Another m103 Head gasket
 

Well, 200,000, it's about damn time. Noticed a lot of oil on the block today when I was disabling that damn air pump (mmm, no more clickity clack on startup). Planning on completely cleaning of the engine, and then checking it every few days so I can pinpoint the spot of the leak to verify that it is the head gasket because I go through with this. Maybe I'll be lucky and find out that I spilled some oil down there at the last change. While I'm in there, I think I'll change the manifold gasket. I can smell exhaust in the engine compartment when it's running, but a light breeze could've brought it from the tailpipe into my nose. Hm. Comments?

200k total on the engine, or 200k since you last did the head gasket?

I'm looking at an 89 300TE with 75k since a complete valve job and head gasket. 194k total... should I expect another head gasket soon?
k

I've seen the M103 externally leak in 3 places:

a. passenger side corner back near #6 plug.
b. The imfamous U-gasket up front below dist. cap.
c. Valve cover gasket

There may be more.

I would believe that a & c would be most likely to leak on to the exh. system.

My 2 cents.

The head gaskets on the 103 engines rarely fail as do the 104's. By far, the most common engine oil leak on the 103 is the upper timing cover.

Good luck,

Just how bad can this leak be? I have a significant leak, blows under the car, even gets some on the right side of the back bumper. Probably drips ten drops under the car when parked. Drips off area where trans attaches to engine. It IS engine oil.

I figured it was the head gasket but when I looked from below it was dry in the suspected right/rear area.

The front of the engine has always been nasty, especially on the right. But can the upper timing cover really be a BIG leak and blow back like that?

Thanks

Unless a lots of oil come from the back of the engine head, you are most likely looking at a rear crankshaft seal leak or an oil pan leak.
If the crankshaft seal is the culprit, the transmission has to come out.

My 89 300te had the oil slick on the belly of car, from the passenger side of the engine, along the transmission, and all the way down the floorpan. It was leaking from the front-cover-at-top (the infamous U seal), so I replaced it. But it was also leaking from behind #6 plug, which I didn't realize until I found the oil kept leaking. Only happened when the engine was running and tough to notice. If you prop the hood all the way up (vertical) and shine a light behind the back of the head, so you can see where the engine connects to the tranny you might be able to see where the oil is coming from. A dentist's mirror might help. You can also shove a rag back in there and pull it out. Even a small amount of fresh oil on the rag indicates a leak. I noticed that this leak would also drip onto the exhaust and smoke. New head gasket fixed that.

Here is my experiance with a 117 engine on a 560SL 107,000 miles.

I first thought this was a rear main seal leak and actually pulled the transmission and flex plate to inspect it. I found out from this NG that the 117 engine does have a tendancy to leak oil and it goes into the valley between the heads and through a drain hole where it come out the bottom of the bell housing. All the inspections of head that I could do with the engine assembled could not confirm that I definately had a head gasket leak. I bit the bullet and pulled the left head. It was only then that I could tell that the head gasket was really the problem, see attached photo. Since it was only the left head leaking, I only pulled the left head. But I found the head bolts to be so loose that I retorqued the right head as well. During the retorque I got between 1/8 and 1/4 turn extra out of each bolt. Therefore despite what MB says about this head not having to be retorqued, I will once again retorque my left head at about 10,000 miles. I think that anyone with a 117 engine should consider retorquing the heads if they have over 50,000 miles. This would most likely prevent the oil leaks.

John Roncallo

So the leak was at the BACK of the head...Not the right-side rear?

Thanks