M104 Rear Main Seal leak? - PeachParts Mercedes-Benz Forum

RamahX · #1 07-19-2011, 07:15 PM

Sorry if this has been discussed before, but I'm tired of searching and very frustrated and hot... (yes... I looked in the oil section, like Hunter says, oil post pop up like weeds ;-)

'94 E320 W124 car M104 with 140K miles. Head Gasket was replaced at about 100K.

I have an oil leak. It's getting pretty bad, it's pooling in the bell housing in the front access hole/cavity. When I leave -my driveway is downhill -and the car leaves a pretty good trail of it down the driveway. I originally thought it was the oil filter cover. Replaced filter/gasket.

Checked - oil level is good, between the full and add (yes, I know about the TSB about 7.0 vs 7.5). There is no oil leaking around the head gasket or under the timing belt cover. Dry as a bone. In fact, the whole engine is clean of oil, except for where it seemed to leak from the oil filter cap as mentioned.

Raised front of car, no pooling oil on bottom cover. Suspect it to be rear main seal, or question: could oil have leaked from the oil filter cap into this cavity?

Help!

mbdoc · #2 07-20-2011, 08:11 AM

Sure sounds like the rear main oil seal. Just a plain rubber seal ring.

RamahX · #3 07-20-2011, 04:06 PM

Thanks, but we are still trying to rule out if oil is seeping into there from somewhere else.

It's not just a rubber seal, I have to remove the transmission to do that

so i'm hoping thats not it... plus, at 140-150K it's not common is it on the 124 cars?

whunter · #4 07-21-2011, 03:48 PM

Just in case the seal is bad, here is the part number.

Crankshaft Seal, Rear (93 X 114 X 13 mm)
MB# 017 997 74 47

.

J. M. van Swaay · #5 07-22-2011, 11:24 AM

There are two choices for the rear seal. One is just like the original, the other is called a repair seal. The repair seal is dimensioned slightly different so that the lip of the seal does not contact the crank surface in the same place as the original. If the original seal wore a groove in the crank sealing surface, and you replace it with an original seal, it is likely to leak also.

J. M. van Swaay

RamahX · #6 01-29-2012, 11:54 AM

Question, are W124's prone to either Rear Main or Front Tx Pump Seal leaks?

Talked to a tech last week, told him car leaves a trail down our driveway when we leave from the oil spilling out of the flywheel inspection well at the bottom of the Tx Bell.

He said he's NEVER heard of that.

BTW our driveway when leaving is downhill, which is why I guess its spilling.

RamahX · #7 01-29-2012, 11:55 AM

And now this has happened... I just posted 94 E320 W124 No Oil Pressure at idle

Hirnbeiss · #8 01-29-2012, 04:09 PM

My MBs have always been a little oily in that area, but usually it's from a leak forward being blown back. On the M104 the most common leak spot is the front timing cover, right at the corner where it meets the head gasket. Of course, that tends to leave oil in the belly pan too, which you said was dry, but I would check there first.
Double-check your oil level. High levels had a tendency to cause the seal to leak: 104 Rear Main Oil Leak?

RamahX · #9 01-30-2012, 10:50 PM

Already went down the road of that bulletin. Lost 2 quarts in 7 days, so ship is moored : (
It leaks this bad even at bottom of dipstick.
Someone posted it could be the 0W30 being too thin, suggested 15W40 etc. Oil is all over the starter.
Help...

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Hirnbeiss · #10 01-31-2012, 07:42 AM

Chief, first you need to find the leak. If oil is on the starter, it most likely didn't come from the rear main seal. Your first thought was the filter housing.Get a mirror and a flashlight and check all around the oil filter housing and block/head interface. Have the engine running for this so that oil is being pumped.
I once had a sizeable leak (stready trickle at idle) at the filter cap gasket after a shop used a cheap (e.g. Purolator or Fram) filter whose included rubber o-ring was undersized. Check down around the base of the filter housing as well.

RamahX · #11 02-06-2012, 01:21 PM

Hirnbeiss, thanks. New Post here.

Replaced filter housing gasket, and filter/cap gasket with dealer gaskets. Refilled with new oil, 10W40 Mobile Super. STILL same leak. Big puddle this morning and same stream path. I already knew about the rear main seal/only fill to bottom mark on dipstick bulletin. So that's not it, but thanks though.

At this point I'm assuming its maybe a cracked filter cap? If so, why isn't it easily discernible?

*runs and pulls out hair*