SENSOR GP-PO 4900656 - 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.
Termination Date
March 31, 1999Problem
The bond between the steel and the rubber on the 3Q7749 Seal may allow gas to leak from the accumulator. All the 3Q7749 Seals need to be removed from dealer inventory, and replaced in all applicable seal kits with date codes between January 1995 and June 1995.
Action Required
Remove all 3Q7749 Seals from Parts Stock. Rework all applicable seal kits with date codes between January 1995 and June 1995 in Parts Stock by replacing the existing 3Q7749 Seal with a new 3Q7749 Seal. See the attached Rework Procedure. Those seal kits include:
3Q7325Seal Kit - H703Q7437Seal Kit - B1153Q7476Seal Kit - B1303Q7534Seal Kit - H1703Q7535Seal Kit - H1603Q7763Seal Kit - H703Q7938Seal Kit - H1403Q7953Seal Kit - H195 1094745 Seal Kit - H63 1168212 Seal Kit - H100 1170467 Seal Kit - H120 1207351 Seal Kit - H115 1209989 Seal Kit - H130 1210227 Seal Kit - H180 1508828 Seal Kit - H90C 1522515 Seal Kit - H45 1522553 Seal Kit - H50 1531110 Seal Kit - H120CService Claim Allowances
Submit one claim for all 3Q7749 Seals removed from Parts Stock or any seal kit reworked in dealer inventory.
Parts Disposition
Handle the parts in accordance with your Warranty Bulletin on warranty parts handling.
Attach.(1-Rework Procedure)Rework Procedure
1. The color of the Usit-rings has been changed from blue to black. This is because the supplier change because the blue ones had quality problems.2. The black Usit-rings have been taken in production partially starting in June of 1995. The Usit-rings with blue rubber have been used since June 1997. Since 1997, only black Usit-rings have been used in production and in parts department.3. Visually inspect the new unused Usit-ring.a. The rubber part inside the steel part should not rotate.b. There should not be any cracks or other irregularities in the Usit-ring.c. There should not be excessive burrs in the rubber part (rubber should not cover all steel surface). See Illustration 1.
Illustration 1