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Onan MDJA, Service Manual

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Summary of Contents for MDJA

Page 1: ...Service Manual MDJA MDJB MDJC MDJE MDJF MarineDiesel GenSetEngines 974 0750 12 85 PrintedinUSA...

Page 2: ...ly secured and free from leaks Piping at the engine should be ap proved flexible line Do not use copper pipingfor flexible lines as copper will work harden and become brittle enoughto break Be sure al...

Page 3: ...Governor System 60 EngineTroubleshooting 7 Exhaust System 14 OilSystem 62 Starting System 68 Engine Disassembly 75 INCORRECT SERVICE OR REPLACEMENTOFPARTS MIGHT RESULT IN SEVERE PERSONAL INJURY AND OR...

Page 4: ...d torque values are within the specifiedtolerances Thewiringdiagramshowshowtheelectricalcompo nents are interconnected A partscatalog availableatthedealerlevel contains detailed exploded views of each...

Page 5: ...essionRatio 19to 1 19to 1 19to1 19to1 19to1 Firing Order 1 2 4 3 1 2 4 3 CrankshaftRotation Governor VariableSpeed Mechanical Variable Speed Mechanical Valve Clearance Cold Spec A C BeginSpec D Intake...

Page 6: ...MaximumAllowableOut of Round 0 001 0 025 Main BearingJournal Diameter 1 2cylinder 2 2437 2 2445 56 99 57 01 Main BearingJournal Diameter 4cylinder 2 2427 2 2435 56 965 56 985 Center Main BearingClear...

Page 7: ...UST VALVE GUIDE VALVE SEATS Intake 1S47 1 548 39 29 39 32 Exhaust 1 361 1 362 34 570 34 595 Depth from Cylinder Head Face 43 439 10 99 11 15 Exhaust 1 364 1 365 34 6456 34 6710 Intake 1 550 1 551 39 3...

Page 8: ...Cam Bearing Driver 420 0326 DieselCompressionTester 420 0283 Valve Spring Compressor Tool 420 0119 Valve Seat Remover 420 0311 RECESS UNDER HEAD A749 TORQUE SPECIFICATIONS Ft Lb Nom Center main bolt 4...

Page 9: ...EngineTroubleshooting 7 Redistribution or publication of this document by any means is strictly prohibited...

Page 10: ...ure couldblow out hot olland causeseflous burns Do NOT check oil while the engine is operating RecommendedFuel Use ASTM 2 D or 1 D fuel with a minimum Cetane number of 45 Number 2 diesel fuel gives th...

Page 11: ...arts to obtain firing or to smooth out all cylinders especially at no load or light loads Do not exceed the one minute preheatperiodstoprevent heat er burn out and conserve the battery Longer preheati...

Page 12: ...d for automatic start and stop but must provideengine preheating The automaticcontrolshouldhaveatimedelayrelay to preheatglow plugsand the manifold heater for at least 20 seconds before cranking occur...

Page 13: ...dding distilled water Check specific gravity recharge if below 1 260 DUST AND DIRT 1 Keep inlet screen free of dirt etc 2 Serviceair cleaneras frequently as necessary 3 Change crankcaseoil every 50 op...

Page 14: ...rn oil drain extension made from standardpipeandfittings inthe 1 2 inch 12 70 mm pipe tappedoil drain hole in the base Crankcasepressure couldblow out hot oiland causeserious burns Do NOT check oil wh...

Page 15: ...mois ture bugs dirt etc Cleanandwipeentireunit Coat partssusceptible to rust with a light coat of greaseor oil Disconnect battery and follow standard battery storage procedure glow plugs 3 Clean and c...

Page 16: ...o warm a room compartment orstorage area WARNING Vent exhaust gasesoutside Useflexible tubing only betweenthe engineexhaust outlet and rigid piping Inhalation of exhausf gases might result in serious...

Page 17: ...p and the water is injectedonthe outletsideat a point four inches 102 mm above the bottom of the loop A condensationtrapisusuallyinstalledatthebottom of the dry exhaust lineseciton Drainthetrap at reg...

Page 18: ...N PLUG DRAINING COOLING SYSTEM Openalldrainsand hoseconnectionswhere coolant may be trapped when changingthe antifreezesolu tion or when preparing a unit for storage in freezing conditions Open the fi...

