robinfortmill

I am helping my brother in law get his mustang running. It is a 1999 GT, 4.6L of course. It has not ran in 3 yrs. He had some radiator issues so he just parked it and it sat. I replaced the radiator because it had a crack in it and was leaking. I changed the oil and battery and got it running again. I ran it for about 30 minutes and all seemed fine but the temp gauge never moved and the fan never kicked on. Not sure what to do. Does the thermostat need replaced? Any advice would be great.

jrherald420

Did the upper radaitor hose get hot/warm at all? what about the heat?

StangManBen

Do you have a temp laser? I'd make sure it's up to operating temperature. If the temp gauge isn't moving and it's getting hot, you've probably got a sensor issue. The fan won't come on unless the computer thinks the car is hot. I'd check it and make sure it's getting up to operating temperature with a heat laser and then check your temp sending unit.

SeanAndKate

sounds like the thermostat most likely.

StangManBen

Take your radiator cap off when you start the car... that'll tell you if your coolant is flowing. If you've got flow, your thermostat is fine. Regardless, that shouldn't account for the fan not working.

jrherald420

In an overflow tank system you will not see coolant flow in the tank. The best way to tell is the way i stated, if the upper radaitor hose does not get warm and the heat does not get warm that right there tells you the t-stat is stuck open. To test the temp gauge in the car just unplug the wiring harness at the sensor and run a jumper wire to complete the circuit, the gauge should max out all the way in the red if its fine.