Originally Posted by rockdude

Thank you BSSN. I'm not going worry about it..

Originally Posted by turbo2001

the cure for this is cat delete and corsa extremes

Originally Posted by Z11409

#PIP4499A: Short Duration Lifter Tick Noise On Cold Start - Aerated Oil In
Lifter - keywords BQMI - (Jun 16, 2009)


Subject:Short Duration Lifter Tick Noise on Cold Start - Aerated Oil in Lifter

Models:2009 Buick Lacrosse Super, Allure Super (Canada Only)
2007 Buick Rainier
2007-2009 Cadillac CTS-V
2007-2009 Cadillac Escalade
2007-2009 Chevrolet Avalanche, Corvette, Express, Silverado, Suburban, Tahoe, Trail Blazer
2007-2009 Chevrolet Impala
2007 Chevrolet Monte Carlo
2007-2009 GMC Envoy, Savana, Sierra, Yukon
2007-2009 Hummer H2
2008-2009 Hummer H3
2007-2008 Pontiac Grand Prix
2008-2009 Pontiac G8
2007-2009 Saab 97x
With Any of the Following V8 Engine RPOs:
L76, L92, L9H, LC9, LFA, LH6, LH8, LMG, LMF, LS2, LS3, LS4, LS7, LY2, LY5, or LY6



This PI was superseded to revise repair instructions to include replacing the oil pump and pick-up tube o-ring. Please discard PIP4499.
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:

Some customers may comment on a short duration lifter tick noise that occurs after cold start and can last for several minutes. This may be the result of air in the high pressure chamber of the lifter affecting valve train lash. When this occurs, valve closing velocity is increased, which causes the noise. Air can be present in the lifter at shutdown due to an aerated oil condition, or it can be ingested into the lifter during a cold start from a suction side leak at the oil pump or oil pump pick up tube o-ring. Oil aeration level, oil viscosity, time to achieve oil pressure, engine speed, and lifter design all play a part in whether lifter noise is observed. Once air gets into the high pressure chamber, it will slowly be expelled through the very tight clearance of the plunger and body.
Recommendation/Instructions:

If the SI diagnostics do not isolate the cause of this concern, perform a cylinder power balance test with the Tech 2 while listening to the noise.
If the noise is eliminated, or is greatly improved, each time a specific fuel injector is cancelled, there is most likely a concern with the clearance of the related piston pin or piston to cylinder wall of that cylinder.
If there is no change in the noise when canceling the fuel injectors with the Tech 2 and this noise occurs at valve speed, the noise is most likely a result of air in the lifters as described above. The air may be the result of a suction side leak at the oil pump and/or pick up tube o-ring, or it may be the result of the lifter design.
If this concern is encountered, replace the oil pump and pick up tube o-ring and re-evaluate the noise. If this does not repair the noise, updated lifters will most likely repair the noise but they will not be available until the 4th quarter of 2009. This P.I. will be updated with additional information as soon as they are available. Replacing the lifters with the ones currently in GMSPO stock may not repair the noise.
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.