Ford 4000 3cyl water temp

[jinman]

What I've done,

Thermostat
Hoses
Radiator
Water pump
sending unit
I checked the block while engine running, with infared thermometer it reads 160 degrees. I thinking temp gauge now or could it be the voltage going in?

Take the wire off your sending unit and attach a ground wire (to the wire, not to the sending unit). Turn on your key and see if the gage goes to maximum heat. If it doesn't go to maximum or only partially to maximum, then the gage is probably bad.

The sending unit is just a thermal resistor (thermistor) that goes down in resistance as the temperature goes up. You can check its operation by hooking up an ohmeter to the probe and watch for resistance change as it heats up. It should start around 160 to 180 ohms when cold (possibly more) and then drop resistance as the engine warms. By shorting the wire to ground as previously described, you are simulating maximum heat.