
116. t positive battery lead first and negative lead last when connecting battery Testing Engine It is recommended engine be operated on a test stand or bench prior to installation in equipment 1 Make sure all hardware is tightened and hose clamps are properly secured 2 Setup engine on a test stand Install an oil pressure gauge Start engine and check to be certain that oil pressure 20 psi or more is present Run for 5 10 minutes between idle and mid range 3 Check all cooling system components and joint connections for leaks 4 Make sure maximum engine speed does not exceed 3750 RPM no load Adjust throttle choke controls and high speed stop as necessary Refer to Fuel System section 5 Place throttle control into idle or slow position and check low idle speed RPM Refer to Fuel System if adjustment is required 6 Stop engine 7 Recheck oil and coolant levels Oil level should be at F mark on dipstick and coolant level in reservoir should be midway between ADD and FULL marks Add additional amounts as required KohlerEngines com 71 1P66 690 01 2011 by Kohler Co All rights reserved 6 50531 9842 72 KohlerEngines com 66 690 01 Rev A 5
117. tarts can cause severe injury or death Disconnect and ground spark plug lead s before x servicing f Se A CAUTION Do not touch wires while Electrical Shock can cause injury engine is running Before working on engine or equipment disable engine as follows 1 Disconnect spark plug lead s 2 Disconnect negative battery cable from battery A WARNING CH Rotating Parts can cause severe injury A8 ZP Stay away while engine A WARNING A cauTION Damaging Crankshaft and Flywheel Can Cause Jo Personal Injury K Hot Parts can cause zt severe burns an Do not touch engine while operating or just after stopping Using improper procedures can lead to broken fragments Broken fragments could be thrown from engine Always observe and use precautions and procedures when installing flywheel is in operation Keep hands feet hair and clothing away from all moving parts to prevent injury Never operate engine with covers shrouds or guards removed Never operate engine with heat shields or guards removed WARNING Carbon Monoxide can cause severe nausea fainting or death Avoid inhaling exhaust fumes poisonous carbon monoxide Carbon monoxide is odorless colorless and can cause death if inhaled A WARNING S Cleaning Solvents can Si cause severe injury or 4 dea
118. teeth Replace gear if it is worn chipped or if any teeth are missing Inspect governor weights They should move freely in governor gear Disassembly NOTE Governor gear is held onto shaft by small molded tabs in gear When gear is removed from shaft these tabs are destroyed and gear must be replaced Therefore remove gear only if absolutely necessary Governor gear must be replaced once it is removed from closure plate 1 Remove regulating pin and governor gear assembly 2 Remove locking tab thrust washer located under governor gear assembly 3 Carefully inspect governor gear shaft and replace it only if it is damaged After removing damaged shaft press or lightly tap replacement shaft into closure plate to depth shown Reassembly 1 Install locking tab thrust washer on governor gear shaft with tab down 2 Position regulating pin within governor gear flyweight assembly and slide both onto governor shaft 66 690 01 Rev A Oil pump is mounted inside of closure plate If service is required refer to these following service procedures Disassembly 1 Remove screws 2 Remove oil pump assembly from closure plate 3 Remove oil pump rotor 4 Remove oil pickup by unhooking locking clip and pulling it free from oil pump body 5 If relief valve is similar to shown drive out pin to remove oil pressure relief valve piston and spring Refer to following inspection and reassembly pr
