so my GTU started to have a little leak underneath the casing that holds the radiator cap near the front of the engine. the next day i notice my the temp guage is rising really fast almost up 3/4 and the idle is at 2 1/2 grand. as im driving home to try and fix it i notice the temp guage keeps fluxuating between 1/4 and 3/4. so i buy new thermostat and radiator cap thinking that is the problem (it is not an OEM stat because i wanted to get a new one in there just for the short run because none of the dealerships carried them). so i fixed the leak and installed the new thermostat but my temp keeps rising really quick (after 2 min of idling) to about 3/4. so any suggestions would be nice on what it could be. thanks

 

have you checked your fan to see if its turning on?

 

ya its on

 

Air in system
Bad sender
Bad clutch fan
Clogged RAD
Leaking system or non pressurizing system
Blown coolant seals

That is the norm of overheating.