I have a 2005 CLK 500 with 722.9 Transmission. When I wipe my finger inside the bell housing I get oil, no transmission fluid just oil on my finger. Can the upper engine oil pan be leaking into the bell housing? A shop just replaced the rear crankshaft seal and now they tell me the upper oil pan is leaking after I brought the car back to them (having driving 200 miles in two days) as I saw it continued to leak oil from the bell housing. It was such a mess under there I could not definitively tell if there was also oil leaking on the outside of the engine oil pan near the transmission or only from inside the bell housing. As you all know there isn't much room under these cars when laying on your back in one's garage and looking through a pair of tri-focal glasses. Does the engine have to come out to remove/install the upper oil pan or can you get by with just raising the engine a little?
Of course I'm having my doubts as to the cause of the leak. The shop may just be trying to recover their labor expense from my wallet. Can the upper engine oil pan leak into the bell housing? Does the engine have to come completely out of the car to replace an upper engine oil pan?

Rear main seal. I presume they replaced the one on the front of the engine? Transmission has to come out to replace it.

Not sure what the upper oil pan refers to.

Rear crankshaft seal is the rear main seal, they probably only replaced the seal and not the seal metal housing the comes pre-coated with sealant that is also known for leaking

i agree with DanielFD

Followup: I got the car up on blocks, cleaned the area as best I could and then started the car. It idled for 20 minutes and I could see oil working its way down the seam between the "bell housing" and the transmission. I also found it inside the bell housing by wiping my finger through the inspection plates. I suspect the oil is leaking from the bottom of the plate (backing plate) that holds the seal and the joint with the upper engine oil pan. The oil follows the seam rearward to the joint with the transmission and finds a way to the exterior where I saw it on the exterior of the housing flowing down. I do not see any wet oil on the seam of the upper oil pan and the engine block.
Two independent MB shops both told me they need to remove the upper oil pan and reseal it. No one wants to just try removing and resealing only the backing plate. The shops solution should stop the leak IF they get the job right. It will set me back around $1,000. Even thought the parts aren't much I just can't see me trying this at home laying on my back; removing transmission etc. From what I see on parts diagrams and looking under the car the lower half of the "bell housing" is actually an extended piece of the upper oil pan. So the "bell housing's" lower half is the upper oil pan's rear and the oil seal that keeps the lubrication oil in the pan transitions from the engine block to the backing plate at the rear of the engine. Thus removing the upper oil pan and resealing would give a continuous unbroken seal all the way around the oil pan. If you just try removing and sealing the backing plate area only I may still have a leak where the sealing surface/joint between engine block and backing plate meet. Are we having fun yet?

I've not come across a leakage issue with the upper oil pan in the m113 engine before. It is sealed with MB RTV at the factory and I wouldn't think it would be subject to leaking. My guess would be the the end cover plate that the bearing sealing ring fits into. How much oil are you talking about?

About one droplet in twenty minutes, so it can make an ugly mess pretty fast. Thing is if it is just the backing plate leaking from around the engine block when you remove the backing plate for resealing you would of necessity break the seal with the upper oil pan. As I tried to explain in my earlier post no shop wants to try just resealing the backer plate without also resealing the complete upper oil pan by dropping it down and reinstalling it also. It makes sense to me, but that is an awful lot of work. I'm driving the car now and just letting it leak. ( It stays hidden because of the shields)I am reluctant to get this job done as I worry about all the other things that could go wrong when you start moving the engine around. If I can get a guarantee in writing from the shop before starting the job then I guess I'll get it done in the next few months when I save enough $.

I'm not sure when you would have to reseal the upper oil pan and threads I've seen on the plate replacement don't mention it, like this one: https://mbworld.org/forums/w211-amg/...main-seal.html