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2007 Yukon Denali XL..6.2L Noticed blue smoke on start up

Resolved Question:

2007 Yukon Denali XL..6.2L
Noticed blue smoke on start up a couple months ago. got worse and then went away overnight. Oil consumption..low oil light followed an oil change and about 1000 miles..changed oil again and same issue...2-3 quarts in 1000-3000 miles. Doing oil consumption test with dealer now. just tonight noticed oil pressure dipping to 12-13psi at idle in drive. barely breaking 40 psi under full acceleration. ..anyone seen this stuff on a truck this new....45k miles on truck.
Submitted: 4 years ago.
Category: GM
Expert:  Dave Nova replied 4 years ago.

 

Welcome. This sounds like an issue with the drivers valve cover and the baffles under the top that are designed to keep the oil out the throttle.

#PIP4492K: Excessive Oil Consumption And/Or Blue Exhaust Smoke - Possible PCV Baffle Or Lifter - (Feb 1, 2010)

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Subject:Excessive Oil Consumption and/or Blue Exhaust Smoke - Possible PCV Baffle or Lifter

Models: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This PI was superseded to remove the 2007 LH6 and 2007 ST models since these have been incorporated into PIP4574.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:

  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. PCV Baffle Drain Holes:
    Object
    View Full Image


  4. 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.

  5. PCV Baffle Comparison
    Object
    View Full Image


  6. 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


Object
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Customer: replied 4 years ago.
Thank you for the quick response...This sounds very plausible, but when my dealer brought it up they seemed to think it didnt apply to the 07 Denali 6.2 l....?? Anyways, they filled the oil and marked and sealed it all up for the cosumption test 1200 miles ago and ive taken it in once and they said it wasnt low...(it only had been 300 miles at that point)..now its got about 1200 miles sinced changed and i see the oil pressure dipping. First it was at a stop light it went to 18 psi..then i throttled it to about 60 mph and it didnt break 40 psi....a few minutes later it dropped to 13-14 psi...that has me concerned there is something more. Im going to take it in tommorow for the comsumption check but i wanted someone elses opinion as they seemed to think i was crazy.

Thanks!
Expert:  Dave Nova replied 4 years ago.

You are welcome. If the oil pressure is dropping, get to the dealer for the oil check first thing, as you do not want to cause any damage to the engine.

 

This bulletin does apply to the 6.2, just not some of the 5.3 liter engines.

Dave Nova, GMC Technician
Category: GM
Satisfied Customers: 18859
Experience: ASE Master Certification. GM World Class Certification
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