GM oil consumption and blue smoke
On rare occasions, customers may complain of excessive engine oil consumption and/or blue exhaust smoke. This applies to a number of GM vehicles, including 2009 Buck Lacrosse Super, 2004-2007 Buick Rainier, 2004-2009 Cadillac CTS-V, 2003-2009 Cadillac Escalade, 2003-2006 Chevrolet SSR, 2003-2009 Chevrolet Avalanche, Corvette, Express, Silverado, Suburban, Tahoe and Trail Blazer, 2006-2009 Chevrolet Impala, 2006-2007 Chevy Monte Carlo, 2003-2009 GMC Envoy, Savana, Sierra and Yukon, 2003-2009 Hummer H2, 2008-2009 Hummer H3, 2006-2008 Pontiac Grand prix, 2008-2009 Pontiac G8 and 2005-2009 Saab 97x. Affected engines include L33, L59, L76, L92, L9H, LC9, LFA, LH6, LH8, LQ9, LMG, LM7, LMF, LQ4, LQ9, LR4, LS1, LS2, LS3, LS4, LS6, LY2, LY5 or LY6.
The problem may be the result of:
* A PCV fresh air hose that is pinched or restricted by plastic casting flash.
* Over-aggressive valve lifters.
* Plugged PCV baffle drain holes in the valve cover that has the PCV vacuum pipe.
* An improperly sealed PCV valve cover baffle.
* Cylinder head casting concern (on select 2009 models only).
Important: For 2007 full size trucks and utilities with the 5.3L engine (LC9 – VIN 3), please refer to the latest version of PIP4574 for recommendations.
Important: If Step 3 or 4 leads to valve cover replacement, perform Step 4 on the replacement valve cover before installing the valve cover.
Important: If the following steps identify a concern, look through the throttle body opening for a large puddle of standing oil in the bottom of the intake manifold. If present, drain/clean the oil out of the intake manifold and install the intake with new intake gaskets. If this is not done, the customer may return with an exhaust smoke complaint even though the oil consumption complaint may be repaired.
1. Inspect the fresh air hose/pipe and all related connections to make sure that no restrictions are present, such as plastic casting flash or a pinched hose. If OK, remove the valve cover that features the PCV vacuum pipe and perform the remaining steps.
2. Check for an over-aggressive lifter by monitoring oil flow at the top of each pushrod with the engine at idle. It should not be necessary to raise the RPM to check for an over-aggressive lifter. Very little flow should be observed at idle. It will be obvious if an over-aggressive lifter is present because its flow will be greatly excessive when compared to others, and a great deal of cleanup will be required. Replace any over-aggressive lifters and re-evaluate the concern.
3. Inspect the PCV baffle drain holes to see if they are plugged with hardened oil deposits. If they are plugged, replace the valve cover, and make sure that the customer is changing the engine oil according to the maintenance schedule in their owners manual. Generally, this would not be a concern until several thousand miles have accumulated.
4. Inspect the PCV baffle to insure that it is properly sealed to the valve cover by flipping it over and adding a little oil to the corner of the valve cover. The oil should stay in place as shown in the 2 outer valve covers shown below. If the oil drains into the PCV baffle as pointed out on the middle valve cover shown below, replace the valve cover.
5. Only on low-mileage 2009 models, also inspect the Julian date of the cylinder heads, which is located just above the #2 and #7 exhaust ports. Also inspect for the 2 casting marks below the #2 and #7 spark plugs. If these casting marks are present AND the Julian Date is 8210-8309, replace the related cylinder head(s) and re-evaluate the oil consumption concern.