Page 19: ...system with the propercoolant When flushing is completed check the system thoroughly for anyleaksuncoveredbytheclean ing operations flush heatexchanger Flush the engine water jacket as previously dis...

Page 20: ...ecause marine generator sets operate typically in very smallcompartments itisimportantthatthe heat radiated from the exhaust system be kept to a min imum To accomplish this the heated sea water is usu...

Page 21: ...tubes and absorbed by the flotation water Keel coolers function similar to radiators except that the heat is dissipated to the flotation water insteadof to the air An engine driven pump is used to cir...

Page 22: ...ALIFT MUFFLERSYSTEMS FIGURE 12 TYPICAL MARINEWATER FILTER DOnot usea scoop type waferinlet lzz3fiffing When the boat is underway and fhe generafor sef is not running sufficienf ram pressure can force...

Page 23: ...st systems are designed so that a minimum amount of heat will be radiated from the exhaustsystemcomponents This isdoneto keepthe heat build up in the engine compartmentto a mini mum Exhaust heat is di...

Page 24: ...Figure15 is usedwith the MDJAandMDJBandwas usedwithearliermodelsof the MDJE andMDJF Itis mountedatthefront ofthe engine perpendicularto the engine center line The end caps are removablefor cleaning an...

Page 25: ...on Use a chemical cleanerto remove rust and scale deposits following the procedure recommendedby the sup plier KEEL COOLERS Keelcooling seeFigure17 isavailableasan option on the MDJA MDJB MDJC MDJE an...

Page 26: ...ate the engine oil Remove the pump end cover see Figure 18 and inspect the impeller for cracking or signs of wear The impeller deteriorates with time becauseof continuous flexing and must be period ic...

Page 27: ...B MDJC BeginSpec D MDJF before1976 wlo heat exchanger wlheat exchanger Spec D R with heat exchanger MDJESpec A AA MDJFwlo heat exchanger 132 0059 132 0147 MDJF Begin 1976with heat exchanger MDJA Spec...

Page 28: ...If furtherdisassemblyis required disconnectthe hosesand removethetwo capscrews holdingthe pump to the engine Step c Lift pump from engine Loosentheset screw onthesideofthe pumpand tap it lightlyto fr...

Page 29: ...T ASSEMBLY BELLOWS SEAT PUMP BODY SCREW d RETAINING RING WEAR CAM PLATE e 6 2 6 0 1 0 8260 8 IMPELLER f 8260 6 I FIGURE 2 1 PUMPM31 0152 27 Redistribution or publication of this document by any means...

Page 30: ...theseal can be loosenedand removed with ascrewdriver or needle nosepliers 8 Removethe internal retainingringfrom the drive pulley end of the pump housing 9 Carefully drive out the shaft and bearingas...

Page 31: ...ing assembly off the drive end of the shaft 7 Insertthe drive end of the shaft into the impeller endofthepump Guidetheshaftthroughthesea1 untiltheshaft shouldersagainstthe bearing Tap lightly on the s...

Page 32: ...Insertthe impeller end of the shaft intothe drive end of the pump housing and pressthe shaftand bearing assembly intothe bearing bore 3 Press the adapter ring into the drive end o f the pump body 4 In...

Page 33: ...or impeller Use a new end cover gasket when reas sembling 1 Install the impeller sidesealwith theseal lip fac ing away from the impeller bore Lubricate the seal lip with grease 2 Install the flangesid...

Page 34: ...headjoints Since expansionor contractioncanaggravateleakage the block should be inspected both hot and cold while the engine is running Internalleakageoccurswhencoolant passesintothe engin e oil throu...

Page 35: ...1 9 0 88OC 215 f5 102OC 180 83 C 205 25 97 C 160 f5 7 1 C 200 1 7 93 C 2 0 0 25 93 C 160 57 71 C 2 5 0 f 5 121 C 2 3 0 1 7 110 C 290 18 143 C 250 f12 121 C 2 0 0 f5 9 3 C 160 f7 71 C HIGHTEMPERATURE C...

Page 36: ...ty thermostat is sus pected test as follows WIDEOPEN TEMP F MIN STROKE 150 360 in 66OC19 14mml 1 2 3 4 5 6 7 309 0130 I 140 to 145 Removethermostat from the cylinder head Heat a pan of water to the op...

