Sounds like good advice. The fan was working well and turned off on cue
when engine went back to normal temperture. I'll have to check inside
the radiator in the morning to make sure it's topped up all the way.
Considering that the resevoir is at the min level when the engine is
cool, it'll probably be ok. I guess the next thing to do would be to
replace the radiator cap. I also suspected the rad cap as the culprit.