I have a '94 3.8L and my temperature gauge is fluctuating between 1/2 and 3/4, mainly when I'm idling. If I'm doing any kind of steading driving though, i.e. freeway or highway, it's stays pretty constant at 1/2. I'm used to having my temp gauge never fluctuate. Could it just be a bad thermostat?

 

could be low on coolant. just a guess, if you haven't checked it already.

 

every mustang should have mechancial gauges..I suggest buy a nice set..those electric ones are terrible

 

check coolant and your thermostat.....

 

several things...a new stat maybe in order..when was the last time the rad was flushed?....napa make some good ****. it's a powder

 

Hey man Ive got the same troulbe too Ive 83 3.8L V6 stang I could be at the Mc D's driv thru and it could temp could hit 3/4 hot, But I know my gauges are shot though, Ive got a new rad / New therostat / Alot could be is the coolant could not be mixed properly, That plays a big role, I would first open youre rad cap check youre coolant level, Then run youre car with the rad cap off at idle let it warm up too see if youre coolant is moving through the cooling system, Most cases its youre thermostat and coolant mixture, Maybe you rad is plugged as well.

 

could be temp sender thats in your intake, might replace that. it sends the signal to the gauge as to how hot the coolant is. check your coolant level, sounds like the problem, my 93 f250 did that and it was low on coolant

 

Vfast is right the stock gauges suck.

Get some mechanicals and then go from there.