Page 37: ...rer s installationinstructionsif the muffler does not func tion properly All mufflersmustbewellsupported andinthecaseof a neoprene muffler completely separatedfrom the hull of the boat If a neoprene m...

Page 38: ...en the engineis running Fuel leakscreate fireand explosion hazardswhichmightresultinsevere personalinjuryordeath Alwaysusealengthof flexi ble tubingbetweenengineand thefuelsupplylinei o avoidline fail...

Page 39: ...nnectinga pressuregauge and tee at the fuel outlet A vacuum gauge connectedat the fuel inlet will show whether the pumphasenoughcapacityto liftfuel about6feet 1 86 m The fuel pump should produce 15 to...

Page 40: ...COVER PRESSURE A GASKET SPINDLEASSEMBLY NOZZLECAP NUT 7 SHIELDGASKETf F FUEL CUP GASKET CYLINDER HEAD A 7 Ul A0aQ j FIGURE 31 INJECTOR NOZZLEASSEMBLY INSTALLATION Operating Principle Nozzleoperation...

Page 41: ...ingscrew Clockwiseadjustmentincreasesthe 1 Removeeach nozzle assembly from engine and removefuel inlet and returnlines 2 Clamp nozzle holder body in a vise and remove nozzlecap nut and nozzle 3 Instal...

Page 42: ...aper to clean the nozzle pressure chamber gallery The hooked endofscraperisinsertedintothegalleryandthen carefully rotated 4 5 Clean nozzle valve and polish with tallow and a wooden polishingfixture T...

Page 43: ...ger pulls into the solenoid body When de energized the solenoid spring forces the plunger out against the operating leverto hold it in the fuel shutoff position The solenoid has two coils Both are ene...

Page 44: ...ations MDJA INJECTIONPUMP INJECTIONLINE CAP NUT VALVE HOLDER SPRING BLEED VALVEASSEMBLY PUMPHOUSlN GASKET GASKET LOCATINGSCREW PLUNGER BARREL CONTROL SLEEVE CLOSINGPLUG UPPERSPRINGSEAT PLUNGERSPRING P...

Page 45: ...the port closing mark PC of the com pressionstroke 2 Usingadepth micrometer measurethedistance from the pumpmounting padonthecrankcaseto the tappet center See Figure39 3 Subtract from the port closing...

Page 46: ...the two cylinder models Thefunctionofthepumpasadistributorand its location on the serviceside of the engine arethe same on both2 and 4 cylinder engines Repair Internal repairson the injection pumps re...

Page 47: ...l is injected only during the high velocity portion of each plunger up stroke When the tappet slips off each lobe of the camshaft the spring loaded plunger is forced down opening the fuel supply portt...

Page 48: ...NG BUTTON CODE The timing button has a code number or letter stamped on it that correspondsto its dimension in thousandthsof an inch SeeTable8 Figure47shows thetiming button Onebuttonwill providetheco...

Page 49: ...omTable8 Thiscodeshould bethesameas the code numberstampedon injection pump Figure48 OnallPSUpumpsbesureto E 3hold the pump drive gear securely againstthepump body whenremov ing the tappet If not the...

Page 50: ...LINE HERE FLEXIBLELINE PUMP W FIGURE 51 FUEL LINETO INJECTORS 5 Rotateflywheel clockwise whenfacing front of engine Figure 5 2 1 to point where PC mark on flywheel is about 15 degrees 1 25 to 1 50 inc...

Page 51: ...009 3 x 076 229mm Since 0 1 inch 2 54 mm equals 003inch 076 mm in buttonthickness the installed buttonistoo thin by 009 inch 0 229 mm This means a button 009inch 0 229 mm thickerthantheoneinstalledisr...

Page 52: ...at one intakelobepoints outward and down45 degrees 2 Remove screw Figure 55 on side of injection pump Rotatedrive gear until a0 125 inch 3 175 mm brassrodcan beinsertedintodrivegearslot This locks the...

Page 53: ...opening pres sure for new nozzles should be 2100 to 2200 psi 14480 15169 kPa HighPressure InjectionLines Both high pressurefuel lines between the injection pumpandthetwo nozzlesaredesignedtobeinstall...

Page 54: ...terassembly Positionfuel control shaft and yoke as shown in Figure61 Then liftpumpoff of adapterassembly Carefully clean injection pump assembly and place it in a clean place Retain shims between pump...

