Replacing rear crankshaft oil seal - new part is leaking again ?!

[je11]

Hello

I got the same issue on two cars: 500E and E420

Both cars got new trasmissions last year and the rear crankshaft oil seal got replaced.
But there is still a leak there.
The oil gets even swirled to the starter ?!

I can see that there is a leak inside the transmission housing - its 100% engine oil !
But dont know if its the rear crank seal or maybe the upper oil pan :-/

Is it possible that the upper oil pan is leaking extremely till it gets out of the trans-housing/torqueconverter-housing ?

So next weekend I want to unmount the transmission and replace the seal again.
Ive taken a look into the EPC and see that there was a crank seal for repair-solution (maybe for high-mileage cranks ?!)

The part-no for that repair seal is: 001-997-87-47
but it already changed to this new number: 120-997-02-46 (which is the same part-no for the default seal without repair-solution).

So at the dealer I dont get the repair-solution seal anymore ?!

When I take a look to the aftermarket I can buy a repair-solution seal with the old part-no (001-997-87-47) from ELRING.

So I dont know which is the best I should do now and which part I should buy und replace.

Have anyone got the same oil leaking issue ?

Thank you

 

[darek_u]

See here for more info.

 

[je11]

Wow thank you very much. Nice thread ! So the Elring Repair size Seal should be the best choice ?

 

[darek_u]

It worked for me but it was difficult to buy.

 

[gsxr]

I got the same issue on two cars: 500E and E420

Both cars got new trasmissions last year ... The oil gets even swirled to the starter ?!

Make SURE the oil isn't coming from the stud screwed into the block, located above the starter. I think the trans dipstick attaches to this stud. See photo below.

That stud is supposed to have micro-encapsulated sealant on the threads, because it goes into a hole which is open to an oil return passage. If the stud has been removed and re-installed without sealant, the leak will appear to be from the rear main seal or carrier, and you'll keep on replacing it over and over and over. Don't ask how I know. A new stud is was cheap from the dealer. It can be installed without removing the transmission.

Edit: The stud is p/n 914131-010302 and is no longer cheap. It had been ~$5 MSRP back in 2020, and is now almost $40 MSRP as of March 2024.

Also, if you haven't removed the rear carrier to re-seal it, you can apply a bead of external sealant along the seams; note the bead of orange RTV in the photo (doesn't hurt anything).

Additional reading here:

rear engine cover / rear main seal INSTALLED - THANK YOU JONO | M119 Engine

Some of you know I had a slight oil leak from the rear of the engine. I pulled the transmission yesterday morning (not a nightmare as I thought it might be). About 3 hours. Anyhow, Yesterday, I removed the rear engine case to clean up the sealing surfaces in preparation of reinstalling...

www.500eboard.co

 

[je11]

Make SURE the oil isn't coming from the stud screwed into the block, located above the starter. I think the trans dipstick attaches to this stud. See photo below.

That stud is supposed to have micro-encapsulated sealant on the threads, because it goes into a hole which is open to an oil return passage. If the stud has been removed and re-installed without sealant, the leak will appear to be from the rear main seal or carrier, and you'll keep on replacing it over and over and over. Don't ask how I know. A new stud is cheap from the dealer. It can be installed without removing the transmission.

Also, if you haven't removed the rear carrier to re-seal it, you can apply a bead of external sealant along the seams; note the bead of orange RTV in the photo (doesn't hurt anything).

Additional reading here:

rear engine cover / rear main seal INSTALLED - THANK YOU JONO | M119 Engine

Some of you know I had a slight oil leak from the rear of the engine. I pulled the transmission yesterday morning (not a nightmare as I thought it might be). About 3 hours. Anyhow, Yesterday, I removed the rear engine case to clean up the sealing surfaces in preparation of reinstalling...

www.500eboard.co

.....what the hell ?! Very very huge thank you for this information ! I hope this will be the issue - because the leak is also near the starter.
Ive never replaces this stud but I will replace in a few days. - Should I renew this stud or remove and reseal ?
And how can I remove this stud ? Is there enough space to lock two nuts ?

I will tell you if it works and the engine keeps dry! If not - I will pull out the trans again
I will report you If the leak is gone !
Thank you very much for your help

Best regards from Germany

 

[gsxr]

Photo below. I'd buy a new stud from the dealer, they are not expensive. I don't know exactly what that yellow sealant is applied to the threads.

Clearance is VERY tight accessing this stud. It may require removing the transmission dipstick tube, and maybe the exhaust/catalyst pipe too. There should be enough thread protruding to get 2 nuts on the stud for removal. If it's leaking from here, the stud may remove and unscrew easily. It also may be coated with oil. If it is difficult to remove, and completely dry, the stud was probably not leaking. Unfortunately there's no way to find out without removing it. Very easy with the transmission out of course.

If you pull the transmission again, verify the rear main seal is completely flush, and that the seal has not popped outward. I found the orange Victor seal was too loose and backed out within a few hours of running. It can be "glued" in place with sealant, but removal next time will be harder. A new OE seal is a very, very tight fit and may be a challenge to install perfectly flush. If it is not perfect, rip it out and do it all over. (Again, don't ask how I know.)

Also make sure to use new flywheel bolts, as most sealants won't keep oil out... if you re-use the 8 bolts, clean the crankshaft threads carefully to remove all oil, and use anaerobic sealant. LocTite / blue threadlock does not last long term as an oil sealant. I'd also let the anaerobic dry for 1-2 days before starting the engine.

 

[je11]

Ok I will buy one at the dealer. Price is about 25EUR/28USD for one stud.

 

[gsxr]

Yikes! Is the stud that expensive in Europe? In USA they are $5 USD list, about $4 discount, each for p/n 914131-010302.

Edit - I see they are indeed €30 each at MB Classic Germany (link below). That is CRAZY expensive.

https://partssearch.mercedes-benz-classic.com/parts/N914131010302?tt=

Edit: The stud is no longer cheap in USA. It had been ~$5 MSRP back in 2020, and is now almost $40 MSRP as of March 2024.