My engine shuts off ONLY if I open the Drivers Door!
 

300CD

My engine shuts off if I open the drivers door.

It doesn't happen every time, but usually with a cold engine system...after the car warms, it seems normal.

And no, the door locks only work if I am driving and activate them. And then slowly.

Any suggestions?

Maybe you have a leak in the locking/unlocking line? (I have no clue as to which). However it is logically sound to me that there's a leak in one of 'em. Have you looked at each diaphrams? I would do that first. Start from the driver's door and look at the rubber lines joining the master vacuum switch and the plastic vacuum lines.
Then work your way around with the other door, trunk, and fuel filler door. Also the coupe has its backrests activated by vacuum. I think that is my source of leak because one of them does not work.


I have a slow vacuum leak too, however the car shuts off fine, runs fine, shifts fine, etc. I hate the vacuum system...

I had just the opposite
 

Mine would not shut off unless the door was closed.

As the plastic vacuum lines harder they tend to crimp at door openings, especially the driver's door. I found it by turning off the car with the driver's door closed and then opening it up. I listened down near the rubber boot where the lines are routed from the door frame to the door. Try just the opposite approach.

My fix was to splice in the rubber repair hose, and it has lasted so far.

Final note, unlike other leaks I have had in the past, it was easy to find, a bear to fix. You have to remove the door panel, the drivers kick panel and work in some extreme tight places. If this is your issue, be sure to keep the hoses accessable while you are working on them, as it would be very easy to lose one that would be next to impossible to recover from behing the interior door frame.

Good luck

JCD

I had the same problem, only turned off if the door was locked though.

I had a co-worker drop me off somewhere and he was driving my 300CD, as I would get back to the original point another way.
Yup,

When I finished my errand and returned to the rendevous, he was still there with the engine running, wearing an appropriate expression...
Yup...

Is there a vacuum element under each front seats in the W123C?
If there is, is removing the seat the only way to access it?

I have a feeling that my driver's side seatback vacuum element is not working correctly. It could be the cause of my vacuum leak (It wouldn't hold the vacuum over more than 8 hours..)

HOWEVER....
today... I opened the car after leaving it for more than 12 hrs... and voila... all the locks opened quickly.. I was like.. "What the..."
It even had enough vacuum to lock everything and open 'em up again. All this before starting the engine.

It's been doin' this for the past two weeks... Maybe the car fixes itself up... :D The water leak is gone now. I don't think I can explain it...