Electric fan probe placement

[Gerdo]

When you use the probe in the hose type, the instructions say to put it in the upper radiator hose. This is the hot return from the engine. If your thermostat is working properly the return water would be at operating temp. This doesn't account for the radiator airflow from driving.

The big question is...
Shouldn't the probe go into the lower radiator hose?

This would turn the fan on if there is inadequate airflow (measuring a high coolant temp) and needs the fan to draw air thru the radiator.

 

[Singtoe]

If you look at the OEM (who use electric fans) mount locations for the fan thermal switch. It is always on the hot side of radiator. Unless the hot side is the top of the radiator, then it is mounted low.


The way I figure is that if your probe you return, it is too late and you will have already over heated the coolant taking too long to cool down. But if you take temps pre-intake, then the fans can cool the coolant before it returns to the motor.

 

[Gerdo]

If you look at the OEM (who use electric fans) mount locations for the fan thermal switch. It is always on the hot side of radiator. Unless the hot side is the top of the radiator, then it is mounted low.


The way I figure is that if your probe you return, it is too late and you will have already over heated the coolant taking too long to cool down. But if you take temps pre-intake, then the fans can cool the coolant before it returns to the motor.

I'm a little confused by your first statement.

Your second statement makes perfect sense, that is what I was thinking too.