How should a K-car cooling system operate?

[Jacks1986Lebaron]

The "Coolant Temperature Sensor" is the two-terminal device in the thermostat housing that measures coolant temperature by way of being a thermistor (negative temperature coefficient resistor). As temperature increases, its resistance decreases non-linearly. Its signal goes to the ECM to adjust the air/fuel mixture and at a defined value, to turn on the cooling fan.

[89ARIES]

I see sort of. I am a little confused. All I know is that the fan should not be kicking on when the guage is 2/3. I would think that it should kick on at 1/2, like the LeBaron I drove, and stay there. It makes me nervous to see that high reading. The head went after the 2/3 became 4/5 or whatever.

[bamman]

The fan should come on at around 210 degrees. Unless you have measured temperature values that correspond to the mechanical gauge you will not really know. I can tell you they have varied on my cars though. With reading the sensor from my scan tool I've found:

My dodge daytona hits 195 degrees at 1/3 and the radiator fan turns on at 2/3.
My dodge omni hits 195 at any point between 1/4 and 1/2 and the radiator fan never turns on but the scan tool never reports any temperature over 196 to turn on the fan.

My friends dodge ram hits 3/4 and stays there all the time but the scan tool says that its about 199 degrees.

Heck even the service manual states that running on 7/8 on the temperature gauge is normal in extreme conditions.

Bottom line is that you need to know what the temperature actually is in relationship to the temperature needle.

[84reliantk]

what my K used to do is the temp gauge would do the "dance" but very rapidly, and it was what i belive is a faulty thermostat, i have since taken the thermostat out and the problem has stopped, i just put pieces of plastic infron of the radiator according to the temp, and also use the heat in the car to fine tune the running tempurature, but i have ordered a new thermostat and am going to see if that fixes the problem, so it could just be a bad thermostat. the cooling fan comes on in my car at about 1/4 of the was up the temp gauge, so usuing the heat and the plastic infront of the rad i am able to keep it at a proper running temp. I know it may not be the proper way, but it works, and i am going to fix it when i get the parts to fix my valve followers and cam, so i will let you know how it goes.

[ARTTY]

Hello there, 89 ARIES. Member, ARTTY, from San Diego, here. My '87 Reliant 2.2 does the same temp gauge dance. The previous owner replaced the sensor in the thermostat housing, but the fan does'nt come on. Sometimes the gauge runs very low, then will go halfway up then back down, over and over. The previous owner also rigged the fan to run all the time, apparently, but as I said, now "It's dead, Jim!" I think there's an evil spirit in the cooling system somewhere. Mopar to ya! artstrader20@ymail.com