SHUDDER/VIBRATION ON ACCEL. FROM STANDING START

SHUDDER/VIBRATION ON ACCELERATION Subject: FROM STANDING START (INSTALL NEW CRANKSHAFT PULLEY AND FLYWHEEL)

Models Affected: 1992 GRAND AM W/3300 V6 ENGINE (RPO LG7)

THIS BULLETIN IS BEING REVISED TO CHANGE THE SUBJECT MATTER, CORRECTION PARAGRAPH, AND ADD THE SERVICE PROCEDURE INFORMATION. THIS BULLETIN CANCELS AND REPLACES BULLETIN 92-6-23 ISSUED 11/91. PLEASE DISCARD BULLETIN 92-6-23.

CONDITION:

--------- Some early production 1992 Grand Am models with 3300 - V-6 engine may exhibit a shudder and/or vibration from a standing start.

CORRECTION:

---------- This condition could be corrected by changing the engine balance characteristic. The balance characteristic is usually changed enough to correct the condition with the installation of a new crankshaft pulley. When the crankshaft pulley alone does not correct the condition, installation of the new flywheel may be necessary. The new pulley and flywheel were introduced into production vehicles beginning on November 12, 1991 with the VIN breakpoints of "C" 212347 and "M" 022459.

SERVICE PROCEDURE:

1. Road test the vehicle to verify the condition.

2. If the shudder is present, replace the crankshaft pulley with part no. 24501985 and road test.

3. If the shudder is still present, replace the flywheel with part no. 24501986.

4. Road test the vehicle to verify the repair.

NOTE: Most vehicles will be repaired by just replacing the balancer. It is not necessary to replace the flywheel if replacing the crankshaft pulley repairs the vehicle.

NOTE: If installing flywheel, make sure there is sufficient clearance between the flywheel weight and the block. Rotate the flywheel 360 degrees by hand to verify sufficient clearance. If there is an interference between the weight and the block, remove stock from the block to obtain sufficient clearance.

NOTE: Early flywheels (before above VINS) can be identified by "33" stamped on the balance weight. Late flywheels (after VINS listed above) can be identified by "AN" stamped on the balance weight.

PARTS INFORMATION:

Parts are currently available from GMSPO.

PART NO.

Crankshaft Pulley 24501985

Flywheel 24501986

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.