True....an electrical problem will not cause a boilover. After I cleaned of the grills (and yes, there was some stuck to the radiated which I removed), I never had a second boilover. But the temperature gage was registering hot very quickly, even when the tractor had just been started, and was cool to the touch. I think the short was related to the meter...rather than to the cooling system.
But I still need to find our what really was going on.