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Spark Plug Gap .020Crankshaft Main Bearing Journal - Standard Size 1 .9992 2 .000Main Bearing Diameter 2 .0015 2 .0040Main Bearing Clearance 0 .0015 0 .0043Crankshaft Rod Bearing Journal - Standard Size 1 .6252 1 .6260Cylinder Bore - Standard Size3 .56253 .5635Ignition Timing (Engine Running or Static)25 ° BTC6

ASSEMBLY TORQUESTORQUE SPECIFICATIONS IN LB . FT .Connecting Rod BoltsMIN .27MAY .29Flywheel Mounting Screw 35 40Oil Pump 7 9Gearcase Cover 8 10Rear Bearing Plate 19 21Oil Base Mounting Screws 18 23Cylinder Head Nuts 17 19Intake Manifold 18 20Exhaust Manifold 10 12Oil Pan Screws (18) 8 12Starter Mounting Bolts 18 20Generator Through-Studs 15 18Armature Hold-Down Nut (12 Point) 45 50Spark Plugs 15 20SPECIAL TOOLSThese tools are required when overhauling theengine . Other tools are also available from Onan .Order Tool Catalog (900-0019) .VALVE SEAT DRIVERVALVE GUIDE DRIVEROIL SEAL GUIDE AND DRIVERCOMBINATION BEARING DRIVER (MAIN & CAM)COMBINATION BEARING REMOVER (MAIN &CAM)FLYWHEEL PULLER7

ENGINE DISASSEMBLYGENERALWhen complete engine disassembly is necessary,first remove all complete assemblies . Individualassemblies like fuel pump and carburetor can bedisassembled and repaired at another time . Almost allengine maintenance, with the exception of changingmain bearings or crankshaft, can be performed withunit mounted on slide rails . Removal should beseldom, if ever, necessary .Keep all parts in their respective orders . Keep valveassemblies together . Return rod caps to their respectivepistons . Analyze the reasons for parts failure . Seespecific sections of this manual covering dimensionsof parts, tolerance and wear limits, etc .DISASSEMBLYCommon sense dictates the order of disassembly and assembly .The suggested disassembly procedure is as follows :1 . Drain crankcase oil .2 . Disconnect exhaust pipe, fuel line, battery cablesand electrical connections . Tag all electricalwires .3 . Slide unit to its full out position .4 . Install lifting eye in 3/8-16 threaded hole in intakemanifold . Support unit on a suitable hoist .5 . Remove six bolts on sliding arms, three on eachside . Two of the bolts on each side are located onthe arms near the front supports . The third bolt oneach side is located through an access hole on thearm near the rear supports .6 . Lift unit out of its slide rails and place on a suitablebench or work stand .When removing generator and control box, tag all wiresaccording to their respective locations.7 . Remove flywheel, using a puller or pry-barmethod .8 . Remove flywheel alternator stator .9 . Remove the gear cover, being careful to protectthe oil seal from keyway damage .10 . Remove the crank gear, using a gear puller andring .11 . Remove fuel pump, oil filter, starter, carburetor,fuel lines, spark plugs, etc .12 . Remove breaker box .13 . Remove oil base, oil pump and cylinder heads .14 . Remove valves, springs, lifters, etc .15. Remove camshaft and gear assembly .16. Remove connecting rods, pistons and bearings .17 . Remove rear bearing plate .18. Remove crankshaft .19. Remove front main bearing .ASSEMBLYThe engine assembly procedure is normally thereverse of the disassembly procedure, observingproper clearances throughout the engine . Use atorque wrench to assure proper tightness . Coat theinternal engine parts with SAE 30 oil as they areassembled . After the internal engine parts areassembled, the engine should turn over by handfreely . Use only genuine Onan parts and Onan specialtools when reassembling your engine .1 . Use the proper bearing driver to install front mainbearing . Front bearing kit has flanged mainbearing and must be installed with Loctite provided.2 . Insert rear main bearing in rear bearing plate .3 . Install crankshaft and rear bearing plate .4 . Install connecting rods, pistons and bearings .5 . Install camshaft and gear .6 . Install valve assemblies .7 . Install oil pump, oil base and cylinder head .8 . Install breaker box .9 . Install fuel pump, oil filter, starter, generator,carburetor, fuel lines, spark plugs, etc .10 . Install crank gear, aligning crank gear mark withcamshaft .11 . Install gear cover and oil seal .12 . Install flywheel alternator stator .13 . Install flywheel .14 . Install all housings, air cleaner, control box, etc .15 . Reinstall power plant in vehicle, making properfuel, battery, electrical and exhaust connections .(Refer to wiring diagram when making electricalconnections .)16 . Replace six mounting bolts .17 . Fill crankcase with oil .9

TIMING GEARSIf replacement of either the crankshaft gear or thecamshaft gear becomes necessary always install bothgears new .To remove the crankshaft gear, first remove the snapring and retainer washer, then attach the gear pullingring (Onan Tool No . 420-0248) using two No . 10-32screws (Figure 6) . Tighten the screws alternately untilboth are tight . Attach a gear puller to the puller ringand proceed to remove the gear .The camshaft and gear must be replaced as anassembly . Before removing the camshaft and gearassembly, remove the cylinder head and valveassemblies . Then remove the operating plunger forthe breaker points and tappets .Each timing gear is stamped with "O" near the edge .The gear teeth must mesh so that these marks exactlyalign when the gears are installed in the engine . Wheninstalling the camshaft gear and shaft assembly, besure that the thrust washer is properly in place behindthe camshaft gear . Then install the crankshaft retainingwasher and lock ring .PISTONS AND CONNECTING RODSRemoval : Observe the following procedure whenremoving pistons and connecting rods from theengine .1 . Drain oil .2 . Remove the cylinder heads and oil base pan fromthe engine .3 . Remove the ridge from the top of each cylinderwith a ridge reamer (if necessary) before attemptingpiston removal (Figure 7) . Forcing the pistonfrom the cylinder before reaming may causedamage to the piston lands .4 . Turn the crankshaft until the piston is at thebottom of its stroke and remove the connectingrod bolts . Lift the rod bearing cap from the rodand push the rod and piston assembly outthrough the top of the cylinder using a hammerhandle . Avoid scratching the crankpin andcylinder wall when removing the piston and rod .FIGURE 7 .REMOVING RIDGE FROMTHE CYLINDERTHESE MARKS MUSTALIGN WHEN INSTALL-ING TIMING GEARS .Mark each piston and rod assembly so they can be returned totheir respective cylinders after overhaul . Keep connecting rodbearing caps with their respective rods .FIGURE 6 . TIMING GEAR REMOVAL AND INSTALLATION5 . Remove the piston rings from the piston with apiston ring spreader as shown in Figure 8 .Remove the piston pin retainer and push thepiston pin out .13

FIGURE 8 .REMOVING PISTON RINGSInspection : The following text contains inspectionprocedures concerning pistons and connecting rods .1 . Piston Inspection :a . Inspect the pistons for fractures at the ringlands, skirts and pin bosses . Check for wear atthe ring lands using a new ring and feelergauge as shown in Figure 10 . Replace thepiston when the side clearance of the topcompression ring reaches 0 .008 inch .b. Replace pistons showing signs of scuffing,scoring, worn ring lands, fractures or damagefrom preignition . Excessive piston wear nearthe edge of the top ring land indicates preignition.2 . Connecting Rod Inspection :a. Replace connecting rod bolts or nuts withdamaged threads . Replace connecting rodswith deep nicks, signs of fractures, scoredbores or bores out of round more than 0 .002inch .b . Use a new piston pin to check connecting rodfor wear . A gush fit clearance is required andvaries from engine to engine . If a new pistonpin falls through a dry rod pin bore as a resultof its own weight, replace the rod .FIGURE 9 .PISTON RING GROOVE CLEANINGCleaning : Remove dirt and deposits from the pistonsurfaces with an approved cleaning solvent . Clean thepiston ring grooves with a groove cleaner or the endof a piston ring filed to a sharp point (Figure 9) . Caremust be taken not to remove metal from the groovesides .Do not use a caustic cleaning solvent or wire brush for cleaningpistons.When cleaning the connecting rods in solvent, includethe rod bore . Blow out all passages withcompressed air .FIGURE 10 . CHECKING RING SIDE CLEARANCE1 4

