Usage:
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 be administered either before or after a failure. In either case the decision whether to apply the Program is made by the dealer. When reporting the repair, use "PS4079" as the Part Number and "7755" as the Group Number. If administered before failure, use "56" as the Warranty Claim Description Code and use "T" as the SIMS Description Code. If administered after failure, use "96" as the Warranty Claim Description Code and use "Z" as the SIMS Description Code.
Termination Date
August 31, 1998Problem
The pilot steering valve (stic steer) needs to be replaced to eliminate noise and instability on certain 988F, 990, and 992D Wheel Loaders. A new capsule assembly has been designed to address this instability. This new design also incorporates an interlocking T-slot for connecting the top and bottom portions of the capsule and an improved cap to allow for smoother operation
Affected Product
Model & Identification Number
988F (8YG1-Up 2ZR1-773 )
990 (7HK1-Up 4FR1-248 )
992D (7MJ1-Up)
Parts Needed
Action Required
See the attached rework procedure.
Service Claim Allowances
NOTE: This is a 1-hour job.
Parts Disposition
Handle the parts in accordance with your Warranty Bulletin on warranty parts handling.
Attach.
- (1-Rework Procedure)
Rework Procedure
Instructions for replacing an existing 6E3182 Stic Steer Valve with a 1432855 Stic Steer Valve.
1. Locate the machine on a level surface and engage the parking brake.
2. Loosen the hydraulic tank cap (for 990 machines loosen the cap to the steering system tank).
3. Refer to the service manual for instructions for removing the 6E3182 Stic Steer Valve from the cab. (988F SENR5737, 990 SENR6655, 992D SENR5717).
4. Install the new 1432855 Valve Group in place of the old 6E3182 Valve Group, using the 6V8625 Fittings with the 3K0360 Seals to connect the pilot pressure lines.
5. Apply equal torque to the valve body when installing in the cab, so as to not distort the valve body.
6. It is important to note when installing the handle mechanism to the stic steer shaft, that an " open end wrench be used on the handle of the valve to secure the joystick locknut. Otherwise side loads can be transferred to the valve plungers contributing to sticky operation.