Having recently bought an 83 300CD Turbo I am in the process of going thru the thing with tremendous aid of this forum. You have no idea how valuble it has been for me...Now to the problem at hand. I am renewing all the vacuum lines in the engine compartment as is recommended here so often. Well after finishing this little adventure and I go out for a ride and of course now the car goes like the preverbial raped ape compared to before. It is literally like a totally different car. I get back all excited and I turn the key off and it doesn't turn off. I have read about this before and decide to go to the engine to starve it for fuel with the stop lever on the inj pump. I didn't get that far however. I open the door and the engine stops. I try this again and sure enough the engine turns off when I open the drivers door. By the way now the locks work as they didn't at all before the vacuum lines replacements. Idea's anyone...Broken vacuum line in the door...something else...too weird

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83 300CDTurbo 307,000
2005 Honda Element 266,000
56 Nash Ambassador Country Club Special 34,000(under restoration presently)

http://www.peachparts.com/shopforum/showthread.php?t=125099

Does it shut off when you pull up on the lock button?-could be a line or one of the lock diaphragms is leaking in one of the doors.

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1982 300DT 190K (Diesel Purge + synthetic oil=smoothness at last!!!)
2004 Ford E-350 6.0 L PSD 227K
2006 Dodge Ram 3500 SRW HO Cummins 4X4 48RE 42K (brute force tow vehicle)
2005 Scion xB wife's rolling pop can
1993 GMC Sierra C3500 6.2 142K

you have vacuum leak somewhere.
Get the mityvac, search the plethora of threads on diagnosis.
One thought comes to mind, when the ip shutoff valve starts to fail, it can take extra vacuum to kill the motor, and can draw motor oil into your new lines at the same time.
I would start there, just to be sure you don't have that problem. I bet the real culprit is one of the pods...could be climate control, door locks, gas cap door, seats, ect.

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Think Alternative Energy!
300CD '80 (now gone but not forgotten...)

it certainly could be oil in the shutoff valve line. try disconnecting both ends and blowing the line out with a hand pump to see.
use a soccer ball pump with the needle which will fit the vac line perfectly.

i remember one fellow member's engine that would only shut off if he locked the car with the key from the outside..

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1984 300D Turbo - 231k....totalled 11/30/07 RIP