Mercedes: wont shut off, diesel mercedes, problem thanks

Question
I have a 1979 turbo diesel mercedes. it starts and runs fine but the key shutoff doesnt work ,i need to open the hood and manually close the throttle to shut it off. do you have any suggestions of what i could do to solve this problem? thanks alot

Answer
Answers will be found in these threads.

Run away diesel, why does it happen?
http://www.mercedesshop.com/shopforum/showthread.php?p=824840#post824840

Motor / engine keeps running
http://www.mercedesshop.com/shopforum/showthread.php?p=80108#post80108