TecBrake Engine BrakeModel T425A-STCFor Cummins 855 STC Series EnginesThe TecBrake T425A-STC engine brake may be installedon Step Timing Control (STC) versions of the Cummins855 series engine. It can not be installed on theCummins 86NT MVT, 88NT, or 89NT model engines. Itshould only be installed on engines whose CPL numbersare included in the Application instructions are detailed in themodel T425A Installation Manual (TB990105).The changes in procedures required for model425A-STC is covered in this installationaddendum. Please read this addendum andnote the changes on the Installation Manualbefore beginning ToolsThe following special tools are required for installation:1. Crowfoot wrench- 9/16"2. Crowfoot wrench- 5/8"3. Socket, extra deep- 5/8"4. Feeler gauge- "5. STC Tappet setting tool- Cummins Part 3A -VALVE AND INJECTOR ADJUSTMENTDifferent procedures are used in setting injectors on STCversus fixed timed engines. Refer to the Injector and ValveSetting Chart (Figure 3A-1) to determine the crankshaftposition when adjusting injectors and exhaust Valve Setting- Crankshaft Position ChartBar in Direction ofPulleySetSetRotation Position InjectorValveSTARTA35ADVANCE TOB63ADVANCE TOC26ADVANCE TOA42ADVANCE TOB14ADVANCE TOC51Figure 3A-11. If you did not previously position the crankshaft forthe valve and injector adjustments, turn the crankshaftclockwise until the "A" mark on the accessory drive pulleyis aligned with pointer on the gear case At this point, the intake and exhaust valves should beclosed for cylinder No. 5 and the rocker levers should be"loose". The injector plunger for cylinder No. 3 must alsobe at the top of its travel. If it is not, turn the crankshaftanother 360 degrees and realign the mark "A" with InjectorsStep Timing Control (STC)A special tappet tool (Cummins No. ST-3822648) must beused to set the STC style injectors. This tool has a smalllocating pin that locates the tool in one of the four holes inthe 3A-21. Place the tool on top of the tappet then rotate it untilthe pin is inserted into one of the holes in the tappet. Applythumb pressure to the tool handle in order to hold the tappetat the maximum extended Set the injector rocker arm adjusting screw to 5-6 injector torque wrench (P/N 3376592) may beused to set the torque. Remove tool before baring the engineto the next position as indicated in the setting chart (Figure3A-1).3. Tighten adjusting screw locknut to 45 lbft (60 N*m).SECTION 4A -BRAKE HOUSING INSTALLATIONSlave Piston Adjusting Screw:The T425A-STC engine brake kit has adjusting screw PartNo. TB924917, color-coded green already installed in thebrake housings. This configuration is the only one requiredfor all possible Cummins 86 NT STC applicationsregardless of turbocharger piston lash setting for TecBrake T425A-STCis always " for all with Step Timing Control (STC)1. An oil connection is required from the rear enginebrake housing to the STC valve (Figure 4A-1). Theoil connection allows operation of engine brakewithout overloading the engine s valve Addendum:TecBrake Engine Brake Model T425A-SCTFigure 4A-12. Remove the oil drain line from the STC valve andengine Cap off fitting in the block with cap supplied on STCInterface 4A-24. Remove the plug from the rear engine brakehousing as shown on figure Install the TecBrake elbow fitting into the rearof brake housing. Be sure that O-ring is fully seatedagainst housing. Elbow fitting must be Install one end of TecBrake hose assembly tothe fitting. Tighten the fitting Install the other end of sensing line on the STCvalve as shown on figure 4A-3. Tighten Secure the hose to the engine using 4A-3CAUTIONFailure to use this sensing line on these engines cancause major engine CHARTADJUSTING SCREWCPL MODEL PART NO. COLOR 806NTCC365/400 STC TB924917GREEN 821NTC444 BCIV STC TB924917GREEN 833NTC365/400 NBCIV TB924917GREEN 903NTC444 NBCIVTB924917GREEN 904NTC365/400 NBCIV TB924917GREEN1215NTC444 NBCIVTB924917GREENTecBrake Inc. Box 27822 Houston, Texas 77227 1999 TecBrake Bulletin No. TB990179 04/09/99Cummins , STC , Step Timing Control and Celect are registered trademarks of Cummins Engine Co. Inc.
Installation Addendum: TecBrake Engine Brake Model T425A …
TecBrake Engine Brake Model T425A-STC For Cummins 855 STC Series Engines The TecBrake T425A-STC engine brake may be installed on Step Timing Control (STC) versions of the Cummins
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