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Originally Posted By: azsynthetic
Fact 1: I TOLD YOU the thermostat CONTROLS THE FLOW OF COOLANT and not the temperature. Without a radiator the temperature of the coolant will not change, hence the thermostat does not control the temperature.
I just about don't know how to respond to this. Yes, if you want to parse semantics down to the last nit, then the thermostat controls water flow. It opens at a certain temperature and lets water flow through the radiator where it is cooled, and then returns to the engine. When the flow rate is sufficient that the radiator is removing heat faster than the engine is generating it (the normal condition for any vehicle actually moving through the air) then the thermostat closes just enough to maintain the water exiting the engine block at the set temperature.
In other words to make a long paragraph short: the thermostat controls the engine temperature!
Originally Posted By: azsynthetic
Fact 2: The radiator removes heat (i.e. a heat exchanger) from the coolant so therefore it controls the temperature of the coolant.
Gadzooks, man! The radiator is an entirely PASSIVE device. It has no control function whatsoever, it will simply reject heat as fast as it can according to the laws of thermodynamics, based on how fast coolant is flowing through it (which is CONTROLLED by the thermostat), how fast air is flowing over it (which is controlled by the electric fan or fan clutch or vehicle motion), and the temperature differential between the water inside it and the air outside it.
Originally Posted By: azsynthetic
Once the engine is warmed up the thermostat is pretty much useless.
Demonstrably false. Even in 100+ degree weather, if there is enough airflow over the radiator (due to vehicle movement or fan operation) then the thermostat will partially close or else the engine temperature will drop lower than the thermostat's setpoint (160, 180, 195 etc. degrees F, significantly hotter than the surrounding air), unless the cooling system is not operating up to par or the engine's output is much higher than the cooling system was designed for. I'm not talking about the extreme case of blasting up Wolf Creek Pass with your pedal to the floor, towing a loaded cattle trailer behind you and the AC blasting, I'm talking about *normal* to even semi-extreme driving conditions that are within the design specs of the vehicle.(*)
Now if you want to talk about those extreme cases where the thermostat has "lost control" of the system, you're limited strictly by thermodynamics. The biggest barrier to effective heat transfer in a maxed-out system can be one of several things- most likely is steam pockets in the cooling system. NOT lack of sufficient wetting of the water jackets and radiator, especially if there is antifreeze in the system. And I've already stated that I agree wetters could help the situation over pure water. I just don't think they help when added to antifreeze. Based both on the science of it and on personal experience.
(*) Note- I've actually owned some vehicles that wouldn't overheat even when overloaded and operated WFO for extended periods.