First the door locks started to respond very slowly and then not at all. The engine shut off was slow and now must be shut off under hood. I have bought a vacuum gauge and pump and tried to track down the problem but to no avail. There is adequate vacuum at the brake booster, so I assume it isn't the pump. Some of the lines have been replaced with black colored lines, so no color coding. Is there a schematic diagram of the vacuum systems for these cars?

Mofarmer

84 300td wagon

There are. Search the forum for "vacuum diagrams."

__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

Yep, sounds like a typical leak in one of the doors. That Mityvac will come in handy to track it down. The lines to the doors must hold vacuum or the doors won't function and the shutoff may also be affected if it's on that line.

online FSM (factry Servic Manual) at
http://mb.braingears.com or

http://pauldrayton.com/plainpages/merc

Well, I have spent 2 hours tinkering with the vac system and have made some progress, I guess. One door lock, the rear passenger side, kinda/sorta works, and I have discovered that I can shut the engine off. This would be funny if not so annoying. When I use the key to lock the driver side door if I hold it in the lock position for a few seconds the car will shut off. Kind of weird but I suppose that would be better than raising the hood every time. Anyone have any idea what's up with that?

Mofarmer
84 300td wagon

You probably have a vacuum leak in the "unlock" portion of the door lock system, so locking the doors eliminates the leak and allows the car to shut off. This info should also be applicable to your car:

http://www.peachparts.com/shopforum/showthread.php?t=159743