Help identifying a leak!
Thread Starter
Junior Member
Joined: Apr 2018
Posts: 64
Likes: 2
W210 E55
Help identifying a leak!
My 2001 E55 has it share of leaks since I bought it in 2018. I am beginning to fix some the leaks and need some guidance on where trace some of the leaks back to. I am trying to do most of the work as a DIY so I save some $$$.
Recent maintenance:
- Valve cover gaskets replaced - September 2020
- Upper valve cover resealed - September 2020
- Breather hose replaced - September 2020
- Steering pump reservoirs replaced - September 2020
- Timing cover gasket replaced - September 2020
- Oil filter housing gasket replaced - September 2020
- Oil cooler gasket replaced - September 2020
Current leaks:
- A recent inspection from a shop claimed the rear main seal was leaking
****Not sure where to look exactly to trace this back to rear main seal
- Oil pan appears be soaking wet but not currently dripping oil
****No idea if lower oil pan is leaking or upper pan is leaking
****Is there a way to definitively tell leak from lower and upper pan?
-Transmission pan appears to wet as well and has droplets forming
****Transmission pan has a 2016 date drawn with marker on it. Previous owner said it was changed in past few years.
****I have inspected the pan perimeter and I can't find any leaks around the entire pan
****Unsure if droplets are engine oil or transmission fluid
****Is there another gasket or place near the transmission that could be leaking?
Recent maintenance:
- Valve cover gaskets replaced - September 2020
- Upper valve cover resealed - September 2020
- Breather hose replaced - September 2020
- Steering pump reservoirs replaced - September 2020
- Timing cover gasket replaced - September 2020
- Oil filter housing gasket replaced - September 2020
- Oil cooler gasket replaced - September 2020
Current leaks:
- A recent inspection from a shop claimed the rear main seal was leaking
****Not sure where to look exactly to trace this back to rear main seal
- Oil pan appears be soaking wet but not currently dripping oil
****No idea if lower oil pan is leaking or upper pan is leaking
****Is there a way to definitively tell leak from lower and upper pan?
-Transmission pan appears to wet as well and has droplets forming
****Transmission pan has a 2016 date drawn with marker on it. Previous owner said it was changed in past few years.
****I have inspected the pan perimeter and I can't find any leaks around the entire pan
****Unsure if droplets are engine oil or transmission fluid
****Is there another gasket or place near the transmission that could be leaking?
MBWorld Fanatic!
Joined: Feb 2020
Posts: 1,995
Likes: 394
1991 190E 2.3
Since this is an AMG version, I wouldn't give up on this car just yet. The rear main seal is typically where the rear of the engine meets up with the transmission and is usually an engine out type of repair to get at that rear main seal. I would suggest going to your local auto parts store to purchase some engine dye to put in the engine. This can help you determine where the leaks might be. I think this is a good first step to try to determine where the problem is.
Super Member
Joined: Nov 2001
Posts: 789
Likes: 55
From: Henrico, Virginia
2014 ML350 4Matic
The rear main seal is done by removing the transmission, not the engine. Before doing any more work clean the engine and transmission with a safe cleaner like citrus degreaser. Then look for the leaks. The RMS will evidence itself as dripping oil at the seam between the bell housing and the engine. It is not an uncommon leak for a car at this age. I have done 3 RMS replacements on these cars. It can be done DIY but I advise getting the WIS instructions. There are several steps that are different than most folks expect. And I strongly using the factory seal driver (expensive tool to buy). This is not a seal you want to try tapping in with a hammer and socket or other rube goldberg setup.
MBWorld Fanatic!
Joined: Feb 2020
Posts: 1,995
Likes: 394
1991 190E 2.3
I've heard of this being done as an engine out job. Either way, it's done, there needs to be separation between the rear of the engine and the transmission to remove the rear main seal if it's been determined that the rear main seal is in fact leaking. vinceC offers a good cleaning suggestion for determining if there is a leak from the rear main seal.
Super Member
Joined: Nov 2001
Posts: 789
Likes: 55
From: Henrico, Virginia
2014 ML350 4Matic
For the OP, to give you a rough idea of what you need to know to do the RMS as a DIY, I have attached some of the WIS instructions that you would need to replace the RMS. Also, the 722.6 transmission is large and heavy! If trying to do the job on jack stands there must be al least 21" of clearance under the car and you must use some sort of transmission jack (the is a cheap Harbor Freight one that works pretty well).
Note that the seal must not be removed from the end plate while the endplate is installed. Also note the warnings about removal of the sealant from the end plate. There are several Loctite products specified. The sealant and cleaner are available from the dealer. To my knowledge the Loctitie 7200, which is a gel that softens and facilitates removal of the sealant is not available in the US. I use a similar Permatex product but it seems to be gone from the market also. It is critical that the engine block and the end plate surfaces not be damaged in the process of removing the sealant. One other note - the is a WIS document that I cannot find in my digital files that states the the seal ring must be inserted 1mm below the surface of the end plate, i.e. 1mm in the direction of travel below the surface - not flush with the surface. That is why to factory seal driver is a must.
Consider this job carefully before proceeding.
Note that the seal must not be removed from the end plate while the endplate is installed. Also note the warnings about removal of the sealant from the end plate. There are several Loctite products specified. The sealant and cleaner are available from the dealer. To my knowledge the Loctitie 7200, which is a gel that softens and facilitates removal of the sealant is not available in the US. I use a similar Permatex product but it seems to be gone from the market also. It is critical that the engine block and the end plate surfaces not be damaged in the process of removing the sealant. One other note - the is a WIS document that I cannot find in my digital files that states the the seal ring must be inserted 1mm below the surface of the end plate, i.e. 1mm in the direction of travel below the surface - not flush with the surface. That is why to factory seal driver is a must.
Consider this job carefully before proceeding.
