Onan BGD,NHD Service Manual BeginSpec H Pg 51-98

8/3/2019 Onan BGD,NHD Service Manual BeginSpec H Pg 51-98

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SERVICING BRUSHES AND SLIP RINGSR em ove the air cleaner and the brush block coverand inspect for burned brushes and grooved orpitted s lip rin gs an d an y othe r d am age. (T um the ro-tor w ith a 3/8 inc h alle n w renc h to be able to in spe ctall the w ay around the slip rings.)If everyth ing looks good, check brush w ear w ith apiece of w ire m arked off as s hown in F ig ure 46. Re-p lac e th e b rush es an d b rush sp ring s if the w ire canb e in se rte d more th an 1 inch (25 mm ) into the h ole inthe brush ho ld er. (M ak e s ure the w ire re sts on top ofthe brush and not on part o f the brush spring.)If th e slip rin gs a re groo ved or pitted it m igh t be pos-sible to clean them up w ith a com mutator stone. Ifthe slip rings are w orn and need to be replaced, seeR em oving and R eplacing the Slip R ing A ssem blyu nd er GENERATOR ASSEMBLY /D ISASSEMBLYin th is s ec tio n.T o rep lace the brushes or to clean up th e s lip rin gs :1. D is con nec t the lead s m arked F1 and F2 fromth e b ru sh b lo ck te rm in als .2. R em ove the brush b lock m ounting screw s andlift o ut th e b ru sh bloc k as sem bly .3. If the s lip rings need to be c le an ed up, in su la tethe ends of leads F1 and F2, disconnect allle ad s from th e p os itiv e (+) te rm in al o f th e ig ni-tion co il to keep the engine from starting , holdthe commutator stone lightty against the sliprings and crank the engine for 3 to 6 seconds.C heck th e slip ring s and re pea t the pro ced ureas necessary until the pits and groves havebeen removed.4. R eplace the brushes and brush springs w ithnew parts. Connect each brush pigtail to thete rm in al o n its s id e o f th e in su la tin g d iv id e (F ig -

u re 4 7).

5 . R em ount the brush b lock. C enter the brusheo n th e s lip rin gs b efo re tig hte nin g th e mou ntin gscrews.6. Rec on ne ct th e le ad mark ed F1 to th e o utb oa rdb ru sh te rm in al a nd th e le ad mark ed F2 to th e in

bo ard brush term inal an d s ecu re the co ver a na ir c leaner .

FIGURE 46. CHECKING BRUSH W EARBRUSHPIGTAILS

BRUSHSPRING

BRUSH

FIGURE 47. BR US H B LO CK A SS EM BLY

5


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REMOVINGJREMOUNTING GENERATORRemoving the Generator from the Genset1. Drain the engine oil while the genset is

mounted in the vehicle. (Oil will spill out whenthe genset is tipped up on end to remove thegenerator unless the oil has been drained.)2. Remove the genset from the vehicle and placeit on a sturdy work bench. See P re pa rin g for

Service.3. Remove the blower housing so that the gensetcan be rested flat on the blower wheel. See EN-GINE COOLING SYSTEM in Eng in e Sub sy s-tems for instructions.4. Disconnect the fuel line at the carburetor.5. Disconnect the leads at the low oil pressure cutoff switch and B+ terminal of the ignition coil.6. Use a 318 inch allen wrench and rubber malletto remove the rotor through-bolt.7. Thread a 9/16-12 eyebolt into the end ofthe r0-tor and tip the genset up with a hoist until it restssquarely on the blower wheel. See Figure 48.

14 CAUT10N I Do not lift the genset with theeyebolt The weight of the genset couldcause the tapered cranlcshaft~tor fit tobreak loose, leading to generator damage.

8. Disconnect the ground strap from the drip tray,remove the four vibration isolator center-bolts(for reassembly. note the locations of the largeflat washers) and pull the tray away.9. Remove the four bolts, nuts and lock washersthat secure the generator housing to the gen-set.

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10. Remove the eyebolt and insert the rotor remov-al rod (headless bolt, Figure 49) and thread it inwith a screwdriver until it bottoms. Thread inand tighten a 9/16-12x1-314 bolt against the roduntil the rotor breaks loose from the crankshaft.

EYEBOLT(9116-12)

FIGURE 48. GENERATOR UFT

AGURE 49. ROTOR REMOVAL TOOL


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Remounting the Generator on the GensetEssentially, remounting is the reverse of removal.Note the following:1. First reassemble the generator housing, stator

and rotor as instructed, if they have been takenapart.2. It is recommended that the rotor removal toolbe threaded into the crankshaft to guide the ro-tor into the crankshaft as the assembly is low-ered, using an eyebolt (Figure 48) and hoist.3. The lock washers go under the bolt heads of thegenerator mounting bolts.4. Locate the large flat washers at the locationsnoted when disassembling the vibration isola-tors (Step 8 under Removal).5. Torque the generator housing, rotor through-bolt and vibration isolator center-bolts to As-s emb ly Torq ue s.6. Make sure to secure the ground strap to the driptray using one EIT (external and internaltoothed) lock washer on each side of the strapterminal for a good electrical connection.7. Reconnect or reassemble all other parts thatwere disconnected or removed. Do not forgetto refill the crankcase with the appropriategrade of engine oil after the genset hasbeen re-installed in the vehicle. Seethe Op-

erator's Manual for engine oil recommenda-tions.GENERATOR ASSEMBLYJDISASSEMBLYRemoving the Rotor from the Generator1. Remove the generator from the genset, asinstructed under Removing the Generator from

the genset.2. To keep from damaging the brushes and tokeep them from interfering when inserting the

rotor, either:A Remove the brush block assembly by dis-

connecting the leads marked F1 and F2from the brush block terminals and then re-moving the two mounting screws.

B. Insert a stiff wire into the small hole in theend of the stator housing to hold the

brushes up and out of the way (Rgure 50).To do this, first pull both brush pigtails to lifthe brushes off the slip rings.

3. Turn the generator over onto its bearing endand withdraw the rotor straight up. It may benecessary to have an assistant hold down thegenerator housing.IiCAUllON Ie careful not to nick thestatorwindings with the rotor while withdrawingthe rotor.

INSERT A RETAINING WIRETO KEEP THE BRUSHES OUTOF THE WAY WHENASSEMBLING ANDDISASSEMBLING THEGENERATOR

RETAININGWIRE --- _

FIGURE 50. BRUSH BLOCK ASSEMBLY

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Re-installing the Rotor in the GeneratorIt is recommended that the rotor be re-installed inthe genera to r first a nd th en th atth e e ntire g en era to rbe m ounted on the genset as instructed under R e-m ountin g the G en erator on the gense t.Re -in sta lla tio n o f th e ro to r is th e re ve rs e o f removal.No te the follow ing :1 . R eplace the slip ring assem bly. rotor bearingand s ta to r, if necessary.2. M ake sure the brush block assem bly has beenremoved or that the wire is holding bothbrushes up and out of the way.3 . M ake sure the rubber O-ring is in place in theb earing bore and then carefully low er the rotor

into th e ge nerator. T he ro to r bea ring sh ould fi tsn ugly in to th e bea ring bore.4. Install the brush block assem bly if H was re-m oved . If it w as left in place. pu ll the brush pigta ils and rem ove the retaining w ire . If neces-sary, loosen the b ru sh block m oun ting screw s.a lign the brush b lock so that the brushes arecentered on the slip rings and retighten themoun tin g s crews.5. Connect the lead m arked F1 to the outboardbrush term ina l and the lea d m arked F 2 t o the in-board brush term inal and snap the cover on.

Removing the Stator from the GeneratorS ee F igure 51 . T o rem ove the stator fro m the ge ner-a to r hous ing :

1 . U pend the generator as show n.

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2. R em ove the rotor as instructed under R em ov-ing the R otor from the G ene ra to r.3 . D isconnect all the stator leads and pull themfrom the c ontro l bo x.4. R em ove the three stator clam ps.5 . L ift th e s ta to r s tra ig ht u p a nd o ut o f t he h ou sin g.

14CAUTION I careless handling of the statorcan damage the insulation on the statorwindings.

FIG UR E 51 . REM OVING THE STATORRe-installing the Stator in the GeneratorR e-installing the stator is the reverse of rem oval.M ake sure the stator leads line up w ith the exit ho lein the housing while lowering the sta tor into thehousing. Connect the leads according to the ap-p ro pria te c on ne ctio n d ia gram in F ig ure 5 9. 6 0 o r 6 1.


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Removing and Replacing the RotorBearingU se a gear puller to rem ove the bearing from the ro-to r s ha ft if it or the slip ring assembly is to be re-p la ce d, o th erw is e le ave it in p la ce . See Figure 52. Ifthe b ea rin g is to be reused, m ake sure the fingers ofthe gear puller bear on the inner race of the bearingonly.licAU110N I The bearing will be damaged andbecome unusable if force is applied to the outerrace either when pulling itoff or pressing it on.Rep la ce th e b ea rin g as fo llo ws :1. R eplace the slip ring assem bly first. if neces-sary.2. P ress the bearing on w ith a press, m aking sure

to bear down on the inner race only.

FIGURE 52. BEARING REMOVALRemoving and Replacing the Slip RingAssemblyUnsolder the two rotor leads from the Slip ring as-s emb ly a nd pull th e s lip rin g a ssembly o ff w ith a ge arp ulle r. T ap e th e k ey to th e s haft to k ee p from lo osingit if a new assem bly is not going to be ins ta lled r igh taway.Press on a new slip ring assembly with a press.m aking sure the key is in place and the assem bly isaligned with the k ey . S old er th e tw o rotor le ad s to th es old er te rm ina ls o n th e slip rin g a ssemb ly .

TESTING THE GENERATORTesting the RotorIt is p os sib le to te st th e ro to r w ith ou t remov in g it f romthe generator by rem oving the brush block assem -bly.Testing for a Grounded Winding: A dig ita l ohm-mete r is rec ommend ed fo r this te st. S ele ct th e h ig h-es t res is ta nce s cale o n th e mete r a nd to uch on e te stprobe to the rotor shaft and the other to either slipring as show n in F igure 53. Replace the rotor as-semb ly if th e mete r d oes n ot in dic ate a n o pen c ircu itto ground (the sam e high resistance as w hen them eter probes are separated by an air gap).

