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Oil Seepage From Back of Cylinder Head on Mercedes M272/273 Engines


If you receive customer reports of oil seeping from Mercedes vehicles equipped with M272/273 engines, the cause could be the round plastic expansion plugs on the back of the cylinder heads (Figure 1). To resolve, perform the following.

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Note:  As of June 2008 production, new improved plugs were phased into production.

There are two different size plugs as listed below:   

 • p/n – A000 998 55 90 – 2 small expansion plugs  

 • p/n – A000 998 56 90 – 1 large expansion plug (engines without vacuum pump)

Remove the existing plugs, clean the opening and install new plugs (Figure 2). Note: The plug opening should free of grease or oil.  No sealer should be used in the installation of the new plugs. 

Some or all of this information was provided by the Automotive
Parts Remanufacturers Association (APRA). For more information on
technical bulletins available through APRA call 703-968-2772 or visit
figure 1Figure 2



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