2007 Yukon Denali XL..6.2LNoticed 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.
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)
This PI was superseded to remove the 2007 LH6 and 2007 ST models since these have been incorporated into PIP4574. Please discard PIP4492J.
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.
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).
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:
Important: If this step leads to valve cover replacement, perform step 3 on the replacement valve cover before installing it.
Important: If this step leads to valve cover replacement, perform this step on the replacement valve cover before installing it.
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.
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!
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.
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