I noticed this a couple of months back on my 01 E430 - oil leak near the passenger's side coil packs. The shop thinks it's from the valve cover gasket. So I checked my 05 500 (same engine as the E) and same leak. I don't think it's the valve cover gasket and tend to agree with others that it's the oil collector. I did clean the E's leak area and for a month or so of driving, I don't see any oils - so, it's definitely not the gasket. In any case, if you're interested in my original post on this, go here: http://www.pointedthree.com/disc/for...p?tid=7291&amp... I happen to believe it's a common problem with these V8 engines so please if you don't mind, would you pop off the plstic engine cover and let us all know if you have a oily mess in the passenger side motor. Thanks. For those who aren't mechanically inclined, the plastic cover just pops off - pull on the sides and the think will simply come off. Below are some pics of my ML's right side!!! Also, please let's know what year. I will post this on all three popular W163 sites.

 

Nice close up pictures. This problem is common not only in the V8 (M113), but also in the V6 (M112) engines. The leak you pictured is not from the valve cover gasket (although I have seen it, it is less common). It is coming from the upper portion of the valve cover. I wish I had taken pictures of when I did mine to show you.
1-Get the mass air flow sensor And intake piping out of your way (carefully remove it if possible).
2-Unbolt the coil packs (use T30 torx socket) and fold them out of the way (there is no need to unplug the spark plug wires from the coils or plugs, just move the coils out of the way).
3-Remove rubber hoses that attach to the upper valve cover portion, careful, if they are old they like to crack, you may want to just order new rubber hoses, I don't think they're that expensive.
4-Undo the small bolts in the upper portion (use T20 torx driver, bit, or socket).
5-Undo the larger bolts (Just the ones on the upper portion, you don't have to unbolt the whole valve cover. Use E10 torx socket).
6-With small prybar, evenly and carefully pry and lift off the upper valve cover portion off the main valve cover.
7-clean BOTH surfaces very thoroughly, CLEAN and DRY is a must!
8-Apply MB sealer to grooved surface. (Ask for "a tube of black sealer" from your local MB parts department, they should know what it is and IT IS the right stuff for the job. But, just incase they don't know what you're talking about... It is MB Part Number: A 003 989 98 20 10).
9-Install in REVERSE order. NOTE EXCEPTION: on the way back together tighten up the bigger E10 torx bolts before the smaller T20 torx bolts. CAUTION: go hand tight on both these bolts NO AIR TOOLS, if you over tighten these bolts they WILL either strip or the heads with break off the bolts.

Good luck, it's not a hard job... the worst of it is trying to clean both sealing surfaces. Best bet is probably a wire brush and a pocket screw driver for the stubborn old sealer, then clean and dry with "brake clean" or similar product.

I hope this is helpful!!

 

If the small T20 torx bolts don't want to go in all the way, don't force them. It means there is sealer in the bolt hole that needs to be cleaned out. Since the sealer is basically a thick "liquid"... it can not be compressed.

 

So, below that alluminum valve cover is another one? Or is the a "hump" cover piece over that main valve cover located back towards the firewall end? Is that what's called the oil collector? The ML is still under warranty so I'll have them do it, then I may DIY the E depending on how the ML's repair works. Thanks for the detailed instructions.

 

Crazy, Ok, I believe I know what you're talking about. I went back and looked at the E (there's less stuff to move out of the way) and took some pics. I believe the piece you're talking about is best shown in the last pic. It shows the valve cover with a black rubber tube sticking out from the "hump." The hump is what you're talking about, isn't it? Thanks.