Rear main seal leak - PeachParts Mercedes-Benz Forum

peachykeen · #1 03-08-2012, 12:18 AM

Apparently have a bad rear main seal leak on my 79 300td --

After it sits over night or just sitting after driving it -- it will leave a 5-6" diameter puddle...

With the engine completely cleaned off -- my mechanic and I looked closely at it up in the air and confirmed my worst nightmare --

So, in 09 I had a new/used tranny put in it -- and it has worked flawlessly. The car runs nice and it doesn't have too bad of rust.

About $1000 is probably what it'll take I imagine -- since the engine needs to be pulled, what else should be done? engine mounts?, other things?

Thanks for grieving with me a bit -- I was hoping it was going to be a easy fix...

todd

kerry · #2 03-08-2012, 12:22 AM

How did you confirm a leaking rear main seal? It's easy to mistake an oil filter housing gasket leak for a rear main leak. Oil filter housing leaks are far more common. Also could be a valve cover gasket leak.

79Mercy · #3 03-08-2012, 12:29 AM

As Kerry stated these leaks can appear to be rear main seal leaks:

oil filter housing gasket
valve cover gasket
headgasket

I have also heard there is a plug which plugs the oil gallery which is behind the flywheel, i have ONLY HEARD that it can leak. I have no proof though

charmalu · #4 03-08-2012, 01:14 AM

That will cost you a bundle to have a shop pull the engine, slip in a seal, drop the engine back in and have it all buttoned up.

Here is a DIY write up.
PeachPartsWiki: Rear Crankshaft Rope Seal Replacement Without Removing Crank

All depends if you have the time and room, and if this is your only set of wheels.

Use one of those DIY car washes and clean off all the oil, then see if it is coming from up above.

Charlie

peachykeen · #5 03-08-2012, 05:20 PM

Quote:

Originally Posted by kerry

How did you confirm a leaking rear main seal? It's easy to mistake an oil filter housing gasket leak for a rear main leak. Oil filter housing leaks are far more common. Also could be a valve cover gasket leak.

They cleaned everything off the bottom of the engine and all of us looked at a day after driving it around...the drips/wetness is all right in between the tranny and the engine (sorry, don't know the correct parts here)...they didn't find any other leaks that were putting out that kind of oil up higher...but, anything is possible I guess -- sure wish it were...

Everyone around here is pretty hesitant to do it -- so am I -- over $2k is out of the ballpark...

I'll keep driving it--- keep it parked in the same place in the street to minimize the Exxon effect....if you think I should get a second opinion, please let me know...or anything else you might think..

THANKS for the replies..

todd

PS -- any low mileage 300TDs around that you know of for sale? I sure like the wagons...

peachykeen · #6 03-08-2012, 10:23 PM

Quote:

Originally Posted by 79Mercy

As Kerry stated these leaks can appear to be rear main seal leaks:

oil filter housing gasket
valve cover gasket
headgasket

I have also heard there is a plug which plugs the oil gallery which is behind the flywheel, i have ONLY HEARD that it can leak. I have no proof though

The oil filter housing gasket died last winter and has a new one now...the valve cover gasket is new too just a few months ago when I adjusted the valves...headgasket could be looked at again...I think I'm going to have someone else take a close look at it for a second opinion...even though it is pretty convincing that it is the rear main seal, I have a bit of faith that it could be something else...so hope so...there is no way I can come up with 2k...or even justify it given all the other little things I need to attend to...

thanks

shadetree77 · #7 03-08-2012, 11:14 PM

700K on that engine? not bad for the rear main to hold that long...

sleepstar · #8 03-09-2012, 12:11 AM

if its got 700k on it, and you can't afford the work.. maybe drop in some rear main seal stop leak? i mean, what else do you have to lose?

engatwork · #9 03-09-2012, 07:30 AM

Quote:

About $1000 is probably what it'll take I imagine -- since the engine needs to be pulled, what else should be done? engine mounts?, other things?

If it is high mileage it will be the "other things" that will drive it over $2k.

shertex · #10 03-09-2012, 08:37 AM

Sorry to hear of your leak, but I LOVE to see that kind of high mileage....you are an inspiration to the rest of us!

If it were me, I would probably try a stop leak product first.

peachykeen · #11 03-09-2012, 08:59 AM

Quote:

Originally Posted by shertex

Sorry to hear of your leak, but I LOVE to see that kind of high mileage....you are an inspiration to the rest of us!

If it were me, I would probably try a stop leak product first.

OK -- I've asked around about doing that and no one said that it would do any good-- but I don't have anything to lose at this point. Anyone have any recommendations for a good stop leak???

Also -- on the mileage --- I think it is actually around 300k --- after reviewing old maintenance invoices, I noticed the mileage recorded as being the same from year to year...and the odo doesn't work ... but once and a while will rotate a the hundreths place...then another...it is definitely not sure --- I was wanting to believe it for sometime..

Anyway, thanks for any info on the stop leak..

todd

shertex · #12 03-09-2012, 09:02 AM

Quote:

Originally Posted by peachykeen

OK -- I've asked around about doing that and no one said that it would do any good-- but I don't have anything to lose at this point. Anyone have any recommendations for a good stop leak???

Also -- on the mileage --- I think it is actually around 300k --- after reviewing old maintenance invoices, I noticed the mileage recorded as being the same from year to year...and the odo doesn't work ... but once and a while will rotate a the hundreths place...then another...it is definitely not sure --- I was wanting to believe it for sometime..

Anyway, thanks for any info on the stop leak..

todd

From different things I've read (I have no first-hand experience), I would try a Lucas Oil product.

Interesting about the odo....

charmalu · #13 03-09-2012, 09:15 AM

The spedo would be the easy fix.

Charlie

shadetree77 · #14 03-09-2012, 05:59 PM

that stop leak stuff won't work on a rope seal

peachykeen · #15 03-12-2012, 01:25 PM

Quote:

Originally Posted by kerry

How did you confirm a leaking rear main seal? It's easy to mistake an oil filter housing gasket leak for a rear main leak. Oil filter housing leaks are far more common. Also could be a valve cover gasket leak.

Hi again,

Had another shop take a look and re-confirm that it is indeed leaking from the rear main seal -- a shop that is willing to do the work is telling me about $2900 for the job.

No way I have that -- so, just keep driving and adding oil? If anyone is interested in near MN -- I'm considering selling it as is.

Thanks for any other tips/advice,

todd