790/795/797 Series

Jacobs Engine Brake

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INSTALLLATIONINSTRUCTIONSFOR790/795/797SERIESJACOBSENGINEBRAKES

Table of Contents

PageSection 1: Introduction 4-5HousingIdentification 4EngineIdentification 4SpecialTools 5RecommendedTorqueValues 5EngineCovers 5

Section 2: Engine Preparation 6-7Series 60 Engines with DDEC IV & VUndercoverWireHarnessInstallation(Retrofit) 6

Section 3: Brake Housing Installation 8-10SlavePistonAdjustment 10

Section 4: Engine Brake Controls 11

Section 5: Engine Brake Operational Check 12RockerCoverInstallation

Section 6: Engine Brake Maintenance 13-19TheoryofOperation 13ExhaustBlowdown 13PartIdentification 14ControlValve 15SlavePistonAdjustingScrew 16SolidScrew 16SolenoidValve 16MasterPiston 17-18SlavePiston 19

INSTALLATIONINSTRUCTIONSFOR790/795/797SERIESJACOBSENGINEBRAKES 3

General Information

TheseinstructionsdescribetheinstallationoftheModel790/795/797SeriesJacobsEngineBrake,designedfortheDetroitDieselSeries60engine.Forspecificapplicationinformationandslavepistonclearancesettings,refertotheJacobsEngineBrakeforDetroitDieselEnginesApplicationGuide,P/N4770,whichcanbefoundonwww.jakebrake.com.

Foradditionalinformationonthe790/795/797Seriesenginebrakes,refertotheSeries60EngineServiceManual,P/N6SE483.

UseOSHA-approvedcleaningsolventforcleaningparts.Originalpartstobereusedshouldbeinspectedforwearandreplacedasrequired.Besuretocoatpartswithcleanengineoilwhenreinstallingthem.

ThestandardJacobsVehicleSystemsWarrantyappliestotheinstallationofaJakeBrakeKit.ThewarrantyisadministeredbyDetroitDieselCorporation.ForspecificwarrantycoveragespleasecontactDetroitDiesel.

Safety PrecautionsThefollowingsymbolsinthismanualsignalconditionspotentiallydangeroustothemechanicorequipment.Readthismanualcarefully.Knowwhentheseconditionscanexist.Thentakenecessarystepstoprotectpersonnelaswellasequipment.

THISSyMBOLWARNSOFPOSSIBLEPERSONALINJURy.

THISSyMBOLREFERSTOPOSSIBLEEqUIPMENTDAMAGE.

NOTE: INDICATESANOPERATION,PROCEDUREORINSTRUCTIONTHATISIMPORTANTFORCORRECTSERVICE.

Fuels,electricalequipment,exhaustgasesandmovingenginepartspresentpotentialhazardsthatcouldresultinpersonalinjury.Takecarewheninstallingequipmentorparts.Alwayswearsafetyglasses.Alwaysusecorrecttoolsandfollowproperproceduresasoutlinedinthismanual.

NOTE:

NOTE:

THEJACOBSENGINEBRAKEISAVEHICLESLOWINGDEVICE,NOTAVEHICLESTOP-PINGDEVICE.ITISNOTASUBSTITUTEFORTHESERVICEBRAKINGSySTEM.THEVEHI-CLE'SSERVICEBRAKESMUSTBEUSEDTOBRINGTHEVEHICLETOACOMPLETESTOP.

NEVERREMOVEORADJUSTANyENGINEBRAKEORCOMPONENTWITHTHEENGINERUNNING.

4 INSTALLLATIONINSTRUCTIONSFOR790/795/797SERIESJACOBSENGINEBRAKES

Section 1: Introduction

HousingIdentificationThemodel,partnumber,serialnumber,andadjust-mentinformationarelocatedonthenameplateatthetopofeachhousing.(SeeFig.1andFig.)

