Just want to get my thought process verified by a few of the brains here...

Have recently been getting the following symptoms:

Engine shutting down more slowly than normal with key shutoff.

Occasionally (very rarely) the brakes will go hard, as if the booster is suddenly not getting vacuum.

Findings:

- oil definitely being sucked up into vacuum line to Injection Pump shutoff valve.
- bit of oil now dripping from ignition switch vacuum lock fitting. (got a couple of oil drops inside car to prove it!)
- Vacuum at brake booster line 'T' fitting reads 20"
- Vacuum applied directly from brake booster line 'T' fitting shuts the car down pretty quickly.

Vacuum systems in these old diesels have been discussed exhaustively here - and I've read virtually all of it!

So I'd just like to test my thinking here:

1) Oil in IP shutoff valve vacuum line is pretty much diagnostic of leaking diaphragm, right? Time to replace.

2) Will oil in the ignition vacuum lock do damage to it? Am I likely to need to replace this, too?

3) Is 20" of vacuum adequate, or indicative of a weakening vacuum pump? I have a rebuild kit around somewhere...

I've also sourced the bearings for the vacuum pump, in anticipation of rebuilding it at some point. Is now that time?(!)

__________________
'83 300 SD
'05 E320 4Matic
'06 BMW 530 xi
'68 Triumph TR 250 - The only car I ever loved more than the Mercedes; who needs electricity, anyway? - Damn, why did I sell it?!
'59 Jaguar 3.4 'Le Chat Noir' - Damn, why did I sell it?!

It's difficult to make predictions, especially about the future.
- Niels Bohr