FUNNY THING HAPPENED tonite .filled my 91 gt with gas and went thru the car wash .then i went to a local car show ,after i parked the car for about 1/2 hr could not start it ,it seemed to get very hot ,would start but not turn over .had it in frist gear then treid in neutrel got it started .as i was driving home the temp gauge kept going up and down ,ie very hot then below normal . what the heck is happening

 

Might be a bad thermostat. I'd also might say a bad gauge as Foxes are known for faulty temp gauges (at least mine were).

I'd check the thermostat first, and check for leaks around the water pump.

 

ok will do that ,anyone else have more ideas of what happend

 

maybe the coolant temp sensor is going bad? I also heard the factory gauges (on all year mustangs) are crap, mine seem ok, but it never hurts to go to autometer!

 

got car checked out by a mech. says everthing seems find .had to add 1/2 gal of antifreeze ,do these cars use up a lot of antifreeze . i checked fo leaks ,seems good .anyone have any info on this
thanks

 

Your gauge was fluctuating because of the low coolant....the sending unit would rise when there was only hot air/steam and then fall when a burst of coolant hit it. These cars do not use coolant normally so you have a problem....especially having to add 1/2 gallon! Check out your water pump...when the bearing starts to wear it will leak out of the little seep hole under the snout....but only when it cools down so it won't leak all the time and usually not when you are around. Very common problem with the water pumps when they go bad.

 

ok thats greatvinfo will keep an eye on my water pump
thanks

 

This happened to me in 2 different Stangs.. When the guage would read HOT I would pull over and check the vitals. Everything was ok and definately not running hot. The stock guages do this all the time in older stangs.. I changed to a auto meter guage and never looked back.

 

In the '86 and older Mustangs this is often caused by a bad voltage regulator on the back of the instrument cluster.

 

man anthony, the car in your sig makes me miss my 86 vert!

 

Could be bad thermostat, but when I have had that issue with my Fox it always seemed to be air in the system. After burping the coolant system the gauge works just fine.