300D Won't Shut off - PeachParts Mercedes-Benz Forum

Colorado220 · #1 02-12-2008, 03:18 AM

The car is a 1979 300D, I was able to get this car running (sat for 9 years) and she runs great, but there is one problem. When you turn the ignition off the car just keeps running, Key out of ign. keeps running, battery unhooked, keeps running,

So where do I start looking? I have heard of this before but was unable to find anything when I did a search!

Thanks!

Unfortunately it ran out of fuel before I figured out how to stop it... JOY time to bleed the air...again!

Zerohour3k · #2 02-12-2008, 07:47 AM

You, sir, have a vacuum leak.. and a pretty bad one at that. You could have stopped the car using the "stop" lever on the engine, under the hood, however.

If the car sat for nine years, it's perfectly understandable, however. Get yourself a Mityvac at Sears, and start testing all the vacuum connections under the hood. The first thing I'd check is the main vacuum line, to make sure that your vac pump is in working order (should be giving at least 17hg of vacuum, 20+ preferred).

From there, just start testing your connections. While the engine is running, you can try applying some vacuum to the engine shutoff diaphragm. If the engine shuts off, you know that the diaphragm isn't your problem. Good luck!

kerry · #3 02-12-2008, 09:58 AM

You wont get 20 inches at your elevation. 18 is more like the best you'll get. But as Zero said, it's a vacuum problem. Given the fact that you don't mention not having power brakes, I'll assume the vacuum pump is working. I'm guessing the most likely source of the problem is that the vacuum line to the shut off valve is disconnected. Brown line, going down to shut off valve onthe back of the IP between the IP and oil filter housing.