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The following diagnosis might be helpful if the vehicle exhibits the symptom described in the PI.
Platinum tip spark plug maintenance Information
The following information was originally sent to all General Motors dealers as a DCS message on October 14, 1999:
It has come to our attention that some GM dealers sell a customer service to remove platinum tipped spark plugs and clean the threads at regular intervals to prevent the seizure of the spark plugs in the cylinder heads at high mileage. Platinum tipped spark plugs are designed to operate under normal vehicle operating conditions for up to 100,000 miles (160,000 kms) without periodic maintenance. When no engine performance concerns are present, platinum tipped spark plugs should not be removed for periodic inspection and cleaning of threads, doing so would compromise the spark plugs ability to withstand their corrosive environment. The threaded area, although not sealed, serves as a protective environment against most harmful elements. Removing and cleaning spark plugs will introduce metallic debris and brush scrapings into the thread area which may further the corrosion process. Chromate coated spark plugs should not be wire brushed or handled in any way once they are put in service. Chromium topcoats form a protective oxide on spark plugs that is not effective if scratched. Both coated and uncoated spark plugs will have the best chance of surviving a corrosive environment if they are left in position. Attempts to maintain spark plugs by removing them and cleaning the threads can actually create the corrosive condition that the procedure was intended to prevent.
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Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance.
(95 - 02 All Passenger Cars with gasoline engines) and (95 - 02 All Passenger Trucks with gasoline engines)
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GM bulletins are intended for use by professional technicians,
NOT a "do-it-yourselfer". They are written to inform these
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 your GM dealer for information on whether
your vehicle may benefit from the information. |
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