DFIGURE 53. ROTOR INSULATION RESISTANCED

FIGURE 54. ROTOR WINDING RESISTANCE

55


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Testing Winding Resistance: A digital ohmmeteris recommended for measuring rotor winding resis-tance. Select the best scale for measuring a 20 to 25ohm value. Touch the test probes to the slip rings asshown in Figure 54.If the meter indicates a high resistance, first checkthe connection between the slip rings and the rotorleads and resolder if necessary. Replace the rotorassembly if the connections are good but the wind-ing does not meet the resistance specification inTable 5 or 6, as appropriate.Testing the StatorThese tests can be done by disconnecting all the Txwinding leads from terminal block TB1 and the Bxand ax winding leads from their connectors. Single-phase generators have winding lead pairs T1-T2,1"3-T4 and Q1-Q2. Three-phase generators havelead pairs T1-T4, T2-TS, T3-6, T7-T10, T8-T11 andT9-T12. Spec H generators also have lead pair81-82. Alternatively, a plug-in tester is available forconducting stator winding tests.Testing for a Grounded Winding: A digital ohm-meter is recommended for this test. Select the high-est scale on the meter. Test each lead as shown inFigure 55. Replace the stator assembly if any read-ing is low indicating a breakdown in the winding in-sulation.Testing Winding Resistance: A digital ohmmetercan be used to determine ifa stator winding is open,as shown in Figure 56. A Wheatstone (Kelvin)bridge should be used to measure stator winding re-sistance. Replace the stator assembly if any wind-ing is open or does not meet the resistance specifi-cation in Table 5 or 6, as appropriate.

56

D

FIGURE 55. STATOR INSULATION RESISTANCE

D

FIGURE 56. STATOR WINDING CONTINUrrv


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Checldng Open-Circult Output Voltage: A1tema-tiv ely , c he ck th e open-c irc uit o utp ut v olta ge (VAG) o fe ac h s ta to r w in din g a s fo llo ws :1 . If n ec es sa ry . s erv ic e th e b ru sh es , s lip rin gs a ndro to r a nd a dju st fo r ra te d fre qu en cy .2. D isconnect leads F1 and F2 from the brushb lock termina ls .3 . C onnect brush block term inal B- (in boa rd ) toth e n eg ativ e (-) b atte ry te rm in al o n th e g en se t.

4 . C on ne ct b ru sh b lo ck te rm in al B+ (ou tboard ) tothe pos it ive (+) batte ry te rm inal on the g enset(K1-B+). This jumper should have a 10 ampfuse and swttch.5 . M ea sure the output across ea ch lead pair w hileru nn in g th e gen se t.

Repla ce the s ta to r a ssembly if an y w ind ing do es nom eet the output specification in Table 5 or 6 , as ap-propriate.

TABLE 5. SINGLEPHASE GENERATOR STATOR SPECIFICATIONSWINDING RESISTANCES* (OHMS)

lEAD PAIRFREQUENCY lEAD PAIRS LEAD PAIR Q1-02 ROTOR(Hz) T1-T2. T3-T4 B1-B2 (SPEC H ONLy) WINDING60 0.327 0.058 2.089 22.550 0.502 0.112 2.873 22.5

OPEN-CIRCUIT WINDING VOLTAGE (yAC) WHEN FIELD VOLTAGE IS 12 veeLEAD PAIRFREQUENCY lEAD PAIRS LEAD PAIR Q1-Q2 ROTOR(Hz) T1-T2, T3-T4 B1-B2 (SPEC H ONLy) WINDING

60 49 7 58 -50 49 7 58 -

- These values are approximate. plus or minus 10 percent at 68 F (20 C).

TABLE 6. THREE-PHASE GENERATOR STATOR SPECIFICATIONSWINDING RESISTANCES* (OHMS)

LEAD PAIRS LEAD PAIRFREQUENCY T1-T4. T2-T5, T3- T6. LEAD PAIR Q1-Q2 ROTOR(Hz) T7-T10, TB-T11, B1-82 (SPEC H ONLy) WINDINGT9-T1260 1.089 0.101 - 24.7850 1.625 0.114 - 24.7860- 0.716 0.101 - 24.78

OPEN-CIRCUIT WINDING VOLTAGE (yAe) WHEN F1ELD VOLTAGE IS 12 veelEAD PAIRS LEAD PAIRFREQUENCY T1-T4. T2-T5. T3-T6, lEAD PAIR Q1-Q2 ROTOR(Hz) T7-T10, TB-T11, B1-B2 (SPEC H ONLy) WINDINGT9-T12

60 60 7 65 -50 60 7 65 -60** 60 7 65 -

- These values are approximate. plus or minus 10 percent at 68 F (20" C)... -1201240 DELTA

57


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TESTING FOR FIELD VOLTAGE

To check the field voltage, rem ove the brush blockco ve r a nd co nn ect a DC v oltm ete r to th e b ru sh b lo ckte rm in als . S ee F ig ure 5 7. C on ne ct th e p ositive le adto th e B + (ou tb oa rd) term ina l an d the ne ga tive lea dto th e B- ( inboard) term ina l.S tart the genset and allow it to stabilize. M easurethe fie ld voltage with no load applied and then w ithfu ll lo ad a pp lie d. B oth re ad in gs s ho uld fa ll b etw ee n25 and 1 00 volts D C and be stable at constant load.If fie ld voltage fluctuates a t constan t load, a poss ib leg overno r o r voltage reg ulator prob lem exists. S eeTroubleshooting.

TESTING 1-PH VOLTAGE REGULATORS

S ee Figure 58 . C onfirm that the voltage regulator(VR1 ) is fau lty be fo re re placin g it. U se the testera vaila ble or a m ete r w ith a diod e ch eckin g fu nction(F lu ke Mode l 7 3 Mu ltime te r, fo r e xample ) to perfo rmthe fo llow ing tests :

1 . D isco nn ect th e ne ga tive (-) ba tte ry cable.2. R em ove th e g en erator co ntrol bo x co ve r.3 . D isengage the w iring connector and rem ovethe voltage regu la to r.4. With th e mete r o n "D io de Che ck", te st b etw ee nconnector term inal pairs 5-9, 7-9, 1 0-9, 1 1-9,1 2-9, 1 0-5, 5-1 1, 5-1 2 and 5-3 . It is importantthat the positive lead of the meter be con-nected to the first term inal of each pair. Re-place th e voltag e reg ulator if an y re ad in g in di-cates "short" or "open", except for pair 1 0-5,

w hich sh ou ld in dica te "o pe n".A good reading is approximately 0.5, which isthe voltage drop across a diode. "Short" is indi-cated by zero or a number very nearty zero. Me-ters of different typemay indicate "open" differ-ently. Read the meter instructions. If in doubt,compare readings with a regulator of the samepart number known to begood.

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GENERATOR RECONNECTIONSWhen it is necessary to reconnect a generator, re-m ove the contro l panel and reconnect the leads atterm inal block TB 1 and circuit breakers C B1 , CB 2and CB3 as shown in the appropriate diagram inFigure 59, 60 or 61 . It should be noted that otherleads are also connected to term inal b lock TB1 inth e co ntro l b ox a nd th at th ey sh ou ld b e re co nn ec te das ma rk ed , if in ad ve rte ntly d is connec ted.

FIGURE 57. BRUSH BLOCK ASSEMBLY

AGURE 58. VOLTAGE REGULATOR TERMINALS(1-PHASE GENSETS)


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WHITE *,/ W HITE (NEUTRAL)GREEN (GND)

r 220-240 VACBLACK (CB1-LOAD)

'---t----+-,----++ WHITE (NEUTRAL)l 2 . ~ T O R _ _ .J I ' - - _ _ ' _ _ ' _ _ _ _ ~.L- BLACK (CB2-LOAD)L L - _ - _ - _ - _ - _ - : _ _ - _ - _ - _ - - C O N T R O L ~ _ - _ B O - X - + - t - - - - - - GREEN (GND)

- 110-120 VACL f - - I - - - - - r l . . . . . . . BLACK (CB1-LOAD)BLACK (CB2-LOAD)

2-WlRE 60 HZ 240 VAC1--------------,I =;,_CB1 ~ I

r 220-240 VAC,--......;...;;..---+---t--' 1 '------+-+-----,.- BLACK (CB2-LOAD)

I I L...- ...-~-----L- WHITE (NEUTRAL)L--,_ h _j ~ : ~ ' = -. ~ - [ ~ ~ _ B O : : J J GREEN (GNO) - IN ST AL LE R MU ST P RO VI DE A NO.1 2 AWG 1Y P E X LP E C ONDU CTOR (1 25 C)AND I NSULATED F EMALE 1 / 4 I NCH FA SlON CONNECTOR .- - R EM OV E A N D D IS CA RD BO TH L EA DS C ON NEC TE D TO C Bl.lEA VE C Bl IN P LA CE T O K EE P T HE O PEN IN G C OV ER ED .

FIGURE 59. SINGLE-PHASE (4-LEAD) 60 Hz GENERATOR RECONNECTIONS

59


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I GENEAAlOR _j1------I~ I

: LTB1~J ~, I I

L ~JWHrTEWHITE (NEUTRAL)GREEN (GND)

I I~~RATOR __ J I LTB1 JJl_ _ J ' - - - - - ' - - ' - - - - _ _ _ . _ ~ aLACK (Ca2-LOAD)L ~-_ - _ - ~ - _ - _ - _ - _ - _ C O N T R O L = - _ - _ B O - X - + - - t - - - _ - GREEN (GND)

r 220-240 VACaLACK (Ca1-LOAD)

'-------4---f---r-----1_+_ WH rTE ( NEUTRAL)

:~- ~u _--, Ii : ia i: T4 L2 ......._ :L _j

: 110-120 VAl

2-W lR E 50H Z 220-240 V ACJ--------------II ~CB1 ~ I

I20-240 VAC'--"";"__---+---I--' : L-.__--+--I-----i- aLACK (CB2-LOAD)

I I - '-------------r---r-----L- WHITE ( NEUTRAL)I LTB1 _LO__ [..l - ;L ~ _ B O i 1 J GREEN (GND) -IN STA llE R M US T PR OVID E A N O.1 2 A WG "TY PE X LPE C ON DU CTO R (1 25 C ) A ND IN SU LA TE D FE MA lE 1/4 IN CH F AS TO N CON NE CT OR .. - R EM OV E A ND D IS CA RD BO TH L EA DS C ON NEC TED TO C 81 . L EA VE CB1 IN PlA CE TO K EEP TH E O PEN IN G C OV ER ED .- - R EM OV E ..R JM PE AW 2 F OR ISO LA TED N EU TR AL

FIGURE 60. SINGLE-PHASE (4-LEAD) 50 Hz GENERATOR RECONNECTIONS

60


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3-PHASE 4-WlRE DELTA, 60 HZ 120 1240 VAC AND 50 HZ (110-120) 1 (220-24Cl) VACr- ----I",-::,:;:"':'~F;;j:==-::'-"':-:""-::::;-- - - -- - - -- - - -- - - -- - - ~ ~ T6T9712 L~I ~- 1

i L3~ITS T. i1 l$r.z

L2LJ . : - : : : : Jn- UNE-TO-UNE4-!"""""T""--i---i- BLACK (CB1 ' (_()AD)

'--r-......-+--r--+-+- BLKlYEL (CB2-LOAD)'----t-t--++--L-L- BLACK (CB3-LOAD)

'-----....,......,......_L....._-- WHITE (NEUTRAL)'-----------+--1-+-1---- GREEN(GND)

~ UNE-~EUTRAL

__________________ ~_BOX

, 1L_~_:__- = . Jn- UNE-TO-UNE'-+-1r-r----i--i- BLACK (CB1 -LOAD)

L-........j,-,-t--r--+-+-- BLKlYEL (CB2-LOAD)L--_-+--+-+--+-.~....L-LACK (CBa-LOAD)

......__-----t-~~--- WHITE(NEUTRAL)L------------++-+-+-r-- GREEN(GND)

J....-l--"-- __ UNE-~EUTRAL

1.pHASEt 3-WlRE OOUBLE-DElTA, 60 HZ 120 1240 VAC AND 50 HZ (11()"120) 1(220-240) YACr:-- -----------------~ r---L,--":::II _..:T1 II T12-17 : 1'9- ~ ! >:'

~ I TIO 1L 3 : =*,FB3 =** I L-~_:_= = - - - JI I UNE-TO-UNEI BLACK (CB1 -LOAD)

~-r--+-r-_'__- BLKlYEL (CB2-LOAD)'--------If---J------'---- WHITE(NEUTRAL)L--------------+,_++----GREEN(GND)

~_____ UNE~~E~ - U SE A D OU BL E-E ND M AL E1/4 I NCH FAS TON CONNECTOR TO CONNECTTHE GENERATOR lADS .- - R EMOVE AND D IS CA RD B OTH L EADS C ONNECT ED TO C B3 . L EA VE CB 3IN P LA CE TO K EE P THE O PENIN G C OV ER ED .