FIGURE 11 .POSITIONS FOR MEASURINGDIAMETERS OF PISTONSREPAIR :1 . Fitting Pistons :a . Proper piston tolerances must be maintainedfor satisfactory operation .b . Measure the piston as shown in Figure 11 to besure the total piston-to-cylinder clearancefollows specifications .2 . Fitting Piston Rings :a . Install the piston ring in the cylinder bore .Invert the piston and push the ring to the end ofring travel, about halfway into the bore, whichtrues the ring end gap . Check the gap with afeeler gauge as shown in Figure 12 .b . The practice of filing ring ends to increase theend gap is not recommended . If the ring endgap does not meet specifications, check for thecorrect set of rings and the correct bore size . Acylinder bore that is 0 .001 inch under size willreduce the end gap 0 .003 inch .CYLINDER BLOCKInspection :1 . Make a thorough check for cracks . Minute cracksmay be detected by coating the suspected areawith a mixture of 25 percent kerosene and 75percent light motor oil . Wipe the part dry andimmediately apply a coating of zinc oxide (whitelead) dissolved in wood alcohol . If cracks arepresent, the white coating will become discoloredat the defective area .2 . Inspect the cylinder bore for scoring . Check theWelsh plugs for a tight, even fit and the fins forbreakage .FIGURE 12. CHECKING RING END GAP3 . Check the cylinder bore for taper, out of roundand wear, with a cylinder bore gauge, telescopegauge or inside micrometer (Figure 13) . Thesemeasurements should be taken at four places -the top and bottom of piston ring travel .4. Record measurements taken lengthwise at thetop and bottom of the piston travel as follows :a. Lengthwise of the block, measure and recordas "A" the diameter of the cylinder at the top ofthe cylinder where greatest ring wear occurs .b. Also, lengthwise of the block, measure andrecord as "B" the cylinder diameter at thepiston skirt travel .c . Crosswise of the block, measure and record as"C" the diameter of the top of the cylinder atthe greatest point of wear .1 5

3 . Connect drill to hone and start drill . Move thehone up and down in the cylinder approximately40 cycles per minute . Usually the bottom of thecylinder must be worked out first because it issmaller . Then when the cylinder takes a uniformdiameter, move the hone up and down all the waythrough the bore . Follow the hone manufacturer'srecommendations for wet or dry honing andoiling the hone .4. Check the diameter of the cylinder regularlyduring honing . A dial bore gauge is the easiestmethod but a telescoping gauge can be used .Check the size at six places in the bore : measuretwice at the top, middle and bottom at 90 degreeangles .5 . The crosshatch formed by the scratching of thestones should form an angle of 23 degrees . Thiscan be achieved by moving the hone up and downin the cylinder about 40 cycles per minute .A cylinder wall micro finishing brush produces an idealcylinder wall finish to help rings seat faster . It also Is used fordeglazlng cylinder walls and provides a good crosshatchpattern . See Figure 14 .FIGURE 13 . METHODS OF MEASURING THEDIAMETER OF A CYLINDER6 . Clean the cylinder block thoroughly with soap,water and clean rags . A clean white rag should notbe soiled on the wall after cleaning is complete .Do not use a solvent or gasoline since they washthe oil from the walls but leave the metal particles .7 . Dry the crankcase and coat it with oil .d .Measure and record as "D" the diameter at thebottom of the cylinder bore and crosswise ofthe block .e. Reading "A" compared to reading "B" andreading "C" compared to reading "D" indicatescylinder taper .f . If cylinder taper exceeds 0 .005 inch, reboreand hone to accommodate the next oversizepiston . Reading "A" compared to reading "C"and reading "B" compared to reading "D"indicates whether or not the cylinder is out ofround . If the out of round exceeds 0 .002 inch,the cylinders must be rebored and honed forthe next oversize piston . A reboring machine isused when going to oversize pistons . Thefollowing repair data covers honing to oversizeby use of a hone .Repair:1 . A hone can be used to refinish a cylinder .2 . Anchor the block solidly for either vertical orhorizontal honing . Use either a drill press orheavy-duty drill which operates at approximately250 to 450 rpm .FIGURE 14 . CYLINDER WALL FINISHING1 6

CRANKSHAFTInspect the bearing journals . If they are scored andcannot be smoothed out by dressing down, replacethe crankshaft .PRECISION TYPE -DO NOT LINE REAM OR BOREWhenever making major repairs on the engine,always inspect the drilled passages of the crankshaft .Clean them to remove any foreign material and toassure proper lubrication of the connecting rods .BEARINGS (Figures 15-17)Removal : Removing camshaft or crankshaft bearingsrequires complete disassembly of the engine . Use apress or a suitable drive plug to remove the bearings .Support the casting to avoid distortion and avoiddamaging the bearing bore during removal andinstallation . Use oil on the bearings to reduce frictionwhen installing and again lubricate with oil afterinstalling .Replacement: Crankshaft main bearings are precisiontype which do not require line reaming or lineboring after installation . They are available in standardsize and .002 inch undersize . Expand the bearingbore by placing the casting in hot water or in an ovenheated to 200 0 F .ALIGN HOLE IN BEARING_WITH HOLE INBEARING BORECAMSHAFT BEARINGFIGURE 15 . CAMSHAFT BEARINGLOCK PINALIGN BEARING OIL HOLESWITH OIL HOLES INBEARING BOREIf a torch is used, apply only a little heat .To ease assembly, cool the precision bearing toshrink it . Align the oil hole(s) in the bearing with theoil hole(s) in the bearing bore . The oil passage mustbe at least 1/2 open . Lubricate bearings with SAE20oil before installing . The cold oiled precision bearingshould require only light taps to position it with adriving tool . If head of lock pin is damaged, use sidecutters or Easy Out tool to remove and install new pin .Apply oil to thrust washer (one used with eachbearing) to hold it in place while installing thecrankshaft . Oil grooves in thrust washers must facethe crankshaft and washers must be flat (not bent) .The two notches on each washer must fit over the twolock pins to prevent riding on the crankshaft .FIGURE 16 . BEARINGS FOR REARBEARING PLATEFRONT MAINBEARING BOREOriginal front bearing uses a separate thrust washer. Replacementfront bearing is a one piece assembly with thrust washer part of thebearing . Do not use a separate thrust washer when installing thisreplacement part . See Figures 16 and 17 .New camshaft bearings are precision type which donot require line reaming or line boring after installation. Coat the bearing with SAE20 oil to reducefriction . Place the bearing on the crankcase over thebearing bore with the elongated hole in properposition and narrow section facing out (except boreswithout oil holes install with bearing groove at thetop) . Be sure to start the bearing straight . Press thefront bearing in flush with the outside end of thebearing bore . Press the rear bearing in flush with thebottom of counterbore which received the expansionplug (see Figure 15) .ALIGN BEARINGNOTCHES WITHLOCK PINSAND MATCHOIL HOLESB49 RevPRECISION TYPE -DO NOT LINE BORE OR REAMFIGURE 17 . FRONT MAIN BEARINGINSTALLATION1 7

CRANKSHAFT ENDPLAYAfter the rear bearing end plate has been tightenedusing the torque recommended in Assembly Torques,check the crankshaft endplay as shown in Figure 18 . Ifthere is too much endplay (see Dimensions andClearances for minimum and maximum endplay),remove the rear bearing end plate and add a shimbetween the thrust washer and plate . Reinstall the endplate making sure the thrust washer and shim notchesline up with the lock pins . Torque and recheckend play of the crankshaft .Checking Bearing Clearance with Plasti-Gage :1 . Make certain that all parts are marked or identifiedso that they are reinstalled in their originalpositions .2 . Place a piece of correct size Plasti-Gage in thebearing cap the full width of the crankshaft rodsurface about 1/4 inch off center (Figure 19) .3 . Rotate the crank about 30 degrees from bottomdead center and reinstall the bearing cap ; tightenthe bolts to the torque specified in the Table ofTorques and Clearances . Do not turn the crankshaft .4. Remove the bearing cap . Leave the flattenedPlasti-Gage on the part to which it has adheredand compare the widest point with thegraduations on the Plasti-Gage envelope todetermine bearing clearance .FIGURE 19 . MEASURING BEARING CLEARANCEWITH PLASTI-GAGEOIL SEALSThe bearing plate must be removed to replace the oilseal . Drive the oil seal out from the inside . Beforeinstalling the seals, fill the space between lips with amulti-purpose grease . This will improve sealing .When installing the gear cover oil seal, tap the sealinward until it is 31/32 inch from the mounting face ofthe cover . When installing the bearing plate oil seal,tap the seal into the bearing plate bore to bottomagainst the shoulder in the plate bore . Use a sealexpander or place a piece of shim stock around theend of the crankshaft, when replacing the bearingplate to avoid damaging the seal . Remove the shimstock as soon as the plate is in place .MEASURE ENDPLAY HERE(REFER TO DIMENSIONSAND CLEARANCES)FIGURE 18. CRANKSHAFT ENDPLAYASSEMBLY1 . Lubricate all parts with engine oil .2 . Position piston on its respective rod and installthe pin .3 . Install the rings on the pistons starting with the oilcontrol ring (Figure 21) . Use a piston ringspreader to prevent twisting or excessive expansionof the ring . Some oil control rings and allcompression rings have a dot or the word "top" onone side of the ring to indicate which side facesthe top of the piston . Unmarked piston rings canbe installed either way . If the oil control ring has acoil expander, install the expander first and thenclose until the coil ends butt . The joint should be180 degrees from the gap of that ring .1 8

