I dont know if Im in the right forum for this, but i can be driving my 1989 F150 and the temperature gage hardly moves at all. Is this a problem.

 

Maybe.

Use an IR thermometer and see what the actual operating temperature is at the thermostat housing.

A thermostat that is stuck open will give the indication you have described.

Of course, so will a defective gauge or sender.

Steve

 

Mine barely moves too, once the engine reaches operating temperature. It stays just below the halfway mark. Of course, on 2005s, the coolant temperature is not measured, instead, it is "inferred" from the cylinder head temperature. I suspect 89s might use a genuine coolent temperature sensor.

But, I can also monitor my CHT directly, since I gave a Gryphon programmer. It also stays fairly constant. Under prolonged very heavy load, I've seen it rise to 216 degrees. Usually, it's around 210-212.

The thermostat's job is to regulate the temperature so that it stays hot enough to efficiently use fuel and reduce emissions. If the engine runs too hot, it increases NOx emissions, to cool, and the HC emissions go up. Sounds like yours may be just fine.

- Jack