OK everyone I need your advice / opinions!

The subject is, WHERE the temperature sensor for an electric fan should be!

If you have an electronic controller such as the SPAL FAN-PWM, you have the option of connecting it to the STOCK temperature sensor. Then you don't need to add any sensor.

However, this sensor is on the TOP side of the engine, where the hot water first comes out of the engine, before it goes into the radiator.

I have seen guides in the past that say that ideally, the sensor should be on the BOTTOM hose, so that it measures the temperature of the water coming out of the radiator.

Why? Because what you're really looking for when deciding whether to turn on the fan, is whether the water is being cooled down by the radiator. So you should check the water as it comes out of the radiator. This way, if the water coming INTO the radiator is very hot, it's OK and you don't need to turn the fan on, as long as the water coming OUT of the radiator is cool enough.

Also, a lot of fan controllers put the sensor ON the radiator fins, for the same reason: The fan should turn on based on whether the radiator is too hot, not the engine itself.

But my theory is, you can guess pretty close whether the radiator fan needs to turn on based on the engine temperature, because the only reason your engine temperature should get too high is if you are not getting enough airflow through the radiator... usually.

What do you all think? Is it worth the extra work, if I currently am tapped into the stock engine temperature sensor (which is before the water goes into the radiator), to ADD a sensor at the BOTTOM hose of the radiator instead, so I'm measuring the temperature after the radiator, and turn the fan on based on that?

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