FIGURE 61. THREEPHASE ( 12 -LEAO) GENERATOR RECONNECTIONS

61


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Engine Block AssemblyPerforming major service on the engine block: as-sembly requires that the genset be removed fromthe vehicle. See Preparat ions. The control, genera-tor and all engine subsystems must also be re-moved for complete access to the block assembly.Refer to the previous sections for disassembly andremoval procedures.

CYLINDER HEADSSee Figures 62 and 63. Remove and clean the cylin-der heads as follows when poor engine perfor-mance is noticed:1. Remove the cylinder head bolts by using a 1/2inch socket wrench. Lift off the cylinder head.

14CAunON I The heads may warp jf they areremoved while hot. Waituntil the engine hascooled before removing the heads.2. After removing the heads, clean out all carbondeposits. Be careful not to damage the outer

sealing edges where the gaskets fit. The headsare made of aluminum and can be damaged bycareless handling.3. It is a good idea to also remove the valves andclean carbon deposits from the valves and theintake and exhaust ports. See VALVE SYS-TEM.4. Use new head gaskets and clean both the

heads and the cylinder block thoroughly wherethe gaskets rest.

6. Retorque the head bolts before the engine hasru n a total of 25 hours.

FIGURE 62. MODEL BGO CYUNDER HEAD BOLTTORQUE SEQUENCE

LEFTSIDE* RIGHTSIDE*5. Place the heads in position and torque the head THE OIL FILTER SIDE IS THE RIGHT SIDEbolts in steps of Slbs-ft (7 N-m) inthe numbered

sequence shown in Figure 62 or 63 up to the FIGURE 63. MODEL NHD CYUNDER HEAD BOLTspecified torque of 15-17Ibs-ft (20-23 N-m). TORQUE SEQUENCE

62


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VALVE SYSTEM tio nin g v alv e s ys tem is e ss en tia l fo r to p e ng in e p er-formance.S ee Figures 6 4 and 6 5 for the valve system layoutso f t he re sp ec tiv e e ng in es . T his e ng in es h av e a "s id evalve" type o f v alv e s ys tem la yo ut. A p ro pe rly fu nc -

See VALVE C LEAR ANCE (LASH ) AD JU STMEN Tunder Eng ine $ubsystems for in stru ctio ns o n how toadju st valve c lea rance.

VAlVE STEM S EAL VALVE SPRING VALVE CLEARANCE VALVE ADJUST INGNUT

VALVE

VAL VE CAP

FIGURE 64. MODEL BGD VALVE SYSTEM

VAlVE SPRING VALVE CLEARANCEA lVE SEA TINSERT VALVE ADJUST INGNUT

CAMSHAFT

TAPPET

RETAINERLOCK

EXHAUST VALVEROTATOR

~VALVEGUIDE RUBBERGASKET VAJ_VESTEMSEAL (OPTIONAL )

FIGURE 65. MODEL NHD VALVE SYSTEM

63


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Inspecting the Valve System ValveStem Seal: A valve stem seal is used on theintake valve guides. This seal must be replacedThe valve system is accessible by removing the cyl- each time the valve is removed.inder heads and the valve covers on top of the en-gine. Use a valve spring compressor (Figure 66) toremove and replace the valves from the cylinderblock. Make sure to first plug the breather hole intheNumber 1cylinder valve box (opposite oil filter side)to prevent the valve keepers from falling into thecrankcase.Valve Face: Check the valve face for evidence ofburning, warping, out-of-roundness and carbon de-posits (Rgure 67).Burning and pitting are caused by the valve failing toseat tightly. This condition is often caused by hardcarbon particles on the seat. It may also be causedby weak valve springs, insufficient tappet clear-ance, valve warpage and misalignment.Warping occurs chiefly in the upper stem, because itis exposed to intense heat. Out-of-roundness re-sults from warping, when the seat is pounded by avalve whose head is not in line with the stem. If avalve face is burned or warped, or the stem is worn,install a new valve.Excess clearance in the intake guide admits air andoil into the combustion chamber, upsetting carbure-tion, increasing oil consumption and making heavycarbon deposits. Carbon prevents heat dissipation.Clean metal is a good heat conductor, but carbon in-sulates and retains heat. This increases combus-tion chamber temperatures, causing warping andburning.

FIGURE 66. VALVE SPRING COMPRESSOR

FIGURE 67. BURNED VALVE FACE

Unburned carbon residue gums valve stems, caus-ing them to stick in the guide. Deposits of hard car-bon with sharp points projecting become white-hot,causing pre-ignition and "pinging".Va/veStemsand Guides: Check valve stems andguides for wear (Figure 68). Use a hole gauge tomeasure the valve guide bore diameter. When valveclearance with the stem exceeds the originaJ clear-ance by 0.002 inch (0.05 mm), replace either thevalve or guide or both, as necessary. Always regrindthe seat to make it concentric with the newly FIGURE 68. VALVE STEM AND VALVE GUIDE BOREinstalled guide. DIAMETERS

64


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Springs: Check the valve springs for free-height,squareness. end wear and tension. If the springends are worn, check the valve spring retainer forwear. Check for height and squareness by placingthe spring on a flat surface next to a square. Rotatethe spring against the square edge to measure itsdistortion. Check the spring tension at the installedheight in both the valve open and closed positions,using a valve spring tester. Replace a weak, broken,worn or distorted spring.Reconditioning Valves and Valve SeatsSee Figure 69. The interference angle method ofvalve seating is used on these engines. The valveface angle is 44 degrees. The valve seat angle is 45degrees. This 1-degree interference angle results ina sharp seating surface between the valve and thetop of the valve seat.The valves must not be hand lapped, because thesharp contact between the valve and the seat will bedestroyed. This is especially important wherechrome cobalt faced valves and seats are used.Valve faces must be finished to 44 degrees, in a ma-chine.Each valve must have a minimum of 1/32 inch(0.8 mm) margin (Figure 70). If the valve has lessmargin than this it will heat up excessively. It will re-tain this heat during the compression stroke andpre-ignite the mixture, causing loss of power andeconomy. This valve is also susceptible to warpingand breakage.Not all valves can be reconditioned. A badly warpedvalve must be replaced, because the amount ofgrinding required to make it seat correctly removesits margin. To make a valve gas-tight. remove all pit-ting from the valve face and seat. Deeply pitted orcut valves must be replaced, because grinding re-moves the margin.Grind or cut the valve seats at 45 degrees. The seatband should be 1/32-3164 inch (0.79-1.2 mm) wide.

Remove only enough material to ensure propervalve seating. If a valve seat is cracked or loose odoes not have enough material left to seat the valveproperly. replace the entire block assembly.Check each valve for a tight seat. Make severalmarks at regular intervals across the valve face using machinist's bluing. The marks should rub off uniformly when the valve is rotated a quarter-tumagainst the seat, indicating even contact all the wayaround. The line of contact should be at the center othe valve face.

VA lVE HEAD

IIINTERFERENCEANGLEFIGURE 69. VALVE INTERFERENCE ANGLE

WARPED VALVE KNIFE EDGE'__~_,._71(

GOOD MARGIN ,. )-==' 1 ( 0.30 INC~ (.8 mm)MINIMUMFIGURE 70. VALVE MARGIN

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Replacing the Valve GuidesWorn valve stem guides can be replaced from in-side the valve chamber. The smaller diameter of thetapered valve guides must face toward the valvehead.

Removal:

1. Before removing the valve guides, use an elec-tric drill with a wire brush to remove carbon andother foreign material from the top surface ofthe guides. Failure to do this may result in dam-age to the guide bores.

2. Drive the guides out with a hammer and a valveguide driver.14CAUTION I Driving out the old valve guidescan damage the tappet bores. Becareful notto strike the bores with the driver.

Installation:1. Run a small polishing rod with crocus cloththrough the valve guide holes, to clean out car-

bon and other foreign rnateriaJs.2. Place a new gasket on the intake valve guideand coat the outer edge of each new guide with

anhydrous lanolin (available at the drugstore).

NUT WASHER PLATE

3. Place the guide. notch up, in the cylinder blockand press it in until the shoulder of the guide FIGURE 71. SUGGESTED TOOL FOR INSTALLINGrests against the cylinder block (Figure 71). THE VALVE GUIDES

66

ROD

NUT WASHER

7in(178mm)

5116FLATWASHER(2 REQUIRED)

2-318 in(60mm)5/16-1851 8 in THREADED(16mm) ROD


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GEAR COVERRemovalSee Figure 72. Remove the flywheel, flywheel keyand the gear cover mounting screws. See ENGINECOOLING SYSTEM under Engine Subsystems.Gently tap the gear cover with a leather or plasticmallet to loosen it.Installation1.When installing the gear cover, make sure that

the pin in the gear cover engages the hole with

the nylon grommet in the governor cup. SeeOIL SEALS inthis section for replacing the gearcover oil seal.

2. Tum the governor cup so the hole with the nylon grommet is at the three o'clock position.Use a small amount of grease to help hold thecup in position. The rounded side of the gover-nor yoke must ride against the governor cup.

3. Tum the governor arm and shaft clockwise afar as possible and hold it in this position untithe gear cover is installed flush against thecrankcase. Be careful not to damage the geacover oil seal.

