Replacing crank oil seals?
 

I'm considering a local 300TD auto that has leaking front and rear crank seals. The car leaves quite a few oil spots where parked, and the front end parts are rather oily near the front of the engine. The car has about 240,000 miles. I don't know what the lifespan of those seals are, maybe it's been overdue for a change for some time. My 240D has 215,000 miles and doesn't have any drip front or rear (maybe the seals were replaced at some point in the past...)

1. will the leaks get worse with time, and does something like this need to be addressed sooner than later? The owner told me his MB mechanic always told him not to worry about it.

2. how involved/expensive is it to replace those seals? The rear one would need the transmission removed I assume, which is a LOT of work or money. How easier is the front one to do? I just did the front crank seal on my 12 valve Cummins truck, but on that the seal is in the timing gear cover, so it's pretty easy to replace when you take the cover off, and the seal kit has a plastic guide to fit it onto the crank.

Thanks.

Rear crank seals are of the rope type and are incredibly reliable. How certain are you that the rear seal is leaking?

The front seal is a piece of cake compared to the rear. The crankshaft has to be raised up to replace it. Easy to do during a rebuild though.

http://www.peachparts.com/Wikka/OM617CrankshaftSeal for the front

I haven't crawled under and seen it myself. The owner told me it leaked. Which I find odd since he had the transmission rebuilt a few years ago, and one would think the mechanic may have replaced the seal as a matter of course when he had the transmission down?

Anyway, good to know the rear seal is reliable, and if it develops a small leak, will probably keep going a long time that way.

Thanks. I assume you meant the "engine" has to be raised up (to access the front of the crank)? The engine was rebuilt some years ago apparently, but evidently only the top end was rebuilt (it had low compression in 2 cylinders so I assume they replaced rings etc. - I haven't seen the records yet, but will look at them before putting any money down on the car).

Thanks for the link. Pretty simple and ingenious way to guide the seal on there. As I said, the Cummins seal kit includes a plastic piece to guide the seal in, as well as a round metal piece that fits on top of the seal and that one bangs on to drive the seal in place. Very well thought out kit. Sounds like with MB, you just get the seal in a bag...:rolleyes:

Here are some pictures of the rear seal

The crank needs to be lifted

http://www.peachparts.com/shopforum/showthread.php?t=288644

It is a serious bit of work - particularly if you pay some one else to do it.

Not with a rope seal.

Here is a thread from Rollguy, that replaced his rear main seal.

http://www.peachparts.com/shopforum/showthread.php?t=298852

Charlie

Thanks for the additional info and link on the rear rope seal. Indeed, I can see this is a serious piece of work, especially trying to do that with the engine in situ! Well, if I do end up buying this TD, the rear seal will stay where it is, and I'll put up with the drips. The front seal however, will likely get replaced sooner than later. Cheers!!

Front Main Seal or....Vacuum Pump Gasket Leak
 

You may even find that it is your vacuum pump to chain cover joint that is leaking. I had two reputable MB Indies say my leak was in fact the front main based on oil spray & drip location. Drips on the street like your photos. Not a lot of oil lost. I figured I had bigger fish to fry for the $ like a new vacuum pump.

So I put a new V.Pump in and...go figure...the oil leak stopped. Now I can park in the driveway! Check it out. I've heard of several others finding the same result.

PS the car now has 330k on the original front main seal.

And don't forget the obvious rocker cover gasket!

If the 300D has a Turboed Engine is it possible it could be leaking from the Turbocharger Drain or the Oil Separator Drain.
Could part of the Rear leak be the Oil Filter Housing Gasket?

Thanks for additional things to consider for sources of leaks. Sounds like if I get this TD, I would be wise to wash the engine and carefully determine the actual source(s) of leak(s), then re-seal or re-gasket whatever needs doing.
Cheers.