Mercedes Air Oil Separator (AOS) Replacement

2008-2014 Mercedes vehicles equipped with M272 (E, M, GL, GLK, SLK, and C class) often require an Air Oil Separator (AOS) replacement. It is not always obvious where the issue is with the most common symptoms, but we see it all the time here in the shop.

What are the symptoms?

The AOS on M272 engines can wear out and fail over time. These have a factory built-in gasket that is not a serviceable unit through Mercedes genuine parts suppliers. Symptoms of this failure are rough running and oil leaking from the back of the engine.

How is it repaired?

At the time of servicing the AOS on Mercedes-Benz vehicles equipped with the M272, we also replace all expansion plugs on the back of both heads. It is a cost-friendly repair due to the plugs being on the back of both heads (AOS is located on the back of the passenger head).

Oil level check and engine degrease is recommended if oil leak is present, to make sure everything is buttoned up.

If you have a 2008-2014 Mercedes vehicle equipped with M272 (E, M, GL, GLK, SLK, and C class), and are experiencing rough running or oil leaking from the back of the engine, please give us a call, we can help get you sorted out in no time.