119. th Use only in well ventilated areas away from ignition sources Liquid coolant can get extremely Engine exhaust gases contain Carburetor cleaners and solvents are extremely flammable Follow cleaner manufacturer s warnings and instructions on its proper and safe use Never use gasoline as a cleaning agent KohlerEngines com A WARNING 4 Hot liquid can cause severe burns Do not loosen radiator cap while engine is operating or warm to touch hot from operation Turning radiator cap when engine is hot can allow steam and scalding liquid to blow out and burn you severely Shut off machine Only remove radiator cap when cool enough to touch with bare hands Slowly loosen cap to first stop to relieve pressure before removing completely 66 690 01 Rev A Maintenance MAINTENANCE INSTRUCTIONS E A WARNING Accidental Starts can cause severe injury or Before working on engine or equipment disable engine as KO death follows 1 Disconnect spark plug lead s 2 Disconnect negative battery cable from battery Le Disconnect and ground spark plug lead s S before servicing Normal maintenance replacement or repair of emission control devices and systems may be performed by any repair establishment or individual however warranty repairs must be performed by a Kohler authorized dealer MAINTENANCE SCHEDULE Every 200 Hours e
120. ther external surfaces Dirt or debris on these areas can cause overheating Check for obvious fuel and oil leaks and damaged components Excessive oil leakage can indicate a clogged or inoperative breather worn or damaged seals or gaskets or loose fasteners Check air cleaner cover and base for damage or indications of improper fit and seal Check air cleaner element Look for holes tears cracked or damaged sealing surfaces or other damage that could allow unfiltered air into engine A dirty or clogged element could indicate insufficient or improper maintenance Check carburetor throat for dirt Dirt in throat is further indication that air cleaner was not functioning properly e Check if oil level is within operating range on dipstick If itis above sniff for gasoline odor Check condition of oil Drain oil into a container it should flow freely Check for metal chips and other foreign particles Sludge is a natural by product of combustion a small accumulation is normal Excessive sludge formation could indicate over rich fuel settings weak ignition overextended oil change interval or wrong weight or type of oil was used CLEANING ENGINE A WARNING k k Cleaning Solvents can cause severe injury or 4 death Use only in well ventilated areas away from ignition sources Carburetor cleaners and solvents are extremely flammable Follow cleaner manufacturer s warnings and instructions on its proper and s
121. tion Torque fasteners in torque sequence shown to 24 4 N m 216 in Ib Install Cylinder Studs Piston Connecting Rod Details A N A A Stud End with Loctite Dri Loc NOTE Do not reinstall or attempt to reuse any cylinder studs that have been removed Discard any removed stud s and replace with new If any of cylinder studs were removed install new stud s as follows 1 2 Identify longer threaded end of new stud containing Loctite Dri Loc Tighten nuts together on shorter threaded section with identification mark on end Thread end of stud with Loctite into crankcase until an exposed stud height of 75 mm 2 61 64 in is obtained End with dash mark must be out When threading in studs use a steady tightening motion without interruption until proper height is obtained Frictional heat from engaging threads may otherwise cause locking compound to set up prematurely Remove two nuts 4 Repeat steps 1 3 for each of studs KohlerEngines com 61 Reassembly Cylinder Head Components Install Hydraulic Lifters A Valve B Head C Hydraulic Lifter D Push Rods E Valve Stem Seal F Valve Spring Cap G Spring H Valve Spring Retainers Valve Spring Keepers J Rocker Arms K Rocker Arm Pivot L Rocker Arm Screw M Valve Cover N Fuel Pump Assemble Cylinder Heads NOTE Hydraulic lifters should always be installed in same pos
122. tions Make sure clamps for wiring harness are positioned on long screw on each side Torque six intake manifold mounting screws in two steps first to 7 4 N m 66 in Ib finally to 9 9 N m 88 in Ib in sequence shown 66 690 01 Rev A KohlerEngines com If thermostat and thermostat housing were removed from intake manifold reassemble them at this time 6 Make sure sealing surfaces of housing and manifold are clean and free of nicks or damage Install thermostat into recess in intake manifold so larger spring end is down Place a new thermostat housing gasket onto manifold surface aligning screw holes Make sure that one of notches in gasket is aligned with by pass slot in manifold and thermostat housing Do not use a substitute gasket 7 65 Reassembly 8 Position thermostat housing on gasket and intake manifold Notch in manifold gasket and thermostat housing must all be aligned Install and torque screws to 9 9 N m 88 in Ib 9 Apply rubber lubricant to inside end of upper radiator hose and install hose to thermostat housing if separated for servicing Secure with clamp Make sure tangs of clamp point toward cylinder 1 away from fan Install Coolant By pass Hose If separated from intake manifold through individual component servicing 1 If connector fitting for by pass hose was removed from manifold reinstall it at this time Apply pipe sealant with Teflon Loctite 592 or equivalent