OILSEAL

GOVERNORSHAFT

IF FEELER WILLENTERHOlE lfllN.(13 mm) BALL HASFAlLEN OUT

TOP OF ROLL PIN314 IN (19.0 mrn)

ROTATE THE GOVERNOR CUP soTHAT THE ROLL PIN FITS INTO THEHOLE W ITH THE GROMMET

FIGURE 72. GEAR COVER ASSEMBLY

6


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GOVERNOR CUPRemoval1. Remove the gear cover. See GEAR COVER.2. Remove the snap ring from the camshaft cen-

ter pin (Figure 73).3. Slide the governor cup off, making certain to

catch the flyballs. Replace any flyball that isgrooved or has a flat spot.

4. Examine the ball spacer. If the arms of the ballspacer are worn or otherwise damaged. re-move the spacer by splming itwith a chisel. Usea press to install a new spacer on the camshaftgear.

5. The governor cup must spin freely on the cam-shaft center pin without excessive looseness orwobble. Ifthe race surface of the cup is groovedor rough, replace it with a new one.

InstallationThe governor cup and flyballs are easily installedwhen the camshaft assembly is removed from theengine. If necessary, the engine may be tilted up toinstall the cup and flyballs.1. Put the flyballs between the spacer arms andinstall the cup on the center pin.2. Lock the cup in place with the snap ring.

camshaft Center Pin Installation1. The camshaft center pin extends 314 inch(19 mm) from the end of the camshaft. This dis-tance provides 7/32 inch (5.5 mm) travel for the

govemor cup, as shown. Measure this distance

68

while holding the cup against the flyballs. If thedistance is less, the engine may race, especial-ly at no load.

2. Remove the center pin and press in a new pinthe specified amount. Do not hammer the newpin into place, or it will be damaged. The cam-shaft center pin cannot be pulled outward or re-moved without damage. If the center pin ex-tends too far, the cup will not hold the flyballsproperly.

3f4in(19mm)CAMSHAFTGEAR

71 32 in(5.5 mm)

GOVERNOR ---~CUP

WHEN TIiE GOVERNOR IS PROPERLY ASSEMBlEDTIiE DIMENSIONS SHOWN ON DRAWING WIU BE ASINDICATED

FIGURE 73. GOVERNOR CUP


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TIMING GEARS AND CAMSHAFTIf either timing gear needs replacement, both gearsshould be replaced. Also, the camshaft and its gearare replaceable only as an assembly. See Fig-ure 74.Removal1. Remove the valve tappets so that the camshaftcan be withdrawn.2. Remove the snap ring and retainer washer infront of the crankshaft timing gear.3. Withdraw the camshaMiming gear assembly.4. Remove the oil pump.5. BoH the gear pulling ring to the crankshaft tim-

ing gear USingtwo Grade 8, 1/4-20x1 inch bolts(lesser grade boHs will snap off) and removethe gear with a gear puller as shown. Altema-tively. special shoulder bolts are available foruse with the flywheel puller to remove thecrankshaft gear.Installation1. Service the crankshaft as necessary and rein-stall it. See CRANKSHAFT in this section.2. Preheat the crankshaft timing gear in an ovento 3250 F (168 C).3. Make sure the key is in place in the crankshaftand then tap the gear down to the shoulder on

the crankshaft.4. Install the camshaft assembly. Make sure thethrust washer is in place between the back of

the timing gear and the block and that the "0marks on the timing gears line up as shownFigure 74.5. Install the oil pump assembly.6. Install the retainer washer and snap ring infrono f the crankshaft timing gear.

GEARPULLER CRANKSHAFTGEAR

GEARPULLERRING

RGURE 74. T IM ING GEAR REMOVALAND INSTALLAT ION

6


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OIL PUMP ASSEMBLYThe oil pump is mounted on the front of the crank-case behind the gear cover and is driven by thecrankshaft gear. The inlet pipe and screen assem-bly is attached to the pump body. A discharge pas-sage in the pump cover is aligned with a passagedrilled in the crankcase that leads to the front mainbearing via the oil fiHer. A circumferential groove inthe front main bearing allows oil to cross over to adrilled passage that leads to the front camshaftbearing. A copper colored crossover tube carries oilto the rear main bearing. The connecting rod jour-nals are lubricated through drilled passages fromthe main journals. The oil overflow from the bypassvalve lubricates the camshaft drive gears.Replace the oil pump if the crossover tube is tightand the oil bypass valve is functioning properly butthe oil pressure is below specification. The gasketand pick-up cup are the only individually replace-able parts. Oil the pump generously when reassem-bling it so that itwill prime faster when the engine isfirst started.

70

"

OIL PICKUP SCREEN OIL PUMP

FIGURE 75. OIL PUMP ASSEMBLY


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PISTON ASSEMBLYThe piston assembly consists of the piston, ringsand connecting rod assembly. After removal fromthe engine, all parts must be carefully inspected fordamage and wear before they are replaced.Removal and Disassembly1. Remove the ridge at the top of the cylinder with

a ridge reamer before attempting to remove thepiston (Figure 76).14CAUTION I Improper use of a ridge reamercan damage thecylinder bore. Use this toolwith extreme care.

2. Tum the crankshaft until a piston is at the bot-tom of its stroke.3. Remove the bearing caps from the connectingrods and push the rods and pistons out the topof the cylinders. Be careful not to scratch the

crankpin or the cylinder wall when removingthese parts.4. Mark each piston, rod and bearing cap so thatthey can be reassembled together in the samecylinder.5. The pistons are fitted with two compressionrings and one oil control ring. Remove these

rings from the piston using a piston ring spread-er (Figure n).6. Remove the piston pin retainer from each sideand push the pin out.7. Remove dirt and deposits from the piston sur-

faces with an approved cleaning solvent. Cleanthe piston ring grooves with a groove cleaner,or with the end of a piston ring filed to a sharppoint (Figure 78). Take care no t to remove met-aI from the sides of the grooves.14CAunON I Using a caustic cleaning sol-vent or wire brush for cleaning pistons willcause piston damage. Useonly parts clean-ing solvent for this Job.When cleaning the connecting rods in solvent,make certain to include the rod bore. Blowoutall passages with low-pressure compressedair.

FIGURE 76. CYUNDER RIDGE REAMER

FIGURE 77. PISTON RING SPREADER

FIGURE 78. PISTON RING GROVE CLEANER

71


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Piston and Connecting Rod InspectionPiston Inspection: Inspect the pistons for fracturesat the ring lands, skirts and pin bosses. Check forwear at the ring lands, using a new ring and feelergauge (Figure 79). Replace the piston if the sideclearance of the top compression ring is 0.008 inch(0.20 mm) or more.Improper ring width or excessive ring side clearancecan resuH in ring breakage. New rings in wom ringgrooves do not make adequate contact with the cyl-inder wall (Figure 80).Replace pistons shOwing signs of scuffing, scoring,worn ring lands, fractures or damage from pre-igni-tion.Connecting Rod Inspection: Replace connectingrod boHs and nuts having damaged threads. Re-place connecting rods with deep nicks, signs of frac-tures, scored bores or bores out of round more than0.002 inch (0.05 mm).Use a new piston pin to check the connecting rod forwear. A push-fit dearance is required; this variesfrom engine to engine. If a new piston pin fallsthrough a dry rod pin bore as a result of its ownweight, replace the rod or bushing, as required.Piston Pin Inspection: Replace piston pins thatare cracked, scored, or out of round more than0.002 inch (0.05 mm).Bearing Inspection: Inspect bearings for burrs,breaks, pitting and wear. Replace bearing insertswhich are scored, have their overlay wiped out,show fatigue failure, or are badly scratched. If thebearings appear to be serviceable. check them forproper clearance.Piston ClearanceCorrect piston tolerances must be maintained. Usea micrometer to measure the piston diameter at thepoin t shown in Figure 81. When the cylinder bore ismeasured (see CYLINDER BLOCK). subtract thepiston diameter from the cylinder bore diameter toobtain the piston-to-cyJinder wall clearance. SeeTo le rances and C lea rances.

72

FIGURE 79. CHECKING RING LAND

CYUNDERWAU

IMPROPERRINGCONTACT

RGURE 80. NEW RING IN WORN RING GROVE

MEASURE...,_ DIAMETER HERE

FIGURE 81. MEASURING PISTON DIAMETER


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Piston Ring GapBefore installing new rings on the piston, check thering gap by placing each ring squarely in its cylinder,at a position corresponding to the bottom of its travel(Figure 82). The gap should be 0.010-0.020 inch(0.25-0.50 mm).Do not file the ring ends to increase the end gap. Ifthe ring end gap does not meet the specifications,check the correctness of ring and bore sizes. A cyl-inder bore that is 0.001 inch (0.03 mm) undersizewill reduce the end gap 0.003 (0.08 m).Rings that are 0.010,0.020,0.030 and 0.040 inch(0.25,0.51, 0.76 and 1.02 mm) oversize should beused on corresponding oversize pistons.Piston Assembly1. Lubricate all parts with clean engine oil.2. Line up the piston and connecting rod and in-sert the piston pin. The piston pin is a full-float-ing type kept in place by a lock ring on eachside. Push the lock rings in by thumb pressureor pry them in with a small screwdriver. Makesure they are properly seated.

1 4 CAUTION J Wear safety glasses and holdyour thumb over the lock ring to keep it fromflying out and getting lost or causing per..sonst injury.

3. Refer to Figure 83. Use a piston ring spreaderto install the piston rings to prevent twisting orexcessive expansion. Follow the instructions inthe ring kit exactty. Note which ring goes inwhich groove and which side of the ring is "up".Also note that the oil control ring is an assem-bly.

Piston Installation1. The crankshaft must be in place and should

have been serviced already if crankshaft ser-vice was required. See CRANKSHAFT.2. Tum the crankshaft to position the Number 1

rod bearing journal (side opposite oil filter side)at the bottom of its stroke.3. Lubricate the Number 1 piston assembly andcylinder with engine oil. Compress the rings

with a ring compressor as shown in Figure 85Install the bearing insert in the piston rod.4. Position the piston and rodassembly in the cy

inder block with the connecting rod oil hole u(Figure 84).

FIGURE 82. CHECKING RING GAP

AGURE 83. PISTON RINGS

O IL HOLEUP

FIGURE 84. CONNECTING ROD OIL HOLE

7


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5. Tap the piston into the bore with the handle endof the hammer until the connecting rod isseated on the crankshaft joumal (Figure 85). Ifthe crankshaft has been reground andlor newrods are being installed, check the bearingclearance with Plasti-gage as instructed belowunder Rod Bearing Clearance.

6. Install the rod bearing cap as follows:A. Lubricate the cap bolts with engine oil andtorque to 5lbs-ft (7 N-m).B. Strike the cap/rod joint using a hardwood

block and a leather or plastic mallet to re-move any misalignment (Figure 86).

