ENG. TICK/KNOCK/RATTLE NOISE (NORMAL CONDITION. Chevrolet Chevy P42 Commercial Chassis 1997

SUBJECT: ENGINE TICK/KNOCK/RATTLE NOISE (NORMAL CONDITION)

MODELS: 1996-98 CHEVROLET AND GMC C/K, G, P TRUCKS WITH 7.4L ENGINE (VIN J--RPO L29)

CONDITION:

SOME OWNERS MAY COMMENT ABOUT A LIGHT TICK OR KNOCK NOISE THAT RESEMBLES EITHER A VALVE LIFTER TICK/RATTLE OR A PISTON OR PISTON PIN SLAP. THE CONDITION WILL BE MOST NOTICEABLE ON COLD START. THIS NOISE CAN BE PRESENT UPON ENGINE DECEL AFTER INITIAL STARTING FLARE AND MAY NOT BE CONSISTENTLY REPEATABLE. THIS CONDITION HAS NO ASSIGNABLE CAUSE AT THIS TIME AND AS A RESULT NO REPAIRS SHOULD BE ATTEMPTED. ALTHOUGH THE NOISE MAY SOUND UNUSUAL, THERE IS NO INDICATION THAT THIS WILL IN ANY WAY AFFECT THE DURABILITY OR LONGEVITY OF THE ENGINE. CHANGING PARTS SUCH AS THE VALVE LIFTER, VALVE SPRING, ROCKER ARMS, OIL FILTER, OIL TYPE, OR MAIN OR ROD BEARINGS UNLESS OBVIOUSLY SCORED HAVE NOT PROVEN EFFECTIVE IN REMOVING THE NOISE AND FOR THAT REASON SHOULD NOT BE CHANGED.

AS SOON AS AN ASSIGNABLE CAUSE AND FIX ARE DETERMINED, THIS BULLETIN WILL BE RE-ISSUED WITH THAT INFORMATION.

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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.