Page 55: ...Itmaybenecessary to tap assembly with lead or plastic hammer in order to loosenadapter from gasket 3 Discard old gasket and clean area on engine block A newgasketis requiredfor reassemblyof adapter t...

Page 56: ...llationdepth Distancefrom adapter flange to cam of pump is 3 2598 inches 82 8 mrn lobe base circle as measured subtractfrom above inches Requiredshim mrn thickness Manyearlierspec AB MDJEengineshavean...

Page 57: ...0 25 0 76 mm FIGURE 65 FUELSOLENOIDADJUSTYEW Flow Timing TroubleshootingOnly Flow timing is performed at either injection line to establish or confirm the port closing PC point of each fuel injection...

Page 58: ...er and torque Bryce holder to 29 to 33 ft lb 39 to 44 Nm Torque Kiki holderto 44 to 47 ft lb 60 64 Nm If fuel leakageoccurs replacethedeliveryvalvegasket 10 Reinstall high pressure line between pump a...

Page 59: ...the Onanfactory for repairs or replacementif still under warranty Otherwise refer all Ser vice problemsto authorizedB yceRucas andDiesel Kikiser vicecenters THROTTLING PINTLE NOZZLETESTS The followin...

Page 60: ...l spray against skin surfaces A KlKl CAPNUT L u ADJUSTINGSCREW LOCKNUT SPRING MERICAN BOSCH FIGURE 68 NOZZLEADJUSTMENT KlKl NOZZLEADJUSTMENT If the opening pressure is incorrect connect nozzle to ates...

Page 61: ...gand full liftcausesthe fuelto emerge inastream changetoflag likeformations andfinally reach atomized spray pattern at full lift with lever movements producing 4 to 6 nozzle opening cycles per second...

Page 62: ...ing Spec R the sensitivity is adjustedwith an adjusting ratchet Speed Adjustment Prior to Spec R To adjust the governed speed hold the governor spring stud in position and turn the governor spring nut...

Page 63: ...g ratchet nut Ifspeed drops too much when full load is applied turn the justment approaching no speed drop when load is applied may result in a hunting condition alternate increase and decrease in spe...

Page 64: ...oil filter tothe rocker housing through the crankcase drillings to the crankshaft bearings camshaftfront bearing crankshaft passagesto con nectingrodbearingsandconnectingrodpassagesto piston pin bushi...

Page 65: ...52 mrn 2 5 16 inches 1 16 inch 74 613 1 588 mm 2 225 Ib at 1 3 16 inches compressed 1 01 kg at 30 163 rnm compressed Free Length FIGURE 76 BYPASSVALVE CYL HEAD CYL HEAD 3 AND 4 l A N D 2 4 CYLINDER ON...

Page 66: ...trequiresreplacement every200hoursof normaloperation Removefilter by turning counterclockwise using a filter wrench Install new filter finger tight plus 1 4to 1 2 turn FILTER FIGURE 78 FULLFLOW OIL FI...

Page 67: ...the blowby fumes to prevent them from getting intothe intake manifold and combustionchamber OVERFLOWHOSE O I L DRAIN FIGURE 8 2 PULSATION DAMPER OIL PRESSUREGAUGE Some engines have an oil pressure gau...

Page 68: ...buildupsufficient oil pressuresothat itcan be started For correct operation maintain the switch gap at 0 020 inch 0 51 mm See Figure85 Checkthe contactsfor dirt or pitting when adjusting the gap Clea...

Page 69: ...is sticking or worn replace the cam and weight assembly If the cam is loose on the gear shaft replacethe assembly If the breakergap cannot be maintainedat 020 inch 0 51 mm check the fiber plunger and...

Page 70: ...d 1 225 when75percentcharged Ifnot rechargethebattery Check electrolyte level If battery will not recharge replaceit Keepbatteryconnectionstight andclean With the starting motor operating check thevol...

Page 71: ...in a lathe FieldCoils Usingatest lampandprobes checkthefield coilsfor groundingtothemotorframeoropencircuit Inspect all connectionsto besurethey are properlyclinched andsoldered Inspectthe insulation...