C. Torque the cap bolts to 14lbs-ft (19 N-m).Recheck the torque on each bolt after bothbolts have been torqued.14CAUTlQN I Failure to align the rod and capcan resuft in high engine oil temperatureand failure of the rod.

7. Install the other piston assembly and crank theengine by hand to see that all bearings are free.Connecting Rod Bearing Clearance1. Wipe all parts clean o f oil and grease.2. Select Plasti-gage that corresponds to the con-necting rod bearing clearance specification(0.0020-0.0033 inch [0.051-0.084 mm]). Place

the piece of Plasti-gage across the full width ofthe bearing cap, about 1/4 inch (6 mm) off-cen-ter (Figure 87).3. Install the rod bearing caps as instructed in

Step 6 of Piston Installation above. Make surenot rotate the crankshaft or the Plasti-gage willsmear.

4. Remove the bearing cap, leaving the Plasti-gage on the part it sticks to. Check the widestpart of the flattened Plasti-gage with the gradu-ations on the envelope to determine the bear-ing clearance.

74

FIGURE 85. INSERTING PISTONTorque the cap bolts to 5 Ibs -ft flN-m ), r emove anymisalignment by striking t he cap/ rod joint us in g aha rd wo od b lo ck an d a le athe r o r p la stic m ajle t a ndth en to rq ue th e cap bo lt s to spec if ic a tion

FIGURE 86. AUGNING CONNECTING ROD CAP

FIGURE 87. USING PLASn-GAGE


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CRANKSHAFTRemoval1. Remove the piston/rod assemblies if they have

not already been removed.2. Remove the gear cover and crankshaft timing

gear. See GEAR COVER and TIMING GEARSin this section.

3. Loosen the rear bearing plate screws and re-move the bearing plate, gasket, thrust washerand shims. See BEARINGS in this section.

4. Tum the crankshaft so the crankthrow isaligned with the notch in the rear opening ofthecrankcase and carefully slide the crankshaftout.

InspectionInspect the rod and main bearing journals. If theyare worn or scored and cannot be smoothed by pol-ishing, either the journals should be reground to thenext undersize, or the crankshaft should be re-placed.Clean out the dril led oil passages in the crankshaft.Installation1. Lubricate the front and rear main bearings withengine oil.2. Use oil or gear lubricant to hold the front thrustwasher in place against the engine block (seeFigure 90). The flat side of the thrust washer

goes against the block.3. Position the crankshaft so that the crank throwis aligned with the notch at the rear of the crank-case and install the crankshaft. Make sure thefront thrust washer did not slip out o f place dur-

ing installation.4. Place the oil seal loader on the oil seal guideand driver and insert it into the rear bearing

plate. Remove the seal guide and driver leavingthe loader in the bearing plate. The loader pre-vents the seal from being cut on the crankshaftkeyway during installation of the rear bearingplate.

5. Use oil or gearlubricantto hold the shim(s) andrear thrust washer in position on the rear bear-ing plate (see Figure 89). The shim goesagainst the bearing plate and the flat surface ofthe thrust washer goes against the shim.

6. Place the bearing plate gasket in position o nthe block, making sure the oil hole on the backof the block is exposed.

7. Install the rear bearing plate and fasten with twonuts (or capscrews) tightened to the specifiedtorque. Make sure the rear thrust washer andshim(s) did not sUpout of place during installa-tion. The crankshaft should tum freely by hand.

Crankshaft EndplaySee Figure 88. After tightening two rear bearingplate nuts (or capscrews) to the specified torque,check the crankshaft endplay at the point shown us-ing a feeler gauge.1. Ughtly tap the front o f the crankshaft with aplastic-faced hammer to take up the endplay.The endplay should be 0.006-0.012 inch(0.15-0.30 mm).2. If necessary, remove the rear bearing end plateand add or remove shims.3. Install the end plate and tighten all nuts (or

capscrews) to the specified torque.4. Make sure the shim and thrust washer are inplace and recheck crankshaft endplay. Verifythat the crankshaft turns freely without binding.

FIGURE 88. CHECKING CRANKSHAFT ENDPLAY

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BEARINGST o re pla ce the cranksh aft and cam shaft be aring s,the engine m ust be com plete ly dis assem bled. U sethe special drivers available to drive out the oldbearings and drive in the new . S upport the enginecasting so as not to cause distortion or dam age tothe bore or castin g.Crankshaft BearingsC ra nk sh aft b ea rin gs a re a va ila ble in s ta nd ard s iz e,0.002, 0.010, 0.020 or 0.030 inch unders ize .When in sta llin g e ith er th e fro nt o r re ar ma in b ea rin g,a lw ay s a lig n th e o il h ole (s ) in th e b ea rin g with th e o ilhole(s) in th e bea ring bore. T he oil passa ge m ust b ea t le as t 112 open.Rear Searing: Use the spe cia l drive r a vailab le todrive in th e re ar m ain bea ring. P ush the b earin g intoth e bea ring pla te from the inne r sid e to the depth a l-lowed by the flange on the d river. S ee F igu re 89.Front Bearing: UseL oc tite b ra nd B ea rin g Mou nt o re qu iv ale nt when in sta llin g th e fro nt b ea rin g. Use th eto we le tte fu rn is he d w ith th e b ea rin g kit to cle an theoutside o f the bearing and the bearing bore in theb lo ck . A pp ly th e L oc tite to th e matin g s urfa ce s o f t hebe aring and bea ring bore. A llow three to four m in-u te s fo r d ry in g.IWARNING IBreathing the vapor from the lowe-lette provided with the Loctite, or prolongedcontact with skin, can be harmful. Be sure thework area Is well ventilated.Use th e spec ial d river a vailable to drive in the fro ntb ea rin g. Pu sh th e bea rin g in to th e d ep th a tlo we d bythe flang e o n the d river. W ipe off any excess Loc tit ean d allo w o ne h our for harden ing at room tem pera-ture. See F ig ure 9 0.E ng in es s hip pe d from the factory have separatethrust w ash ers a nd m ain bea rings for both front andre ar o f e ng in e. T he fro nt b ea rin g re pla ceme nt p art isa o ne -p ie ce b ea rin g (with a tta ched th ru s t washe r) .as s how n. D o not add an a dditional thrust w asher toth is fro nt b ea rin g.

76

REARBEARINGEND PLATE LOCK AliGN BEARING OILPINS HOLES WITH OILHOLES IN BEARINGBORE

SHIM THRUSTWASHEREARING

FIGURE 89. REAR CRANKSHAFT BEARING

NOTE: DONOT ADD ADDITIONAL THRUSTWASHERS WHEN REPLACING THE FRONT BEARING

ALIGN BEARING NOTCHESWITH LOCK PINSANDMATCH OIL HOLES FRONT MAINBEARING

FIGURE 90. FRONT CRANKSHAFT BEARING


27/48

Camshaft BearingsIt should be noted that identical bearings are usedfor replacing the front and rear camshaft bearingsand that they may look different from the old bear-ings.1. Clean the outside of each bearing and the bear-

ing bore in the block and coat the outside of thebearing with Loctite brand Bearing Mount orequivalent just before pressing it into its bore.

2. Press the front bearing in so that the oil hole inthe bearing lines up with the oil hole in the bore(Figure 91).

3. Press the rear bearing in so that it is positioned112inch (12.7 mm) from the outside edge ofthebore. There is no oil hole in the rear bore withwhich to line up the hole in the bearing (Fig-ure 92).

4 Coat the bearing surfaces with engine oil afterinstallation.

ALIGN THE HOlE IN THE BEARINGW ITH THE HO LE IN THE BEARING BORE

AGURE 91. FRONT CAMSHAFT BEARING

1/2 inch(12.7mm---"AGURE 92. REAR CAMSHAFT BEARING

OIL SEALSRemove the rear bearing plate to replace the rear oiseal (Figure 93) and the gear cover to replace thefront oil seal (Figure 94). Use an oil seal remover topry out the oil seals. Clean the bores of all old seal-ing compound before installing the new seals.Use an oil seal guide and driver to drive the rear seainto the rear bearing plate until it bottoms against theshoulder of the plate.Drive the front oil seal into the gear cover until it is0.95-0.99 inch (24.1-25.1 mm) from the mountingface o f the cover.Place a light coating of grease on the lips o f theseals before installing the rear bearing plate andgear cover. This provides initial lubrication until engine oil reaches the seal. Refer to CRANKSHAFTfor the rear bearing plate installation procedure. Refer to GEAR COVER for the gear cover installationprocedure.

DRIVE THE OIL SEALTO THE SHOULDEROF THE PLATE BORE

FIGURE 93. REAR CRANKSHAFT OIL SEALMOUNTING FACEOF GEAR COVER

DRIVE THE OIL SEALTHUS FAR INTO THEGEAR COVER BOREFIGURE 94. FRONT (GEARCASE) CRANKSHAFTOIL SEAL

77


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ENGINE BLOCKThe engine block is the main support for all other ba-sic engine parts and subassemblies.CleaningAfter removing the pistons, crankshaft, cytinderheads, etc., inspect the block for cracks and ex-treme wear. If it is still serviceable, prepare it forcleaning as follows:1. Scrape all old gasket material from the block.Remove oil bypass to allow cleaning solution tocontact inside of oil passages.2. Remove grease and scale from the cylinder

block by agitating in a bath of commercialcleaning solution or hot soapy washing solu-tion.3. Rinse the block in clean hot water to removecleaning solution.

Inspecting the BlockWhen rebuilding the engine, thoroughly inspect theblock for any condition that would make it unfit forfurther use. This inspection must be made after allparts have been removed and the block has beenthoroughly cleaned and dried.1. Make a thorough check for cracks. Minutecracks may be detected by coating the sus-pected area with a mixture o f 25 percent kero-sene and 75 percent light motor oil. Wipe thepart dry and immediately apply a coating of zincoxide (white lead) dissolved in wood alcohol. Ifcracks are present, the white coating will be-come discolored at the defective area. (Re-move this coating after the test and before reas-sembly.) Always replace a cracked cylinderblock.2. Inspect all machined surfaces and threadedholes. Carefully remove any nicks or burrs from

machined surfaces. Clean out tapped holesand clean up any damaged threads.

78

3. Check the top of the block for flatness with astraight-edge and a feeler gauge.Inspecting the Cylinder BoresInspect the cylinder bores for SCuffing. scratches,wear and scoring. Ifthese conditions exist, the cylin-ders must be rebored and honed for the next over-size piston.Ifthe cytinder bores look good and there are no scuffmarks, check the bores for wear and out-of-round-ness as follows:1. Check cylinder bore for taper. out-of-round-ness and wear with a cylinder bore gauge, tele-scope gauge or inside micrometer. These mea-

surements should be taken at four places: thetop and bottom of piston ring travel, and paralleland perpendicular to the axis of the crankshaft.See Figure 95.

