I would look into the rear valve cover option. I am a gm tech and I know we had issues with the trucks with excessive oil consumption- the fix was to replace the pcv valve and modify the oil baffle in the valve cover. you may have a similair issue- the new valve cover may help. the new pcv valve was not even a valve- just had a small hole to regulate a constant supply of vaccum to pull out crankcase vapours. I'm guessing the valves may have been sticking open and allowing excessive oil vapour to be pulled from the crankcase and burned. I searched gm service information: hope this helps.
#PIP4492K: Excessive Oil Consumption And/Or Blue Exhaust Smoke - Possible PCV Baffle Or Lifter - (Feb 1, 2010)
bject:Excessive Oil Consumption and/or Blue Exhaust Smoke - Possible PCV Baffle or LifterModels:2009 Buick Lacrosse Super, Allure Super (Canada Only)
2004-2006 Buick Rainier
2004-2008 Cadillac CTS-V
2003-2010 Cadillac Escalade
2010 Chevrolet Camaro SS (Only Models with RPO L99)
2003-2007 Chevrolet Corvette
2009-2010 Chevrolet Colorado
2003-2010 Chevrolet Avalanche, Express, Silverado, Suburban, Tahoe,
2006-2009 Chevrolet Impala
2006-2007 Chevrolet Monte Carlo
2003-2006 Chevrolet SSR
2003-2006 Chevrolet Trailblazer
2008-2009 Chevrolet Trailblazer
2009-2010 GMC Canyon
2003-2006 GMC Envoy
2008-2009 GMC Envoy
2003-2010 GMC Savana, Sierra, Yukon
2003-2010 Hummer H2
2008-2010 Hummer H3
2006-2008 Pontiac Grand Prix
2008-2010 Pontiac G8
2005-2006 Saab 97x
2008-2009 Saab 97x
With any of the following V8 Engine RPO Codes
4.8L - L20, LR4, LY2
5.3L - L33, L59, LH8, LH9, LM7, LMF, LMG, LS4, LY5, LC9, LH6 (*except 2007 model year LC9 and LH6)
6.0L - L76, L77, L96, LFA, LQ4, LQ9, LS2, LY6, LZ1
6.2L - L92, L94, L99, L9H
This PI was superseded to remove the 2007 LH6 and 2007 ST models since these have been incorporated into PIP4574. Please discard PIP4492J.
Important:
This PI does not apply to 2007 model year vehicles equipped with the 5.3L Engine RPO Code LC9 or LH6. Please refer to the latest version of PIP4574 for 2007 model year vehicles equipped with RPO Code LC9 or LH6 Engines that have an oil consumption concern. For all others, refer to the recommendations below.
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
On rare occasions, some customers may complain of excessive oil consumption and/or blue exhaust smoke. Upon inspection, obvious oil will be found in the intake manifold and/or PCV vacuum tube.
This may be the result of:
• A PCV fresh air hose that is pinched or restricted by plastic casting flash (this would normally be a concern since new, or shortly after engine repairs).
• Plugged PCV baffle drain holes in the valve cover that has the PCV vacuum pipe attached to it (this would normally be a concern at high mileage).
• An improperly sealed PCV valve cover baffle (this would normally be a concern since new, or shortly after valve cover replacement).
• Over-aggressive valve lifters (generally occur at low mileage - less than 10,000 miles or so).
Recommendation/Instructions:
Important: This PI does not apply to 2007 model year vehicles equipped with the 5.3L Engine RPO Code LC9 or LH6. Please refer to the latest version of PIP4574 for 2007 model year vehicles equipped with RPO Code LC9 or LH6 Engines that have an oil consumption concern.
If bulletin 01-06-01-011 identifies excessive oil consumption but SI diagnosis does not isolate the cause of it, inspect the PCV vacuum pipe to see if obvious oil drips out of it and look through the throttle body opening to see if there is obvious standing oil in the bottom of the intake manifold (normally a 1/4 quart or more if this PI applies). If there is obvious oil in the PCV vacuum pipe or in the bottom of the intake, perform the steps below and re-evaluate the oil consumption concern:
- Inspect the fresh air hose/pipe and all related connections to make sure that no restrictions exist (plastic casting flash, pinched hose, etc.), which may cause excessive crankcase vacuum. Repair the restriction as necessary. Generally, the oil consumption would have been a concern since new, or shortly after engine repairs, if this is the root cause.
- Inspect the PCV baffle drain holes shown below to see if they are plugged with hardened oil deposits. These are located in the valve cover that has the PCV vacuum pipe attached to it. If they are plugged, replace the valve cover, ensure that the customer is changing their oil according to the maintenance schedule in their owner's manual, and re-evaluate the concern. Generally, the oil consumption would not have appeared until several thousand miles accumulated if this is the root cause.Important: If this step leads to valve cover replacement, perform step 3 on the replacement valve cover before installing it.
- PCV Baffle Drain Holes:
- Inspect the PCV baffle to ensure that it is properly sealed to the valve cover by flipping it over and adding a little oil to the baffle to valve cover joint as shown below. The oil should stay in place as shown on the 2 outer valve covers below. If the oil drains into the PCV baffle as pointed out on the middle valve cover below, replace the valve cover. Generally, the oil consumption would have been present early in the life of the vehicle or shortly after valve cover replacement if this is the root cause.Important: If this step leads to valve cover replacement, perform this step on the replacement valve cover before installing it.
- PCV Baffle Comparison
- If there is no problem found above but there is obvious oil in the PCV vacuum pipe or bottom of the intake manifold, this may be the result of the PCV system ingesting excessive oil due to an over-aggressive lifter. Sometimes this may occur intermittently so inspecting the lifter flow may or may not isolate the suspect lifter. As a result, all 16 lifters should be replaced if steps 1-3 above do not isolate the cause of excessive oil in the intake.
Important: If Step 2 or 3 leads to valve cover replacement, perform Step 3 on the replacement valve cover before installing it.
Important: Drain/clean the oil out of the intake manifold and install the intake with new intake gaskets before releasing the vehicle to the customer. If this is not performed, the customer may return with an exhaust smoke complaint even though their oil consumption complaint may be repaired.
Important: Make sure that the replacement lifters do not have any sign of debris in the plunger area as shown in the bottom-center lifter below. If there is debris present, remove it with some light shop air. Do not stick anything in the plunger area to remove it such as a screwdriver.
Example of Debris in Lifter
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.
