INABILITY TO SET IGNITION TIMING

MODELS AFFECTED: 1987 SKYHAWKS WITH LT2 2.OL OHC AND LT3 2.0 OHC TURBO ENGINES (VIN CODE K AND M)

Early build LT2 and LT3 engines used a crankshaft dampener that could experience an outer "timing" ring rotation relative to the inner crankshaft drive. The result is the inability to check or set spark timing.

If this occurs, install a new dampener pulley, P/N 10083143. Below are the VIN code breakpoints of potential affected vehicles.

ENGINE VIN CODE VEHICLE VIN PRIOR TO K HK427650 M HK443011

WARRANTY INFORMATION

Use Labor Operation J0700 for dampener pulley replacement.

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.