- Truck Engines:
- C-10 (S/N: MBJ1-UP; 3CS1-UP)
- C-12 (S/N: MBL1-UP; 2KS1-UP)
One of the primary failure modes of exhaust valves under 100,000 miles originates at the D-Lash screw in the compression brake housing. This failure needs to be correctly diagnosed in order to prevent repeat failures on the same engine and in order to provide engineering with accurate data for corrective actions and improvement of products. The following simple inspection procedure of the D-Lash screw can help to determine the cause of the failure.
- Remove the D-Lash screw.
- Pull lightly on the plunger that is located within the D-Lash assembly.
- If the plunger separates from the body of the D-Lash assembly, then the snap ring that is located on the inside of the D-Lash assembly has failed.
Failure of the snap ring will allow the valve to contact the piston. If a failure of the snap ring has occurred, the part number 143-6664 D-Lash screw should be reported as the part that is causing failure. Jacobs introduced a new D-Lash test fixture in February 2001 and Jacobs introduced an improved retaining wire in March 2001.