Use improved plugs for leaky Benz

This bulletin applies to Mercedes Benz vehicles equipped with engine M272/273, up to June 2008 production. If a customer complains about an engine oil leak, the cause could be the round expansion plastic plugs on the rear of the cylinder heads (as of June 2008 production, new improved plugs were phased into production).

1. Remove the air filter housing. For models 164 and 251, refer to WIS document AR09.10-P-1150GZA.

2. Remove the existing plugs, clean the opening and install new plugs.

NOTE: The plug opening should be free of grease and oil. No sealer should be applied during the installation of the new plugs. There are two different size plugs: A000 998 55 90 (two small expansion plugs) and A000 998 56 90 (one large expansion plug, for engines without vacuum pumps).

The initial supply of plugs feature the old part number molded into the plug and a white dot.

View of rear of cylinder head. Large plug (left) and small plug (right).
<p>View of rear of cylinder head. Large plug (left) and small plug (right).</p>

Initial replacement plugs feature a small white dot.
<p>Initial replacement plugs feature a small white dot.</p>

Tags: engine oil 
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