When I start my mustang the temp gauge moves back and forth very quickly. When I push the gas it will jump very quickly. While Im driving on the highway it will act like its going to stay in the NORMAL range but will fall very quickly past the cold mark. But once I return home I pop my hood and feel the radiator its cool. Its not running hot. But if I leave it runnin the radiator will get pretty hot to the touch of the finger. Im scared of driving it because I dont know if my radiator is letting water get to my motor or not. But it does have antifreeze in it. Where my thermostat was I replaced it because of a leave. The red silicone was bad, so I went ahead and put a new thermostat, head gasket, and new red silicone. Theres no leaks. But it was doing this before I installed a new thermostat also. I just replaced it because of the leak. I have a 95 lx regular 3.8 mustang. Is there a water sensor that might be messed up thats throwing my gauge off like that? Please let me know something that would help. Thank you.

Jess

 

You could have a dicked-up guage, bad thermostat, or bad water pump. You could also have air in the cooling system causing the water pump to cavitate. This can happen when you are sucking air into the water pump.

Are you blowing off any coolant?? This will happen if you start to get hot from any of the above mentioned situations.

 

I just replaced a new thermostat about 1 week ago.

The water pump is not leaked anywhere.

But,

I did take the AC compressor off my car, and put a ac elimanator on. Could air get into the water pump from the A/C lines that I took loose from the compressor? I have the 2 holes tied off with special cloth tho.