GEAR COVEROIL SEALA877WONGEAR COVER OIL SEAL+ MOUNTING FACEOF GEAR COVER*31/32"*New style thinopen-face sealdimension is1-7/64"THIS SURFACE SHOULD BECLEANED OF ALL OLDSEALING COMPOUND BE-FORE INSTALLING SEAL .REAR BEARING PLATEREAR BEARING PLATEOIL SEALTHIS SURFACE SHOULD BECLEANED OF ALL OLDSEALING COMPOUND BE-FORE INSTALLING SEAL .- DRIVE OR PRESS OILSEAL TO SHOULDEROF THE PLATE BOREFIGURE 20 . GEAR COVER AND REAR BEARING PLATE OIL SEALSHEAVIEST COMPRESSION- RING IN TOP GROOVEFIGURE 21 . PISTON RINGSInstallation of Piston in Cylinder :1 . Turn the crankshaft to position the number onerod bearing journal at the bottom of its stroke .2. Lubricate the number one piston assembly andinside of the cylinder . Compress the rings with aring compressor as shown in Figure 22 .3. Position the piston and rod assembly in thecylinder block .4 . Tap the piston down into the bore with the handleend of a hammer until the connecting rod isseated on the journal (Figure 22) .Make sure edge of rod does not nickcrank journal .FIGURE 22 . INSTALLING PISTONInstall the bearing cap on the rod with the witnessmarks and stamped reference numbers matchingthe marks on the rod . Install and tighten the boltsto the specified torques .The bearing cap must be tapped several times toproperly align it with the rest of the connectingrod . Clearance varies on the journal if this is notdone .19

Install the remaining pistons and rods in the samemanner . Crank the engine over by hand to seethat all bearings are free .5 . Install the oil base and pan using new gaskets .Torque oil base thru-bolts to 18-23 ft .-lb . Torqueoil pan bolts (18) to 8-12 ft .-lb .6 . Install the cylinder heads and torque 17-19 ft . l b .7 . Replace oil and break-in engine .CYLINDER HEADSRemove the cylinder heads for cleaning when poorengine performance is noticed .1 . Use a 1/2-inch socket wrench to remove cylinderhead nuts . Lift heads off .Do not remove heads when they arehot . Warpage may occur .2. After removing heads, clean out all carbondeposits . Be careful not to damage the outersealing edges where gaskets fit . The heads aremade of aluminum and can be damaged bycareless handling .3. Use new head gaskets and clean both the headsand the cylinder block thoroughly where the headgaskets rest .4 . Place heads in position and follow head torquetightening sequence shown in Figure 23 . Start outtightening all nuts to 5 ft.-lb, then 10 ft .-Ib, etc .,until all nuts are torqued 17-19 ft .-lb .0-0C6rc_©\sLEFT CYLINDERRIGHT CYLINDERFIGURE 23. CYLINDER HEAD TORQUE TIGHTENING SEQUENCE20

OIL SYSTEMCRANKCASE OILChange crankcase oil every 100 operating hours andonly when engine is warm . (EXCEPTION : Drain initialoil fill at 25 operating hours .)To drain, remove the oil drain plug on oil pan . After oildrains, replace the plug and refill crankcase with 4quarts (4-1/2 with filter change) of a good qualitydetergent oil . Oil must meet or exceed the API(American Petroleum Institute) designation SE orSE/CC ; this oil was formerly designated as MS,MS/DG or MS/DM .For temperatures above 30°F use SAE 30 oil ; fortemperatures below 30"F, use IOW or 5W30 . 1 OW40 isa good choice for all around use and can be usedthroughout the year .In extremely dusty conditions or in very cold weather,change oil at least every 50 hours of operation .OIL FILTERChange the crankcase oil filter at least every 200operating hours . Filter is located above starter onright side of engine . Remove by turning filtercounterclockwise with a filter wrench . Before installingnew filter, coat the gasket on base of filter with alight film of oil . Install by turning clockwise untilfriction is noted, then turn an additional 1/4 to 1/2turn . See Figure 25 .Do not over-torque oil filter. Be sure ring isCAUTIONinstalled around oil filter. This ring acts as anair seal and prevents loss of cooling air .Do not overfill crankcase . Do not use serviceDS oil . Do not mix brands nor grades of motoroil .FIGURE 24 . DIPSTICK LOCATIONFIGURE 25 . OIL FILTER LOCATION21

CRANKCASE BREATHERThis engine uses a crankcase breather valve formaintaining crankcase vacuum . No maintenance isgenerally required . If the crankcase becomespressurized as evidenced by oil leaks at the seals,clean baffle and valve in a suitable solvent . (Apressurized crankcase could also be caused byoverfilling with oil or leaving the fill cap loose .)Crankcase breather disassembly requires removal ofexhaust manifold . See Figure 26 .FIGURE 26 . CRANKCASE BREATHER2 2

FUEL SYSTEMCARBURETOR DISASSEMBLY ANDREPAIRRemoval :1 . Disconnect fuel inlet hose, crankcase breatherhose and air inlet hose .2 . Disconnect governor, throttle linkage, and chokecontrol .3 . Remove two hold-down nuts and lift carburetorfrom intake manifold .Always work on carburetor in clean conditions .Replacing Needle and Valve Seat :1 . Remove 7/16 inch hex at base of fuel bowl and liftbowl from carburetor .2 . Push out pin that holds float to carburetor body .3 . Remove float and set aside in a clean place . Pullout needle and using a large screwdriver removeneedle valve seat .4. Install new valve seat and needle and replacefloat .5 . Adjust float .IDLE ADJUSTMENTELECTRIC FUELPUMPFUEL INLET TOCARBURETORFIGURE 27 . FUEL SYSTEM23

CARBURETOR FLOAT ADJUSTMENT1 . Invert float and casting .2 . With the float resting lightly against the needleand seat, there should be .07 to .11 inch clearancebetween base of float and carburetor casting .A drill bit can be used for this measurement as shown in Figure28. Use a 3/32 inch drill bit or any bit between .07 inch (No. 50)and .11 inch (No . 35) .3 . If it is necessary to reset float level, remove thefloat from carburetor and bend the float tang, nearthe pin, to obtain correct float level .CAUTIONDo not bend the float when installed ; doing somay cause deformation of needle or seat .4. Check the float closely for signs of leakage .Repair or replace float if damaged or filled withgasoline .5. Before assembling carburetor, remove filterscreen from float bowl and clean both screen andbase of float bowl .6 . Install new gaskets when reassembling .FIGURE 28. CARBURETOR FLOAT ADJUSTMENTFIGURE 29 . EXPLODED VIEW OF CARBURETORCARBURETOR CLEANING AND INSPEC-TIONTo clean the carburetor, soak all componentsthoroughly in a good carburetor cleaner, followingthe manufacturer's instructions . Be sure to remove allcarbon from carburetor bore, especially in the area ofthe throttle valve . After soaking, clean out allpassages with filtered, compressed air .Check the adjusting needles and nozzle for damage .If float is loaded with fuel or damaged, replace it . Thefloat should fit freely on its pin without binding .Check the choke and throttle shafts for excessive sideplay and replace if necessary . Figure 29 shows anexploded view of carburetor .FUEL PUMP FILTER ELEMENTEvery 500 hours or sooner, drain fuel pump and checkfilter element . Remove fuel pump mounting screwsand turn off hex nut on base of pump . If elementappears dirty, replace with a new one . Be sure toreplace gaskets when reassembling .AIR CLEANER ELEMENTCheck and clean element at least every 100 hours .Loosen wing nut to remove . Clean by tapping baselightly on a flat surface . Replace element at least every500 operating hours ; clean or replace more often industy conditions .2 4

FIGURE 30 . FUEL PUMP FILTER ELEMENTFIGURE 32 . GOVERNOR BALL JOINT3CARBURETOR ADJUSTMENTSThe carburetor has a main fuel (power) adjustmentand an idle fuel adjustment . The main adjustmentaffects operation under heavy load conditions . Idleadjustment affects operation under light or no loadconditions . Under normal circumstances, factorycarburetor adjustments should not be disturbed .Normal settings are 1-1/4 turn open for main fuel jetand one turn open for idle fuel jet .B125FIGURE 31 . AIR CLEANER ELEMENTCARBURETOR BOWLRemove carburetor bowl every 500 hours and cleanfilter screen in solvent . Blow out with low pressurecompressed air and reassemble, making sure gasketsare in place .GOVERNOR BALL JOINTEvery 200 hours or sooner, check the governorlinkage for freedom of movement through its travel .Clean and lubricate ball joint with lubricatinggraphite .FIGURE 33. CARBURETOR ADJUSTMENTS25

