79 300SD engine won't shut off - Mercedes Forum

drifterdan · #1 10-27-2009, 03:32 PM

I am new to Mercedes. I just got a 79 300SD. The engine stays running when I shut off the ignition. Any info on how to fix? Thanks.

Register today for free or log in if already registered to remove this ad!

ForcedInduction · #2 10-27-2009, 07:10 PM

Its a vacuum issue. On the back of the injection pump is a brown tube, thats what shuts it off. Look for any broken, loose or cracked hoses and rubber joints.

drifterdan · #3 10-28-2009, 07:51 PM

Thanks for the info.

Diesel9112 · #4 10-28-2009, 10:55 PM

To see if the Vacuum Shutoff on the IP works and you do not have a Vacuum Tester you can actuall hook a piece of Vacuum Hose to it and suck on the end. If it shuts off like that there is a good chance the Vacuum Shutoff is OK and you have a Vacuum Leak Problem.

If it is not a hose or hose connection and you believe your Vacuum Pump is working OK (your Power Brakes would be working OK) there is another Shutoff valve attatched to the Steering Wheel Lock. It also has hose connectors to check there that can go bad and the Valve itself can also go bad (the valve cost about $25 for my year of car).


Mercedes Benz Forums - Photo Galleries - Create an Account - Mercedes Benz cars