Temperature Gauge

I just picked up a 99 Explorer. It is a 6 cylinder OHV...has an X as the eight digit in the VIN...the temperature gauge isn't working. I saw where you can test the gauge by pulling the connector and grounding the pin, at which time the gauge pegs at HIGH. So the gauge should be OK.

I bought part WT724 from Advance shown here http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/product_engine-coolant-temperature-sender-bwd_18970664-p?vehicleIdFromReq=40914&isAllVehicle=false&vehicleIdSearch=40914&searchTerm=wt724&showTitle= changed it out and still nothing....

Can anyone help me on this and/or verify the part I have. Maybe verify the Ford part number as well...

OK...I changed out the switch with one from Autozone TU241. It moves, but to be honest I have NO IDEA where the needle should be anyway....after about 10-15 minutes of idling it was here

http://www.imgur.com/p2rEVkF.jpeg

Have you driven the truck to see if the gauge moves? You might have an air pocket at the sensor that keeps it from reading an accurate temperature. Or you may have a stuck open thermostat. Driving the truck while keeping an eye on the gauge may help you determine if it's just air since the coolant will be circulating more at higher engine speeds. I'd expect the gauge to run more in the 1/3 to 2/3 range after idling for that amount of time. Two minutes at 2000 rpms after a cold start would yield a reading close to where your photo shows.

-Rod

Thanks for the reply. Today i tested the sender by grounding the threads on the alternator bracket and warming the tip briefly with a small butane torch. Temperature on gauge shot up. SO, this is NOT the sender or gauge I don't think. Could it be maybe a stuck thermostat in the OPEN position..even then the vehicle coolant SHOULD warm up to temp eventually and show correctly on the gauge....

Yes, I mentioned in the post above that it could be a stuck open thermostat, but I also mentioned it could be an air pocket in the cooling system. Have you driven the truck to see how the gauge behaves?

-Rod

Could it be maybe a stuck thermostat in the OPEN position..even then the vehicle coolant SHOULD warm up to temp eventually and show correctly on the gauge....

Nope. It will never get up to normal temps.

Once the engine is at operating temperature the upper radiator hose should be so hot you cant hold it....replace thermostat.