Forcing the needle against its seat willdamage it. The needle does not completelyshut when turned fully in .Before final adjustment, allow the engine to warm up .Make the idle adjustment under no load . Open themain jet until the engine runs smooth underacceleration . Slightly with no more loadfuel may be needed(open about 1/4 turn further) when sudden load isapplied or if operating in very cold weather .1 . Adjust the carburetor idle needle with no loadconnected .2 . Adjust the carburetor main jet for the best fuelmixture while operating the set with a full ratedload connected .3 . Adjust the length of the governor linkage andcheck linkage and throttle shaft for binding orexcessive looseness .4. Adjust the governor spring tension for ratedspeed at no load operation .5 . Adjust the governor sensitivity .6. Recheck the speed adjustment .7 . Set the carburetor throttle stop screw .Set the throttle stop screw (located on carburetorthrottle lever) with no load connected and whilerunning at a low speed setting . Turn the screw to giveapproximately 1/32 inch clearance between the screwand pin .If the engine develops a "hunting" condition (alternateincrease and decrease of engine speed), trycorrecting by opening the main adjusting needle alittle more . Do not open more than 1/2 turn beyondthe maximum power point .GOVERNORBefore making governor adjustments, run the unitabout 15 minutes under light load to reach normaloperating temperature . (If governor is completely outof adjustment make a preliminary adjustment at noload to first attain a safe voltage operating range .)Engine speed determines the output voltage andcurrent frequency of the generator . By increasing theengine speed, generator voltage and frequency areincreased, and by decreasing the engine speed,generator voltage and frequency are decreased . Anaccurate voltmeter or frequency meter (preferablyboth) should be connected to the generator output inorder to correctly adjust the governor . A small speeddrop not noticeable without instruments will result inan objectionable voltage drop . The engine speed canbe checked with a tachometer .A binding in the bearings of the governor shaft, in theball joint, or in the carburetor throttle assembly willcause erratic governor action or alternate increaseand decrease in speed (hunting) . A lean carburetoradjustment may also cause hunting . Springs of allkinds have a tendency to lose their calibrated tensionthrough fatigue after long usage . If all governor andcarburetor adjustments are properly made, and thegovernor action is still erratic, replacing the springwith a new one and resetting the adjustments willusually correct the trouble .FIGURE 34. AC VOLTAGE AND FREQUENCY TESTERLinkage : The engine starts at wide open throttle . Thelength of the linkage connecting the governor arm tothe throttle shaft and lever is adjusted by rotating theball joint . Adjust this length so that with the enginestopped and tension on the governor spring, the stopon the carburetor throttle lever just contacts the bosson the carburetor body . This setting allows immediatecontrol by the governor after starting . It also synchronizestravel of the governor arm and the throttleshaft .Speed Adjustment : With the warmed-up unitoperating at no load, adjust the tension of thegovernor spring . Refer to Voltage Chart and the SpeedChart and select the column which corresponds to thenameplate of the unit in question . Turn the speedadjusting nut to obtain a voltage and speed readingwithin the limits shown .26

Sensitivity Adjustment : Refer to the Governor Adjustmentillustration, and to the Voltage and Speed Charts .Check the voltage and speed, first with no loadconnected and again with a full load . Adjust thesensitivity to give the closest regulation (least speedand voltage difference between no load and full load)without causing a hunting condition .To increase sensitivity (closer regulation), shift thespring toward the governor shaft .An adjustment for too much sensitivity will causealternate increase and decrease of engine speed(hunting) .To decrease sensitivity, shift the spring toward theouter end of the governor arm . Too little sensitivitywill result in too much difference in speed between noload and full load conditions .Any change in the sensitivity adjustment usuallyrequires a compensating speed (spring tension)adjustment .ELECTRIC CHOKEManually check movement of choke travel to be sureit is not stuck open or closed . Voltage at choke shouldbe 12 volts during start and drop to zero during run . Ifchoke does not move at room temperature with 12volts applied, replace .This choke should not require any seasonal readjustment. If adjustment becomes necessary proceed asfollows :1 . Remove clip and bushing .2 . Loosen choke lever clamp screw .3 . With lever fully forward (away from carburetor),adjust so choke valve is completely closed .4. Tighten clamp screw .5 . Replace bushing and clip .BALL JOINTVOLTAGE CHARTFOR CHECKINGGOVERNOR REGULATIONMAXIMUMNO-LOAD VOLTAGEMINIMUMFULL-LOAD VOLTAGE120 VOLT1 PHASE2 WIRE126110SPEED CHART FOR CHECKINGGOVERNOR REGULATIONMAXIMUM NO-LOAD SPEED (RPM) 1890HERTZ (CURRENT FREQUENCY) 63MINIMUM FULL-LOAD SPEED (RPM) 1770HERTZ 59FIGURE 35 . GOVERNOR ADJUSTMENTS2 7

FUEL SYSTEM TROUBLESHOOTING GUIDETROUBLE CAUSE REMEDYFUEL LEAKS FROM 1 . Float level set 1 . With fuel bowl removedCARBURETOR WHEN too high and carburetor inverted,FUEL SHUT-OFF ISset float parallel toOPENbowl flange(3/32" clearance)2 . Dirt under inletvalve2 . Remove inlet valve, cleanseat by rinsing in cleanfuel and blow off withcompressed air3 . Bowl vent plugged 3 . Remove bowl and blowclean with compressedair4 . Collapsed floatcaused by blowingassembled carburetorwith compressed air4 . Replace float5. Carburetor gummedfrom storage .Float stuck to screen5. Remove fuel bowl andclean with suitablesolvent .ENGINE SMOKES ANDRUNS RICH1 . Dirty air filter 1 . Clean or replace2 . Improper adjustment 2 . Set idle and power needlesat one turn open . Afterengine starts and runs,set for optimumperformance3 . Nozzle boss gasketleaks . Engine runswith power needleseated3. Remove fuel bowl andreplace gasket . Tightenbowl retainer securely4 . Air bleeds incarburetor plugged4 . Remove fuel bowl, idleand power needles . Cleanthoroughly with compressedair .2 8

FUEL SYSTEM TROUBLESHOOTING GUIDE(Continued)TROUBLE CAUSE REMEDYENGINE RUNS LEAN 1 . Improper adjustment 1 . Set idle and power needlesat one turn open . Afterengine starts and runs,set for optimum performance2 . Idle holes plugged .Dirt in fuel deliverychannels3 . Float level set toolow . Low level infuel bowl4 . Fuel filter in electricfuel pump dirty2 . Remove fuel bowl, idle andpower needles . Cleanthoroughly with compressedair3 . With fuel bowl removedand carburetor inverted,set float parallel to bowlflange (3/32" clearance)4 . Remove filter and replace5 . Fuel filter (screen) inbowl plugged5 . Remove fuel bowl .Clean thoroughly and replaceENGINE STARTS HARD 1 . Improper adjustment 1 . Set idle and power needlesat one turn open . Afterengine starts and runs, setfor optimum performance2 . No fuel in carburetor 2 . Check carburetor drainvalve . If no fuel in bowlclean tank filter andcarburetor . Check electricfuel pump operation .3 . Choke valve notclosing3 . Check controls for propertravelGOVERNOR SURGEThrottle shaft andvalve bindingRemove and replace shaft ifworn . Clean carburetor body .Reassemble throttle shaftassembly into carburetor bodyas far as possible . Holdfirmly in place in thisposition while assemblingthrottle valve . Makecertain valve does not bindin throttle bore whenopening and closing throttle .2 9

