I have a cooling question I installed a champion 3 row aluminum radiator with a spal 13" electric fan and a nissan brand 180 degree thermostat. now my fan sensor is a american volt brand that is 200 degree on and 185 off that is installed in the thermostat housing cover. at highway driving my fan runs all the time. around town it will cycle on and off. I do not think this is normal for highway driving at 70 degrees outside. anybody have a thought ? in the old days the water pump would leak when bad the seal. not leaks at all and I run water wetter with premix prestone antifreeze. thanks

No, it doesn't make sense for the fan to run all of the time at highway speeds. You usually have enough air flowing through the radiator then. Are you sure it's running at highway speeds?

Where is the sensor located?

yes, it is running at highway speeds I can tell by the ammeter.  the sensor is located in the thermostat housing cover!  the cover has a port in it which I tap for 1/4" npt sensors .

Are you seeing the temp gauge creeping up at highway speeds? Could you be running too lean?

I can add more fuel with my potentiometer and the temp comes down quite a bit. Lean it out and it runs warmer. Just an fyi post.

 

I just picked up a digital cooking thermometer and placed it in the radiator under the cap and the fan come on at 172 degrees.I purchased a 200 degree on and a 185 degree off , I can not believe for the life of me that is off by 30 degrees . it is made by american volt company. go figure I guess I will look on amazon for a different brand . I did try to buy usa go figure. when the new sensor come here I will post my report thanks kully

That is odd. My Nissan 180F thermostat opens and circulates at 175. 176 sitting in my garage only flowing an OE zx fan and shroud. No road driving flow.

 

1 hour ago, kully 560 said:

I just picked up a digital cooking thermometer and placed it in the radiator under the cap and the fan come on at 172 degrees.I purchased a 200 degree on and a 185 degree off , I can not believe for the life of me that is off by 30 degrees . it is made by american volt company. go figure I guess I will look on amazon for a different brand . I did try to buy usa go figure. when the new sensor come here I will post my report thanks kully

The sensor is going to pick up surrounding heat through the threads connected to the metal.  It could be in a hot pocket or stagnant flow area also under the thermostat.  Which hole is it in?  

the sensor is in the top thermostat cover, the cover is rare. I am not sure what motor it came off of maybe the 280 zx turbo automatic car but there is a port in the top thermostat cover that was 1/4" bspt and I retaped it to except 1/4" npt threads .

just for an update, I did install the new sensor switch which is 200 on and 185 off in the thermostat cover. with a digital probe in the top of the radiator the fan turns on now at 209 degrees but does not turn the fan off with temperature down to 174 degrees, that was tested in my garage. now driving around town and highway the fan never kicks on at all and my temperature gauge is at the start of the m in the temp word. I did order 2 sensor switches at the time to compare them both and both have the same results. the outside air was dry and around mid 60s. I would like to have been closer to the 200 degree on, and even 180 off would have been nice. I guess when it does get warmer here like 90s I will see what happens. I may have to go to a adjustable controller. but I really like just having just 1 relay, 1 sensor switch, and a bypass turn on switch in the cabin . all of the fan adjustable temperature controllers that I have seen are not waterproof and need to be installed in the cabin.  the car never see the rain unless I get caught in it. 

Pictures would be neat of the cover  Sensor part numbers or links too.  I can't find any sign that Nissan made a thermostat cover tapped for a switch or sensor.

1983