The incident I was referring to involved my '79 240D, which had the old style vacuum pump.

My first indication of trouble was the loss of oil pressure at idle, though the pressure was ok at higher rpm's. Investigation of the oil pump revealed about a dozen 1/8" ball bearings in the strainer, along with several smaller pieces of metal. Further investigation found some more of the smaller bits in the oil pressure relief valve. Once all the debris was cleared away, the oil pressure was fine, and I certainly was curious where the debris might have come from. Mind you, during all of this, the vacuum was quite ok.

A month or two later, I was driving home from the city when...what do you know, no vacuum boost for the brakes. No engine shut off, either. And no vacuum anywhere. Well, the vacuum pump had failed entirely, probably leaving some more debris in the oil pan, and most definitely leaving me with no vacuum system. That it had continued to work for so long, with its thrust bearing (probably not its real name) half destroyed, is quite amazing indeed. A "new" pump from the wrecking yard solved this problem.

I don't recall which year your diesel was made, so I don't know which vacuum pump you have, but if you've experienced a total loss of vacuum coincident with a loss of oil pressure, then I guess you know what's up.

At any rate: (1) don't drive it; (2) remove the oil pump; (3) clean the screen and the relief valve. None of this is very difficult, especially if you have means of getting your car up into the air.

Phil