Oh boy we may be fighting for the only check valve in the USA. My dealer ordered mine today and said there was only 1. We'll have to see wether there is just 1 or You ordered 1 and only 1 was left when I ordered mine. He did say the "clamping sleeve had to come from Germany.
Talked to the reliable W123 mechanic at the dealer. The check valve is pressed in just like the oil dipstick tube. So It may be some work getting it out. Not hard just cramped. The Dealer also said that the clamping sleeve is probably the attachment point for the drain tube. We looked and could not find any other part number for the connecting tube. So we concluded that that is what the "clamping tube" is.
I do thiink that I'm having the same problem as you are. The mechanic also supported my finding in both my car and yours.
I will ask him when the part comes in if any gasket sealer should be used in installing the check valve. I will treat it like the oil dipstick tube and follow the directions in the manual for that.

Don't forget to order your oil pan gasket. You'll need one to do the job. It might be a good time to change the oil and filter at the same time.

Dave

PS First one with pictures wins. . But then of course a photo essay for the forum is required.

__________________
1970 220D, owned 1980-1990
1980 240D, owned 1990-1992
1982 300TD, owned 1992-1993
1986 300SDL, owned 1993-2004
1999 E300, owned 1999-2003
1982 300TD, 213,880mi, owned since Nov 18, 1991- Aug 4, 2010 SOLD
1988 560SL, 100,000mi, owned since 1995
1965 Mustang Fastback Mileage Unknown(My sons)
1983 240D, 176,000mi (My daughers) owned since 2004
2007 Honda Accord EX-L I4 auto, the new daily driver
1985 300D 264,000mi Son's new daily driver.(sold)
2008 Hyundai Tiberon. Daughters new car

That if you didn't need to replace the clamping ring life would be easier but I have a sneaking supicion that you have to pull that upper tube out to knock out the valve.
I can pick up the pan gasket ina day from Phil and I am definately more worried about my dealer parts guy getting the parts.

Personally I'm not too concerned aboput just blocking it off other than having to dump the oil seperator every few hundred miles or so. I was thinking tht if I can get a used drain tube at the wreckers then I will cut itoff and rig up a bottle to the end so I cna leave it conencted and then just dump the botle occasionally.

Anyway, I can wait to see what this part is made up like...

__________________
'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique

Well I got my check valve today...
Interesting, it is simply a plastic disk inside what appears to be a brass ring that is supported by a very light spring.
The clamping sleeve part appears to be a spring steel insert about 3/4 of an inch long that I assume is knocked into place supporting or holding the check valve into place.

Looks like a very, very simple device with no big mystery. It'll be a few weeks before I can make the install. I'll try to update later.

__________________
'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique

Got mine today. The check valve is the same, or appears to be the same as the vacuum pump check valves.
I still need the clamp sleeve. I also ordered the upper tube that the drain tube goes over. Just in case I need it.
The vacum pump uses gaskets to seal the check valve. Nothing is shown as a part in the diagram for this check valve. So I'm curious about the sealing of the check valve against the upper oil pan.

Dave

__________________
1970 220D, owned 1980-1990
1980 240D, owned 1990-1992
1982 300TD, owned 1992-1993
1986 300SDL, owned 1993-2004
1999 E300, owned 1999-2003
1982 300TD, 213,880mi, owned since Nov 18, 1991- Aug 4, 2010 SOLD
1988 560SL, 100,000mi, owned since 1995
1965 Mustang Fastback Mileage Unknown(My sons)
1983 240D, 176,000mi (My daughers) owned since 2004
2007 Honda Accord EX-L I4 auto, the new daily driver
1985 300D 264,000mi Son's new daily driver.(sold)
2008 Hyundai Tiberon. Daughters new car

I won't have a chance to tear into this for another week or two.

__________________
'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique

Just drove down to the Bay Area today and low and behold with the drain tube plugged I did not leak one drop of oil out the wastegate.

I can't wait to replace that valve..

__________________
'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique

Where are we on this post???? Probably whereI am, delayed
I was going to replace the unit this past week but had to fix my daughters car instead. Then my sons. They were both home form College.
I'm flying all this week so I don't want to take the car apart until I replace the chain tensioner on the SL. concerned about the chain slap at startup and woudl rather fix it then drive it. Also its not good to have just 1 car and then your working on it. Something will always to wrong with that setup, and your stuck with NO cars

Dave

__________________
1970 220D, owned 1980-1990
1980 240D, owned 1990-1992
1982 300TD, owned 1992-1993
1986 300SDL, owned 1993-2004
1999 E300, owned 1999-2003
1982 300TD, 213,880mi, owned since Nov 18, 1991- Aug 4, 2010 SOLD
1988 560SL, 100,000mi, owned since 1995
1965 Mustang Fastback Mileage Unknown(My sons)
1983 240D, 176,000mi (My daughers) owned since 2004
2007 Honda Accord EX-L I4 auto, the new daily driver
1985 300D 264,000mi Son's new daily driver.(sold)
2008 Hyundai Tiberon. Daughters new car

I've been out for the past week ill and with spring break this week here in Oregon there is little to no chance that I will get time.

One of these days though...

__________________
'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique

Well I finally got the new check valve installed yesterday. Here is a link to the post I made for the job.

617 engine, replacing the oil separator check valve in the upper oil pan.

I will let everyone know how the repair does. Any more oil leaks in this area????

Dave

__________________
1970 220D, owned 1980-1990
1980 240D, owned 1990-1992
1982 300TD, owned 1992-1993
1986 300SDL, owned 1993-2004
1999 E300, owned 1999-2003
1982 300TD, 213,880mi, owned since Nov 18, 1991- Aug 4, 2010 SOLD
1988 560SL, 100,000mi, owned since 1995
1965 Mustang Fastback Mileage Unknown(My sons)
1983 240D, 176,000mi (My daughers) owned since 2004
2007 Honda Accord EX-L I4 auto, the new daily driver
1985 300D 264,000mi Son's new daily driver.(sold)
2008 Hyundai Tiberon. Daughters new car