6.9 rear main seal - PeachParts Mercedes-Benz Forum

Emmerich · #1 03-25-2004, 12:42 AM

I have a leaking rear main seal on my 6.9. I am trying to find out if the crank needs to be pulled to fix this. I have conflicting stories, some say only the tranny needs to be yanked. Anybody know for sure?

thanks
Fred

mbdoc · #2 03-25-2004, 08:04 AM

The 6.9 uses a 2 piece rear main seal kit, MB number 100-010-01-80.
The crankshaft must be removed to install the upper portion.

Emmerich · #3 03-25-2004, 03:04 PM

This is not good news. The shop that is telling me that I need this said they knew of no other MB that required a crank removal to do the seal. Is this a true statement? I asked the mechanic if he had ever done this on a 6.3 and he said yes and it did not require crank removal. isn't the 6.3 the same block? (I am hoping that the procedure would be the same)

thanks
Fred

mbdoc · #4 03-25-2004, 04:52 PM

Almost all of the "EARLY" MB engines required removal of the crankshaft to reseal the rear main! The last gas engine was the M110 engine in 1984, also the cast iron diesel engines upto 1985 required that type of work!
All of the M100 engines require that much work!
Guess they haven't worked on MB's very long, have they??

MikeTangas · #5 03-25-2004, 05:16 PM

Question Doc. Can the job be done by loosening the crank rather than dropping it?

I know on some older large displacement American V-8's I could do a two-piece rear seal by removing the rear main and loosening the rest of the mains, which allowed the crank to drop just a fraction. This was enough to push out the upper half of the old seal and slide in the new one. Setting the ends of the seal at 8 and 2 rather then 9 and 3. Would that work in this case?

Emmerich · #6 03-25-2004, 05:34 PM

I was also wondering if the upper half (it is a 2 piece seal) could be shimmed in there somehow without removing the engine.

gerryvz · #7 03-26-2004, 05:01 AM

Fred,

I had MBI here in Portland do this work on my former 6.9 several years ago, and it did require removal of the crankshaft in order to replace the seal. I wasn't happy with the cost of the job, but what could I do.

How bad is your leak?

Cheers,
Gerry

Emmerich · #8 03-26-2004, 10:32 AM

Its pretty bad, kinda weird it came on very sudden. Like within a week. I noticed a trail into my garage one day. I figured there must have been a pool on the motor somewhere and when I crossed the bump it fell on the ground as I drove in. My valve cover gasket is leaking and I am not 100% convinced that the shop is correct about the rear seal. But I had the valve cover gaskets changed last year. Unfortunately since I moved to Dallas I don't have a mechanic I can trust. I have been on the phone to my old guy in Houston and he is trying to come up with a cost estimate. He used the phrase "ton of cash" which caught my attention...

The oil hoses are leaking too and I am getting those fixed and then I will see exactly where the leaks are coming from. They are trying to tell me the tranny is leaking too but I saw no evidence of red fluid.