Finally got some decent weather to try and troubleshoot my vacuum issues . . . I've had the HVAC and door locks plugged with golf tees since I bought the car. I'm going to tackle that green line (HVAC) after I get the door locks worked out.

So . . . I tested the vac pump and its giving plenty o' vac. Tested the pods in the doors, trunk and filler flap . . . found one slow leaking pod in one door . . . teed it off for now, I'll order a replacement. The rest of the system looked good, except possibly the reservoir. I couldn't get any vac readings with my mighty vac? How many pumps does it take to build up vac in that thing? The reservoir may be part of the problem BUT . . .

With the HVAC and door locks teed off, the car shuts off instantly. If I plug the door locks into the system, the car runs on and eventually dies, but the door locks don't work. If I plug in only the door locks, and disconnect the ignition switch (brown vac line), the door locks work fine (obviously, the engine doesn't shut off though, since that circuit is unplugged).

Curious, isn't it? I have read everything in the forum history (6x times over) and haven't found a good answer. My theory is that the vac valve on the the ignition switch is bad? When nothing else is attached to the system, all the vac gets routed to turning the car off so its quick, but then when vac has other places to go there isn't enough to overcome the leaky valve? Anyone with ideas, by all means please let me know.

Also, how responsive are the locks supposed to be? Even when they are working there is a bit of a delay while activate, and then the move slowly up or down. Is this normal?

This is on the 300D BTW.

Eric

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1981 300D - {172,000}
1971 220D {Sold to TomJ}

You are going about it the right way. You will have to pump till your arm is sore to get the reservoir pumped down very far and its possible to wear out a MityVac! BTDT so I use a special method, its very simple:
You tee your mityvac into the line running to the reservoir using a one way valve (blue or green cylinder with two hose fittings) ahead of the reservoir (towards the vac source), that way any leaks up stream will not show up. Run the engine to pump it down then shut it off and see if it changes at all. If it shows any drift off vacuum then its a leaking reservoir. And there are several reservoirs as I have noted in the wagin its in a different place than a sedan as I recall. Have you checked the fuel tank filler actuator and the trunk lock? they can be leakers too. Also did you plug off the pods under the dash? That is the bad place to fix! The small vac valve on the back of the key switch can be a source of leaks. I believe I have one if you need it.

The locks should be surprisingly quick when the vac system is tight. Slower means more leaks. You should be able to leave the car about a week and still get the doors to unlock.

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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!

Its too late to go try tonight, but should the key switch hold vacuum in both on and off positions?

If so, I could just put the mighty vac on the brown line and make sure it holds in both spots, that would tell me if the switch is bad, correct?

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1981 300D - {172,000}
1971 220D {Sold to TomJ}