Engine - Duramax(R) Valve Guide/Stem Oil Seal Change
INFORMATIONBulletin No.: 10-06-01-009
Date: October 06, 2010
Subject: Information on Duramax Valve Guide and Valve Stem Oil Seal Change
Models:
2006-2010 Chevrolet Express Vans, Kodiak C4500/C5500 Series, Silverado
2006-2010 GMC Savana Vans, Sierra, TopKick C4500/C5500 Series
Equipped with Duramax(TM) Diesel Engine (RPOs LLY, LBZ or LMM)
A technician may notice a change in the valve guides and valve stem oil seals on replacement cylinder heads or engines for 2006-2010 model year vehicles. This change may also be noticed on 2006-2010 vehicles that have received a replacement cylinder head or engine during a previous repair.
Beginning in 2010, production LGH and LML engines were made with a new design valve guide and pressed fit valve stem oil seal. Replacement cylinder heads and remanufactured engines for 2006-2010 vehicles will also be made with the new design valve guide and pressed fit valve stem oil seal. The new design requires special tool EN-49761 to install the valve stem oil seal to the correct height.
Identify the valve guide design before servicing the valve stem oil seals on a 2006-2010 model year vehicle.
The first design valve guide can be identified by the presence of a valve stem oil seal locating groove (1). This design used GM P/N 97212994.
The second design valve guide does not have this groove, as the valve stem oil seal is a pressed fit to the guide (1). This design used GM P/N 12624396. When servicing an engine with the second design valve guides, be sure to use EN-49761 to install the valve stem oil seal to the correct height. The EN-49761 is tapped down until it bottoms on the lower valve spring seat.
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