jld,

I don't agree that the radiator cap will help cooling as I leave mine loose all the time and I have no cooling problems. Really all the cap does is raise the boiling point of the coolant by creating pressure in the cooling system.

If your cooling system was overfilled, some coolant would leak out because of expansion, and this is why there is an overflow hose. Next time your engine gets hot, notice if the auxilary fan is running. If it isn't running, getting it fixed will help cool the engine at idling speeds.

You may ask why I leave my radiator cap loose. Its because I use Evans waterless coolant which boils at ~375*F and thus requires no pressure in the cooling system. No pressure means there is much less stress on all the cooling system componants: Radiator, hoses, water pump, heater core, valves and any others parts that have any engine coolant in them.

P E H