GRUNT/SQUEAK SHIFT FROM PARK TO REVERSE/DRIVE

Subject: GRUNT/SQUEAK SHIFTING FROM PARK TO REVERSE/DRIVE OR UNDER HEAVY ENGINE LOAD (USE DIAGNOSTIC PROCEDURE)

Models Affected: 1992-93 GRAND AM MODELS

THIS BULLETIN IS BEING REVISED TO PROVIDE UPDATED PARTS INFORMATION (LOWER ENGINE MOUNT STRUT, P/N 22595752, INCLUDE VIN BREAKPOINTS, AND ADD A LABOR OPERATION NUMBER. THIS BULLETIN CANCELS AND REPLACES BULLETIN 93-6-29 ISSUED 2/93. PLEASE DISCARD BULLETIN 93-6-29.

ENGINE APPLICATION:

2.3L (VIN 3 - RPO L40) 2.3L (VIN A - RPO LGO) 2.3L (VIN D - RPO LD2) 3.3L (VIN N - RPO LG7)

CONDITION:

--------- Some customers may comment about a grunt, squawk or squeak noise when shifting from park to reverse or drive. The same noise may also be heard during heavy engine load, such as quick acceleration. The noise will most likely occur in cold ambient temperatures or wet conditions. This noise may be misdiagnosed as coming from the exhaust seal. Use the procedure found in "Service Information" below to determine the location of the noise.

CAUSE:

----- On 1992-93 vehicles, the lower engine mount strut rubber may move against its metal casting during the shift or heavy engine loads. On 1992 Quad 4 engines, a similar noise can be caused by high clamp load on the exhaust seal. This condition is addressed by 92-6-20A issued 9/92.

CORRECTION:

---------- When the diagnosis indicates the exhaust system is at fault on 1992 Quad 4 engines, refer to Pontiac service bulletin 92-6-20A to repair the exhaust system. All 1993 model year production vehicles with Quad 4 engines have a redesigned exhaust manifold and seal. Install revised lower engine mount strut, P/N 22595752, when diagnosis indicates the lower engine mount strut is at fault. Vehicles built after the following VIN breakpoints have the revised lower engine mount strut installed in production:

Lansing (A) PM602516 Lansing (B) PC789942

SERVICE INFORMATION:

IMPORTANT: Torque axis mounting systems allow more engine movement than other engine mounting systems. This movement may seem excessive but that is the design intent of the mounting system. Do NOT replace any torque axis mounts for movement unless there is damage to the mount or rubber.

Spray 3M silicone lubricant P/N 51135-08935 or equivalent on the lower engine mount strut between the rubber and metal. NOTE: Use only silicone type lubricant between the rubber and metal surfaces. Any other lubricant will destroy the rubber making replacement of the lower engine mount strut necessary.

If the noise still exists, refer to Pontiac service bulletin 92-6-20A for exhaust system seals and submit labor operation T1948. If the noise is gone, replace the lower engine mount strut with P/N 22595752 and submit labor operation T3368. The silicone lubricant will eliminate the condition for a short time only.

Parts are expected to be available on September 6, 1993.

Labor Operation Number: T1948 - Lower engine mount strut diagnosis T3368 - Lower engine mount strut diagnosis and replace

Labor Time: 0.2 hrs. - T1948 0.4 hrs. - T3368

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.