LINES GP-WATER 2P7728 - Caterpillar

Caterpillar: Confidential Yellow
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.
This Program can be administered either before or after a failure. However, it is recommended that it be administered before a failure occurs. In either case the decision whether to apply the Program is made by the dealer. When reporting the repair, use "PS4531" as Part Number, "7755" as Group Number, and "96" as Description Code.
This Revised Service Letter replaces the October 8, 1990 (Revised April 1992) Service Letter. Changes have been made to remove 3306B and 3406B Truck Engines from the listed Affected Product.
Termination Date
April 30, 1993Problem
The 3G3835 Pin may loosen and disengage from the Governor Rack Servo Cylinder Assembly on certain 3304, 3306, 3306B, 3406 and 3406B Engines.
Affected Product
Model & Identification Number
3304 (10E2309-2538; 13E885-911; 83Z4257-5061)
3306/3306B (2AJ219-299; 49S3463-3517; 64Z6310-8973; 66D50259-50313; 84Z1287-1822; 85Z3671-6899)
3406/3406B (2WB5527-6930; 4RG150-211; 4TB1448-1836; 6TB4575-5571)
Parts Needed
3304 and 3306 Engines
1 - 7C0791 Cylinder As.1- 8N2496 Gasket3406 and 3406B Engines
1 - 7C0790 Cylinder As.1 - 8N9384 GasketAction Required
Parts Stock
Inspect all 8N9678 and 8N2507 Servo Piston Assemblies, and all 7C0790 and 7C0791 Cylinder Assemblies in parts stock. Remove all servo piston assemblies and cylinder assemblies assembled with a flat faced pin. Illustration 2 in the attached procedure shows pins having a smooth spherical radius and a flat face on the ends.
Affected Product
See the attached procedure.
Service Claim Allowances
This is a 2.5-hour job.
Parts Disposition
Any parts removed (with the exception of cores used for Caterpillar Remanufactured parts) can be rendered useless and scrapped immediately upon completion of the repair.
Attach. (1-Rework Procedure)Rework Procedure
Check the upper rear corner, right hand side of the engine cylinder block for the code "D5". If the code is present, the engine has already been reworked. If the code is not present, rework as follows:
Disconnect throttle linkage. Remove fuel shut-off solenoid, air fuel ratio control, the rear governor housing and gasket, and rack servo piston assembly. See Illustration 1.
Remove the rack cylinder assembly from the servo piston assembly and replace.
Use the recommended rack cylinder assembly only (See Illustration 3). Also, do not attempt to restake pin to salvage the cylinder assembly.
Assemble and seal the governor housing. Stamp "D5" on the upper rear corner, right hand side of the engine cylinder block.
If the engine has operated significantly above high idle at any time, refer to the November 2, 1987, October 17, 1988, and March 27, 1989 Service Magazine Articles for the recommended diagnostic procedures.
Illustration 1 - Rack Servo Cylinder Assembly
Illustration 2
Illustration 3 - Recommended Cylinder Assembly Using Pin With Smooth Spherical Radius