Wow that looks nasty under that oil cooler.

I concur, the seal was not perfectly seated when the cooler was placed. Or it wasn’t torqued properly on installation.

A little concerned you may have had mixing of oil and coolant. If you drained the oil and coolant first, how clean did they look?

I am going to have to fix my other son’s car (the E320) over the Christmas holiday as well, he’s experiencing high oil consumption and it’s definitely leaking (not burning) oil. Got the parts in hand already.

One other piece of good news, they now have the updated brake boosters in stock, so if your booster is bad, they should be able to address it quickly (not 5 months like I had to wait).

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech