Are you sure the oil leak is at the rear main seal? That is not a common place for oil to leak on this engine.

These M104's almost always leak at the right rear corner of the head gasket (passenger side). The oil could be leaking down from there.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".