Subaru Repair: engine shut off, car overheats, best bet

Question
My son is driving a 1993 Loyale Subaru.  The engine over heated and shortly after the light came on the engine shut off.  He was stopped at a red light and a policeman came and helped him get it off the street.  We checked the water in the radiator and it was low.  After letting the engine cool we added water and it started right up.  I am afraid it might just shut off any time any where and let him sit.  We live in the country and I don't want the car shutting off in the middle of the night on a country road or worse on the turnpike going 65 mph.  What caused it to shut off?  Does the car have a shut off switch when the car overheats so the engine isn't damaged?  Any help you can provide would be greatly appreciated.  Thank you in advance.  Sandy

Answer
Hi Sandy,
  
   Sorry to hear about what happen to your son. I worry about this with my kids all the time. This is a multi-part, multi-complicated question. There is no switch that kills the engine when it starts to overheat. only a light or a gauge. I don't work on very many of these older subaru's, but most cars  are the same when this occurs. First thing is, you need to find out why the coolant was low. Coolant just doesn't evaporate like water would. It has to go somewhere, whether somewhere it doesn't belong in the engine, or on the ground. The second thing is the engine did quit for a reason, and the question is why. The most common answer isn't very good. Most commonly it's because damage has occurred to the engine and it couldn't run anymore in that condition. Most commonly the headgaskets blow. Sometimes the cylinder heads warp, and sometime but not often the block warps as well. Depends on how hot the engine really got. Even with this damage the engine will sometimes run ok cold, but when driving for more then 10 miles or so they start to overheat again. Your best bet is to have a technician take a look at it. Honestly, it doesn't sound good though. My fingers are crossed for you though, and good luck. The worst part about my job, is giving bad new like this.

Sincerely,
Frank