603 Heat Exchanger Seal Ring?
 

Could some kind soul tell me what the seal ring looks like for the fuel heat exchanger? Is it an aluminum ring, or perhaps rubber? Don't see it on the threads, so perhaps it fell off while my head was off.

Here is the russian parts site (in English):
It will give you the Mercedes part number if you can find the part.
http://www.detali.ru/cat/oem_mb0.asp?TP=1

I can't find the connection in the Russian site but I know it's the same ring used for the heat exchanger fitting at the water pump which is a thick o-ring p/n 0129975148.

Sixto
87 300D

p/n 0129975148 is confirmed in the second diagram in http://www.detali.ru/cat/oem_mb2.asp?TP=1&F=124133_501&M=603.960&GA=722.317357&CT=M&cat=503&SID=20&SGR=015&SGN=01

Sixto
87 300D

Thanks. I looked at the EPC, and it shows a seal, but I wondered what it consists of. Maybe I already have it, but don't realize it. Any idea?

Thanks.

It's a relly thick o-ring that's gun metal in color. A real oddball color as o-rings go.

Sixto
87 300D

Don't see one of them. Guess a trip to the dealer is in order...

Maybe it's stuck to the head.

Sixto
87 300D

I wonder if it might have been when it went to the machine shop. It sure isn't now.

Got the seal-- a gun-metal-colored rubber o-ring. I don't see anything instructive in the cylinder head R&R manual (01-5800) regarding installation, but it looks like very little torque is called for. Should I include some loctite to keep the collar solidly attached to the cylinder head? Too much torque deforms the seal, and the pipe elbow remains freely-swiveling even when attached to the head, regardless of how tight the collar is. I'm now thinking the anti-seize compound I put on the threads was a very bad idea...

Are we talking about the same thing? The fitting I'm thinking of that uses that seal is a slip fit with an an external spring clip. The fitting with the hex doesn't have to come off the head even for machine shop work. I don't know if there's a seal between the fitting and the head but it'll more likely be a crush washer than an o-ring.

Sixto
87 300D

I'm looking at the rubber o-ring that fits into an indentation around the threaded extension of the heat exchanger elbow, part 176 in the diagram. It becomes compressed against the flat milled surface of the head as I tighten it down. There's no potential for a crush washer beneath the end of the threaded part of the elbow, but I can imagine the possibility of placing one around the threads. But this is what Mercedes gave me--the rubber o-ring, which is colored with a sort of gun-metal finish. The part number matches the EPC, too. Still seems a little strange, but it wouldn't be the first time I thought something was a little odd on this car.

Seal 176 fits in a groove in fitting 170. Fitting 170 slips into the extension in the head. I suppose there's some compression of the seal. With the fitting in the extension, spring clip 173 is pressed on the extension and fitting to keep the fitting in place.

I don't know where you see threads on the fitting.

Sixto
87 300D

So the clamp (173) is serving as the nut locking device here--like a lock washer. Then I shouldn't be concerned about how much the elbow still wiggles around once the seal is compressed a bit. It shouldn't leak after that. Thanks!

The spring clip keeps the fitting from backing out. A bracket on the fitting that attaches it to the oil filter housing keeps the fitting from twisting.

Sixto
87 300D