electric fan sensor

[kully 560]

I am removing the radiator electric fan sensor [sucks]and going to install it  in the radiator hose with the hose adaptor . some people say to install in the upper hose and others say to install it in the bottom hose. so some say the upper hose will read the hot water coming out of the motor hotter than what is going in and others say to control the water going into the motor . my stat is a 180 degree and the sensor is a 180 degree that  will close the contact at 192 degrees to turn on the fan. so where is ever body installing these sensors on this z forum? thanks

[sweatybetty]

mine is in the lower hose. the water going into the engine is what counts

[kully 560]

thanks for the reply that is what I was thinking also

[7tooZ]

mine is in the lower hose. the water going into the engine is what counts

Sweaty can you explain that a little more?


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[Mike W]

I did not want to cut into my hoses and I also did not want to use a temp probe that goes through the radiator fins, so I chose to install a sensor in the block.  I removed the plug on the back side of the block on the drivers side and replaced it with an appropriate sensor.  Works like a champ.  I also used a fan controller from Dakota Digital.  It is fully programmable in terms of on / off temps and even lets you program the fans to run for XX number of seconds after the engine is turned off.  You can find more info about it here if you are interested:

http://www.dakotadigital.com/index.cfm/page/ptype=product/product_id=852/category_id=403/mode=prod/prd852.htm

Hope that helps.

Mike.

[ksechler]

12 hours ago, sweatybetty said:

mine is in the lower hose. the water going into the engine is what counts

The water in the lower hose is the temperature of the radiator.  That doesn't tell you anything about the motor.  The temperature of the water in the upper hose is the temperature motor.  That's what you want to know.  Consider this scenario...  Your thermostat is stuck mostly closed.  The sensor on the lower hose will see nothing wrong.  The radiator is easily able to cool this small volume of water.  Meanwhile you engine is roasting.  A sensor in the upper hose would detect this condition.

[Captain Obvious]

That's a great point. And I would go one step further and say that the sensor should probably be on the engine side of the thermostat. You know... the side with all the other sensors on it?  

[kully 560]

thinking about this if it was on the upper radiator hose the water is all ways hotter coming out from the engine so the fan would run non stop ???

[Captain Obvious]

I would assume that all depends on where you set the temperature.

I'm thinking I would want the temperature of the fan switch some token amount higher than the thermostat temp. If the system can operate in equilibrium without the fan running, then you are getting enough heat rejection from just natural airflow through the radiator. But if the temperature of the engine starts to creep above the thermostat temp, then it means the system has gone out of control and you have exceeded the heat dissipating capacity of the radiator (under the current conditions).

And at that point, you need more flow. Either more water, or more air. If you are already maxed out on water flow (thermostat is all the way open), then you need more air.

Turn the fan on.

[kully 560]

good point I ordered a 180 degree fan sensor switch and when I tested it in hot water it will close the contact at 192 degree to turn the fan on so that should be fine in the upper radiator hose . thermostat is a 180 degree and sensor is 192 degree now that I am thinking about it and reading these posts it does belong in the upper hose thanks kully

[kully 560]

well I just finish install new hoses and antifreeze and the sensor in the upper radiator hose works great in the upper hose, on -off no problem temp gauge stays on the m letter in the gauge cycles perfect much better than the crappy radiator sensor. it belongs in the upper hose thanks for all the reply kully

[ksechler]

4 hours ago, kully 560 said:

good point I ordered a 180 degree fan sensor switch and when I tested it in hot water it will close the contact at 192 degree to turn the fan on so that should be fine in the upper radiator hose . thermostat is a 180 degree and sensor is 192 degree now that I am thinking about it and reading these posts it does belong in the upper hose thanks kully

Would you share the details on the switch you ordered.  Does it thread in directly or use an adapter?  Which location are you using?

Edited October 16, 2017 by ksechler