[Healeys] Radiator cap thermostat combinations

[Oudesluys]

Op 12-2-2013 9:14, Derek Job schreef:
> A thermostat is there to ensure a minimum operating temperature. 
> Changing the thermostat and radiator cap will not make any engine run 
> cooler.
> Derek


Derek,
This is not completely correct.
In a proper system the cooling capacity of the radiator is much more 
than ever needed. In such a system a thermostat with a lower opening 
temperature will lower the engine temperature to say about 5 degrees 
above the opening temperature. Because the radiator will cool the 
coolant more than the engine will heat it up the thermostat will than 
start to close so less coolant flows to the radiator and cooling is 
decreased. This opening and closing will be continuous and will create a 
sort of equilibrium at a certain load of the engine and the speed the 
car travels (airflow). In stop and go situations this airflow is 
restricted hence a  thermostatically controlled electrical fan is added 
in modern systems and should also be fitted to older cars if driven in 
dense traffic.
This is the reason a radiator should always have an overcapacity so that 
the thermostat is the only factor that controls the temperature of the 
coolant.
Kees Oudesluijs
NL