Well, the clearance between the tube and the orifice surely isn't big enough to get a drywall screw in there. I'll see if I can think of something that will fit in there and dig out more of the old grommet. The car has been sitting overnight with most of the engine's weight on that deep socket jacked up into the orifice from below.

Yes, it can be a bear when the grommet is hardened rock hard .

None of the penetrants mentioned will soften that old grommet and drills/sheet metal screws will damage the tube, it's only sheet metal .

I used a sharp X-Acto ( X-ACTO Knives | Cutting Tools, Hobby Knives, Craft Knives ) knife to cut away most of the boot from above, not easy, mind you don't slash your fingers ! .

Harbor Freight Et. Al. has cheap copies .

The grommet came out very slowly and it little tiny bits and pieces, took me a while .

Then push the tube up and out from below ~ the diameter of the pusher is important ~ not too big, not too small, experiment with different 3/8" drive sockets inverted on a 6" extension before applying the lifting pressure .

You only want to press on the _tube_ not the rubber at all .

If you simply -must- try to soften that old rock hard rubber grommet, use clean & fresh brake fluid, it'll need to soak a while and the brake fluid will soften up other rubber items so don't be careless with it ! .

Now you know why Mechanics are all RICH and GOOD NATURED ! .

(or, not ) .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

Maybe an exacto knife. The HF kit has many thin cutting blade contours.

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78 W116 300SD 'Desert Rose' new as of 01/26/2014
79 W116 300SD 'Stormcloud' RIP 04/11/2022

I brought my 85 300D for the Mercedes-Benz dealer for this job, they used an exacto knife to cut it out (tech was specialized in the older models). When I saw it out, I noticed how hard and rock solid this rubber was, I was shocked that I was only charged one hour labor for the whole thing. Makes me want to change all rubber on the car.

The grommet was in pieces and the pieces were literally solid as a damn rock. Be careful and good luck this is a difficult one for the W123!

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1976 Mercedes 240D (Sold)
1985 Mercedes 300D Turbo Diesel: 500,000KM
1986 Mercedes 300E (Sold)
1988 Mercedes 300E (Sold)
2002 Mercedes C240 (Sold)
2008 Mercedes C350 4matic

A great site for purchasing industrial rubber products!

Industrial Rubber

Success! I got the lower turbo drain tube out. Like you all suggested, I had to chip away at with a 90 degree pick from below and a straight pick from above. It helped to sharpen the picks with a grinder and I also heated them to red hot and got in deeper. Surely, putting it in will be a breeze compared to the ordeal I've just been through.

Great news

While the oilpan is off, you may want to verify that the check valve on the oil separator drain is functioning properly.
Now you have easy access to replace it, if need be.
Also a good time to replace the o-ring on the oil separator nipple on the sump.

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78 W116 300SD 'Desert Rose' new as of 01/26/2014
79 W116 300SD 'Stormcloud' RIP 04/11/2022

Can the replacement of the O rings and gromet be done from inside the oil pan without removing the turbo ?

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Revenge is a meal best served cold

1980 300SD, Shotzie
1996 Volvo 850, Dark Night
1997 Ford F350 7.3, The Tuna Clipper

You don't have to remove the turbo, if you unbolt the upper oil drain tube from the turbo.
If the drain tube can lift out readily, then you don't need to remove the oil pan.

You do have to lift the lower drain tube up, in order to remove, and replace the lower o-ring and lower grommet.
(IIRC there is a lip on the bore in the sump to prevent the drain tube from entering into the lower oil pan.)

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78 W116 300SD 'Desert Rose' new as of 01/26/2014
79 W116 300SD 'Stormcloud' RIP 04/11/2022

Alec, when you say "oil separator drain", what you're talking about that is the tube from the air cleaner that enters the pan next to the turbo lower tube, right? Does anyone have a part number?

The check valve is no longer available new. I have a good one that I bought before I realized that my block doesn't need it, if you do end up wanting one.

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Milan Brown 1979 240D, rebuilt OM617.952 turbo diesel, rebuilt 722.315 transmission (my only daily driver)

Instagram: @maximed93

Yes, that's the one.
O-ring size and MB Part Number are at home...will edit in the info later today.
Edit: Seal Ring - Oil separator o-ring is MB Part Number (006-997-26-45), size 2mm CS X 12mm ID...(also used on oil dipstick).
You need two o-rings, one for the nipple on the top of the sump, and one for the nipple on the bottom of the air cleaner.

Check valve is MB Part Number (617-018-00-29), but listed as NLA new ...

However, check valves are still available as one of the components in the vacuum pump repair kits.

The dual diaphragm vacuum pumps in my 78 and 79 W116 300SDs have 5 check valves in each unit.
Two kits are needed to rebuild a dual diaphragm pump
The 000 586 13 23 kit has one check valve.
The 000 586 12 23 kit has four check valves

Good used spares work well, if your check valve has failed.
I rebuilt a junkyard spare dual diaphragm pump to install in 'Stormcloud',
and still have some good used check valves available for minimal cost if any forum member needs one.
Just send me a PM.

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78 W116 300SD 'Desert Rose' new as of 01/26/2014
79 W116 300SD 'Stormcloud' RIP 04/11/2022

Oh, oh ~ where exactly is this valve located ? .

I've never noticed it before, silly me .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

It is next to the turbo oil return bore in the sump...only visible with the oil pan removed.
The image is from Post #2 on dmorrison's thread.
617 engine, replacing the oil separator check valve in the upper oil pan.

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78 W116 300SD 'Desert Rose' new as of 01/26/2014
79 W116 300SD 'Stormcloud' RIP 04/11/2022

THANK YOU ! .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

So tomorrow I'll finish assembling the turbo onto the exhaust manifold. I'm torn between whether or not to install the turbo lower drain tube and grommet before or after I install the turbo/manifold assembly. Everyone says it is a pain to install the lower turbo tube. I got to believe it will be way easier to install the lower turbo tube without the turbo/exhaust manifold in they way. But, will I be able to install the turbo and upper, curved tube with the lower tube and grommet already on place?