[1515]

My coolant temp gauge is always very low, usually on the "C" and never even gets in the range. I get plenty of heat from the heater and defrost so i figured it wasn't the thermastat because if it was stuck open i would get more of a reading on the gauge. Maybe the coolant sensor. Went to my local NAPA and they didn't show a coolant sensor available for my '89 F250 7.3L. Do you think this is the sensor, just hard to find part? I didn't try other parts house yet. Could this be the thermastat?

 

[tim94f250]

There is probably nothing wrong with your truck. The factory Ford gauges are normally reading low on the temp. and oil pressure. Most guys here either install a mechanical sender and gauge, or just ignore it. That's what I did. I know I should install the mechanical gauges. Now that this has come up again, I think I will install the gauges. Tim

 

[cdnsarguy]

With good heat in the cab then the Tstat is probably ok. There are several reasons why guages read low, bad sensor, bad ground*** on the sensor or a bad guage. The sensor grounds out in the block, if Teflon tape is used it can insulate the sender from the block. Always use Liquid Teflon Sealant on sensors which ground to the block like oil pressure, coolant temp and engine overheat..etc.

 

[nubiecanobie]

It could be the thermostat. I had the same problem solved by replacing the thermostat. Before T stat was replaced, IR thermometer reading of the upper rad hose of fully warmed engine was 160 to 170 F. After a new T stat temps went up to 190 with IR thermometer as well as an increase in the oem temp gauge.

My bad T stat had a slight leak when closed and the rubber gasket was missing.

You may want to try taking a reading with an IR thermometer, $30 will get you one at Radio shack. Worth every penny.