IGNITION AND BATTERY CHARGINGBREAKER POINT (Cold Setting)To maintain maximum efficiency from the engine,change the breaker points every 200 hours of operation. Proceed as follows :1 . Remove the two screws and the cover on thebreaker box .2 . Remove the two spark plugs so engine can beeasily rotated by hand . Check condition of sparkplugs at this time .3 . Refer to Figure 36 . Remove mounting nut (A) andpull the points out of the box just far enough soscrew (B) can be removed and leads disconnected.4. Remove screw (C) and replace condenser with anew one .5 . Replace points with a new set but do not completelytighten mounting nut (A) .6 . A small hole on rear of blower housing providesan access to view timing mark (Figure 37) .7 . Rotate the engine clockwise (facing flywheel) byhand until the 25°BTC mark aligns with hole .Turn another 1/4 turn (90°) to ensure points arefully open .8 . Using a screwdriver inserted in notch (D) on theright side of points, turn points until gapmeasures .020 inch with a flat thickness gauge .(Be sure feeler is clean .) Tighten mounting screwand recheck gap . Timing is automatically set at25°BTC when point gap is .020 inch .FIGURE 37 . TIMING ACCESS HOLEIGNITION TIMINGThe timing on the engine is preset at the factory . Anon-movable breaker point box is used, however aslight timing change could be made by adjustingpoints .The engine is equipped with an automotive typebattery ignition system . Both spark plugs firesimultaneously, thus the need for a distributor iseliminated . Spark advance is set at 25° BTC (beforetop center) and should be maintained for best engineperformance . (Check timing if in doubt about pointgap .) Proceed as follows :FIGURE 36 .BREAKER POINT ADJUSTMENTTiming Procedure - Engine Running (Hot Setting)1 . To check the ignition timing with unit running,use a timing light . Connect the timing lightaccording to its manufacturer's instructions .Either spark plug can be used as they firesimultaneously .2 . A small hole on the rear portion of blower housingprovides an access to view timing marks . Twomarks are provided ; one for T/C (top center) andone for 2/5 (25° BTC) .30

FLYWHEEL ALTERNATORThis unit is equipped with a permanent magnetflywheel alternator and solid-state voltage regulatorrectifier(output control) . As with all solid-stateelectrical units, precautions are necessary whenservicing . Observe the following :Precautions :1 . Do not connect battery cables in the wrongpolarity .2 . Do not short together alternator stator leads .3 . Do not run without a battery . Damage will occurto regulator and battery ignition coil .Preservice Checks :1 . Check for a good ground between equipment andregulator-rectifier case .2. Be sure output control plug (connector) isproperly inserted into stator receptacle . Thismeans the plug must push in and solidly bottom inthe receptacle to eliminate any resistance due to apoor connection . Keep it clean and tight .3 . Check battery and its connection to be sure it isserviceable .Charging system tests require a fully chargedbattery.FIGURE 41 . FLYWHEEL ALTERNATOR SYSTEMTESTING BATTERY CHARGING SYSTEMBASIC TEST I PROCEDURE I TEST VALUES1 . Battery Battery Voltage - unit not running 12 VDC2 . Regulator Battery Voltage after unit isrunning 3 to 5 minutes .13 .6 to 14.7 VDC3 . AlternatorStator andWiring withFully Chargedbattery .Ohmmeter reading from statoroutput - unit not running .Disconnect wire terminating atAC terminal of voltage regulatorand wire terminating at BATterminal of start solenoid . Insertohmmeter between these wires ..2 to .6 Ohms4 . AlternatorStator andWiringMeasure AC stator output voltagewith unit running . Disconnectwire terminating at AC terminalof voltage regulator . MeasureAC voltage (unit running) betweenthis wire and BAT terminal ofstart solenoid .28 VAC3 2

STARTING SYSTEMSPECIFICATIONSEngaging SystemSolenoid-operated Over-running ClutchNominal Output1 .0 HPRated Voltage D .C .12 V .Field ConnectionSeriesDirection of Rotation Counterclockwise (Viewing from pinion end)Weight 3 .7 lbs .STARTER DISASSEMBLYAfter removing the starter from the engine, disassembleas follows :1 . Loosen the nut that attaches the solenoid motorterminal to the field coil connector lead and takeoff the connector lead .2. Loosen the retaining screws and remove thesolenoid from the front bracket . Simultaneously,the fiber washers, the return spring and thesolenoid plunger will be removed .3. Unscrew the through bolts and the screws attachingthe brush holder assembly to the rearbracket, so the rear bracket will be removed fromthe yoke .4 . Remove the yoke with the brush holder assembly .5 . Removing the brushes from the brush holderspermit separation of brush holder assembly fromthe field coil .6. Remove the armature from the front bracket .Simultaneously, the shift lever, the lever springand the spring holder will be removed .7 . To remove the overrunning clutch, put a metalcylinder of suitable size over the end of armatureshaft so it rests on the stop ring . Tap cylinderlightly with hammer, the stop ring sliding towardarmature and off ring . Remove the ring fromgroove in shaft and then slide the overrunningclutch and the stop ring from the armature shaft .FIGURE 42.FIGURE 43 .33

SWITCH ASSEMBLYTHROUGHBOLTREAR BRACKETFIELD COIL BRUSH ASSEMBLYSET HOLDERASSEMBLY REAR BEARINGFIGURE 44 . STARTER EXPLODED VIEWCLEANING PARTS1 . DO NOT immerse parts in cleaning solvent .Immersing the field coil, yoke assembly, armatureand solenoid will damage insulation . Wipe theseparts with a cloth only .2 . DO NOT immerse the overrunning clutch incleaning solvent . The clutch is prelubricated atthe factory, and solvent will wash lubrication fromclutch .3 . Wash all other parts in solvent and dry the parts .INSPECTING PARTSInspection for Grounded Armature : Grounds in thearmature can be detected by using a test lamp . If thelamp lights when one probe of test lamp is touched tothe commutator with other probe to the core, thearmature is grounded .Inspection for Shorted Armature : A short circuit in thearmature can be located by using a growler tester .Place armature in growler and hold a thin steel bladeparallel to the core and just above it while slowlyrotating armature in growler . A shorted armature willcause blade to vibrate and be attracted to the core .Inspection for Open Circuit in Armature : The mostlikely place to look for an open circuit is at thecommutator bar riser . Inspect for loose connectionson the points where the conductors are joined to thecommutator bars .Commutator Runout : Place armature in pair of V-blocks, and measure runout with dial indicator .Measure both shaft and commutator. A bent shaftrequires replacement of armature . When commutatorrunout exceeds 0 .004 inch, commutator should berefaced . Remove only a sufficient amount of metal toprovide a smooth, even surface .3 4

Inspection for Open in the Field Coil : Connect bothtest lamp probes to the brushes of field coil ends . Ifthe lamp does not light, the field coil is open .Inspection for Grounded Field Coil : Connect oneprobe of test lamp to the yoke and another probe tothe field coil . If the lamp lights, the field coil isgrounded .Inspecting Insulated Brush Holder for Grounds :Touch each of the brush holders with one test probe,while holding other test probe against brush plate .Two brush holders that are 180 degrees apart shouldcause test lamp to light as they are intentionallygrounded . The other two brush holders should notcause lamp to light when tested as they are insulated .If insulated brush holders cause lamp to light whentested, it indicates that brush holders on brush plateare grounded . Replace brush assembly if brushholders are grounded .Brushes: When brush length becomes shorter than0 .45 inch, it should be replaced . Always replacebrushes as a complete set .Check the brushes for freedom of movement in thebrush holders .Brush Springs : The spring tension should be checkedby placing the brush holder assembly in place on thecommutator . Hook a spring scale under the springnear the end and pull scale and take a reading just asspring end leaves the brush .Spring tension should be 49 to 59 ounces .Replace springs that do not meet specifications .Overrunning Clutch : The pinion gear should rotatesmoothly in one direction (not necessarily easily), butshould not rotate in opposite direction . If the piniongear does not function properly, or if pinion gear isworn or burred, replace the overrunning clutch unit .2 . Install the overrunning clutch assembly, the ringand the stop ring on the armature shaft .3 . Apply a small amount of lubriplate on the shiftlever pivot pin and the lever holders .Install the shift lever over the clutch assemblywith position indicated in Figure 45 . This isimportant, if the shift lever is not properlypositioned the pinion gear travel will be restrictedcausing a locking in the clutch mechanism .FIGURE 45 . SHIFT LEVER4 . Apply a film of medium engine oil to the drive endof the armature shaft .Place the thrust washer on the drive end of theshaft . Slide the armature with the lever into thefront bracket .5 . Place the lever spring and the spring holder intothe front bracket in the direction shown in Figure46 .SPRING HOLDERshift leverTO YOKEREASSEMBLYReassembly is the reverse of disassembly .1 . Lubricate armature shaft splines with a very lightgrade oil . A medium or heavy oil and grease maycause the overrunning clutch assembly faultyoperation in cold weather .FIGURE 46 . SPRING HOLDER35

