90 300D 2.5 lost serpentine belt
 

and overheated, boiled off about a gallon of coolant before my kid got the thing in the driveway.
Apparently the belt gave way about 1/2 mile from home and my son , not knowing any better, kept it rolling to the house.

Well, I replaced the belt and replaced the lost coolant. However, I have a leak somewhere. Coolant is getting oil in it. Head gasket (if I'm lucky), warped or cracked head if I'm not.

Dang the luck!!!

oops! wasn't there a shut off relay like with the 603 engines? detects lack of rotation on the AC pulley I believe and shuts off the electronics? Its never happened to me but I read that somewhere in the FSM.

I suggest you have the head checked for flatness and a leak test done in the machine shop (not on the engine) and depending on how many miles you have on it, you may as well consider a valve job at least new valve seals (its not much more) to get back to perfect top end