EXHAUST SYSTEM WATER/SPLASH SHIELD (NEW PART NUMBER)

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 transmitted 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.

CORRECTION FOR 1985-1988 VEHICLES:

1. Order shield from GMSPO (Part Number 2553371 1) which consists of two pieces.

2. Install the shields with three stainless steel clamps and the existing front bracket (See Figure 1).

CORRECTION FOR 1989-1991 VEHICLES:

1. Order shield from GMSPO (Part Number 2553371 1).

2. Notch both the front and rear halves of the shield (See Figure 2) to clear the cross brace welded to the exhaust pipe. Install the shields with three stainless steel clamps and the existing front bracket (See Figure 2).

Parts are currently available from GMSPO.

WARRANTY INFORMATION:

Labor Operation Number: T5179 Labor Time: 0.3 hour (1985-88 vehicles) 0.6 hour (1989-91 vehicles) Trouble Code: 92

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.