car keeps running after it is turned off

I have a 1990300D Mercedes that I am ready to blow up or sink.I had the aircondition fixed and the mechanic hasn't figured out why the car won't shut off.(CHANGE MECHANIC?)
He told me to open hood,press the red button and it will shut off..I am 77 years old,had mercedes cars for 40 years and still love my car,
Any suggestions...(GO TO A MERCEDES MECHANIC)

[MB STARS]

Yes go find a tech knows Mercedes diesel,you have vacuum leak in system.(check all vacuum hose,connectors)

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MB STARS Master Guild Technician,12 years MB tech
6 years independent shop owner

[Mr. BILL]

Here's a possible Mickey Mouse short term solution. Try locking your doors BEFORE you shut off the ignition.

I had the same problem and I this did the trick until I got it fixed. I guess it helps build up vacuum, but it worked for me.

Mr. BILL

Most likely you need the vacuum shut-off box replaced.It is right on top of the injection pump.

[fz500sel]

Yep, sounds like your boy messed up the vacuum when he was fixin' your a/c system. It uses the vacuum as well and he probably knocked something loose or forgot to hook something back up when he was done.

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FrankieZ
84 500SEL EURO 87K
85 300D 267K (and still goin' strong)

[be459]

There are many reasons for the engine run on after the key is removed especially the later model diesel with all the smog devices - a minor vacuum anywhere can cause it.

Here are some of the areas that I can think of now:
(1) bad vacuum shutoff box.
(2) bad key switch.
(3) loose or open rubber connectors
(4) defective smog devices.
(5) defective vacuum valve.
(6) defective or weak engine vacuum pump.

If it is (1), (2), or (6), it will be easy to tell with proper test tools.

David

[Douglas Broome]

The shut-off device is one plausible answer, another is if the vacuum pump diaphragm is leaking engine oil into your vacuum system thence to the vacuum line that reaches your ignition key. Do you have any oil seeping out the key slot? That can be fixed by any contortionist. It happened to me once on my 240D. Also,put those nifty little air filters in your vacuum lines at the strategic locations.

[bigbenzman]

As many have noted, this is very likely related to a vacuum problem. I have experienced a similar problem on my 240d and 300d when changing the oil. When pulling the top off the oil filter canister, I would accidently pull the vacuum line loose from the shutoff valve. You mentioned the recent work on the A/C, I'm assuming this problem didn't exist previously. This could be as simple as a line pulled loose in the engine compartment. If you don't find a loose vacuum line, you could have a tech check out the shutoff valve on the injector pump, or check for other vacuum leaks in the system. Hope this helps.

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1987 300SDL
1989 300E
1986 300E
1981 300D
1983 240D

[This message has been edited by bigbenzman (edited 09-25-2000).]