Hello All,
This is something I'd give an eyetooth to solve. My '89 740 GL sedan does this, and why I don't trust it on the road. Several times in the past, while out driving, it will quit running, inexplicably and without warning. Then it will not restart ... until it completely cools down. Most often, overnight. After sitting overnight, it will start right up again. I've had to be towed home on two occasions. I left it with my mechanic, once for three days, and he could not recreate it.

My best, and only guess, is that it's a failing electrical part that is responding to heat. When it reaches a certain temperature, perhaps, it shuts off, then is able to work again at some point. Please, anyone, who has had this problem, tell me how you solved it. I'm willing to throw a part or two at it if I can make it reliable again. Thank you!
Jim