Hey Rory is right. in fact he helped me raplace it. On my 81 240D manual for the longest time she was consuming oil at a high rate. I assumed that since she had alot of blow bye that was the case. However we found out that that bolt pictured above is not all that it may seem. The bolt in question is not infact bolted at all and it sits inside of a chamber. It moves up and down with the pulse of the engine or the oil pump and oil is pumped through the bolt to engine components. I had a thread up here years ago and it seemed that no one knew what was the problem.
The cause is two rubber o-rings that have dried out and lost their seal. As that bolt moves up and down in the chamber it needs the o rings to seal the oil from getting out of the engine. when they fail it actually pumps out oil on every pulse. I ordered two o-rings from Inter auto parts in san diego...now known as north coast auto...it cost me a couple bucks and a half hour job...no more oil leak. It has been a couple years since I did this so I cant remember exactly how to do it and I cant remember the name of the bolt. However I do remember to acces the bolt you have to have an allen wrench for a bolt near the vacumme pump. search online for detailed engine pictures and you might be able to find out what the name of that thing is.....good luck one you know what you are doing it was a piece of cake

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68 250s SOLD
78 300d non turbo SOLD
1980 240d manual SOLD
1981 300SD 360,000 miles I think she's doomed for a parts car but has a good engine SOLD the engine to spamman
1977 300d non turbo SOLD
1985 300SD california car
1978 240D Manual