Nuke,
Great find! I'll make sure that my installation is isolated from the frame/body.
Were you able to get a smaller pulley?
Everet <img src="/forums/images/graemlins/patriot.gif" alt="" /> <img src="/forums/images/graemlins/cheers.gif" alt="" /> <img src="/forums/images/graemlins/kewl.gif" alt="" />

I haven't found a pulley that fits yet Still looking.

I talked to Spal tech support on the phone. They were not aware that this problem could occur. They said maybe this could explain why they had so many customers struggling with these mysterious error codes. They asked me to let them know whether my fix works and makes the codes go away permanently <img src="/forums/images/graemlins/notooth.gif" alt="" />

It's kind of a shame, they discontinued this product because too many people were having error codes they couldn't figure out. It's possible it's because of this very issue. I can see how it could be hard to figure out. I'm an engineer and it took me years of running this device in my vehicle before I tracked down what was going wrong.

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?

<img src="/forums/images/graemlins/cheers.gif" alt="" />

I used the Davies Craig Mechanical Thermal Switch and installed it beside the radiator.

Personally, I placed my sensors in the thermostat housing. It is where Kia put one so I followed suit.
I'll try and post size of pulley and picture of it.
Everet

Yes, but the purpose of these sensors is to determine the engine temperature, so it makes sense they should be right at the thermostat housing. They are sensing how hot the engine is, not how hot the radiator is. They OEM sensors weren't intended to control a radiator fan. The OEM radiator fan is controlled by the clutch, which is heated by its proximity to the radiator.

I am not sure if it makes more sense for the radiator fan to be controlled by the radiator temperature, rather than the temperature at the thermostat housing. If you're going down the road, the temperature of the water coming OUT of the radiator will be a lot cooler than the water going IN, so no fan is needed. If you're sitting still, however, the temperature coming OUT of the radiator is going to be much hotter, so you need the fan. In a way this seems like it makes more sense, to put the sensor on the cool side of the radiator. I'm not sure it matters a whole lot though, it's way easier to just connect to the OEM sensor, which is how i have it connected currently.

I just think there might be cases where my fan kicks in while the vehicle is moving down the road and doesn't need the fan.

I put the Davies Craig sensor in the top radiator hose as close to the thermostat housing as possible.

Nuke,
Any Update?