Exhaust Pipe - Knock Noise After Water Splash
90cadillac09Bulletin No. T-90-88
File in Group 6F
Number 10
Corp. Ref. NO. 806601R
Date July, 1990
SUBJECT: KNOCK NOISE CAUSED BY EXHAUST PIPE CONTACT WITH UNDERBODY SHIELD, AFTER WATER SPLASH
MODELS AFFECTED: 1985-1990 DE VILLES AND FLEETWOODS
On some 1985-1990 DeVilles and Fleetwoods a knocking noise caused by exhaust pipe contact at the intermediate heat shield (located between the exhaust pipe and the floor panel) may occur when water or slush is splashed on the underside of the exhaust pipe. The resultant rapid cooling and contraction of the pipe may cause it to bow upward resulting in contact.
To repair this condition install exhaust pipe splash shields using the following procedure:
1. Order the shields (two pieces) from GMSPO, P/N 25533711.
Figure 1 - Shield Installation:
Figure 2 - Notching Front and Rear Shields:
2. Install the shields with three stainless steel clamps and the existing front bracket. Refer to Figure 1. For 1989-1990 vehicles, notch both the front and rear halves of the shield (refer to Figure 2) to clear the cross brace welded to the exhaust pipe.
Parts are currently available from GMSPO.