DISC-OUTER 4E7508 - Caterpillar

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 only be administered after a failure occurs. The decision whether to apply the Program is made by the dealer. When reporting the repair, use "PS5365" 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.
This Revised Service Letter replaces the December 28, 1997 Service Letter. Changes have been made to the Swing Cylinder Test Procedure, Step 8.
Termination Date
December 31, 1998Problem
Swing drift can occur on a machine while roading or using the loader without the swing pin installed on certain 416C, 426C, 436C, 428B, 428C, 438B and 438C Backhoe Loaders. This problem can be solved by using the troubleshooting flow chart included with this program, and by replacing the main control spool and flow compensator spring in the swing section.
Affected Product
Model & Identification Number
416C (5YN219-2626 1XR317-485 1WR316-880 4ZN365-2454 )
426C (7WN236-275 1ZR227 1CR164-187 6XN236-745 1YR226-350 1MR254-279 )
436C (1RR299-302 2BR210 8TN184-307 2AR211-229 1PR298-311 1FR216-222 )
428C (8RN290-1152 2CR358-2996 )
428B (7EJ8653-9446)
438B (3KK3635-3814)
438C (9KN344-368 1JR404-409 2DR391-781 1TR449-666 )
Parts Needed
1 - 6E4317 Spring2 - 7F8607 Seal - O-Ring1 - 1486518 Stem AssemblyAction Required
See the attached rework procedure.
Service Claim Allowances
This is a 4-hour job.
Parts Disposition
Handle the parts in accordance with your Warranty Bulletin on warranty parts handling.
Attach.(1-Rework Procedure)Rework Procedure
Part 1 - Troubleshooting Guide And Swing Drift Tests
Use the troubleshooting guide (Illustration 1) to diagnose the cause(s) for the swing drift.
Illustration 1Swing Circuit Drift Test Procedure
1. Position the machine on a level surface with the implements in the service position (boom locked, stick fully in, loader bucket flat on the ground).2. Allowable drift rates are for 38 degrees C oil temperature. If temperature is lower, heat the system by stalling the boom down line relief valve.3. Cycle the swing to the left and right and back to center 5 times.4. Use swing cylinders to position the hoe straight out behind the tractor. Position stick cylinder to full extension. Use the boom cylinder to position the bucket 400 mm to 600 mm above the ground. Use the bucket cylinder to orient the bottom of the bucket parallel to the ground.5. Measure the hydraulic oil temperature. For temperatures other than 38 degrees C, adjust the drift test time as per Table 1. For intermediate points, adjust drift time by interpolating between adjacent points. 6. With the loader bucket flat on the ground, use the stabilizers to tilt the machine 10 degrees toward the machine right-hand side.7. Turn the engine off. Measure the drift on the machines left-hand side swing cylinder. The maximum allowable cylinder drift in either direction is 10 mm of extension in 5 minutes (see Table 1).8. Repeat the drift test with the machine tilted to the left-hand side, measuring drift on the machine right-hand side cylinder.Swing