C 3500 Truck 2WD V8-6.6L DSL Turbo VIN 1 (2002)
Torque Converter: All Technical Service Bulletins
A/T - Allison 1000, Leaks/Knocking Noise at Idle
Bulletin No.: 03-07-30-037C
Date: October 18, 2005
TECHNICAL
Subject:
Allison Transmission Oil Leak, Abnormal Knocking Noise Heard at Idle (Diagnose and Repair as Required)
Models:
2001-2003 Chevrolet Silverado 2500/3500 Series Pickup Models
2001-2003 GMC Sierra 2500/3500 Series Pickup Models
with Duramax(R) Diesel (RPO LB7) and Allison(R) 1000 Series Automatic Transmission (RPO M74)
Supercede:
This bulletin is being revised to update Warranty Labor Time Information. Please discard Corporate Bulletin Number 03-07-30-037B (Section 07 -
Transmission/Transaxle).
Condition
Some customers may comment that an abnormal knock noise is heard when the engine is running, or that there is an oil leak from the bottom of the
converter housing.
Possible Cause
The Plate, A/transmission Flex (Flexplate adapter plate) to converter mounting bolts may have loosened from engine/road vibration. Use the diagnostic
procedure given in this bulletin to diagnose the vehicle for this potential cause.
Technician Diagnosis procedure
If the under vehicle inspection reveals transmission oil leaking from the bottom of the converter housing to engine joint, perform the following diagnostic
procedure.
For the diagnosis procedure, perform the steps indicated below.
1.
Disconnect both of the negative battery cables.
2.
Remove the transmission fluid level indicator.
3.
Raise the vehicle until the right front wheel and tire can be removed.
4.
Remove the right front wheel and tire.
