check the heater core stopped up radiator
It could be the thermostat. Open up the radiator cap when it is hot and see if the water is flowing in the radiator. If it is not then it may be a thermostat.
Take your thermostat out and put everything back together, run your car without a thermostat... If your car no longer overheats, replace your thermostat.
check your radiator. is it clean or does it need to be replaced? a simple cleaning cured my problem.
Your thermostat is stuck closed. you will need to replace it. The thermostat controls the circulation through the radiator - when the engine heats up the thermostat is meant to switch circulation from just-engine to engine+radiator. Sounds like this isn't happening.
You have not bleed the air out of the system after you installed the t-stat, causing the heater not to work and the engine to overheat. Use a coolant filler that screws into the radiator and get the air out
Check that the coolant fans are still working, then check out the water pump.
water pump
did you try replaceing the thermostat or radiator or even check the hoses
Most likely it is a bad thermostat. The switch on the radiator fan could also have failed.
check you water (coolant) level, make sure thermostat is working, radiator leaks, sensor problem
Removing the thermostat can actually make an overheating problem worse. I would check the radiator fan.
Could be the water pump is not working properly.