BASE OIL 6N1128 - 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 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 "PS8828" 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
December 31, 1997Problem
Some cylinder heads may have been manufactured incorrectly. The water passage holes in the cylinder head may not align with the holes in the cylinder block.This could result in an external water leak at the block to head gasket joint.
The cylinder heads that may have been manufactured incorrectly may be identified by the following date codes:
Affected Product
Model & Identification Number
Group 1
3508 (5TL177 4ZL309 , 4ZL310)
3512 (6FL109)
Group 2
777D (3PR155-159)
3508B (4GM158-160 6PN232 )
3512B (6WN105, 6WN107, 6WN108)
3516B (7RN421 8KN92 )
Group 3
G3516 (4EK1008, 4EK1009)
Parts Needed
Group 1
1 - 3E8918 Gasket Kit1 - 0R3648 Head GroupGroup 2
1 - 0R4735 Head Group1 - 1299926 Gasket KitGroup 3
1 - 1281142 Head Group1 - 1371935 Gasket KitAction Required
1. Measure the distance between the front face of the cylinder head casting and the machined surface on the front right hand edge of each cylinder head.2. If the distance is greater than 4.5 mm, then the cylinder head should be replaced.3. If the measurement is 4.5 mm or less, no further action is necessary.
Illustration 1
Illustration 2Service Claim Allowances
Labor Hour Breakdown Parts Dispostion
Groups 1 and 2
Cylinder heads being returned must be identified with the PSP number so that proper core credit can be issued and allow for the cylinder heads to be removed from the system.
Group 3
Cylinder heads from this group's repairs must be destroyed.