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  #1  
Old 02-17-2012, 11:51 AM
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W201 1989 190D Oil Leak - Crankshaft Seal? OM602

So I've sprung a leak somewhere! Could use some help identifying the possible candidates.

The leak seems to be coming down behind the plastic shielding that separates the block from the belts. It is almost entirely on the right side (passenger) of the engine. Once on the bottom of the engine, it has traveled backwards along the oil pan as far back as the crossmember.

It has made a 'T' pattern on the engine bottom splash guard - a thin line across the front of the engine, and then splotching down the right hand side (below the above-mentioned oil pan mess). I've already cleaned the area and let it leak more, but the origin is difficult to pin down because the area at the front of the engine but behind the splashguard is narrow.

Seems to me this is most likely the crankshaft seal? Any other possibilities, or other suggested ways to diagnose?

Help appreciated, I suspect this will be a decent-sized job to fix!

Bruce
1989 190D 60K miles

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W201 1989 190D Oil Leak - Crankshaft Seal? OM602-img_0119.jpg   W201 1989 190D Oil Leak - Crankshaft Seal? OM602-img_0120.jpg  
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Old 02-17-2012, 01:19 PM
1985 190d
 
Join Date: Nov 2006
Location: canadian border vermont
Posts: 518
I had the same problem for a while. I also thought front crankcase seal.
Removed radiator, then belt tensioner system. THere are leak points in that system too. In the end, it was an early warning of impending head gasket failure in my case; the timing chain galley is full of oil, and blow-by pressure from the head gasket forces oil out in the front if the block. So look carefully at where your head bolts to the block, especially in the front, and see if there is staining there. Its a common leak point on this engine.
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Old 02-17-2012, 01:21 PM
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Thanks for the head's up. Sounds like I'm not really going to know until I start removing pieces to get a closer look.
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Old 02-17-2012, 03:38 PM
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You should be able to see where the head gasket sits on the block between the chain tensioner and #1 exhaust runner.



Other possible sources are the belt tensioner arm attachment (unlikely if still original) and the vacuum pump front cover - Oil Leak 300 SDL, Any Ideas?

Sixto
87 300D

Last edited by sixto; 02-17-2012 at 04:01 PM.
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Old 02-27-2012, 12:22 AM
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Alright, I'm a little further into the problem now, so I have a halfway report.

Vacuum pump front cover gasket looks to be leaking near the bottom, will definitely replace while I'm in here.

Still not convinced this is the only source, as the pump is on the driver's side, and most of my oil was coming down the passenger side.

Here's what I found when pulling out the tensioner (see pic). I wasn't expecting there to be crap in here - installation instructions don't say anything about grease, just about M100 (for which I've read Red Loctite on the bolt threads). This look normal?

Will report back when I've purchased the 12mm hex necessary to get the tensioner arm off.
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W201 1989 190D Oil Leak - Crankshaft Seal? OM602-tensioner-main-bolt.jpg  
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  #6  
Old 02-27-2012, 10:09 AM
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That looks to be some kind of burnt up belt debri,maybe before your time the tensioner frose up and burned a belt.
I had and still do live with a leak on my 190d ,the vacuum case was 1 of the sources ,but Im fighting the rear main seal now.
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Old 02-27-2012, 10:12 AM
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Interesting possibility. I did have a belt come undone 6 months ago (after the car sat for 10 years), but turned out to be a loose alternator pulley.

Question is - how would the belt debris get in there? I had a fun time prying the cap off there (not shown), so I presumed the debris was coming from the block side (oil or grease).
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Old 02-27-2012, 11:16 PM
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OK, think I've got it figured, help me through this.

The crud on the fan-facing side of the tensioner is grease from the bearings inside the tensioner. When I turn the tensioner around, I definitely feel choppiness, like the bearings are worn.

On the other side of the tensioner, there isn't much grease, but it looks like the interface between the washer and the tensioner is where it was leaking (oddly, not the washer - block interface - this is totally clean).

The underside of the tensioner is pretty grimy, and all of the mess is below the tensioner.

So: The tensioner bolt was where the oil leak was coming from. This seems consistent with the below-car leak pattern too, because the tensioner bolt is more centrally located, compared with the vacuum pump.

My only question is: Is the gradual failure of the tensioner bearings related to the oil leak, or just a consequence?
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W201 1989 190D Oil Leak - Crankshaft Seal? OM602-far-side-belt-tensioner.jpg  
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  #9  
Old 10-14-2012, 09:40 PM
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So I'm coming back to this job after 10 months, and finding that something is still leaking. Either I mis-installed the vacuum seal, or in fact my front crankshaft seal is the culprit.

My working theory is that oil is getting flung by the spinning crank, hence ending up above the crank. Has that been the experience of other folks as well?

Bruce
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  #10  
Old 10-14-2012, 10:23 PM
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Timing Case Leaks On the front face.

Vacuum Pump Gasket area
Through bolt that holds the Tensioner system.(Impossible if Loctit-ed in)
Front Crankshaft Seal.

Clean it all off and "Watch".

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