CHIRP NOISE FROM INJECTION REACTION SYSTEM AT IDLE

MODEL: 1988 C/K 10-30 TRUCKS WITH 5.0L (VIN CODE H) OR 5.7L (VIN CODE K) EN- GINES

THIS BULLETIN CANCELS AND REPLACES TRUCK SERVICE BULLETIN 88-T-85 DATED FEBRUARY, 1988, ALL COPIES OF WHICH SHOULD BE DISCARDED. THIS BULLETIN HAS BEEN REVISED TO CORRECT MODEL APPLICATION.

Some 1988 C/K 10-30 trucks may have been built with incorret Air Injection Reaction System (A.I.R.) check valves and may experience a chirping noise at idle. This condition may be diagnosed by disconneting the A.I.R. hoses at the check valves and repeating the condition at which the noise occurred. If the noise is eliminated, the A.I.R. hoses should be reconnected and the check valves should be replaced with check valve, P/N 22050642. Parts are currently available from GMSPO.

Labor Op: J6090 - Valve, Air Check Replace, Right Side .2 hr J6091 - Valve, Air Check Replace, Left Side .2 hr

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.