6 . Before installing the yoke, note the position of theholes of front bracket in which the through boltsare fastened . Position the yoke to the frontbracket . Be sure that the yoke is properly indexedto the front bracket .7 . Position the brush holder assembly indexing thecuts of the brush plate to the holes of the frontbracket .8 . Install the brushes in their brush holders . Be sureto center the brush springs on the brushes .9 . Place the thrust washers on the commutator endof the armature shaft and apply a small amount oflubriplate on the shaft .The fiber washer is placed between the steel washers .10 . Position the rear bracket to the yoke, inserting therubber gasket to the slot of the rear bracket.11 . Align the holes in brush plate with holes in therear bracket and install two screws attaching thebrush holder assembly to the rear bracket .12 . Fasten through bolts securely .13 . Install the solenoid plunger over the top of theshift lever in the front bracket . Be sure that thepinion gear is moved when the plunger is pulledmanually .14 . Install the solenoid .The return spring, in this case, should be straight in the properposition between the bore of the solenoid and the bore of theplunger.TESTING AND ADJUSTINGAdjusting Pinion Clearance : After the starter isreassembled, the pinion clearance must be adjustedto give sufficient clearance between the end of thepinion and the stop ring when the pinion is in meshwith the ring gear of the engine .1 . Connect a battery of the proper voltage betweenthe "Switch" terminal of the solenoid and thebracket of the starter (ground), so the pinion willtravel .2 . Then, push the pinion back until play is taken outof the lever and the clutch mechanism .3 . Measure the pinion clearance .4 . The clearance should be 0 .02 to 0 .08 inch . Adjustby removing the solenoid and increasing ordecreasing the number of the fiber washers usedon the mounting surface of the solenoid .Increasing the number of the washers decreases clearance,and decreasing the number of the washers increasesclearance .For the no load test, connect the starter as shown inFigure 48 . The value of the meters should be asfollows :Battery Voltage 10 .5VMinimum R .P.M 5000 r .p .m .Maximum Current Draw 53A1 . Before installing the starter, be sure starterand engine mounting surfaces are free of dirtand oil. These surfaces must be clean to make good electricalcontact.2 . Don't operate the starter more than 30 seconds, or seriousdamage may result. Starters are not designed for continuousoperation .3 . When the engine does not rotate, don't hold the starter in astalled condition more than 10 seconds .4. The wires between the battery and the starter should be ofsufficient size to carry the electric load without excessive voltagedrop .switch0 O Ooammeterstarterbatteryvolt meterFIGURE 47 . PINION CLEARANCEFIGURE 48 . NO LOAD TEST.3_ 6'

AC GENERATOR MAINTENANCEGENERALThe generator uses a revolving armature and normallyneeds little care other than a periodic check of thebrushes and collector rings . If a major generatorrepair becomes necessary, have the equipmentchecked and tested by a qualified electrician who isthoroughly familiar with the operation of electricgenerating equipment .All accessories must be taken off and power plant must be removedfrom its slide rails for disassembly and repair of the generator .BRUSH REMOVAL AND REPLACEMENTTo gain access to brushes, remove plastic end bellscreens . Measure brush wear as shown in Figure 49,using a small, narrow scale inserted into top of brushblock . If brushes need replacing remove and tag wiresconnecting to brush blocks . Then remove brushblocks and lift out of end bell . Pullout the brushes andsprings from bottom of brush block . Clean out anydirt or oil from brush block at this time .New brushes are shaped to fit and seldom needsanding to seat properly . Always replace brushes as aset and use only the correct brushes as listed in thePARTS CATALOG. Never use a substitute brushwhich may appear to be the same but may haveentirely different electrical characteristics .Note that brush blocks are stamped "BRIG END" onone side . Be sure this stamped side faces bearing endof generator for correct brush alignment . Tighten thebrush block screws to 40-70 in-lb . (4-6 ft-lb .) . If somesparking occurs after replacing brushes, run the plantwith a light load until brushes seat properly . Checkbrush springs for freedom of movement .TOP VIEW OFBRUSH LOCKOOOO`0 SRO END O8,BCROSS SECTION OFBRUSH BLOCKREPLACE WHEN WORN TOTHIS DIMENSION OR IFMEASUREMENT "A" EXCEEDSONE INCHNOTE : MEASURE FROM TOP FACEOF BRUSH BLOCK TO TOPOF BRUSH .FIGURE 49 . BRUSH WEAR LIMITS37

GENERATOR DISASSEMBLY1 . Remove power plant from its slide rails .2 . Remove all accessories attached to the generator .3 . Tag and remove all leads .4 . Loosen and lift out both brush rigs .5 . Remove four generator through-stud nuts .6 . Lift or pull end bell from frame assembly . Do notpry loose with a screwdriver, use a plastichammer and tap around edges of end bell toloosen .7 . Remove frame (field) assembly, being careful notto let it rest or drag on the armature .Four seals are used between frame (field)assembly and engine-to-generator adapter .These seals must be used when reassembling generator or thegenerator will overheat.8 . Using a square 3/8 inch drive, insert into 12-point(internal wrenching) armature hold-down nut andremove .9. While pulling outward with one hand under thearmature, strike a sharp end-wise blow on armatureshaft to loosen armature . The armaturehas an internal taper which fits onto the externaltaper of engine adapter . If the armature does notcome loose, place a heavy brass rod on thearmature shaft near the ball bearing and strike asharp downward blow on the rod with a hammer .Rotate the armature 1/2 turn before repeating .Do not strike the collector rings or bearing .ARMATURE (ROTOR)THROUGH-STUDBALL BEARING & CLIPFRAME AND STATORROLL PIN1IGENERATORAIR DUCTSGROMMET FOROUTPUT LEADSBRIDGERECTIFIERASSEMBLYEND BELLFIGURE 50 .EXPLODED VIEW OF AC GENERATOR38

ARMATURE GROUND TESTUse a 120 volt series test lamp set for this test .Armature must be removed from generator for thistest .Place one test prod on one of the collector rings andthe other test prod on the armature shaft . Test lampshould not light . If the test lamp lights, the AC windingor a collector ring is grounded to the shaft . Test bothcollector rings in this manner .TESTING FIELD WINDINGS FORGROUNDSTo test the field assembly for grounds, disconnect allfield leads and use a 120 volt series test lamp set .Touch one prod to F1 (+) and the other prod to theframe . Lamp should not light . If lamp lights, field isgrounded and must be replaced . (Test F2 lead in thesame manner .)TESTING FIELD WINDINGS FOR AN OPENCIRCUITFor this test use either an ohmmeter or a 120 voltseries test lamp set .FIGURE 51 . ARMATURE GROUND TESTARMATURE OPEN TESTUse a 120 volt series test lamp set for this test . Placeone prod on each collector ring . The test lamp shouldlight . If lamp does not light, armature is open andmust be replaced .FIGURE 52. ARMATURE OPEN TESTFIGURE 53 . TESTING FIELD WINDINGS39

LOAD WIRES+ AFIGURE 54. END BELL ASSEMBLYUsing an Ohmmeter: Disconnect external leads andconnect ohmmeter leads to F1 (+) and F2 (-) .Resistance in the windings should read 38 ohms(±3%) at 70 F .Using a Test Lamp Set : Disconnect external leads andtouch test prods to F1 and F2 . The lamp should light . Ifnot, field winding is open and must be replaced .Check terminal ends closely for loose connections .These can be fixed easily without replacing the wholeassembly .TESTING BRIDGE RECTIFIERTo accurately test bridge rectifier proceed as follows :1 . Loosen No . 8-32 screw to remove bridge rectifierassembly (see Figure 54 for location) .2. Disconnect the nylon connector from bridgerectifier assembly, noting the polarity marking ofbridge rectifier assembly and connector .3 . Pull out from end bell and remove bridge rectifierfrom its case .Note that connector can only be mounted Inthe end bell one direction, but the bridgerectifier can be mounted in (4) four directions of which only one willwork .4 . Use an ohmmeter to test bridge rectifier . Set theohmmeter dial to R x 1 scale .5 . Now place meter leads on points shown in Figure55 and note readings from Table below .6 . If any tests do not agree with the above readings,install a new bridge rectifier .All terminals are marked on both bridgerectifier and nylon case . Observe properpolarity when reinstalling . If Installed wrong, generator voltage willnot build up .OHMMETERBLACK LEAD *OHMMETERRED LEAD *10% - Readings taken at 70 F .RESISTANCEA B * 8 ohmsA D * 8 ohmsB C * 8 ohmsD C ` 8 ohmsB A InfinityD A InfinityC B InfinityC D Infinity40

FIGURE 55 . TESTING BRIDGE RECTIFIERCOLLECTOR RINGSCollector rings acquire a glossy brown finish innormal operation . Do not attempt to maintain a bright,newly machined appearing surface . Ordinary cleaningwith a dry, lint-free cloth is usually sufficient . Veryfine sandpaper (#240 or finer) may be used to removeslight roughness . Use only light pressure on thesandpaper, while the plant is running . Do not useemery or carborundum paper or cloth . Clean out allcarbon dust from the generator .GENERATOR BEARINGThe generator is pre-lubricated and double-sealed .Replace bearing approximately every 5 years or ateach engine overhaul .COMPOUNDING REACTORIf output voltage is high with no electrical loadconnected to the generator, with generator running at1800 rpm, then the compounding reactor is probablydefective . Test as shown in Figure 56, using a variac .WITH ONE AMPERE INPUT THEVOLTAGE SHOULD READ 60-70FIGURE 56 . TESTING COMPOUNDING REACTOR4 1

