Yeah just one day my car started overheating. I've changed the thermastat, bled the cooling system, and let it cycle with the cap off. It still hasnt fixed the problem though..it'll heat up while idling and sometimes when driving but it nevers gets to the red. Also when it gets about halfway on the gauge if i hit the brakes the needle will go up and it'll bounce. I don't really know what to do..any suggestions would be greatly appreciated.

 

maybe your water pump is on its way out??.....

 

Same thing happened to my car, i changed the thermostat and didn't work, then i changed the radiator and that fixed the problem, i had a bad head gasket also so i changed that too. Try that stuff