On the 1975 240D there was a kind of a dipstick attached to that cap. And, there was an overflow tube. If you put too much in, it just ran out the overflow tube. I know. That is how I found the overflow tube.

Jim

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Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)

thanks for the great info all

I e-mailed to a German mechanic from Germany about this through a forum in Germany.

His suggestion: check the manual for the volume of oil in the IP.
Make sure the overflow side plug is closed.
Pour that amount of HD30 into the IP from the top.
Wait 24 hours, at least an hour min
Open the side overflow valve and collect the rest.

The older oil, being lighter than the new thick heavy oil, will be displaced and end up above the overflow line.
You just gotta give it time.
I asked him what he does on his 190D- 60 vintage.
He waits overnight, then opens the drain plug after he puts a bowl below, smokes a cigarette, lets the oil flow, closes the plug, gets rid of the old oil.


ganz einfach, ja?

__________________
Strelnik
Invest in America: Buy a Congressman!

1950 170SD
1951 Citroen 11BN
1953 Citroen 11BNF limo
1953 220a project
1959 180D
1960 190D
1960 Borgward Isabella TS 2dr
1983 240D daily driver
1983 380SL
1990 350SDL daily driver alt
3 x Citroen DS21M, down from 5
3 x Citroen 2CV, down from 6

I think I liked the sucking out with a tube idea better. You could use some of that skinney hard plastic vacuum line with a short piece of rubber hose connected to one of those cheap plastic Syringes they use to inject Meat. We have 99cent stores out here that sell them.
That would get the bulk of it out.
After that you could use the "German" method above and end up with cleaner Oil.
Also a thought is that the drain plug could be on the opposite side of the IP.

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84 300D, 82 Volvo 244Gl Diesel