Page 72: ...f Do not attemptto disassemblecluth assembly 8 If necessary to service solenoid remove four capscrewsandelectrical connectionholdingitto motorframe Removetwo screwson rearof sole noidto reachswitch co...

Page 73: ...s to starter 6 Connect battery cables to battery Connect ground last connectground cablefirst from starter starter to mounting bracket MlTSUBlSHlSTARTER DISASSEMBLY 1 Remove M terminal nut and wire le...

Page 74: ...N SHAFT MlTSUBlSHlSTARTER ASSEMBLY CLUTCH PIN GE Forassemblyreversethedisassembly procedure but note the following items SeeFigure 94 Wheneverstartermotor isdisassembled applygrease to each of the fol...

Page 75: ...STALLATION Lever Assembly Installation Figure97 showsthe correct methodof installing the lever assembly spring and packing Note direction of lever LEVER LEVER SPRING ES 1185 FIGURE 97 LEVER INSTALLATI...

Page 76: ...blyas follows 1 Connect an ohmmeter or test lamp 12 volts to the field terminal and to the bracket The test lampshouldnotlightorresistancereadingshould be high infinite If not there is a short and the...

Page 77: ...assure proper tightness without danger of stripping threads 3 As each internal engine part is assembled use a wrench to rotate crankshaft making certain it turnsfreely If tightnessis noted afteranyope...

Page 78: ...h timing pointer on gear cover Then turn flywheel in a clockwise direction for an additional 10 to 45 degrees The timing mark for this position must be established Inthis position the pistonwill be in...

Page 79: ...adingsbecauseof differences in crank ing speed altitude and ambient temperaturecondi tions Therefore the specification is given only as a guide The best indication of leakageisthe pressure difference...

Page 80: ...learance from the valveheadtothefaceof thecylinder head This must beat least0 025 inch 0 64 mm If itisnot regrindthe seat ValveSprings Check the valve springs on an accu ratecompressionscale Valve spr...

Page 81: ...eplace the cap and keepers as a set When replacingthekeepers checkforwearonthevalve spring retainer where it contacts the keepers If wear isover 0 003 inch 0 076 mm replacethe retainer After replaceme...

Page 82: ...4 to 1 2 turn to lock the mechanism 2 Release the mechanism to allow compression Check the clearance between the screw and rocker arm Insert a feeler gauge betweenvalve androckerarmtotakeupvalvecleara...

Page 83: ...yed When properly heated ring will fall into place on flywheel Ifitdoesnotgoonalltheway byitself drive it into place with a hammer Do it fast and do not damagethegearteeth Ringwill contract rapidlyand...

Page 84: ...asillsutrated Holdthe cup against the flyballs when measuring The cam shaftcenter pincannotbepulledoutwardor removed without damage Ifthecenterpinextendsouttoofar the cup will not hold the flyballs p...

Page 85: ...nder for possiblereconditioning PISTON PINS Each piston pin should be a thumb push fit into its piston at roomtemperatures Ifthe pin is excessively loose install a new one If the condition is not cor...

Page 86: ...SHAFT The camshaftisaone piecemachinecasting driven through gears by the crankshaft It rides on sleeve bearings pressed into the crankcase Inaddition to providinga meansofopeningandclos ing the valves...

Page 87: ...nce 2 Install governor components 3 Slidethrustwasherontoshaft Measurecamshaft end play itshouldbe0 007 to0 039 inch 0 178to 0 991 mm See Figure 113 4 Layengine on itsside or endand insert push rod ta...

Page 88: ...16 to shot peen each crankpin fillet THIS A R E A T O B E M A S K E D D U R I N G S H O T P E E N I N 6 O P E R A T I O N I FIGURE 116 SHOT PEENING THE CRANKSHAFT 1 Almen gauge reading0 012 A 0 305 2...

Page 89: ...t of injection pumpshimswill befurnishedwith the new crankcase These must be used and in addition the injection pump mustbe re timedtotheengine If on the four cylinder models the center main bearing s...

Page 90: ...Redistribution or publication of this document by any means is strictly prohibited...

Page 91: ...Redistribution or publication of this document by any means is strictly prohibited...

Page 92: ...N E Minneapolis MN55432 612 574 5000InternationalUse Telex 275477 Fax 612 574 8087 Onan isa registered trademarkof Onan Corporation 1 800 888 ON AN Redistribution or publication of this document by an...

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