Ninety-Eight V6-3800 3.8L (1989)
Heat Shield: All Technical Service Bulletins
Exhaust System Splash Shield - Knocking Noise
NUMBER:
91-T-96
CORP.REF.NO: 806601R
DATE:
April 1991
SECTION:
6F
SUBJECT:
EXHAUST SYSTEM WATER/SLUSH SPLASH SHIELD, NEW PART NUMBER AVAILABLE
MODELS/YEARS:
1986-91 EIGHTY-EIGHT
1985-91 NINETY-EIGHT
THIS BULLETIN CANCELS AND REPLACES DEALER TECHNICAL BULLETIN 90-T-128 WHICH SHOULD BE DISCARDED.
On the above vehicles, it is possible to have a condition of the exhaust pipe contacting the intermediate heat shield, which is located between the exhaust
pipe and the floor panel. This condition could occur when water or slush is splashed onto the underside of the exhaust pipe. The rapid cooling and
resultant contraction may cause the pipe to bow upwards making contact with the shield above it.
It is possible that the knocking noise could be transmftted to the engine through the exhaust pipe. This could be picked up by the ESC knock sensor,
which in turn, would signal the ECM (by lack of voltage), causing it to respond with retarded ignition timing, thinking the engine has a detonation
condition.
Figure 1
CORRECTION FOR 1985-1988 VEHICLES:
1.
Order shield from GMSPO (Part Number 25533711) which consists of two pieces.
2.
Install the shields with three stainless steel clamps and the existing front bracket (See Figure 1).
