One More The Temp Gage Goes Up And Down More Up Then Down

[95UNDERGLASS]

MY GRANDPRIX TEMP GAGE GOES UP AND DOWN MOSTLY UP. I DROVE 30 MILES TODAY THE GAGE WENT UP AND DOWN MOSTLY UP BUT NOT 210 MAYBE 220 I HAVE THE FANS RUN DIRECT I CHECKED THERE WORKING FINE, . WHEN I GOT OFF THE INTERSTATE I WAS AT A STOP LITE AND IT HIT 260 I QUICKLY TURNED OFF THE CAR, GOT TO A GAS STATION OPEN THE HOOD AND TOOK THE RADIATOR CAP RIGHT OFF IT WAS NOT HOT AT ALL. I ADD SOME WATER BUT IT DIDNT SEEM TO MAKE MUCH OF A DIFFERENCE, BUT IT DIDNT HIT 260 AGAIN. MY QUESTION IS---IS IT THE THERMO STAT, SENDING UNIT, OR WHAT? IF ANYONE CAN HELP PLEASE LET ME KNOW. I AM GOING TO CHANGE THE THERMO STAT. ITS A NEW RADIATOR AND SEEMS TO HAVE GREAT FLOW. I DO ALSO KNOW ITS NOT THE GAGE ITS SELF. BUT I'M JUST STUMPED ON WHY THE GAGE GOES UP AND DOWN. IF YOU CAN HELP PLEASE LET KNOW THANKS KYM

[GTP Dad]

Changing the thermostat should cure the problem. It sounds like it is sticking closed. The up and down of the guage indicates that the thermostat was working to a certain extent but when the car hit 260 and there was no hot water in the radiator that indicates it has failed in the closed position. I would also change the radiator cap and make absolutely sure you get all the air out of the system.

[richtazz]

[wlkjr]

Mine did the same thing after changing the thermostat and water pump. I had to purge the air out of the system and then it settled down to a normal condition.