some times I think folks put to much into these things. If it ain't pukin' it ain't over heated. That is the function of the radiator cap, no?
When we were kids we would put a brick on the gas pedal put the car on blocks drain oil and water and see what broke. OK we had too much time on our hands butI remember a particular ply. just shut down and restarted when cool and we did it again. That car was driven to school for the next two years. Sure it didn't win any races but we thought that was a sign of a tough motor.