The Mercedes dealer replaced the rear main seal two months ago on my 2000 ML320. A $900 job. I just noticed today the seal area is leaking worse than before. This is crazy. It is tricky to replace these? Is it possilbe to not install these properly?

Thanks in advance.

NOTE: IF Mercedes parts were used and the work done by a dealer, it is guaranteed for 1 or 2 years. They should redo it for free, labor included.

You could have a stuck pressure regulator piston in your oil pump and the extremely high pressure is blowing the seal out. I bet they didn't check the oil pressure with a cold engine, if at all.

Jim in PHoenix

I bet they didn't check the oil pressure either. Do you know if they replaced the engine rear cover plate (its the piece that the rear main seal is installed in). These usually leak for than the rear main seal on 112/113 engines. Anyways, you should a 12 month/12k mile warrenty if performed at the dealer. And its not really much of a DIY job if you don't have a whole lot of experience especially on a ML with a transfer case.Good luck and keep us informed.

Update -- It was the rear cover plate that was leaking. The dealer replaced it no questions asked. Thanks for your help.