thermostats and fan switches and stuff

[Johnny Blaze]

So, here is an obervation,/ question.



When I got my truck together, I had a 180 thermostat. I installed an electric fan and added a Jegs Thermostat Switch control. The switch I got is recommended for a 195 thermostat, turns the fan on at 200 and off at 185. The sensor is mounted in the intake manifold next to the thermostat. My water temp gauge sender is mounted in the cylinder head.


So, wehn driving here is what I obeserved. When moving the truck ran a consistant 170. Once I got in traffic, it would warm up to 200 and the fan would turn on and cool down to about 190, once I got moving again it would drop to 170.


This is my daily driver, and I figured it should be a little warmer, and I needed the 'right' thermostat to match the fan switch. So yesterday, I swapped in a 195 thermostat.

Now, it heats up to 200 driving and kicks the fan on, fan cools down, thermostat closes and it heats back up.

It seems the combo of the 195 thermostat and sensor is causing the themp to fluctiate, and the thermostat keeps cycling open and close. This does not seem good to me, as I am seeing a 10 degree change or more up and down as driving, wher before it sat at about 170.

My thoguhts were the higher temp would be better for fuel effecency and such, but the constant fluctiation seems like it would not be good.


SO my question is , is this ok? Should I go back to the 180 thermostat and leave the higher fan switch in? Should I move the sensor?

What do you guys think about this?

[anthonys 69]

You must have a very good radiator in your car. In a production car the fan comes on around 215 and turns off around 190. And the cooling system would equal out at around 200 at all times.

[Johnny Blaze]

This is in my 69 C10, btw. New 3 row All aluminum Ebay radiator. Pro Comp Aluminum water pump. 16" electric fan from Jegs, forgot the brand.

[Johnny Blaze]

After driving it some more, it seems it only fluctuates from 190 to 200 while cruising.

[Fuelie Nova]

I have a similar situation. My radiator and fan setup is Ron Davis with dual Spal 12" fans. Around town it fluctuates but once I am on the highway for extended driving it settles in nicely.
Tom

[anthonys 69]

sound ok to me