GENERATOR TROUBLESHOOTING GUIDETROUBLE POSSIBLE CAUSE CORRECTIVE ACTIONNO AC OUTPUTVOLTAGE1 . Blown fuse orcircuit breaker .1 . Replace fuse or resetbreaker and look for cause .2 . Disconnected wire orlead on brushes,bridge rectifier orreactor assembly .2 . Reconnect wire or wires .3. Brushes not makingcontact with collectorrings .3 . Check brush springs forfree movement or brusheswhich may be excessivelyworn .4. Open, grounded orshort circuit infield or armaturewinding .4 . Test with series testlamp and repair or replaceas necessary .5 . Defective bridgerectifier assembly .5. Test with ohmmeter andreplace if defective .6 . Bridge rectifierassembly installedwrong in its case .6 . Reinstall making suremarks on case and rectifiermatch .LIGHTS FLICKERINTERMITTENTLY1 . Loose or broken lead/leads in generator .1 . Repair broken lead orreconnect loose lead .2 . Brushes stuck in holder . 2. Loosen brush and cleanor turn rings in lathe .LOW AC OUTPUTVOLTAGE1 . External short circuiton line .1 . Locate and eliminate shortcircuit problem .2. Generator overloaded . 2 . Remove part of load .t3. Shorted or groundedcircuit in field orarmature winding .3 . Test with series test lampor ohmmeter and replace ifdefective .4 . Engine not runningproperly causing generatorto slow down .4 . Refer to Engine Troubleshootingguide .

GENERATOR TROUBLESHOOTING GUIDE(Continued)TROUBLE POSSIBLE CAUSE CORRECTIVE ACTIONNOISY GENERATOR1 . Defective bearing inend ball .1 . Replace bearing .GENERATOROVERHEATS1 . Generator overloaded . 1 . Remove part of load .2. Windings and partscovered with oil ordirt .2 . Clean generator .3 . Air intake restrictedor incoming air too hot .3 . Take necessary steps toallow for proper cooling .4 . Shorted or groundedcircuit in armatureor field windings .4. Test with ohmmeter orseries test lamp andreplace if defective .5 . Air seals are damagedor missing .5 . Replace air seals ortape over the air leak .AC OUTPUT VOLTAGEHIGH WITH NO LOADCONNECTED ANDGENERATOR RUNNINGAT 1800 RPM1 . Compounding reactordefective .1 . Remove, test and replace .43

H1REACTORr )END BELLITHYRECTORIY1'CIRCUIT PROTECTOR- LlACLOAD LEADSGRD-L2GRD-L2LOADBRIDGE RECTIFIERACFIGURE 57 .AC GENERATOR SCHEMATICGENERATOR VALUES FOR 6KWMODELTYPICAL TYPICALN .L. VOLTS F .L. VOLTSN .L. VOLTSY1 to H1N .L. VOLTSF1 to F2RESISTANCEF1 to F2RESISTANCEH1 to Y1CURRENTFULL LOAD6KW 123 113 80 VAC 50V DC 38 Ohms 0.85 Ohms 50 AmpsN .L. - No LoadF .L . - Full LoadGENERATOR TORQUE VALUESDESCRIPTIONTORQUE VALUEGenerator Through Studs (4) 15-18 Ft .-Lb .Armature Holddown Nut - 12 Point 45-50 Ft .-Lb .Compounding Reactor Studs4- 6 Ft .-Lb.Brush Block Assembly Studs 4- 6 Ft .-Lb .44

ICONTROLSTHEORY OF OPERATIONStartingTo start, push start switch S3 . Battery current flowsthrough K1 solenoid, K2 contacts and start switch S3to battery negative (GND) . K1 solenoid closes contacts,feeding current to starter motorand to choke Elplus K3 relay . K3 relay contacts close the circuit to theignition coil T1 and fuel pump E2 plus fuel solenoidK4 . The engine cranks and the fuel pump, fuelsolenoid and ignition operate to start the engine .Engine StartsWhen the engine starts and rpm increases, theflywheel alternator develops a voltage which is rectifiedand energizes relay K2 . Relay K2 contacts closeto hold relay K3 energized, and K2 normally closedcontacts open to drop K1 start solenoid . K3 contactsmaintain current to ignition coil, fuel pump and fuelsolenoid . The engine runs and K2 remains energized .Stop EngineRelay K3, energized by K2, maintains ignition . To stopengine, push the stop switch which shorts out K3 .Relay K3 drops out to remove power from the fuelpump, fuel solenoid and ignition coil . Resistor R2absorbs the power that was supplied to K3 during theperiod the stop switch is held closed as the engineslows to a stop .This emergency operation DOES NOTprovide fuse protection, start disconnect orlow oil pressure shutdown and should not be used withoutmonitoring the electric power plant .FUSE PROTECTIONA 5 amp fuse, installed on control board, protects theboard from shorts in the remote wiring . If fuse isblown it can be replaced (after correcting trouble) byremoving cover on control and replacing with anidentical 5 ampere fuse .START(ON :STOPLow Oil Pressure ShutdownThe control has a time delay of 2 to 4 seconds for a lowoil pressure shutdown . If a low oil pressure conditionoccurs, the low oil pressure switch S2 closes tocharge capacitor C3 through resistor R3 . When thevoltage on capacitor C3 matches the voltage of thedivider R5-R6, the programmable unijunction transistorQ1 "fires" to trigger CR8 . CR8 turns on to deenergizeK3 relay . K2 contacts open as the enginestops and CR8 turns off .EMERGENCY START-STOP OPERATIONIn an emergency, the control board can be bypassedto start or stop the unit . Connect a jumper betweenterminals 9 and 11 to energize the ignition, fuelsolenoid and fuel pump . Then temporarily jumperterminals 1 and 7 to energize starter . Remove thisjumper as soon as the engine starts and runs . DONOT jumper while engine is running . To stop, removethe jumper from terminals 9 and 11 .5 AMP FUSE(REMOVE COVERTO REPLACE)l IIlIOnan l L JELECTRIC POWERFIGURE 58 .FUSE LOCATION45

SCHEMATICBTIIS2FIYCR7-iR - t- --VIKI•QCR5=C R6 3STOP -S3K2 STARTtIK3TIK4OE2L _ .C2IIF'RIB+CRIALTIACVRIBT1 BatteryB1 StarterE1 Electric ChokeE2 Fuel PumpE3, E4 Spark PlugsF1 5 amp . FuseG1 AlternatorK1 Start SolenoidS1 Breaker BoxS2 Low Oil Pressure SwitchS3 Start-Stop SwitchT1 Ignition CoilVR1 Voltage RegulatorRTM Running Time Meter (Opt .)BCM . Battery Condition Meter (Opt .)K4 Fuel SolenoidFIGURE 59 . CONTROL SYSTEM SCHEMATIC. 46

CONTROL SYSTEM TROUBLESHOOTING GUIDEThis troubleshooting section is divided into fourparts, A, B, C and D as follows :A . Engine does not crank .B . Engine cranks but does not start .C . Engine runs for 3 or 4 seconds, then stops .D . Low battery - low charge rate .Always stop the power plant and disconnect the battery leadsbefore removing the cover or printed circuit board . After removingcontrol cover, use a long nose pliers to remove flag connectorsfrom terminals on board . Pull flag connectors straight out to avoidbreaking control board terminals . Although dust covers on tworelays (K2 and K3) are removable, DO NOT attempt to adjust thecontacts on these relays ; they are precision set at the factory . Theonly maintenance required on these relays is blowing out sand anddirt with a low pressure, compressed air source .To correct a problem, answer the question of the stepeither YES or NO . Then refer to the number inwhichever column question was answered, andproceed to that step next .A . ENGINE DOES NOT CRANK YES NO1A .2A .3A .Check battery . Are battery terminals clean and arecables tight? 2A ---Check battery cables for correct polarity . Is12 volts present across battery terminals withengine stopped and is 8 volts or higher presentwith engine cranking? 3A 10ARemove cover on printed circuit board . Jumperterminal 7 to 3 . Press start switch . Does enginecrank? 4A 5A4A .K2 contact is defective . Replace printed circuitboard . --- ---5A . Jumper terminal 7 to 1 . Does engine crank? 6A 7A6A .7A .Start switch S3 is defective . Replace printedcircuit board . --- ---Jumper from S terminal of B1 starter motor topositive (+) . Does engine crank? 8A 9A8A . Replace K1 start solenoid . --- ---9A .Starter is defective . Remove and perform testslisted in STARTING SYSTEM section and/or replacestarter . --- ---10A . Replace battery . --- ---47

