#PIP4492Q: Oil Consumption And/Or Exhaust Smoke - Possible PCV Baffle Or Lifter Concern - (Aug 31, 2010)
|Subject:||Oil Consumption and/or Exhaust Smoke - Possible PCV Baffle or Lifter Concern|
|Models:||2009 Buick Lacrosse Super, Allure Super (Canada Only)|
|2003-2010 Cadillac Escalade|
|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|
|2003-2009 Chevrolet Trailblazer|
|2003-2010 GMC Savana, Sierra, Yukon|
|2005-2008 Pontiac Grand Prix|
|With any of the following V8 Engine RPO Codes:|
|5.3L - L33, L59, LC9*, LH6*, LH8, LH9, LM7, LMF, LMG, LS4**, LY5|
|6.0L - L76*, L77, L96, LFA*, LQ4, LQ9, LS2, LY6, LZ1|
|*For 2007-2008 LC9, LH6, L76, L92, or LFA engines: Follow the latest version of 10-06-01-008 about sticking oil control rings and re-evaluate the oil consumption. If excessive oil consumption is still present after installing the AFM pressure relief valve shield and cleaning/replacing the oil control rings, follow the PI suggestions below.|
|**For 2005-2009 LS4 engines: Refer to the latest version of PIP4814.|
This PI was superseded to remove reference to PIP4574 right below the model list and refer to 10-06-01-008 instead. This was changed due to the recent release of 10-06-01-008, which has taken the place of PIP4574. Please discard PIP4492P.
Notice: Engine RPOs LS3, LS7, LS9, and LSA are excluded from this because they have the PCV baffle built into the intake valley cover, rather than the valve cover so excessive lifter flow does not affect them in the same manner.
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
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 if this PI applies.
This may be the result of:
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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).
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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).
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.
- 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.
- 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 overaggressive lifter. Sometimes this may occur intermittently so inspecting the lifter flow may not always isolate the suspect lifter. If steps 1-3 above do not isolate the cause of excessive oil in the intake, replace all 8 lifters that are on the side of the engine that has the PCV vacuum pipe attached to the valve cover. It is not necessary to replace the 8 lifters on the other side of the engine.
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.
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.