123. to 16 9 N m 150 in Ib and then to 33 9 N m 300 in Ib using torgue seguence shown 7 Repeat installation procedure for cylinder 2 side head Install Push Rods and Rocker Arms NOTE Push rods must always be installed in same position as before disassembly 1 Note mark or tag identifying push rod as either intake or exhaust for cylinder 1 Lightly apply engine oil or grease to ends of push rods and install Make sure that each push rod ball seats in its respective hydraulic lifter socket 2 Apply grease to contacting surfaces of rocker arms and rocker arm pivots Install rocker arms and rocker arm pivots on cylinder head 3 Install new rocker arm screws with Dri Loc thread locking compound on threads Torque screws to 11 3 N m 100 in Ib When tightening use a steady motion without interruption until proper torque is achieved Frictional heat from engaging threads may otherwise cause locking compound to set prematurely If new screws are not available apply Loctite 242 to bottom 4 or 5 threads Then install and torque screws to 11 3 N m 100 in lb 4 Use a spanner wrench or rocker arm lifting tool to lift rocker arms and position push rods underneath 5 Rotate crankshaft so piston in cylinder 2 is at top dead center on compression stroke and repeat steps for remaining cylinder Do not interchange parts from one cylinder head with parts from other cylinder head 66 690 01 Rev A Reassembly 6
124. untered which is thought to be fault of thermostat it can be checked to determine its operating condition Before removing and testing thermostat make sure all other possible causes such as debris accumulation obstruction leaks belt or fan failure coolant level and damaged components are eliminated as possible causes To Test Remove thermostat from system Hang or suspend thermostat by its frame in a container of water so thermostat does not touch bottom of container Heat water and measure temperature an oven thermometer can be used Spring loaded valve of thermostat should begin to open at 79 4 C 175 F and can be completely open at 90 C 195 F If valve opens at a temperature more than 10 degrees below specified opening or fails to open at a temperature 10 to 15 degrees above specified opening thermostat should be replaced If valve in thermostat can be moved or pushed off its seat with a slight effort when thermostat is cold unit may be considered defective and should be replaced Thermostat should be replaced if operation is found to be questionable or faulty Installation 1 Thoroughly clean sealing surfaces of intake manifold and thermostat housing with an aerosol gasket remover Make sure sealing surfaces are clean and free of nicks or damage Make sure notch in intake manifold is clean 2 Install a new thermostat into intake manifold so larger spring end is down into well of intake manifold Position a new
125. ush Minimum length for each brush is 7 6 mm 0 300 in Replace brushes if they are worn undersize or condition is questionable KohlerEngines com 35 Starter System Armature Components and Details A B A Commutator O D B Mica Insulation C Insulation Check D Armature Coil E Continuity Check 1 Clean and inspect commutator outer surface Mica insulation must be lower than commutator bars undercut to ensure proper operation of commutator 2 Use an ohmmeter set to Rx1 scale Touch probes between 2 different segments of commutator and check for continuity Test all segments Continuity must exist between all or armature is bad 3 Check for continuity between armature coil segments and commutator segments There should be no continuity If continuity exists between any 2 armature is bad 4 Check armature windings insulation for shorting Shift Fork Check that shift fork is complete and pivot and contact areas are not excessively worn cracked or broken Brush Replacement 4 brushes and springs are serviced as a set Use a new Kohler brush and spring kit if replacement is necessary 1 2 36 Perform steps 1 5 in Starter Disassembly Remove screws securing brush holder assembly to end cap plate Note orientation for reassembly later Discard old brush holder assembly Clean component parts as required New brushes and springs come preassembled in
