How to change the upper and lower sump gasket / sealant on a 2011 S204 0m651?

[Brian220CDI]

Sealant and gasket is ordered from Merc.

Looking at maybe wheels off and lowering the subframe with the steering rack so I can get access to the bolts all around but then I will need to have an engine crane on the top to stop the engine coming down with the frame after undoing the engine mounts on both sides? Thinking I might be able to undo the subfrane bolts about an inch and keep the frame up on the bolts.

Does this sound about right?

Been looking for a "How to" but cant find anything even torque settings might be helpful too.

Picture is of a C63 I know but just using it for reference as not may people take pictures of diesels.

Any help or info would be great

 

[Jobsworth]

The sump on the om651 is one piece, and plastic. I have changed one before, but only one, and a long time ago. I held the engine up with a cross brace piece of equipment, and I did have to lower the subframe slightly to get it out. I dont think I had to disconnect the rack, I think there was enough give on everything to just wiggle it over the oil pump pickup and out. Its a rubber seal, comes complete with the sump pan iirc

 

[Brian220CDI]

There is a lower one which has a gasket that attaches to an upper one that has sealant onto the bottom of the block. I had a look the other day as getting oil drips since a service. Started the car while on the ramps got back under and you can see the oil coming through the old sealant. Its quite suprising how much is coming through.

Its good to know you got the lower one done this way as once that is off i would imagine it makes it easier to do the upper one.

 

[Jobsworth]

Ok, the upper piece I think you are referring to is the girdle. I haven’t had reason to drop that off before. A bit more work there. Plastic sumps more often require replacement because they crack when trying to remove the drain plug. You are sure its coming from there and not running down from higher up? If it’s below where the oil filter fits I’d be checking there thoroughly. The filter housing is all plastic too

 

[Brian220CDI]

Ha yeah my plastic one is ok, it seams to be dripping from everywhere else

 

[Brian220CDI]

Ok so tackled the sump this morning.

Got the plastic sump off by lowering the sub-frame and raising the engine off its mounts! Not too much of a problem. Then I tackled the upper sump. Un-done all the bolt and was still confused as to why it wouldnt come off?

Had a look around an found one going through from the bell housing and another behind one of the pully's on the front so undone them.

Then I found 4 points where you can screw the bolts in against the block so the sealant will split and push the upper sump off so started on them but couldn't get the sump off.

Then I looked on Ebay and found that there are 2 bolts coming through from inside the bell housing of the gearbox and you need to split the engine and box! BO770CK5!!!!!!!!!!!!!!!!!!!!!!!!!

I now have a car on axle stands and an engine hoist holding the engine up with the subframe on an axle stand and a split upper sump up to the bell housing with no way of getting it off!

Option 1. Re-build and then split the gearbox and engine to undo the 2 bolts
Option 2 clean up and add sealant between the joints tighten up and hope for the best.

The end by the bell housing is still sealed as I couldn't split it and wasn't leaking in the first place and i can get some sealant all the way around the rest of the upper sump through a pipe added to the sealant gun. This is where I could see the oil seaping through the gaps while the engine was running. If it still leaks I can then tackle the engine as I have a little more knowledge of the car now and will be able to plan it in another day.

Anyone got any advice or anything before I tackle this tomorrow morning?

Thanks Brian

 

[Brian220CDI]

Just incase anyone searches this topic in the future I think I found the main leak.

Last weekend I resealed the upper sump and fitted the lower sump and gasket. There was then another leak above that which was dripping so hunted that down the the oil pressure switch so have done that today and seams to have stopped altogether now fingers crossed.

The socket used for the oil pressure switch I had to borrow of a garage around the corner! It was a 1 and 11/16ths socket that needed a little tap on which is around a 43mm socket in modern day! Its an aukward job like the oil filter housing but i think im a master at it now!

P.s Oil pressure switch was off Ebay from a comercial Mercedes Dealer in Cardiff for £49.99 delivered

Good luck everyone

 

[Brian220CDI]

Ok so this didn't fix this oil leak! I thought it did bet a couple of weeks later it was still there!

I decided over Christmas to take the engine out at first bit of good weather so that was last weekend with the 11 to 12 degrees we had and no rain!

I was a bit more of a job than expected but got it out and replaced the oil filter housing seals again for the fun of it.

With the engine out this meant that I could take the sump and upper sump off which I mentioned I did seal it last time but not very well as I needed to take 3 bolts out from the gearbox side to get this off which are behind the drive plate behind the torque converter! I have now done this with sealant and another new gasket and sump plug on the sump.

I then had a look at the highest place oil was and found it to be from the oil cooler its self, but not from the 2 seals that you get for the unit to the block for oil and water channels. It was from a propeller that sits through the middle of the cooler for the oil pressure switch. It was 2 T20 bolts if I think right and then it popped out but its hidden behind the water pipe (L shaped about an inch thick)for the water pump to thermostat and you need to loosen the bracket that holds the alternator on and the cover for the front of the engine so you can get a good angle to get this shaft out to replace the seal. I also put some sealant on this too as I wasn't putting it back in and finding it leaking again.

It would be a bit of a job with the engine in but would be achievable. Funny thing is this seal and part don't show on the electronic parts catalogue (not that I can find it). I would never have found this with the engine in!



The shaft runs through the back and into the block. On the other side of the unit is the oil pressure switch next to the oil filter housing.

After I did all this, new oil / oil filter and engine has gone back in! I'm quietly confident that this will sort out the problem but my starter motor for some reason blew so I've got a second hand unit going back in tomorrow then top up oil, coolant and gearbox as I lost oil out the torque converter when that came off.

Fingers crossed for tomorrow. I'm just wondering how many diesels are running around with an oil leak that cant be fixed due to there being no seal available for the part and nothing on the EPC for one. I can only presume that it needs a brand new part but I cant find it.