Hi name is Adam. I have a 94 camaro z28, 165000 on it. Had an overheat problem recently. Got low on coolant due to a pinhole leak in the radiator cap neck, and the fans were our as well. Fixed the leak with jb weld, replaced the relays and fuse for the fans. All is working properly. New thermostat as well as coolant temp sensor. However now temp gauge is reading as tho i am overheating but its not. thermometer and laser point thermo read all temps as normal 180/190 fans at 200. The gauge climbs to danger zone/ 260. Remains there while at idle however drops to halfway/ just under half while driving 40/50 mph. Then while stopped climbs back up. Im at a loss for what to do any help would be greatly appreciated. Its not a major issue but i would want to know if i was truly overheating so i want the gauge working properly.

 

Appears you may not have completely bled the air out of the cooling system, and you have air pockets influencing the sensor in the driver's head for the gauge.

Do you have a scanner that will allow you to compare the temperature you see on the gauge to the temperature being reported to the PCM by the coolant temp sensor in the water pump?

 

I do not but im sure i might be able to get ahold of one. I havent tried to properly bleed the system yet tho. I'll give that a shot first. Just the air that escaped through the open radiator cap while running

 

Most likely air is in the system. When you fill it properly most all air is purged.

 

Ok system was bled. Temp gauge still acting funny and it is not actaully overheating. Just bout the temp gauge sensor, ill replace that and let you know how it goes. Also couldnt run the scanner. MY buddy had an obd 2 reader didnt have an adapter for obd1

 

so new temp gauge sensor. Bled system and temp gauge still reading too high. reads normal while driving. Climbs while idling up to about max still...at a loss for what to do now. Flush system, refill? Jb weld didnt take to pinhole leak need to redo that. Could that loss in pressure affect it that much to cause an issue with temp gauge? or is this something purely electrical?