R ING WEARAREA i---. ---"0../ ~

BO TTO M O FRINGTRAVEL

RGURE 95. MEASURING CYUNDER BORE


29/48

2. R ecord the m easurem ents taken at the top andbo ttom of the piston tra vel a s follOWS:A. Mea su re a nd re co rd asA th e c ylin de r b orediam eter (pa ra lle l to cran kshaft) near thetop of cy linder bore where the greatest

am ount of w ear occurs.B . M easure and record as B th e c ylin de r b ored iamete r (p ara lle l to c ra nk sh aft) a t th e b ot-to m o f p iston tra vel.C . M easure and record as C the cy fi nde r bo rediam eter (perpendicular to crankshaft)near the top of cylinder bore where thegrea te st am ou nt o f w ear occu rs .D.Mea su re a nd re co rd as0 th e c ylin de r b ore

diam eter (perpen dicu lar to crank shaft) atth e b ottom o f pis ton travel.E. Reading A s ub tra cte d from re ad in g B an dreading C sub tra cte d from re ad in g 0 indi-c ate s th e c ylin de r ta pe r.F. Reading A com pared to reading C andreading Bcompare d to re ad in g 0 indicateswheth er o r n ot th e c ylin de r is o ut-o f-ro un d.If the out-of-round exceeds 0.003 inch(0.08 mm), the cylinders m ust be raboredand honed to the next oversi ze . A reboring

m achine is used when changing to over-S ize p istons. The fo llo win g re pa ir d ata d e-s crib es th e h on in g p ro ce du re .Machining the Cylinder BoresThe a va ila ble o ve rs iz e p is to ns a nd rin gs will fit withth e re qu ire d c fe ara nc e in c ylin de rs mac hin ed to th ematc hin g o ve rs iz e (standard bore p lus 0.005,0.010, 0.020, 0.030 and 0.040 inch). There is noneed to a dju st o r t o "fit" p is to ns a nd rin gs . P is to n a ndrin g s iz e should be checked as described below toconfirm that they are correct for the standard boreo versize . B oring and honing m ust be a cc ura te a ndremo ve just eno ugh m eta l for the sma lles t ove rs izepossible. T he fin ish hon e sh ould lea ve a2O to 4 0 m i-c ro -in ch c ro ss ha tc h fin is h h av in g a n in cfu de d a ng leof 20 to 2 5 d eg re es . T he c ro ss ha tc h fin is h is n ec es -sary fo r fast p is to n rin g b re ak -in . See F ig ure 9 6.

C le an th e cyfind er bore w ith ho t, soa py w ate r an d abrush a fter mach in ing . A c le an white ra g will no t soiw hen the cylinder bore is clean. D ry the bores andco at them w ith o il.IAcAunON I Do not use gasoline or commercialcleaning solvents to clean the cylinder bores afte r honing-they do not remove abrasives.

RGURE 96. PROPER HONE CROSSHATCHIN CYLINDER BOREDeglazing the Cylinder BoresDegla ze th e c ylin de r b ore s fo r fa st p is to n rin g b re akin if the bores look good and there is not enoughw ear, taper and out-of-roundness to w arrant m ac hin in g. D eg la zin g s ho uld n ot in cre as e th e b ore dame te r, p erm ittin g th e u se o f th e o rig in al p is to ns (th ey a re good) with n ew rin gs . T o d eg la ze th e c ylinderbores:

1. Wip e th e c ylin de r b ore s with a c le an cloth thahas been dipped in light eng ine oil.2. U se a brush-type deglazing too l with coatedb ri st le t ips .3 . D rive the tool w ith a s low -speed drill. M ove thtool up and down in the cylinder bores fas

e no ug h to o bta in th e c ro ss ha tc h p atte rn s hown(Figure 96 ). Ten to tw elve strokes should bSufficient.4. C lean the cylinder bore with h ot, soap y w ateand a brush after deg lazing. A clean w hite rawill no t soil w hen the cylinde r bore is clean . D rthe bores and coat them w ith o il.

7


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Service ChecklistAfter servicing. inspect and test the installation toconfirm that the genset will operate as intended.Check each of the areas described below beforeputting the genset into service.MountingExamine all mounting bolts and supporting mem-bers to verify that the genset is properly mounted.All fasteners should be tightened securely to pre-vent them from working loose when subjected tovibration.LubricationIf the engine oil was drained, refill as instructed inthe Operator's Manual.WiringVerify that all wiring connections are tight andinstalled properly. Check each of these connec-tions: load wires Control wires Ground straps Battery cables

Initial Start AdjustmentsPerform governor and carburetor adjustments ac-cording to Engine Subsystems if they have not beendone already.Output CheckApply a full load to make sure the genset can pro-duce its full rated output. Use a load test panel to ap-ply a progressively greater load until full load isreached.

80

Exhaust SystemWhile the genset is running inspect the entire ex-haust system. including the exhaust manifold. muf-fler and exhaust pipe. Look and listen for leaks at allconnections. welds, gaskets and joints. Also makesure the exhaust pipe is not overheating adjacentmaterials or equipment. Do not run the genset untilall exhaust leaks have been repaired.I'WARNING IExhaust gas Is deadly. The exhaustsystem must not leak and must discharge all ex-haust away from the vehicle. Do not run the gen-set until the exhaust leaks have been repaired.Fuel SystemWhile the genset is running, inspect the fuel supplylines, retum lines, filters and fittings for leaks. Checkflexible sections for cuts. cracks and abrasions andmake sure they are not rubbing against anythingthat could cause leakage. Repair all fuel leaks im-mediately.I'WARNING I Gasoline and LPG are flammableand explosive. Leaking fuel could lead to fireand to severe personal injury or death. Repairfuelleales immediately.ControlStop and start the gensel several times at the con-trol panel on the genset and at the remote controlboard (if provided) to verify that they work properly.MechanicalStop the genset and inspect it for leaking gaskets.loose fasteners, damaged components and inter-ference with other eqUipment. Repair as necessary.Inspect the generator compartment and verify thatthere are no breaks or openings in the vapor-proofwall that separates the compartment from the ve-hicle interior. Seal openings as necessary. Makesure that all soundproofing material is in place.


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TroubleshootingRegular maintenance can prevent many of theproblems listed below. Removing and cleaning thecylinder heads every 500 hours is especially impor-tant for gasoline models. Before considering majorengine service because of abnormal performance,refer to Periodic Maintenance in the Operator'sManual for instructions on how to clean the cylinderheads using Onan "4C".

These troubleshooting charts are designed to hyou think through genset problems. To save timtroubleshooting, read the entire manual aheadtime to understand the genset. Try to think throuproblems. Go over what was done during the lservice call. The problem could be as simple asempty fuel tank, closed fuel shutoff valve, loowire, blown fuse or tripped circuit breaker.

THE ENGINEDOES NOT CRANKIA WARNING I There are hazards present in troubleshooting that can cause equipment damagsevere personal injury or death. Troubleshooting must be performed by qualified persons whknow about the hazards of fuel, electricity and machinery. Read Safety Precautions inside thfront cover and observe all instructions and precautions in this manual.

Possible Cause Corrective Action1. The remote enable switch (if Tum the key switch ON. If necessary. verify that the switch worksupplied) is OFF. and that the customer connected it according to the appropriatewiring diagram in Wiring Diagrams.2. Control fuse F1 on the side Check for and repair ground faults in the choke heater (H1), fueof the control box has blown. pump/solenoid (E2IFS), ignition coil (T1) and remote control con(Beginning Spec J) nectar (P2-5 and P2-S) circuits. See Wiring Diagrams. Replacthe fuse with a 10 amp slow-blow mini-bayonet type.3. Control board fuse F1 has Check for and repair ground faults in the starter relay (K1), fueblown. (Spec H Only) pump/solenoid (E2fFS) and relay KS/K6 circuits. See Wiring Diegrams. Replace the fuse with an Onan supplied fuse only.4. The remote control circuit (if Try starting with the local Start switch. If the engine cranks, fin

provided) is faulty. and repair the fault in the remote control circuit.5. The local Start switch circuit Try starting with the remote Start switch (if provided). If the en

is faulty. gine cranks. replace control board A1 (Spec H only) orthe contrpanel assembly (Beginning Spec J).


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THE ENGINE DOES NOT CRANK (CONTINUED)14 WARNING I There are hazards present in troubleshooting that can cause equipment damage,severe personal injury ordeath. Troubleshooting must be performed by qualified persons whoknow about the hazards of fue/J electricity and machinery. Read Safety Precautions inside thefront cover and observe all instructions and precautions in this manual.

Possible Cause Corrective Action6. Cranking voltage is too low

to crank the engine. a. Clean and tighten or replace the battery cable connectors and ca-bles at the battery and the genset. See the Installation Manual toverify that the battery cable sizes are adequate.b. Recharge or replace the battery. Specific gravity for a fullycharged battery is approximately 1.260 at 80 F (270C).c. If the genset is in standby service, install a battery charger.d. Once the genset has been started, troubleshoot the battery

charging circuit according to THE GENERATOR DOES NOTCHARGE THE BATTERY. Beginning Spec J, if the Low Bat indi-cator stays on during operation, recheck a/l of the above steps.Beginning Spec J

7. The starter motor assem-bly is malfunctioning or notconnected properly.Check and tighten connections at starter solenoid terminals Sand M and push and hold in the Start switch.

If the Start Sol indicator does not light, go to Step 8.If the Start Sol indicator on the control panel lights, measurevoltage at solenoid terminal M.

If there is at least 9 VDe but the motor does not functionproperly, service or replace the motor assembly.If there is not at least 9 VDC, replace the solenoid. SeeELECTRIC STARTER in Engine Subsystems.

8. Control A1 or start relay K5are faulty or not properlyconnected.

Remove the control panel and check for 8+ at relay K5 terminal30. (K5 is mounted in a socket on the back of the panel.)If there is no voltage. reconnect wiring as necessary. SeeWiring Diag rams.If there is B+ at terminal 30, remove the relay from its socketand apply battery voltage across coil terminals 85 and 86.

Ifthe coil does notfunction or if there is no electrical con-tinuity between terminals 30 and 87 when the relay isenergized, replace the relay.If the relay is good. replace the control panel assembly.

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THE ENGINE DOES NOT CRANK (CONTINUED)I . A WARNING I There are hazards present in troubleshooting that can cause equipment damagesevere personal injury ordeath. Troubleshooting must be performed by qualified persons whknow about the hazards of fuel, electricity and machinery. Read Safety Precautions inside thfront cover and observe all instructions and precautions in this manual.

Possible Cause Corrective ActionSpec H Only

9. Control board A1 or start ra- Remove the control panel. Push the Start-Stop switch to Starlay K1 is faulty. and measure voltage at start solenoid terminal S.If there is not at least 9 VDC, see TESTING CONTROLBOARD A1 in Engine Control. Replace parts or reconnectleads as necessary.If there is at least 9 volts at terminal 5, push the Start-Stopswitch to Start again and measure voltage at the motor terminal on the start solenoid. Ifthere is no voltage at the mototerminal, replace relay K1.

