COVER AS-SOUND SUPPRESSION 3990819 - Caterpillar

Introduction
The problem that is identified below does not have a known permanent solution. Until a permanent solution is known, use the solution that is identified below.Problem
Illustration 1 g03685961
Typical exampleMain relief valveThe 4B-9880 Ball (B) in the 9U-8668 Spool (A) of the main relief valve may be missing on the machines listed above. The missing ball may cause pressure instability or noise in the power train oil system.Solution
Caterpillar is aware of this problem, and is recommending the following interim corrective action.If there is a noise or pressure instability in the power train oil system, inspect the 9U-8668 Spool within the main relief valve. Verify the 4B-9880 Ball is installed and the spool is oriented correctly. If the ball is not found, install a new 4B-9880 Ball .