Car shuts off w/driver's door locked, but not when unlocked?

[rickjordan]

This has been an on going problem. With engine running, driver's door locked, the car shuts off fine. With the door unlocked (knob up) she'll keep running. At which point if I push down the lock, it takes a few seconds but she slowly dies. Now, I have looked at the factory CD and there is no diagram of the system and how it is connected to the engine shut off valve. The Haynes manual had a diagram of just the central locking system. The diagram in the Performance Products catalog is even more vague. I took the door panel off and under the dash panel off to trace the lines. The only thing I can see that the 2 system share is a rubber "tree" where by one line goes in and 3 come out. The incoming line is right off the main trunk from the pump. The 3 coming out are 1 green/yellow line, that disappears into the dash somewhere. The second one goes to some sort of check valve/splitter It's yellow and has 2 or 3 lines coming off of it. One of those lines (all yellow) goes to the driver's door lock. And the third shoots up to the ignition which of course has another line that goes directly to the shutoff valve. Anyone have ideas. I don't want to just throw parts at it. I think the actuator for the driver's door is like $29 and it's just a 2 inch long plastic tube with a metal plunger in it.

[MTUpower]

You have two wagons? Which wagon has the problem- the W123 or the later one?

[dmorrison]

Either the master control valve of the lock system is bad. Or one/more elements in the doors is bad. a Mityvac is helpful in diagnosis.
Since it happens with the doors unlocked. First check the master lock in the drivers door for a leak. If it's ok then you will have to check the elements.
A large leaking/problem diaphram will allow all the vacuum to be depleted.
Check the vacuum pump first. Should be 22-25 inches of HG. Then follow the SM on central lock testing.
I am assuming the W123.
Yellow/green is open and yellow/red is closed IIRC. The test for the central lock is done at the drivers floor, and the trunk/rear.

Read this section on the setup and operation of the system.

http://skinnerbox.steaky.org/Service/W123/Index/Groups/80CentralLockSystem.htm

Dave

[MS Fowler]

Its considered normal W123 practice to lock the doors before turning off the engine.
Seriously, I bet you have a leaking diaphram in one of the doors that is NOT the driver's door. As mentioned above, get a Mity Vac, which is an invaluable tool for troubleshooting these system. You can access all door diaphrams from the "Y" connecunder the carpet. The main junction is under the front of the passenger front seat. Slide the seat back and remove the front section of carpet. You'll see red and green tubing connected to "Y" connections. Slide the tubing out of the "Y" and look for cracks. Apply vacuum to the various green tubes and see how well they hold vacuum, or not. Replacing the actuators is simple. If you are adventerous, you can remove the actuators and simply work a balloon or even a male contraceptive over the existing boot and hold it in place with the plastic cap.
Alternatively, once you isolate the defective diaphram, you could plug the vacuum line to that door to stop the leak.

[psfred]

Disonnect and plug the yellow line in the engine compartment (this is the door lock supply). If it now shuts off fine, the lock system is bad. If it's only partially better, check all the vac lines for cracks and bad rubber connectors (most can be replaced with short pieces of standard vac line). Most likely you have a bad unlock diaphram. They are available from Performance Analysis and other sources for about $5 each, you will need four for each door. Don't forget the fuel filler and trunk locks, too.

The MitiVac hand pump is indispensible for this job!

Peter

[rickjordan]

I recently got a Mighty Vac, but didn't know how much vacuum I was looking for on each component. Thanks for the tips/directions.