Victim: 1995 E320 (W124) with M104 engine.
Problem: external oil leak
Questions:
- I just changed from Dino to Synthetic. Should I expect leak to diminish or get worse?
- If I do the head gasket job, I know to send the top off to a machine shop. But what about the bottom that stays in the car - how do you get that surface smooth and clean?
Is the answer to do it manually by hand with scrapers and sand paper? Stuff towels in all the opennings to prevent debris from getting in the engine?

In case you can't tell, this will be my first head gasket replacement.

Hard to say if your leak is the result of the switch to synthetic oil, but if it was me I'd switch right back to high mileage conventional oil - not much to lose.

It was already leaking oil for the past 2-3 months. Slight leak til a few weeks ago it increased . I just did oil change yesterday and for the first time used royal purple synthetic. Wondering whether tendency of synthetic is to leak more or less

For the Investment you've just made...
I'd sure wait a full 5,000 miles to get the benefit...
Who knows?
The seals may adjust to the RP's additive package and swell a little.

LEAVING Disneyland and returning to the REAL world...

If the leaks are too bad,
Kestas has detailed for you the only real solution to the problem in reply # 6
below.

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'84 300SD sold
124.128

Certainly the conventional wisdom, vehemently objected to by some, is that synthetic is more likely to leak. I'd still try a a high mileage conventional oil for a while and see what happens. If it's really coming out it's probably too late.

Where is it leaking? It may be a relatively simple upper timing cover seal leak (common).

With the head off, the head deck surface of the block is prepped by scraping. It's an art. When I do it, I line up a bunch of tools with varying degrees of sharpness. Sometimes the duller tool do a better job of lifting off the residue without gouging the surface. Sometimes you need the sharper tools to carefully shave off the residue. I finish the surface with Scothbrite dipped in oil. I don't fuss much with the debris. I put rags in the cylinders. The coolant should probably be flushed and oil changed after the job.

Synthetic doesn't create leaks, it simply exploits existing ones. If the leaks bother you and aren't within your budget to repair, trying dino oil again is standard practice.

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Gone to the dark side

- Jeff

The leak is coming from the pasenger side towards the very front. From above viewing it is absolutely dry. From below it is hard to see because the alternator is in the way, but just above that is where the oil is coming from.
There is also oil on the passenger rear (closer to the firewall) seal but I can't tell if that is a leak source or if the highway breeze is just blowing the oil back all over everything.
If it is warm out this weekend I'll hose the engine clean all under, take it for a short drive and see if I can pin point the source (sources?)

Sounds like the upper timing chain cover. http://www.continentalimports.com/ser_ic100345.html

Agreed.

yep

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Jim

I tried zeroing in on the leak with these pictures:
- for orientation (picture #2), a general area shot of the passenger side front. If you see a small section of red vacuum tubing just forward of the front of exhaust manifold, that is the area I'll be getting closer to.
- 2 closer shots of the area (pictures 3 & 4), still can't see the leak from here but it resides slightly left of the red vacuum hose, behind the aluminum tubing
- and finally, a very close shot ( picture #1) of the seam where I think the leak is coming from.
This leak seems to be spraying down on the alternator and air pump which are both covered with soot. Must have been leaking somewhat for a while building up layers of grime.

Typical leak pattern. Mine was worse. I waited until it was leaving small puddles everywhere I parked before replacing the upper timing cover seal.

FWIW, I just replaced my front timing seal in my 95 on Monday, since it as of recent started to leak oil pretty steadily. Just little drops here and there, but the pass. side front of the engine was always "wet".

I looked at it carefully, as well as my independant. We both agreed it was "probably" the front cover seal. Well, after replacing it, brake cleaning everything spotless, I drove home (30 miles). I get home, and much to my horrific disappointment, the leak is still there. I dont know if I was more bummed about wasting 4-5 hours labor putting the new seal in, or realizing the headgasket needs replacement. Needless to say, I was discouraged. I will continue to drive it like so with the minor external oil leak, and check the oil more frequently. Come summer time, If I get ambitious, I might do the head gasket. But who knows, its not something I really want to do on a 204K mile car. The head gasket is original, and I guess its surprising it lasted as long as it did.

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93 300D 2.5 Turbo, Black/Palomino 273K
09 E350 Black/Black 41K

To AMG280, If you decide to go ahead and do the head gasket replacement, I'm interested to do it with you/give you a hand.
On further inspection, I have a significant leak at the timing chain cover and another leak at the passenger side firewall corner, so I definitely need a head gasket replacement. I have not done this before - if it normally takes 15 hours, it would take me 30 hours the first time. Second time around I could get it down to 15 hours and eliminate common mistakes.
i don't want to give the job out to my indie because the wiring harness is original and I anticipate it too needing replacement - making this a total of aournd $3000 if I gave it out.
Let me know. Sending you a PM.