Product Support Program For Fuel Injectors On Certain Challenger 75 Tractors And 3176 Truck Engines Caterpillar

NOTE: The information supplied in this service letter may not be valid after the termination date of this program. Do not perform the work outlined in this Service Letter after the termination date without first contacting your Caterpillar product analyst.

NOTE: This Program can only be administered after a failure occurs. The decision whether to apply the Program is made by the dealer. When reporting the repair, use "PS0642" as the Part Number and "7755" as the Group Number. Use "96" as the Warranty Claim Description Code and use "Z" as the SIMS Description Code.

Termination Date

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

NOTE: 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.

NOTE: 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.

NOTE: The leak-down rate is a measure of plunger clearance leakage and should be checked when looking for fuel leaks.

NOTE: 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), or measured power when comparing cylinders may indicate a problem with that cylinder. Be sure to check for air in the fuel, valve settings, injector pre-stoke, electrical connectors, etc. on suspect cylinders.

Drain the fuel manifold by removing the lower plug at the rear of the manifold. Remove the suspect injector(s).

Inspect the injectors for signs of combustion leaks. A combustion leak will leave carbon on the injector cone as well as damage the middle 9X7722 O-ring seal. A Combustion leak will normally result in rough running and/or low power. It is not necessary to replace an injector just because a combustion leak has occurred.

Test the injector(s) with the 1U6661 Pop Tester (this can be omitted if the failure can be visually detected such as a broken C-clip, stuck plunger or loose solenoid valve). Test the injector(s) with the 1U6661 Pop Tester following the procedures in Special Instructions SEHS8867.

Record the VOP (load cell gauge pressure), leak down rate, and spray pattern as well as any external leaks. Specifications for the injector are included in Special Instruction SEHS8884. Include the test information in the claim story for any injector which is to be claimed.

2. Replace any injector which is not within test specifications, has been proven to cause a problem using an ECAP or chassis dyno, or has an obvious failure (such as a broken c-clip). Record the reason for any injector replacement and include this in the claim story.

3. Install all reusable injectors. Inspect the edge of the injector cones for nicks or damage. If any damage is present do not reuse the injector.

4. Ream the injector sleeves before installing the injectors. Ream until the sleeve has been cut to provide a full length concentric taper past the 9X7317 seal/sleeve interface. Full removal of the indentation created by step cone injectors is not required.

5. Check the reamed seat with tool makers ink if a combustion leak was evident or a new sleeve was installed during the repair. This step should be omitted for step cone injectors (part numbers 4P1410, 4P1420, 4P2810, 4P2820, 0R3177 and 0R3178). Check the seat by applying a thin coat of tool-makers ink (9U6075 or 9U6076) to the bottom of the sleeve and allow to dry. Install the injector without O-ring and tighten the hold-down bolt to 33 N-m (24 ft-lb). Remove the injector and check for line contact 360 degrees around the bottom of the sleeve within the reamed area. Continue to ream the sleeve if line contact is not evident.

6. Install new O-rings to the injector. Be sure to include the 9X7317 combustion seal to the tip of the injector. Lubricate the upper two O-rings with STP to prevent cutting during installation.

7. Install the injectors. Apply 6V4876 Molykote to the holddown bolt threads and tighten the bolts to 33 N-m (24 ft-lb). Make sure the longer 5P8347 Bolts and 4P8525 Spacers (or 8T0100 Bolts and 4P1711 Spacers) are used.

8. Inspect the bridge assemblies for wear and install the rocker arm assemblies.

9. Adjust valves, bridges, and injectors. On injector preload adjustment, turn rocker arm adjusting screw to contact plus two turns to remove slack in the system. Back the screw out and hold down on the opposite side of the rocker arm to keep pressure on the push rod/camshaft. Then adjust to contact plus 180 degrees (one half turn).

10. Install the Jake Brake (if equipped) and adjust it. Then, complete assembly.