Engine - Excessive Engine Oil Consumption
TECHNICALBulletin No.: 07-06-01-007A
Date: April 22, 2008
Subject:
Excessive Engine Oil Consumption (Verify Condition, Inspect Valve Stems, Replace Cylinder Heads if Necessary)
Models:
2006-2007 Chevrolet Avalanche, Silverado Classic
2007 Chevrolet Impala, Monte Carlo, Silverado, Suburban, Tahoe, TrailBlazer
2006-2007 GMC Envoy, Sierra Classic
2007 GMC Sierra, Yukon
2007 Pontiac Grand Prix
2006-2007 Saab 9-7X
with 4.8L or 5.3L V8 Engine (VINs C, B, Z, 3, M, T, 0, V, C, J - RPOs LY2, L33, L59, LC9, LH6, LM7, LMG, LR4, LS4, LY5)
Supercede:
This bulletin is being revised to include the 4.8L engine and additional correction information. Please discard Corporate Bulletin Number 07-06-01-007 (Section 06 - Engine).
Condition:
Some customers may comment on excessive engine oil consumption. The rate of oil consumption described may usually be around 0.946 liter (1 quart) of engine oil in 805 to 1125 km (500 to 700 mi).
Cause
The engine oil consumption may be caused by a nick in the valve stem.
Correction
Important:
If one or more damaged valves are identified in one head, BOTH heads should be replaced.
Important:
The completely built-up cylinder heads can be obtained from the Warranty Parts Center.
Complete the current SI diagnosis for any DTCs or symptoms found. Refer to Corporate Bulletin Number 01-06-01-011C for Information on Engine Oil Consumption Guidelines.
If excessive oil consumption has been verified, all of the valve stems need to be inspected for damage. One or more of the valve stems may be nicked.
After removing the valve cover, all the rocker arms need to be loosened to assure the valves are closed.
It is possible to see a nicked valve stem through the valve spring coil (a mirror and flashlight will be required) but in some cases the valve spring may need to be removed. Photos of a nicked valve stem are shown.
A valve stem nick can be in any 360 degree area due to rotation so each valve stem must be examined carefully.
If the engine oil consumption is excessive and a nicked valve stem has been found the cylinder heads will need to be replaced. The cylinder heads will be serviced as an assembly (the head will be complete with valves and springs) and shipped to the dealer by the Warranty Parts Center (WPC). Old cylinder heads will be requested and sent back to the WPC. The dealer will have to order the necessary parts/gaskets to complete the cylinder heads remove and replace. Refer to the Cylinder Head Replacement procedures in the applicable Engine Mechanical sub-section.
The Julian date is part of the cylinder head serial number. The serial number is located at the right hand end of the exhaust face. If looking directly at the cylinder head exhaust ports (exhaust manifold mounting face) the serial number will be just above and right of the farthest right exhaust port. The first digit of the serial number is the calendar year. The second third and fourth digits are the Julian date.
Parts Information
Warranty Information (excluding Saab U.S. Models)
Warranty Information (Saab U.S. Models)
IMPORTANT NOTE WHEN PRINTING THIS FORM:
If the form prints out on two pages, make certain you fax BOTH pages so that the WPC receives all the needed information. Missing information will delay or prevent the part from being shipped.
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