10. The cable between start ra- Service as necessary.lay K1 and the startermotor is loose, damaged ormissing.

11. The starter motor is mal- Push the Start-Stop switch to Start and measure voltage at thfunctioning. starter motor terminal. If there is at least 9 VDC but the motodoes not function. replace the starter motor. See ELECTRICSTARTER in Engine Subsystems.


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THE ENGINECRANKS BUT DOESNOT START[a. WARNING I There are hazards present in troubleshooting that can cause equipment damage~severe personal injury or death. Troubleshooting must beperformed by qualified persons whoknow about the hazards of fue/~electricity and machinery. Read Safety Precautions inside thefront cover and observe all instructions and precautions in this manual.

Possible Cause Corrective Action1. Fuse F2 on the side of the Check for and repair ground faults in the choke heater (H1) andcontrol box has blown. ignition coil (T1) circuits. See Wiring Diagrams. Replace the fuse

(Spec H, Gasoline only) with a 10 amp slow-blow mini-bayonet type.2. The fuel supply shutoff Service as necessary.valve is closed or the fuel

tank is empty.3. Cranking voltage is too low a. Clean and tighten or replace the battery cable connectors and ca-to reach require cranking bles at the battery and the genset. See Installation Manual to ver-speed. if y that the battery cable sizes are adequate.

b. Recharge or replace the battery. Specific gravity for a fullycharged battery is approximately 1.260 at 800F (270C).c. If the genset is in standby service, install a battery charger.d. Once the genset has started, troubleshoot the battery chargingcircuit according to THE GENERATOR DOES NOT CHARGE

THE BATTERY.4. Low engine temperature is Replace the engine oil if it is not of the recommended viscositycausing too Iowa cranking for the ambient temperature. See the Operator's Manual.speed for starting.5. The ignition system is weak a. If the Ignition indicator lights when the Start switch is held in,or has poor connections or check and tighten the connections at the + and - terminals of thethe control is faulty. (Begin- ignition coil (T1). Do the Quick Ignition Test under IGNITIONning Spec J) SYSTEM in Engine Subsystems. If the spark is weak or there isno spark at all, service the ignition system as necessary.

b. If the Ignition indicator does not light, replace the control assem-bly.

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THE ENGINE CRANKS BUT DOES NOT START (CONTINUED)

Possible Cause6. The ignition system is weakor has poor connections.(Spec H Only)

7. Control board A1 is faulty.(Spec H, LPG)

8. Relay K6 or control A 1 isfaulty. (Spec H, Gasoline)

9. The choke is not closingproperly in colder weather.10. The engine is not gettingfuel because the fuel sole-noid is not opening, the fuelpump is not pumping or thecontrol is faulty. (Beginning

Spec J)

14 WARNING I There are hazards present in troubleshooting that can cause equipment damagesevere personal injury or death. Troubleshooting must be performed by qualified persons whoknow about the hazards of fue/~electricity and machinery. Read Safety Precautions inside thefront cover and observe all instructions and precautions in this manual.

Corrective ActionDo the Quick Ignition Test under IGNITION SYSTEM in EngineSubsystems.

If there is only a weak spark, service the ignition system asnecessary.If there is no spark, hold in the Start switch and measure thevoltage at the positive (+) terminal on the ignition coil.

If there is at least 9 VDC, service the ignition system asnecessary.If there is not at least 9 VDC, go to Step 7 or 8, as appropriate.

If there is not at least 9 VDC at the ignition coil during cranking(Step 6), see TESTING CONTROL BOARD A1 in Engine Control. Replace parts or reconnect leads as necessary.If there is not at least 9 VOC at the ignition coil during cranking(Step 6), remove the lead at terminal 85 on relay K6. Hold in theStart switch and measure the voltage at the end of the lead jusdisconnected.

If there is at least 9 VDe, verify that all the leads at relay K6are connected according to the appropriate connection diagram in Wiring Diagrams. If they are, replace relay K6.If there is not at least 9 VDC at the end of the lead markedK6-85, check all the connections back to control board A1and see TESTING CONTROL BOARD A1 in Engine Control. Replace parts or reconnect leads as necessary.

Service as instructed in FUEL SYSTEM in Engine Subsystems.(Gasoline carburetors only.)If the Fuel Pump indicator lights during cranking but you cannohear or feel the solenoid open or the pump vibrate, test the fuesolenoid or pump according to FUEL SYSTEM in Engine Subsystems. If the Fuel Pump indicator does not light during cranking, replace the control board assembly.

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THE ENGINECRANKS BUT DOES NOT START (CONTINUED)1 WARNING I There are hazards present in troubleshooting that can cause equipment damage,severe personal injury or death. Troubleshooting must beperformed by qualified persons whoknow about the hazards of fuel, electricity and machinery. Read Safety Precautions inside thefront cover and observe all instructions and precautions in this manual.

Possible Cause Corrective Action11. The engine is not getting If you cannot hear or feel the solenoid open or the pump vibrate,

fuel because the fuel sole- disconnect the lead to the fuel pump and/or solenoid and andnoid is not opening, the fuel measure voltage at the end of the lead during cranking.pump is not pumping or the If there is at least 9 VDC, test the fuel solenoid or pump ac-control is faulty. (Spec H cording to FUEL SYSTEM in Engine Subsystems.Only) If there is not at least 9 VDC. see TESTING CONTROLBOARD A1 in Engine Control.12. The engine is not getting a. Verify that the LPG fuel solenoid and gasoline fuel pump are con-fuel because the fuel pump nected property, especially where the customer has mounted theandlor fuel solenoid is not fuel pump remote from the genset and added a fuel tank shutoffinstalled property. solenoid. The remote pump and solenoid must be connected tothe genset using insulated conductors of at least 16 AWG, haveadequate bonding paths to the negative (-) terminal ofthe battery

and have corrosion-free connections.b. Verify that the fuel pump (gasoline gensets only) is not more than

3 feet (.9 M)in elevation above the pickup tube in the fuel supplytank. If it is, relocate the fuel pump according to the instructionsin the Installation Manual.

13. The fuel mixture screws are Adjust as instructed in FUEL SYSTEM in Engine Subsystems.not adjusted properly. (Priorto SPEC L only)14. The LPG demand regulator Test and adjust (prior to SPEC L only) and/or replace asis malfunctioning. instructed in FUEL SYSTEM in Engine Subsystems.15. The engine is worn or mal- Do the CYLINDER COMPRESSION TEST in Engine Subsys-functioning mechanically. tems and service as necessary.

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THE ENGINE STOPS WHEN THE START SWITCH IS RELEASED(BEGINNING SPEC J)

Possible Cause

1. The engine oil pressure islow or the cutout switch isfaulty. (The starter disen-gages normally when theStart switch is held in.)

2. The PMG is faulty or notconnected property. (Thestarter does not disengagewhen the Start switch isheld in.)

14 WARNING I There are hazards present in troubleshooting that can cause equipment damagesevere personal injury or death. Troubleshooting must be performed by qualified persons whoknow about the hazards of fuel, electricity and machinery. Read Safety Precautions inside thefront cover and observe all instructions and precautions in this manual.

Corrective ActionGo to Step 1ifthe engine stops when the Start switch is released but the starter disengages normallywhen the Start switch is held in. The problem is probably low oil pressure or a faulty pressure sender.Go to Step 2 i f the starter does not disengage when the Start switch is held in. The problem is prob-ably in the PMG or its connections.

a Check engine oil level and fill as necessary. Go to the next stepif the engine still does not continue to run when the start switchis released.

b. Bypass low oil pressure cutout switch S2 by disconnecting thelead to it and grounding it. (For access, remove the cylinder headshroud on the oil filter side.) Start the genset.

If oil pressure is at least 12 psi, replace low oil pressure cut-out switch S2.If oil pressure is less than 12 psi, service the engine accord-ing to LUBRICATION SYSTEM in Engine Block Assembly.

a. Disconnect connector J8IP8 in the wiring harness in the vicinityof the ignition coil and connect an ohmmeter to check PMG statorwinding continuity. Replace the PMG stator if the windings areopen (normal winding resistance is approximately 0.13 ohms).See PMG in Engine Subsystems.

b. If winding continuity is good, connect an AC volt meter to thePMG stator leads, start the engine, hold in the Start switch andimmediately pull off the wire connector at starter solenoid termi-nal S to disengage the starter. Replace the flywheel assembly(Figure 9) if the output is less than 29 VAC.

8


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THE ENGINE STOPS WHEN THE START SWITCH IS RELEASED(SPEC H ONLy)

I .. WARNING 1 There are hazards present in troubleshooting that can cause equipment damage~severe personal injury ordeath. Troubleshooting must be performed by qualified persons whoknow about the hazards of fue/~electricity and machinery. Read Safety Precautions inside thefront cover and observe all instructions and precautions in this manual.Possible Cause Corrective ActionIn normal operation, run relay K3 on control board A1must remain powered in order to keep thegenset running when the start switch is released. See Wiring Diagrams. Three things must occur tokeep run relay K3 powered: 1) engine oil pressure must be sufficient to close low oil pressure cutoutswitch 52,2) stop relay K5must open and 3) output from generator winding 81-82 must be sufficientto pull in start disconnect relay K2 on control board A 1.To isolate the problem, plug a test lamp or voltmeter into a convenient power receptacle on thevehicle. Start the genset and keep it running by holding in the Start switch and go to NORMAL OUTPUT VOLTAGE or NO (LOW) OUTPUT VOLTAGE, as appropriate.

Normal Output Voltage1. The engine oil level is low. Check engine oil level and fill as necessary.2. The engine oil pressure is Bypass low oil pressure cutout switch S2 by disconnecting con-low or the cutout switch is trol board A1 connector lead Jl-5 I J5 from connector JSandfaulty. grounding it and start the genset. If bypassing switch S2 allowsthe engine to continue running, remove the pressure switch (for

access, remove the cylinder shroud on the oil filter side), installan oil pressure gauge and run the genset.If oil pressure is at least 12 psi, replace low oil pressure cut-out switch S2.If oil pressure is less than 12 psi, service the engine accord-ing to LUBRICATION SYSTEM in Engine Block Assembly.

3. Stop Relay KSis faulty. Disconnect stop relay KSby disconnecting engine control boardA1connector lead J1-10 ICR6 from CR6 (inside the control box)and start the genset. If disconnecting relay K5 allows the engineto continue running, check wiring in the stop relay K5 circuitagainstthe appropriate wiring diagram in Wiring Diagrams. If thewiring is good. replace relay K5.

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THE ENGINE STOPS WHEN THE START SWITCH IS RELEASED(SPEC H ONLV) (CONTINUED)

IA WARNING I There are hazards present in troubleshooting that can cause equipment damagesevere personal injury or death. Troubleshooting must be performed by qualified persons whoknow about the hazards of fuel, electricity and machinery. Read Safety Precautions inside thefront cover and observe all instructions and precautions In this manual.

