I've read multiple posts about replacing the o-ring and contoured sealing ring on the turbo charger oil return line on this fourm (very helpful ) but I can't find the level of detail I need to answer my question.
The question is this: When you put the two pieces of tubing back together and the lower portion of the lower tube is placed in the contoured sealing ring should it be positioned in the groove of the contoured sealing ring? The way I had to put this back together required the lower tube to have the o-ring below the contoured sealing ring. I can't see getting the upper portion bolted back on if the lower tube's lower o-ring is in the groove of the contoured sealing ring. It will be about .25 inches too high up top I think. I didn't find this spelled out anywhere on the forum. If I've missed this posted somewhere else please point me to it. Thanks.

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83 300sd, 280K Blue/Blue Leather (~24mpg)
95 E300D, 150K Champaigne/Parchment(~33mpg)

Sounds like you positioned it in the correct location. If it is not in the right spot you can't get the upper tube located properly to allow you to line everything up.

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Jim

I was afraid of that. I've still got an oil leak after this procedure. Oil pools on top of the pan. The old contoured sealing ring was hard and brittle and the lower tube was lacking an o-ring on the lower portion of the lower tube section. It was not wasted effort but I still have the leak. I was thinking that maybe the lower tube's o-ring was not seated in the contoured sealing ring and therefore still leaking....oh well...more to ponder. Thanks.

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83 300sd, 280K Blue/Blue Leather (~24mpg)
95 E300D, 150K Champaigne/Parchment(~33mpg)

I will post my opinion and tell you that I think the lower o-ring on the lower tube is supposed to rest in the groove of the oil pan grommet. This is what I remember the instructions saying. While you may have to force that tube lower down for assembly, you should be able to push it back up again once all the parts are in place.

The manipulation of that tube is a little easier with the oil pan off, because you can push up on the bottom of the tube with the correctly sized socket. I have done one repair so far (on the 82 300D) and its not leaking at this time. Previous repair attempt used RTV on the grommet and o-ring during assembly - don't do this. They will seal correctly on clean surfaces by themselves.

Its a rewarding repair to get rid of that oil leak, but not a simple bolt-off-bolt-on repair. I think I got everything positioned right after about 20 tries.

Ken300D

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1982 300D at 351K miles
1984 300SD at 217K miles
1987 300D at 370K miles

I agree. That o-ring probably has to seat in the groove of the contoured sealing ring. That must be why it's still leaking. I'll try to correct it tomorrow if I get time. I'll keep you posted...pun intended. Thanks.

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83 300sd, 280K Blue/Blue Leather (~24mpg)
95 E300D, 150K Champaigne/Parchment(~33mpg)

When I did mine there were a couple of tricks that I figured out with some help of friends and my indy.
1. Take a dremel or similar to the upper tube bell housing where the lower tube o-ring seats and grind off a quarter inch or so so that you can fit it back onto the lower tube for reassembly. That bell housing has a good inch of seat so that little bit is not needed.
2. I did not seat the lower o-ring in the groove but I was told that it will seal against the bottom of the upper grommet and should not leak. No problems yet but that may change.
I actually don't remember seeing in the instructions anything about it having to seat. I thought that groove was to work as a relief point for the grommet so that it seats better on the tube.
I'll check the installation instructions again though and let you know if I find that I did it wrong...

Indeterminate whether or not it must be seated. In hte one section is states tht the o-ring section is inserted "in" the grommet and yet during installation it makes it sound like you just stick the grommet in and then the tube nd you're good to go.
I think I remember that when I did mine I inserted the o-ring into the grommet and then forced the whole assembly into place with flat bladed items like screwdrivers, cold chisels, basically anything I could find that wouldn't cut the grommet.

Sorry I can't be of more help.

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

Also, check the oil drain tube from the oil separator in the air cleaner. This connects to the oil pan near the turbo drain, but closer to the engine. There is an o-ring in that connection.

I replaced my turbo drain seals, only to find that this other drain tube was leaking as well. It looks exactly like the turbo drain leak as the oil pools aroud the turbo drain grommet on top of the pan.

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as ever
Paul

1989 560SL
1987 300SDL
1987 300TD
1983 BMW 633CSi
1972 280SE 4.5

[QUOTE=PaulSpringmann]Also, check the oil drain tube from the oil separator in the air cleaner. QUOTE]

Very good advice. Lots of turbo drain grommets get replaced when it's the oil separator line that is the culprit. And the oil separator line o-ring is so much easier to replace.

How exactly does that oil separator line get come off to replace the o-ring? It looks similiar to the connection between the top and bottom pieces of the turbo drain tube. I think I'll check that next.

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83 300sd, 280K Blue/Blue Leather (~24mpg)
95 E300D, 150K Champaigne/Parchment(~33mpg)

If I remember correctly, the oil separator return line is held in place with a bracket/bolt midway between the air cleaner and oil pan. Remove the air cleaner, remover this bolt, and the separator line should lift off the oil pan. The connection at the oil pan is identical to the conection on the bottom of the air cleaner.

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as ever
Paul

1989 560SL
1987 300SDL
1987 300TD
1983 BMW 633CSi
1972 280SE 4.5

It seems that seating it in the groove is the way (although mine's just resting on the lower flange of the grommet, I'm sure.)

http://business.baylor.edu/Richard_Easley//autofaqs/tseals.htm

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The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)