NOISE,MISFIRE,ROUGH IDLE INSPECT VALVE TRAIN

MODELS AFFECTED: 1987 CENTURYS WITH THE LB6 2.8L MPFI V6 ENGINE (VIN CODE W)

Some 1987 early production Centurys with 2.8L multi-port fuel injection engines manufactured prior to September 8, 1986, may exhibit unsatisfactory engine performance due to valve train malfunction. Poor engine performance may be described by the customer as an engine noise, misfire, or rough idle. Poor surface finish on the valve or guide resulting in valve-to-guide wear or seizure, has been found on some early production engines.

If customer comments are received concerning any of the above conditions, inspection of the valve train should be performed for broken, bent, or stuck valves and transfer and/or smearing of metal on the valve stems. If any of the above conditions are detected, BOTH ALUMINUM CYLINDER HEAD ASSEMBLIES MUST BE REPLACED.

Additionally, the top surface of each piston should be inspected for any evidence of contact with stuck valves. Replacement of the complete engine assembly is required if valve contact is evident.

Use applicable labor operation.

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.