80 240D Won't stop running
 

I have 2 problems, I beleive they may be related. My 1980 240D will not stop running when I turn the key off. I have also noticed the brakes get real hard if it idles for a long period of time, like sitting at a long light. If the Brakes are hard, that's when the engine will not shut off. If I have good brakes, and i turn it off, it stops running just fine. I'm sure it's vacuum related. But where do I start?

To shut off a "runaway" diesel...
 

Open hood...stand with both toes against the driver's side front tire...look just behind the air cleaner, you will see a little red lever with STOP printed on it...push the lever, the engine will stop.

Do a search...believe both problems vacuum related.

with your symptoms the first thing i would check is if the brake booster vacuum hose is leaking somewhere. it goes from the vac pump on the engine back to the brake booster on the firewall.