Fig1

Fig

Fig3

EngineIdentificationEnginemodelidentification,serialnumberandmodelnumber,areonthenametaglocatedonthesideofthevalvecoverandstampedonthecylinderblockbeneaththeintakemanifold.(SeeFig.3)

INSTALLATIONINSTRUCTIONSFOR790/795/797SERIESJACOBSENGINEBRAKES 5

SpecialTools

General18mm-1pointSocket10mm-1pointSocket6"Extension13mmWrenchRetainingRingPliers(.047"diameter,45)DiagonalWireCutter

KentMooreRockerShaftLiftingTool P/NJ-35966AStudTorqueSocket P/NJ-44706AMasterPistonAssemblyTool P/NJ-45976(Model797Only)

DetroitDieselSeries60EngineServiceManual

JacobsFeelerGage,0.00"(0.508mm) P/N01778FeelerGage,0.06"(0.660mm) P/N017671FeelerGage,0.03"(0.813mm) P/N030504ControlValveCoverRemovalTool P/N016978

RecommendedTorqueValues

HousingHold-down CapScrews 80lb.-ft.(108N-m)

(lubricatedwithengineoil)

RockerShaftHold-downStud 100lb.-ft.(136N-m)

SlavePistonAdjusting ScrewLocknut 336lb.-in.(38N-m)

SolenoidValve 110lb.-in.(1.4N-m)

SlavePistonSpring ShoulderBolt 00lb.-in.(3N-m)

EngineCoversTheenginebrakehasbeendesignedtofitontheSeries60enginewithnoadditionalvalvecovers.Onenginesequippedwithatwo-piecealuminumvalvecover,itisNOTnecessarytoremovethelowervalvecovertoinstalltheenginebrake.However,onestyleuppervalvecovermayrequiremodificationatthebreatherhousinglocation(inside)forenginebrakeclearance.

NOTE:

Fig4

IFINTERFERENCEEXISTSBETWEENTHEFRONTENGINEBRAKEHOUSINGANDTHEROCKERCOVERCAPATTHEBREATHERHOUSINGLOCATION,GRINDTHEUPPERCOVERTOPROVIDECLEARANCE.CLEANCOVERTHOROUGHLyAFTERGRINDING.

6 INSTALLLATIONINSTRUCTIONSFOR790/795/797SERIESJACOBSENGINEBRAKES

AccessEngineOverhead

1. DisconnectBattery

FAILURETODISCONNECTBATTERyMAyCAUSEECMDAMAGE.

. Thoroughlycleanengine

3. Removevalvecoverandgasket.

NOTE: IFTHEENGINEHASATWO-PIECECOVER,THELOWERVALVECOVERBASEDOESNOTHAVETOBEREMOVED.

ExchangeWireHarness

1. Removeexistinginjectorharness&mountingclipsfromcylinderhead.

a.Separatewireharnessfromcylinderhead

retainingclips.b.Removeharnessmountingboltsfromrear

ofcylinderheadatheadpassthroughholes.(SeeFig.5)

NOTE: FORADDITIONALACCESSTOREARCyLINDERHEADPASSTHROUGH,THEROCKERSHAFTSMAyBEREMOVEDUSINGKENTMOORETOOL#J35996A

Section 2: Engine PreparationSeries 60 Engines with DDEC IV & V

c.Disconnect10pinwiresocketlocatedonintakesideofcylinderblockbelownumbersix(6)intakeport.(SeeFig.6)

d.Removeharnessbymanipulatingharness throughcylinderheadpassthroughatrear

ofhead.

e.Removeharnessretainingclipsfrom threadedholesinheadanddiscardclips.

(SeeFig.7)

Fig5

Fig6

Fig7

REMOVEENTIRECLIPS,HOLESWILLBERE-USEDFORJACOBSSUPPLIEDHOUSINGHOLDDOWNBOLTS

NOTE:

INSTALLATIONINSTRUCTIONSFOR790/795/797SERIESJACOBSENGINEBRAKES 7

Fig8

. InstallnewharnessP/N3536019foron-highwayapplicationsorP/N353444foroff-highwayapplications

a.Manipulateharnessthroughrearheadpass

through.Routeharnessconsistentto previousharness.

TAKECARENOTTODAMAGEWIRINGORCONNECTORS

b.Connectnewharnesstoinjectors.

c.Connect10pinwiringsockettomainengineharnessandsecureharnesswithplasticwiretiesasnecessarytobrakespacertubes(referenceFig11inSection3forimage). d.Secureharnessatrearheadpassthroughwithmountingbolts.

HARNESS IS NOW READY FOR JAKE BRAKE INSTALLATION

8 INSTALLLATIONINSTRUCTIONSFOR790/795/797SERIESJACOBSENGINEBRAKES

Section 3: Brake Housing Installation

InstallEngineBrakeHousings

1. RemoveRockerShaftAssembliesusing18mmSocketandKentmoore#J-35996A

NOTE:

WEARSAFETyGLASSESWHILEBLOWINGTHEOILFROMTHEBOLT

HOLES.

a.RemoverockerarmholddownboltsM1x100mmlong(6).

b.Removerockerarmnutsatfrontandrearofhead().

c.Retorquerockershaftstudslocatedatfrontandrearofcylinderheadat100lb.-ft.(136N-m)withKentmooretool#J-44706A.(SeeFig.9)

.SetRockerShaftAssembliesbackoncamcaps.

