[8D]new guy ,i changed the glow plugs on my daughters 300cd ,83 ,84?. now she tells me it wont shut off unless you push the stop button under hood.[&o] it wont shut down by key ..the good news is it starts right up even when cold weather

 

You probely knocked of a vaccum hose. for it uses vaccum to activate the shutoff valve.

 

Yep happened to a buddy check vacuum hoses near oil filter especially.