126. ush Lead Retaining Nut 8 0 11 0 N m 71 97 in lb Fan Flywheel Rear Fan Shaft to Mounting Bracket Nut 15 8 N m 140 in lb Front Fan Assembly to Fan Shaft Nut 15 8 N m 140 in lb Fan Pulley Hub Assembly Fastener 6 8 N m 60 in lb Flywheel Retaining Screw 66 4 N m 49 ft Ib Lower Flywheel Cover Mounting Screw into hex or weld nuts 9 9 N m 88 in Ib into Timmerman clips nuts 2 2 2 8 N m 20 25 in Ib Lower Pulley Mounting Screw 24 3 N m 215 in lb Governor Governor Lever Nut 6 8 N m 60 in lb Ignition Spark Plug Ignition Module Fastener Rectifier Regulator Fastener 27 N m 20 ft Ib 6 2 N m 55 in Ib into new hole 4 0 N m 35 in Ib into used hole 4 0 N m 35 in lb Muffler Muffler Retaining Nuts Speed Control 24 4 N m 216 in lb Speed Control Bracket Assembly Fastener 10 7 N m 95 in Ib into new holes 7 3 N m 65 in Ib into used holes Stator Stator Mounting Screw Valve Cover Rocker Arms 6 2 N m 55 in lb Valve Cover Fastener 6 2 N m 55 in lb Water Pump Mounting Screw 9 9 N m 88 in lb Pulley Mounting Screw 9 9 N m 88 in lb CLEARANCE SPECIFICATIONS LH630 LH640 LH685 LH690 LH750 LH755 Camshaft End Play with shim 0 076 0 127 mm 0 0030 0 0050 in Running Clearance 0 025 0 063 mm 0 0010 0
127. worn plug center electrode will be rounded and gap will be greater than specified gap Replace a worn spark plug immediately Wet Fouled A wet plug is caused by excess fuel or oil in combustion chamber Excess fuel could be caused by a restricted air cleaner a carburetor problem or operating engine with too much choke Oil in combustion chamber is usually caused by a restricted air cleaner a breather problem worn piston rings or valve guides 66 690 01 Rev A Carbon Fouled Soft sooty black deposits indicate incomplete combustion caused by a restricted air cleaner over rich carburetion weak ignition or poor compression Overheated Chalky white deposits indicate very high combustion temperatures This condition is usually accompanied by excessive gap erosion Lean carburetor settings an intake air leak or incorrect spark timing are normal causes for high combustion temperatures BATTERY A 12 volt battery with 400 cold cranking amps cca is generally recommended for starting in all conditions A smaller capacity battery is often sufficient if an application is started only in warmer temperatures Refer to following table for minimum capacities based on anticipated ambient temperatures Actual cold cranking requirement depends on engine size application and starting temperatures Cranking requirements increase as temperatures decrease and battery capacity shrinks
128. xhaust valve seat inserts are press fitted into cylinder head Inserts are not replaceable but can be reconditioned if not too badly pitted or distorted If cracked or badly warped cylinder head should be replaced Recondition valve seat inserts following instructions provided with valve seat cutter being used Final cut should be made with an 89 cutter as specified for valve seat angle Cutting proper 45 valve face angle as specified and proper valve seat angle 44 5 half of full 89 angle will achieve desired 0 5 1 0 full cut interference angle where maximum pressure occurs on outside diameters of valve face and seat Lapping Valves Reground or new valves must be lapped in to provide proper fit Use a hand valve grinder with a suction cup for final lapping Lightly coat valve face with a fine grade of grinding compound then rotate valve on its seat with grinder Continue grinding until a smooth surface is obtained on seat and on valve face Thoroughly clean cylinder head in soap and hot water to remove all traces of grinding compound After drying cylinder head apply a light coating of SAE 10 oil to prevent rusting Intake Valve Stem Seal These engines use valve stem seals on intake valves Always use a new seal when valves are removed from cylinder head Seals should also be replaced if deteriorated or damaged in any way Never reuse an old seal KohlerEngines com 51 Disassembly Inspection and Service Crank

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