[Healeys] Running Temps--Was: Re: Aluminum Radiator

[Bob Spidell]

Agreed. I am using a (modern) sleeved-type thermostat, have a calibrated gauge and have tried several thermostats (I tested a couple on the stove and they functioned as expected). Still, my BJ8 engine will run below the thermostat set point on a cool day with light load--I would expect the coolant temp even under those conditions to rise to nominal, but it doesn't. Our BN2 behaves the same way. 

The only comparison I can think of is air-cooled aircraft engines, which usually have an oil cooler. There is a valve called a Vernatherm--essentially a bi-metal strip--that closes off oil flow to the oil cooler radiator to allow the engine to warm to operating temperature before the cooler is brought 'online.' But, an air-cooled engine can dissipate a lot more heat than an Austin lump. 

Is it possible the huge chunk of iron in front could be 'self-cooling' to a point then, beyond that point, even with wide-open thermostat, cannot maintain a set temperature? My guess is that at speed there is sufficient airflow to cool the engine--even below the thermostat set point--but once stuck in traffic or with a load there isn't enough excess airflow and the cooling system's capability is exceeded (as Kees mentioned). 

Bob 


----- Original Message -----



In general the temperature should be more or less constant under any 
condition, just slightly above the opening temperature of the 
thermostat. If the temperature shows to be lower than the thermostat 
opening temperature the thermostat is at fault or is the wrong type (it 
should be of the sleeved type), assuming the heater is turned off. If 
very cold, with the heater plus heater fan on maximum, the temperature 
could drop below the opening temperature of the thermostat. 
If the temperature increases significantly the cooling capacity is 
insufficient because of blockages/dirt, faulty water pump or the wrong 
radiator capacity. 
Older cars can have insufficient cooling capacity at low speeds/engine 
revs, hence the advise to fit a thermostatically controlled electric fan 
when the car is used in modern traffic. 
Kees Oudesluijs