Wallknight,

Where do you see evidence of engine oil in the vacuum system? If it is at the back of the "ignition" or starting switch operated by the key, I think you may have a bad vacuum diaphagm in the shutoff mechanism on the injection pump. That requires a new mechanism as I do not think a gasket solves the problem. In my experience with vacuum pump diaphragm leaks is they become visually apparent as the line going from the pump to the air intake gets black (it is a translucent white when new) and when the leakage gets bad you will notice heavy smoking at idle. NOt sure if your car has the vacuum line from the pump to the air intake or not, but it is there on 240D's and earlier models. Good luck, 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)