W212 ('10 E350 4Matic) Oil leak around cam
 

I noticed a slow oil leak on my E350 a few months back. I don't drive it just a whole lot so I ignored it, then forgot about it. I took it to DC and back in July, then noticed that the oil leak has sped up a fair bit. I parked it and didn't drive it for a couple of weeks. Got off early today so I started poking around to see if I could find the problem. Looks like some sort of sensor or some such on the back of the head behind the cam on the left side of the car is where the leak is at.

I'm pointing at the thing in question here:
https://i.imgur.com/dCUDSY8h.jpg

You can see it's a bit wet/sticky looking around the general area, and there's actually a drop of oil about to fall if you look in the mirror.
https://i.imgur.com/35Jmpz5h.jpg

I'm guessing there's a gasket or seal or some such that needs replacing. Anyone offer any advice on what parts to buy and how exactly to get to that thing to take it loose?

Cam plugs!
 

Are you sure the cam plugs aren’t leaking? On my 06 E350 wagon, I had an oil leak in that same area and it was the cam plugs. There are 3 I think; a small one and a large one on the driver’s side, and another smaller one on the passenger side. There is a centrifuge cover on the passenger side that leaks as well. These are easy to replace. And I think there is a write up on this forum. Just FYI I originally bought aftermarket parts (Baptic or something of the sort). The centrifuge cover was fine, but the plugs leaked again soon after they were installed. I went to the dealer and got the Mercedes branded plugs and I’ve been good for 2+ years. I can look up the part no. for what I purchased at the dealer if you think this may be your problem...

I saw a video regarding the cam plugs on the older E350, but the 2010+ doesn't seem to have the cam plug. It has that box thing with the hose coming off of it instead.

That would be the vacuum pump that you're seeing. You could try replacing the o-ring, but most of the time it's the pump itself.

Leave it to Mercedes to put a friggin vacuum pump on a gas burning car. Good grief. I looked over it and it looks like all it does is the brakes. Since the brakes are working fine, that would indicate that maybe it's just the o-ring, right? The car only has 70k miles on it.

Just in case anyone runs into this in a future search, the solution to this problem is posted here - https://www.benzworld.org/forums/w212-e-class/3035102-2010-e350-oil-leak-rear-cam.html