SPARK PLUG USAGE UPDATE PRODUCTION CHANGE- P/N

VEHICLES AFFECTED: 1988 LIGHT-DUTY TRUCKS WITH 4.3L, 5.0L AND 5.7L ENGINES (VIN CODES Z, H AND K)

This bulletin is to advise dealers that there has been a spark plug usage change in production for 1988 trucks with the 4.3L, 5.0L and 5.7L engines. Engines built through August 30, 1987, have spark plugs AC CR43TS, P/N 5614029. Engines built starting August 31, 1987, have spark plugs AC R43TS, P/N 5613325. Due to design differences between the CR43TS and R43TS spark plugs, a radio popping noise may be encountered in vehicles equipped with CR43TS spark plugs. This condition can be repaired by replacing CR43TS spark plugs with R43TS spark plugs. Spark plug gap is 0.89 mm (0.035").

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.