Low water temp.

[96JimmySLE]

I have a'96 jimmy 4.3. I had just replaced my water pump, flushed the cooling system and installed a new t-stat and radiator cap. My question is, my temp guage doesn't go above the 150 deg mark. I know it should be atound 180-190. What could be causing the temp to run lower? My thoughts were temp sensor, fan clutch? I'm at a loss. Any suggestions would be greatly appreciated.
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[blazee]

Did this happen immediately after replacing the thermostat? If so it sounds as though you were given the wrong stat or a bad one.

The sending unit or gauge could be bad, or it could even be a loose wire that connects them. the sign of one of these problems would be that everything functions normally, except the gauge doesn't move.


The sending unit is located on the driver side cylinder head just above #3 and #5 spark plugs. It will have a small wire connector on it.

These things can be tested:

To test the wires and gauge, ground the wire to the sending unit with the key on, the gauge should read full scale.

To test the sending unit, according to Haynes:
1. Remove the sending unit from the engine and clip ohmmeter leads to the sending unit body and the terminal. Place the sending unit in a pan of water on the stove, with a cooking thermometer in the water. On a cold (50-80 degrees F) sender, the resistence should be 5,700 to 2,200 ohms. When it has warmed up to operating temperature (170 to 200 degrees F) the resistence should drop to 200-300 ohms.

This about all the help I can be, I have not done this procedure myself.