Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
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What style of driving do you do, heavy towing, fast sriving, city stop and go, lots of highway?
OK, the amount you have indicated is not excessive by GM standards, however there is the bulletin you indicated about the valve covers. It is below.
#PIP4492H: Excessive Oil Consumption And/Or Blue exhaust Smoke - Inspect PCV Baffle Drain Holes And Valve Train Oil Flow - (Jun 17, 2009)
This PI was superseded to suggest replacing all 16 lifters if there is no problem found with the PCV system. Please discard PIP4492G.
Important: For 2007 Full Size Trucks and Utilities with the 5.3L Engine (RPO LC9 - VIN 3), please refer to the latest version of PIP4574 for recommendations. 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.
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).
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:
1. 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.
2. 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.
3. 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.
PCV Baffle Comparison
4. 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 should be replaced if steps 1-3 above do not isolate the cause of 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.
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.