Exhaust - Metallic Rattle Noise
File In Section: 6 - EngineBulletin No: 57-66-02
Date: October, 1995
Subject:
Exhaust Rattle Noise (Service Procedure)
Models:
1996 Cadillac Concours, DeVille, Eldorado, Seville, STS
with 4.6L Engine (VINs 9, V - RPOs L37, LD8)
Condition
Some customers may comment on a metallic rattle sound, which is present during vehicle operation. This metallic rattle is most noticeable with the NO clutch engaged during idle (brake on or off) and/or under light to moderate acceleration.
Cause
This noise emanates from three tabs within the flex coupling (1) where three sections of the exhaust manifold rear pipe are welded together.
Correction
To determine if the exhaust manifold rear pipe is causing the exhaust system to rattle, refer to the following procedure:
1. Place the vehicle on suitable hoist and raise the vehicle according to the procedure outlined in the service manual.
2. Start engine and turn on air conditioning system.
3. Wearing a heat protected glove, gently push the exhaust system at the three way + oxidation catalytic converter and exhaust manifold rear pipe mating surfaces (2) in a fore to aft direction and listen for exhaust rattle coming from within the flex coupling.
4. If exhaust rattle is present within the flex coupling, the exhaust manifold rear pipe must be replaced. Exhaust manifold rear pipe units are available with an internal single piece sleeve which will correct this condition.
5. If the exhaust system rattles and or contacts the body of the vehicle, the exhaust system must be aligned according to the exhaust system alignment procedure in Section 6F of the 1996 E/K/K Special Service Information Manual.
Parts Information
Whenever it is necessary to replace the exhaust manifold rear pipe, refer to the following part number:
Description Part Number
Exhaust Manifold Rear Pipe 3544526
Parts are currently available from GMSPO.
Warranty Information
For vehicles repaired under warranty, use:
Labor Operation Labor Time
L2160 (replace rear pipe) Use published labor operation time.
L2005 (exhaust system alignment) Use published labor operation time.