B . I ENGINE CRANKS BUT DOES NOT START I YES I NO1 B . Is F1 fuse on control board OK? 3B 2B2B .3B .Replace with an identical 5 amp fuse . Correctproblem which caused fuse to burn . --- ---While engine cranks, check K1-I start solenoidvoltage . Is 12 volts present between terminals10 and 1? 5B 4B4B . Replace K1 start solenoid . --- ---5B .6B .Jumper terminals 9 to 11 . Does engine start whenstart switch is pushed? 6B 7BK2 contacts are defective . Replace printed circuitboard . --- ---7B .Fuel solenoid K4 must be open during starting andrunning . Remove fuel line from carburetor . Does fuelpulsate from line when start switch is pushed?11B8BWARNING : Use extreme care for tests 7B and 8B . Directthe fuel flow into a suitable container and makesure area is well ventilated to prevent accumulationof gasoline fumes .8B .9B .10B .Disconnect fuel solenoid from line and check fuelpump E2 . Pump will click when operating properly .Does fuel pulsate from pump (solenoid disconnected)when start switch is pushed? 1013 , 9BFuel pump (or wiring) is defective and must bereplaced . + --- ---1Fuel solenoid is defective and must be replaced . --- ---11 B . Is electric choke closed when engine is cranking? 13B 12B12B .13B .Voltage at choke terminal when engine is crankingshould be 12 volts . If choke does not move (at roomtemperature) with 12 volts applied, replace it . Alsocheck wire from choke to control for shorts toground . --- ---.The fault is in the ignition system . Check points,plugs, wires and coil . Refer to IGNITION section --- ---48 ;

C . ENGINE RUNS 3 OR 4 SECONDS - THEN STOPS I YES NO1C . Check oil level . Refill to FULL mark on dipstick .Does engine now continue to run? --- 2C2C .3C .4C .Check voltage from terminal 11 to 12 . Is it 12 voltswith engine stopped and does voltage drop to zerowhen engine runs? --- 3CCheck oil pressure sensor wire for shorts toground by visually tracing wire from S2 low oilpressure switch to control . Is wire grounded? 4C 5CReplace or repair wire making sure it isn'trubbing against anything that may again cause agrounding problem . --- ---5C . Replace low oil pressure switch S2 . --- ---D . LOW BATTERY - LOW CHARGE RATE YES NO1 D . With engine cranking, measure voltage at terminal8 to BAT terminal of K1 start solenoid . Is 6 voltspresent? 2D 3D2D .3D .Check battery connections . They must be cleanand tight . --- ---Check flywheel alternator G1 output . DisconnectAC lead that connects to voltage regulator VR1and connect voltmeter to this lead and BATterminal of K1 start solenoid . This checks AC opencircuit voltage . Start engine . Is AC output voltageapproximately 28 volts with unit running at 1800 rpm? 5D 4D4D . Replace alternator stator G1 . --- ---5D . Connect a voltmeter across battery terminals .Start engine . Does DC voltage increase to 13to 14-1/2 volts after engine is running for afew minutes? --- 6D6D . Remove and replace voltage regulator VR1 . --- ---4 9

IREMOTE ACCESSORIES .ONAN REMOTE SWITCH (300-0985)This switch provides a remote start-stop option inaddition to the plant mounted start-stop switch . Asmall amber lamp, located on center of switch, flowswhen the electric power plant is running . To install,proceed as follows :1 . Determine location of remote control and cut ahole in motor home panel to accommodate switch(Figure 60) .2 . Wires provided for remote connections terminatewithin plant junction box . Connect four lengths of#18 multistrand wire to wires in junction boxlabeled 1, 2, 3 and 6 . Connect to correspondingterminals on remote switch .Use an approved connection method within junction box (e .g . wirenuts or connector block) .3 . Route remote wires through a separate knockoutplug on plant junction box .Do not route these remote wires through the same conduit as ACload wires. Use a separate conduit (greenfield) for these wires .FIGURE 60 . PANEL CUTOUT (300-0985)TOPONANSTART. .11111LAMP(GLOWS WHEN PLANTIS RUNNING)POWERSTOPELECTRICTO + 12 VOLT NOM .WHEN GENERATING L 1 _ - 2 _ 3 _ 4 52 TERMINALS ON GENERATORTO STOP C>-PRINTED CIRCUITBOARD TERMINALPRINTED CIRCUIT BOARDSWITCHTERMINALFUNCTIONSCHEMATIC5I I Ground2 2 Stop3 3 Start6 6 LampFIGURE 61 . REMOTE CONTROL SWITCH (300-0985)5 0

4 . Make connections to remote switch (Figure 61),then secure remote switch to motor home panelwith #5 wood screws .ISeal opening made between plant compartmentand motor home interior to preventWA RNINGdeadly exhaust gases from entering motor home .ONAN DELUXE REMOTE CONTROL (300-0986)This switch provides a remote start-stop option inaddition to the plant mounted start-stop switch . Asmall amber lamp, located on center of switch, glowswhen the electric power plant is running . A runningtime meter (time totalizer) shows the total number ofplant operating hours . It is useful for performingaccurate maintenance procedures on the plant . Abattery condition meter monitors battery chargecondition . Connection for control is as follows :1 . Determine location of remote control and cut ahole in motor home panel to accommodatecontrol (Figure 62) .2 . Wires provided for remote connections terminatewithin plant junction box . Connect five lengths ofNo . 18 wire to wires in junction box . These wiresare labeled 1, 2, 3, 5 and 6 ; they must connect tocorresponding terminals on remote control panelUse an approved connection method (e.g . wire nuts or connectorblock).FIGURE 62 . PANEL CUTOUT (300-0986)3 . Route remote wires through a separate knockoutplug on junction box .Do not route these remote wires through the same conduit as theAC load wires . Use a separate conduit (greenfield) for these wires .4 . Make connections to remote control panel(Figure 63), then secure remote control panelwith #5 wood screws .WAR NING Seal any opening make between plant compartmentand motor home interior to preventIdeadly exhaust gases from entering the motor home .LAMP(GLOWS WHEN PLANTIS RUNNING)TOPSolder lessConnectors orTerminalBlockTO STOP1 12 VOLT NOM .WHEN GENERATINGL-'--- 2 --3 - 4 -PRINTED CIRCUIT BOARD5 JTO GNDPRINTED CIRCUITBOARD TERMINALSWITCHTERMINALFUNCTIONTO START1 1 ;round2 2 Stop3 3 Start5BatteryCondition MeterSCHEMATIC6 6Lamp &Running Time MeterFIGURE 63 . DELUXE REMOTE CONTROL (300-0986)5 1

INSTRUMENT CONNECTIONS'The following instructions will help when installingindividual switches and indicators .Remote Start-Stop Switch : A remote start-stop switchcan connect to terminals 1 and 3 for start andterminals 1 and 2 for stop . Use a single throw, doublethrow switch (momentary) rated at 5 amperes, suchas Onan switch 308-0341 . This switch can be remotelyconnected with up to 100 feet of number 18 wire .Remote Voltmeter : A 0-15 volt DC voltmeter canconnect to terminals 1 (-) and 5 (+) to measure batteryvoltage .Running Time Meter : A running time meter, such asOnan 302-0885, can connect to terminals 1 (-) and 6(+) to indicate the total running time of the electricpower plant . These terminals are rated at 12 volts anda maximum load of 1 ampere .Charge Ammeter : A DC ammeter (0-15 amperes) canconnect to unit to read battery charging current .Disconnect alternator lead from K1 start solenoid andconnect to positive side of ammeter . Connectnegative lead to K1 start solenoid (battery terminal) .The charge current should be 9 amperes maximum at1800 rpm (room temperature) . The charge currenttapers to less than 2 amperes as battery voltageincreases to 14-15 volts .5 2

"6111C1094M .MIT NOCITYMATS 1*51WIRING DIAGRAMBT1C2I BATTER 2 VOLTE44E 3,G2S1S2K4TlVRIRIW2K4 _TI E2 C2 LSI 1eCRIVIINOTE :1 . MIN START DISCONNECT 675 RPM .E2I GENERATORII 0-STARTA CAP ASSI SWITCH-LOW OIL PRESS1CO L-16NIT10OLTA6REGULATORSOLENOID- FUELWIRING HARNESS-GE SETWIRING HARNESS-REMOTEti601J119 .