Possible Cause Corrective Action4. Winding 81-82 is faulty. Isolate the 81-82 winding lead pair (orange striped leads) by dis-connecting connectors J7 and J8 (inside the control box) and thetwo leads at the AC terminals on battery charging voltage regula-tor VR2 (mounted on a bracket on the generator) and test thewinding as instructed under TESTING THE GENERATOR in

Generator. If the 81-82 winding is faulty, replace the entire statorassembly.5. Control Board A1 is faulty. Check the control board connector according to TESTING CON-TROL BOARD A1 in Engine Control and replace control boardA1 if cleaning the connector does not help.

No (Low) Output Voltage6. Field voltage is low. Measure field voltage while cranking the engine. See TESTINGFOR FIELD VOLTAGE in Generator. If there is at least 9 VDCacross the brush block terminals, test and service or replace thebrushes, slip rings, rotor and stator according to SERVICING

THE BRUSHES AND SLIP RINGS and TESTING THE GENER-ATOR in Generator.7. Control Board A1 is faulty. Measure voltage between output voltage regulator VR1 connec-tor pin 7 (connector J9 on 3-phase gensets) and ground whilecranking the engine. If there is less than 9 VDC, check the controlboard connector according to TESTING CONTROL BOARD A1in Engine Control and replace engine control board A1 if cleaningthe connector does not help.

8


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THE ENGINE STOPS WHEN THE START SWITCH IS RELEASED(SPEC H ONLy) (CONTINUED)14 WARN ING I There are hazards present in troubleshooting that can cause equipment damage,severe personal injury or death. Troubleshooting must be performed by qualified persons whoknow about the hazards of fuel, electricity and machinery. Read Safety Precautions inside thefront cover and observe all instructions and precautions in this manual.

Possible Cause Corrective Action8. Voltage Regulator VR1 is Measure voltage between VR1 connector pin 9 (connector J10faulty. on 3-phase gensets) and ground while cranking the engine.

If there is less than 9 VDC, replace output voltage regulatorVR1.If there is at least 9 VDC, measure resistance between VR1connector pin 10 (connector J11 on 3-phase gensets) andground. Replace output voltage regulator VR1 if there ismeasurable resistance (greater than zero).

9. Generator output too low. See OUTPUT VOLTAGE IS TOO HIGH OR TOO LOW

THE ENGINE MISFIRES OR BACKFIRES14 WARN ING I There are hazards present in troubleshooting that can cause equipment damage,severe personal injury ordeath. Troubleshooting must be performed by qualified persons whoknow about the hazards of fuel, electricity and machinery. Read Safety Precautions inside thefront cover and observe all instructions and precautions in this manual.

Possible Cause Corrective Action1. The ignition system if faulty. Service the ignition system as necessary according to IGNITIONSYSTEM in EngineSubsystems.2. The fuel mixture is too lean. a. Adjustfuel mixture (prior to Spec L only) according to FUEL SYS-TEM in EngineSubsystems.

b. Check for and repair a vacuum leak.c. Overhaul (prior to Spec L only) or replace the carburetor accord-ing to FUEL SYSTEM in Engine Subsystems.

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THE ENGINEMISFIRESOR BACKFIRES (CONTINUED)I'"WARNING I There are hazards present in troubleshooting that can cause equipment damage~severe personal injury or death. Troubleshooting must be performed by qualified persons whoknow about the hazards of fuel, electricity and machinery. Read Safety Precautions inside thefront cover and observe all instructions and precautions in this manual.

Possible Cause Corrective Action3. The fuel (gasoline) is con- Connect the genset to a container of fuel of known quality and runtaminated. the genset under various loads. Replace the contents of the fuelsupply tank if there is a noticeable improvement in performance.4. The engine is malfunction- Service as necessary according to Engine Block Assembly.ing mechanically.

THE ENGINE LACKS POWERI'" WARNING 1 There are hazards present in troubleshooting that can cause equipment damage,severe personal injury or death. Troubleshooting must be performed by qualified persons whoknow about the hazards of fuel, electricity and machinery. Read Safety Precautions inside thefront cover and observe all instructions and precautions in this manual.

Possible Cause Corrective Action1. There is carbon build-up in Remove the heads and clean using Onan "4C" according the Op-the cylinder heads. erator's Manual.2. The ignition system is faulty. Service the ignition system as necessary according to IGNITIONSYSTEM in Engine Subsystems.3. Fuel mixture and governor a. Adjust according to Governor and Carburetor Adjustments underadjustments are incorrect. FUEL SYSTEM in Engine Subsystems.

b. Check for and repair a vacuum leak.c. Overhaul (prior to Spec L only) or replace the carburetor accord-ing to FUEL SYSTEM in Engine Subsystems.

4. The gasoline fuel pump is Verify thatthe fuel pump is not more than 3 feet (.9 m) in elevationnot installed properly. above the pickup tube in the fuel supply tank. If it is, relocate thefuel pump according to the instructions in the Installation Manual.5. The fuel filter(s) is clogged. Replace clogged gasoline filters and clean out LPG filters andregulators. See LPG System-Liquid Withdrawal under FUELSYSTEM in Engine Subsystems.

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THE ENGINE LACKS POWER (CONTINUED)14 WARN ING I There are hazards present in troubleshooting that can cause equipment damage,severe personal injury or death. Troubleshooting must be performed by qualified persons whoknow about the hazards of fuel, electricity and machinery. Read Safety Precautions inside thefront cover and observe all instructions and precautions in this manual.

Possible Cause Corrective Action6. The fuel (gasoline) is con- Connect the genset to a container of known fuel quality and runtaminated. the genset under various loads. Replace the contents of the fuelsupply tank if there is a noticeable improvement in performance.7. The engine air filter element Replace the air filter element.is dirty.8. The exhaust system is re- Service as necessary.

stricted.9. The valve adjustment is in- Adjust according to Adjusting Valve Clearance (Lash) undercorrect. VALVE SYSTEM in Engine Block Assembly.10. The engine is worn or mal- Do the CYLINDER COMPRESSION TEST in Engine Subsys-functioning mechanically. terns and service as necessary according to Engine Block As-sembly.

THE ENGINE HUNTS1 & WARN ING I There are hazards present in troubleshooting that can cause equipment damage,severe personal injury or death. Troubleshooting must be performed by qualified persons whoknow about the hazards of fuel, electricity and machinery. Read Safety Precautions inside thefront cover and observe all instructions and precautions in this manual.

Possible Cause Corrective Action1. Fuel mixture (prior to Spec L Adjust according to Governor and Carburetor Adjustments under

only) and governor adjust- FUEL SYSTEM in Engine Subsystems.ments are incorrect.2. The governor spring is Replace the spring.weak.3. The governor mechanism is Service as necessary according to GEAR COVER and GOVER-worn. NOR CUP in Engine Block Assembly.

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THE ENGINEOVERHEATSIA WARNING I There are hazards present in troubleshooting that can cause equipment damage~severe personal injury or death. Troubleshooting must be performed by qualified persons whoknow about the hazards of fue/~electricity and machinery. Read Safety Precautions inside thefront cover and observe all instructions and precautions in this manual.

Possible Cause Corrective Action1. The fuel mixture is too lean. Adjust according to Govemor and Carburetor Adjustments underFUEL SYSTEM in Engine Subsystems (prior to Spec L only).2. The engine cooling fins are Clean as necessary.oily and dirty.

3. The installation restricts Verify that the installation is in accordance with the Installationcooling air. Manual.

THE ENGINE HAS HIGH OIL CONSUMPTIONIA WARNING I There are hazards present in troubleshooting that can cause equipment damage~severe personal injury or death. Troubleshooting must be performed by qualified persons whoknow about the hazards of fuel, electricity and machinery. Read Safety Precautions inside thefront cover and observe all instructions and precautions in this manual.

Possible Cause Corrective Action1. The oil is diluted or has too Replace the oil in the crankcase with oil of correct viscosity. Seelight a viscosity. the Operator's Manual for engine oil recommendations.2. The crankcase breather Service or replace the breather valve according to CRANKCASEvalve is dirty or defective. BREATHER ASSEMBLY in EngineSubsystems.3. There are oil leaks. Service as necessary.4. The oil bypass valve is Service as necessary according to LUBRICATION SYSTEM infaulty. Engine Block Assembly.5. The engine is worn or mai- o e the CYLINDER COMPRESSION TEST in Engine Subsys-functioning mechanically. terns and service as necessary according to Engine Block As-sembly.

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THE GENSET RUNS BUT THERE IS NO OUTPUT VOLTAGE14 WARN ING I There are hazards present in troubleshooting that can cause equipment damage,severe personal injury or death. Troubleshooting must be performed by qualified persons whoknow about the hazards of fuel, electricity and machinery. Read Safety Precautions inside thefront cover and observe all instructions and precautions in this manual.

IPossible Cause Corrective Action1. The line circuit breakers are Find out why the circuit breakers were turned OFF, make sure itOFF or have TRIPPED. is safe to reconnect power, and then throw the circuit breaker ON.(Beginning Spec J the Gen Ifthe circuit breakers have tripped, shut down the genset and ser-AC indicator light will be on vice as necessary to clear the short circuit or ground faun that

if generator output volt- caused tripping and then RESET the circuit breakers and restartage-ahead of the circuit the genset.breakers-is normal.)

2.A line circuit breaker is Shut down the genset, make sure the power output lines from thefaulty. genset have been disconnected from all other sources of power,attempt to RESET the circuit breaker and throw it ON and checkfor electrical continuity across its terminals. Replace the circuitbreaker if there is measurable resistance.

3. The generator is connected Remove the control panel and verify that all generator connec-wrong. 110nsare according to the appropriate connection diagram inGenerator.4. A main stator winding is Test and service according to TESTING THE GENERATOR inopen. (Beginning Spec J, if Generator.the Gen AC indicator light isnot on, there is a problem inthe generator or voltageregulator. )5. The quadrature winding of Test and service according to TESTING THE GENERATOR inthe stator is open (single- Generator.phase gensets only).6. Voltage regulator VR1 is Test and service according to TESTING THE VOLTAGE REG-faulty. ULATOR in Generator.

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THE OUTPUT VOLTAGE IS TOO HIGHOR TOO LOW1 & WARNING I There are hazards present in troubleshooting that can cause equipment damage,severe personal injury or death. Troubleshooting must be performed by qualified persons whoknow about the hazards of fuel, electricity and machinery. Read Safety Precautions inside thefront cover and observe all instructions and precautions in this manual.

Possible Cause Corrective Action1. Voltage has been adjusted Adjust the voltage as required. For single-phase gensets, the ad-incorrectly. justing rheostat is on the control panel (inside the control box onSpec J) and for three-phase gensets o

Documents

Onan BGD,NHD Service Manual BeginSpec H Pg 51-98