159645-0720 ZEXEL 9 443 611 165 BOSCH PRESTROKE ACTUATOR 9443611165 1596450720 1156120790

Problem
The fuel injectors may fail on certain Challenger 75 Tractors and 3176 Truck Engines.
Affected Product
Model & Identification Number
Challenger 75 (4CJ1-406)
3176 (2YG1-Up; 7LG1-4822)
Parts Needed
Use the following parts in quantities needed to perform repairs. The application of each injector listed is noted. Use remanufactured injectors, unless it is not available.
0R3397 Injector Grp. (4P9510 if remanufactured is not available for 7LG 250-300 HP)0R3398 Injector Grp. (4P9520 if remanufactured is not available for 7LG 325 HP and Challenger 75 4CJ1-406)0R3399 Injector Grp. (4P9610 if remanufactured is not available for 2YG 250-275 HP)0R3400 Injector Grp. (4P9620 if remanufactured is not available for 2YG 300-325 HP)9X7317 Seal (injector tip O-ring)9X7557 Seal (injector upper O-ring)9X7722 Seal (injector lower O-ring)336044 Seal (injector thrust-pad-retaining O-ring)Action Required
See attached Rework Procedure.
Service Claim Allowances
Challenger 75 Tractors
This is a 2.5-hour job. Add 0.2 hours for 1st injector diagnostic test and 0.1 hours for each additional injector test. Add 1.2 hours for first injector sleeve replaced and 0.7 hours for each additional sleeve replaced.
3176 Truck Engines
Parts Disposition
Handle the parts in accordance with your Warranty Bulletin on warranty parts handling.
Attach. (1-Rework Procedure)Rework Procedure
1. Isolate the problem to the individual injector causing the problem. For this program only the failed injector(s) is covered so it is important to isolate the individual injector(s) causing the problem.A. For fuel dilution of the engine oil, first attempt to find the leak by pressurizing the low pressure system with the hand priming pump and the return line blocked off. Visually inspect each injector for leaks. It is also important to inspect the cylinder head casting for leaks around the injector bore, in the hold down bolt holes and along the gallery which crosses the camshaft compartment. If no leaks are found the injectors should be removed and leak tested using the 1U6661 Pop Tester. Drain the fuel manifold by removing the lower plug at the rear of the manifold. Remove the suspect injector(s). Test the injector(s) with the 1U6661 Pop Tester following the procedures in Special Instructions SEHS8867. Be sure to activate the solenoid valve and stroke the injector to create high pressure inside the injector when inspecting the high pressure plug for leaks. The plug is located at the base of the forged body.
The leak-down rate is a measure of plunger clearance leakage and should be checked when looking for fuel leaks.
Some small amount of leakage at the terminal post is permitted. Refer to Service Magazine September 21, 1991 or Truck Engine News October 1991.
B. For misfire or performance problems identification of a failed injector may require duplication of the conditions where the complaint exists. Interviewing the driver for the load and speed conditions where the problem occurs will be helpful. Diagnosis of the problem may require driving the truck with a load on or using a chassis dynomometer if the complaint arises only under loaded conditions.First attempt to diagnose the problem on the engine. Use the ECAP Tool to cut out cylinders under conditions which duplicate the complaint. Noticeable differences in the sound, fuel position (rack),