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Mercedes 300te
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Discussion Starter #1
Anybody experience engine shuts down after 10-15 seconds after turning the key to off....Its for a 300d '85

Pretty much have to wait for 10-15 seconds then the engine will shut down by itself.

It shuts down right after you turn the key before.. What seems to be the problem? vacuum, shutoff valve? electronic module piece on the key area? I was told it might be one of those or something else/


Hopefully somebody has an idea on this...Thanks in advance....
 

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'77 6.9, 74 240D, 96 Ram 5.9L Cummins
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You may have a vaccum leak in the igntion switch if not somewhere else in the car. I think it's the black line from the engine bay check that first and then if not it will probably be the vac switch tied to the ignition.
 

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Very familiar with this problem - had it on my '85 300D -fixed now.

You must get a vacuum pump with a vacuum gauge, some golf tees, and vacuum caps and start systematically testing the vacuum system for leaks.

First, disconnect the branch lines from the main vacuum line and test the vacuum pump. It should produce about 21 to 22 inches Hg of vacuum at idle. Shut off the engine and see if the vacuum holds, If it drops quickly, you may have a leaky vacuum pump check valve or leaky brake booster.

Then test the engine shut off valve. Disconnect the vacuum line from it, and connect vacuum the pump to the nipple. Start the engine and give the hand vacuum pump a few quick pumps. If the engine shuts off immediately, the valve is good, if not, you may have a valve with a partially torn diaphragm.

Isolate the door lock system at the yellow vacuum valve (lines with yellow stripe) and draw vacuum on the system and see if it holds.

Then do the same for the climate control (line with green stripe) and see if the vacuum holds. If not, you may have a leak in the climate control system. That's what the problem was with my car. If you have a problem with climate control leaks, do the following:
With the A/C controls in the OFF position start the engine, and then turn the key off. Does it take a while for the engine to shut off? Repeat the same test with the controls in the ECONOMY mode and then in the A/C on mode. For my car, it shut off fine with controls in the OFF position and A/C position, but when the economy mode was selected, the it took about 10 seconds to shut off! It was because the line to center vent actuator behind the glove box was unplugged causing a massive vacuum leak!

Isolate the transmission control circuit (black line)and test that for leaks.

Unfortunately, on a 123 diesel car like this one, all vacuum systems are interconnected and any major leak in vacuum system will cause delayed engine shutoff, slow or failed door lock operation, harsh transmission shifting, and crappy A/C vent opening and closing.

I suspect you have a leak in the door lock system or the A/C system, because the symptoms are very much like those in my car. however, systematically check everything I just mentioned. I wish I could help you do this as I would probably find the problem quick. It is not hard, you just need to figure out how the vacuum lines are interconnected and test each branch separately. You will also need a few short pieces of rubber vacuum line to use as an adapter between your vacuum pump and the plastic vacuum line you are connecting your vacuum pump to.
 

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Discussion Starter #4
Thanks for the advice. I'll do that..
 
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