SB-10043579-8211
File in Section:

Service Bulletin

Bulletin No.:
Date:

PIP4750D
January, 2012

PRELIMINARY INFORMATION
Subject:

Belt Squeak Noise And/Or Crankshaft Balancer Appears To Wobble

Models:

2010 - 2012 Chevrolet Camaro SS
2011 - 2012 Chevrolet Caprice
2009 - 2012 Chevrolet Corvette
2008 - 2009 Pontiac G8
With 6.0L 6.2L Engine (RPOs L76 L77 L99, LS3, or LS7)

This PI was superseded to update model, model years and RPO codes. Please discard
PIP4750C.

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:
Some customers may complain of a belt squeak noise and/or a crankshaft balancer appears to be out of balance or
wobbling while watching it with the engine running. In most cases, the wobble is an optical illusion because the
design of the balancer gives the appearance that it is moving more than it actually is.

Recommendation/Instructions:
If this concern is experienced, follow the steps below:
1. Push the crankshaft all the way to the rear of the engine.
2. Using a magnetic base, attach a dial indicator so the measuring tip is contacting the rear of the drive belt
groove.
Notice: An inaccurate reading may be obtained by measuring the face of the balancer instead of the rear of the
drive belt groove.
3. Rotate the crankshaft 360 degrees and note the total amount of crankshaft balancer run out.
• If the balancer run-out is 4mm (0.0157”) or less, do not replace the balancer because the runout is in
specification.
• If the balancer run-out is greater than 4mm, replace the crankshaft balancer and perform step 3 again to
confirm that the run-out of the new balancer is in specification.
4. If the customer has complained of a belt squeak, also replace the drive belt.
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.