If the shop you are using is doing only an upper timing cover reseal (about 4 hours), you should insist that they do a complete timing cover reseal. I have done over a dozen of these and all worked out perfectly.

Lastly, I have seen head gaskets leak from the front as well as the rear.

Good luck

__________________
Benzmac:
Donnie Drummonds
ASE CERTIFIED MASTER AUTO TECHNICIAN
MERCEDES SPECIALIST 11 YRS