1992 Ford Tempo V6 (3.0) Overheating

It sounds like you don't have a serious problem. The gauge is not calibrated, so it is difficult to use it's position to determine if you have a real problem. I suggest that you take the car to a shop that can measure the actual radiator temperature (most use a infrared thermometer these days, it only takes a few seconds). You might also check the operation of your cooling fan. I don't know about your Tempo, but my old Sable with the 3.0 had a two speed cooling fan. The low speed engaged often when you were idling. The high speed only engaged when the car got near the upper end of the acceptable temperature range. It is possible that your low speed is not working properly, so the cooling fan only engages on high speed when the car is near the upper end of the acceptable range. Without the electric cooling fan, the car will tend to run hot at an idle, since there is nothing to move air through the radiator. One more thing, make sure there is no air in your cooling system.

Regards,

Ed White

I think he's right and you don't have a serious problem, but I don't think it's mechanical and my first action wouldn't be to check rad temp or fan. First I would check grounds on the engine block and the battery, if you have a multimeter I would test impedance to make sure you have a good ground. Next I would look for wires coming off the temperature sensor and make sure they're not close to anything that could throw off EMI. This could be any electrical component but especially spark plugs, wires, distributer, and alternator. You could try try putting sheilding around these wires as well, or even go to radio shack and get a noise filter. I think your problem is similar to whines heard in the radio that increase with RPM, which is EMI from your ignition system.

I had a 93 Tempo with the same problem. Turned out to be a bad water pump. Save yourself the time and do this first.