Fig9Fig11

3.Setfront&rearJakeBrakehousingsonrockershaftslocatingonretorquedstuds.Ensurethatmasterpistonpushrodswillengagewithpocketlocatedontopofinjectorrockerarm(seeFig.10).

4.PositionJakeBrakemountingspacertubesunderouterhousingmountinglegs.(SeeFig.11)

NOTE: TOPREVENTDAMAGETOWIREHARNESS,RUNWIRESINBOARDOFSPACERTUBESANDSECURETOTUBESUSINGPLASTICWIRETIES.

Fig10

REMOVINGTHEOILFROMTHEBOLTHOLESPREVENTSTHECyLINDERHEADFROMCRACKINGWHENBOLTSARETIGHTENED.ATTACHALENGTHOFTUBINGTOANAIRGUNNOZZLEANDBLOWOUTTHEOILFROMTHEROCKERSHAFTHOLD-DOWNBOLTHOLES.COVERTHEHOLESWITHHANDTOWELSTOMINIMIZEOILSPRAy

INSTALLATIONINSTRUCTIONSFOR790/795/797SERIESJACOBSENGINEBRAKES 9

Fig15

5. InstallJacobssuppliedmountingbolts,twolengths,andoriginalDDCstudhexnutsremovedearlier.(SeeFig.1)

A-M1x140mm-usedontheexhaustsideoftheengine

B-M1x170mm-usedonintakeside(solenoidside)ofengine

NOTE:

NOTE:

Fig1

Fig13

Fig14

6. TorquedownbrakehousingpersequenceinFig.14at80lb.-ft.(108N-m).

7.VerifyexhaustandintakevalvelashisstillwithinDDCspecificationsforengine.Ifvalvelashisoutoftolerance,refertoDDCmanualforresettingprocedure.

8.Attachsolenoidwirestosolenoidandengagewiresinwireretainerclip.(SeeFig.15)

NOTE:

BEFORETORqUINGENSURETHATWIREHARNESSISINBOARDSOASTONOTINTERFEREWITHVALVECOVER

BEFORETIGHTENINGHOLDDOWNBOLTS,MOVETHEHOUSINGFROMSIDETOSIDEANDTHENLOCATEHOUSINGINCENTEROFTRAVEL.(SEEFIG.13)

A

B

797BAPPLICATIONSUTILIZEADDCWIREHARNESSTRAyWHICHISAT-TACHEDONTOTHEREARBRAKEHOUSING.

REFERENCETHEDDCSERIES60ENGINESERVICEMANUALP/N6SE483FORPROPERTRAyTORqUINGPRO-CEDURE

10 INSTALLLATIONINSTRUCTIONSFOR790/795/797SERIESJACOBSENGINEBRAKES

4. Rechecklashsettings.Iflashsettingisincorrect,repeatsteps(1)through(3)above

NOTE:

MODEL 795/797 SERIES

1. Backouttheadjustingscrewsontheslavepistonsuntiltheslavepistonsdonottouchtheexhaustrockerarmadjustingscrews.

. Inserttheproperfeelergage(correctadjustmentisonhousingdatatag)betweentheslavepistonandtheexhaustrockeradjustingscrew.Usinga3/16"(inch)hexwrenchturnintheadjustingscrewuntiltheslavepistoncontactstheexhaustrockeradjustingscrewthroughthefeelergage,andadragisfeltonthegage.

3. Holdtheadjustingscrewinplaceandtorquethelocknutto38Nm(336lb-in).Rechecklashsettings.Iflashsettingisincorrect,repeatsteps(1)through(3)above.

Adjust Slave Piston Clearance

FAILURETOFOLLOWADJUSTMENTPROCEDURESCANRESULTINENGINEORENGINEBRAKEDAMAGE.

NOTE: MAKESLAVEPISTONADJUSTMENTWITHTHEENGINESTOPPEDANDCOLD.ADJUSTEACHCyLINDERWITHTHEEXHAUSTVALVESINTHECLOSEDPOSITION.

NOTE: REFERENCEJACOBSAPPLICATIONGUIDEP/N4770FORPROPERENGINEANDBRAKESPECI