I have always wondered about this but have never asked...
After I have been driving my MGA and come to a stop, the car obviously
heats up to approx. 230 degrees (no air right). If the radiator is
full, coolant will overflow past the cap down the overflow tube due to
(I assume) increased pressure above the cap rating. Thus, the car comes
to "equilibrium" after a couple of trips after a radiator fill up. The
other night, I parked at the video store on a hill sloping down toward
the filler neck end of the radiator. I lost coolant (have been on many
trips without losing any). Is this because the coolant was already up
to the cap when the pressure went up and the air pocket was up at the
other end? I guess on a "modern" (boring) car, this overflows into the
overflow tank and is siphoned back into the radiator when it cools. Is
this a modification that one should attempt to make or should I leave
well enough alone? It hasn't gotten real hot yet. My car runs at about
195 degrees at speed. I know that this sounds like a dumb question
"Paranoid" MGA 1600 MkII driver"