Document ID: 2065710 #PIP4344: Short Duration Cold Start Lifter Tick Noise - keywords 5.3 6.0 cam engine L76 LC9 LFA LH6 LMG LS4 LY5 oil pressure start - (Feb 18, 2008)
Subject:Short Duration Cold Start Lifter Tick Noise
Models:2007-2008 Chevrolet Avalanche, Silverado, Suburban, Tahoe
2007-2008 GMC, Sierra, Yukon
2007-2008 Chevrolet Impala
2007 Chevrolet Monte Carlo
Equipped with the 5.3 or 6.0 Active Fuel Management engines
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
A customer may comment on a cold start engine tick noise. The noise explained may be an extended duration noise related to AFM (Active Fuel Management) valve lifters. The noise may repeat on subsequent cold starts. Noise will be camshaft speed and may last over 1 minute. Noise will only occur after a cold soak that is greater than four hours in duration.
Complete the current SI diagnostic for any symptom or DTCs found. If an extended duration lifter tick noise has been verified (usually greater than 1 minute), and the noise is considered excessive and repeatable, lifter replacement may be required. To repair this concern all lifters should be replaced with lifters obtained through GMSPO. There is no special part number necessary.Note: The 6.0L engine, RPO code LFA has been built with updated lifters since 1-28-2008. 6.0 LFA engines built prior to 1-28-2008 may need the lifters replaced if the customer concern is as described in this PI. Note: If a cold start lifter tick noise has been verified on any other 5.3L or 6.0L AFM engine, lifter replacement may be necessary. These engines (L76 LC9 LH6 LMG LS4 LY5) do not have a build date released for updated lifters.
Please follow this diagnostic or repair 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.
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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