L26, L32, L36, L67 Excessive Oil Consumption (Replace Exhaust Valve Stem Seals)
2005 Buick LeSabre, Park Avenue
2005-2008 Buick Allure (Canada Only), LaCrosse
2006-2008 Buick Lucerne
2005 Chevrolet Impala, Monte Carlo
2005 Pontiac Bonneville
2005-2008 Pontiac Grand Prix
with 3800 Series II, III V6 Engine (VINs 2, 4, K, 1 - RPOs L26, L32, L36, L67)
This bulletin is being revised to update the model years. Please discard Corporate Bulletin Number 05-06-01-035 (Section 06 - Engine/Propulsion System).
Some customers may comment on excessive oil consumption on 3800 Series II and Series III engines. An engine that has excessive oil consumption uses 0.9L (1 qt) of oil or more within 3200 km (2,000 mi).
This condition may be caused by the retaining ring on the exhaust valve stem seal not securely holding the seal on the cylinder head boss. If this occurs, the exhaust valve stem seal(s) may move off the cylinder head boss and no longer provide a sealing function between the exhaust valve stem and the valve guide.
Inspection and/or Replacement of Exhaust Valve Stem Seals
Follow the appropriate Service Information for the vehicle you are working on to gain access to cylinder head exhaust valves on both cylinder banks. Remove the engine valve rocker arm covers, the exhaust rocker arms and the exhaust valve springs.
Oversize valve stem seals are available. Make sure the correct valve stem seals are installed. An OIL CONSUMPTION concern can be created by installing the oversize valve stem seals. The oversize valve stem seals are marked black in color and are NOT to be used UNLESS installing valves with oversize valve stems.
There are 2 different valve stem seals used - one for exhaust valves and one for intake valves. Exhaust valve stem seals are green in color and have "EX" molded into the top of the seal. Intake valve stem seals are blue in color and have "IN" molded into the top of the seal. Using the wrong seal on a exhaust or intake valve can also contribute to oil consumption. The correct seal usage should be verified while checking for correctly seated exhaust valve stem seals.
Correctly Installed Exhaust Valve Stem Seal
Incorrectly Installed Exhaust Stem Seal (the seal is not seated on the valve guide and the cylinder head boss.) Carefully inspect each exhaust valve stem seal for engagement on the exhaust valve guide (refer to the previous illustration). If one or more exhaust valve seals is found to be incorrectly installed, replace all the exhaust valve seals. If no trouble is found with the exhaust valve seal seating or usage, refer to the service manual Oil Consumption Diagnosis to investigate other sources of oil consumption.
Might want to ask them if they looked at this bulletin, maybe follow this first.
Thursday, May 6th, 2010 AT 8:29 PM