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  #1  
Old 12-15-2011, 12:17 AM
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W123 turned key off, engine keeps running

I thought for sure a search would turn up something but no luck.

My '83 240d has decided it will require that I manually shut the engine off as it will not shut the engine down when I turn the key and remove it from the ignition.

Someone must know this one?

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  #2  
Old 12-15-2011, 12:26 AM
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I have the same issue on mine. If I shut off on a cold day before the engine is good and hot it'll run on.
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  #3  
Old 12-15-2011, 12:47 AM
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The first thing to do is to check for a loose or cracked vacuum line to the shutoff actuator.

If you cannot find one, then you must try to shut the engine down with a Mityvac. If that works, the shutoff diaphragm is OK and the problem is isolated to either the ignition switch or a vacuum line.

Then, you attach the Mityvac to the line that feeds the shutoff diaphragm and turn the key off. The reading should be above 15" vacuum. If it is not, the ignition switch, or one of supply lines to the ignition switch is the culprit.

Good luck.
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  #4  
Old 12-15-2011, 01:34 AM
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Simple test: with the engine running and the brown vacuum line removed from the shut off diaphragm on the back of the IP down between the IP and oil filter housing. Replace that line with a 4' piece of vacuum hose. Suck hard on the hose about 3 times. if that shuts the engine off, just lead the hose out of the engine compartment at the cowl and shut the hood. When you need to turn off the engine just suck on the hose.
I'm sure there are other solutions.
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  #5  
Old 12-15-2011, 04:31 AM
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Well, I have used a simple method that requires no MightyVac and alot like kerry's method.

I just get me a length of good vacuum hose, remove the hose from the vacuum actuator on the rear of the injection pump and put my hose on.

Then I start the car and suck on the hose. If the engine dies, the actuator is good.

I reconnect the original hose. The plastic line should be brown and going into the engine compartment to the ignition key vacuum valve.

Another brown plastic line comes back out to connect to the vacuum supply. I disconnect that, start the engine, turn off the engine with the key, attach my hose to the brown line and suck on it in the engine compartment and see if the engine dies. If it does then I know my ignition switch valve is good.

I then try to verify the Wyes and Tees that were coming off the big thick vacuum hose from the vacuum pump to the brake booster.

Isolate any leaky vacuum systems. Most often this will be the door lock system and the AC vacuum pods.

Replace any old, cracked or otherwise worn out hoses, Wyes and Tees.

If you are successful, you might even get a better shifting transmission out of the deal as well as an engine that will shutoff without raising the hood.
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  #6  
Old 12-15-2011, 08:02 AM
Posting since Jan 2000
 
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Quote:
Originally Posted by kerry View Post
Simple test: with the engine running and the brown vacuum line removed from the shut off diaphragm on the back of the IP down between the IP and oil filter housing. Replace that line with a 4' piece of vacuum hose. Suck hard on the hose about 3 times. if that shuts the engine off, just lead the hose out of the engine compartment at the cowl and shut the hood. When you need to turn off the engine just suck on the hose.
I'm sure there are other solutions.

ROTFLMAO!
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  #7  
Old 12-15-2011, 08:58 AM
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Quote:
Originally Posted by New2MB View Post
My '83 240d has decided it will require that I manually shut the engine off as it will not shut the engine down when I turn the key and remove it from the ignition.
Try locking the doors first.
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  #8  
Old 12-15-2011, 09:16 AM
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Quote:
Originally Posted by kerry View Post
Simple test: with the engine running and the brown vacuum line removed from the shut off diaphragm on the back of the IP down between the IP and oil filter housing. Replace that line with a 4' piece of vacuum hose. Suck hard on the hose about 3 times. if that shuts the engine off, just lead the hose out of the engine compartment at the cowl and shut the hood. When you need to turn off the engine just suck on the hose.
I'm sure there are other solutions.
Hahaha ehhh...can't imagine having to do that every time I take the car out.
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  #9  
Old 12-15-2011, 10:24 AM
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Quote:
Originally Posted by tangofox007 View Post
Try locking the doors first.
That usually works, but sounds strange to a newbie
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  #10  
Old 12-15-2011, 10:41 AM
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Quote:
Originally Posted by Tanksowner View Post
Hahaha ehhh...can't imagine having to do that every time I take the car out.
If you find it embarrassing, it's quite easy to act as if you're adjusting the windshield wiper when sucking on the hose. Almost nobody will notice.
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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13
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  #11  
Old 12-15-2011, 10:49 AM
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Quote:
Originally Posted by MS Fowler View Post
That usually works, but sounds strange to a newbie
It's a pretty benign alternative to sucking on a hose.

I suppose you could route the hose through the bottom of a drink cup and connect it to a drinking straw. You might even give new meaning to the term "vacuum bottle."
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  #12  
Old 12-15-2011, 10:53 AM
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Route the hose inside the cabin, tell everyone it's a reverse sobriety check!
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  #13  
Old 12-15-2011, 08:19 PM
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Get a mityvac or equivalent, Harbor Freight has a vac tester tool works fine, doesn't have to be a mityvac brand. Start by simulating the car's vacuum at the engine shutoff valve by disconnecting the car's vacuum and swapping in the mityvac. A few pumps and it should shut off. You could be losing vacuum somewhere else that just doesn't leave enough vacuum to shut off the engine. Whatever vacuum controlled stuff isn't working could be contributing. Heater vac elements, door lock elements, etc. You might get lucky and find a hose that has come loose.
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  #14  
Old 12-16-2011, 08:42 AM
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The reason that locking the doors often works is that the vacuum door lock actuators develop a leak and that lowers the available vacuum to a point that it is not sufficient to power the IP shut off.
It may seem counter-intuitive to a newbie, but try locking the doors with the key. If the engine promptly shuts off, you need go no further in your trouble-shooting. You may then disconnect and plug the door lock vacuum lines, or replace the door lock actuators at your discretion.

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