my cars tempurature rose very fast, i pulled over and popped the hood and the car was steaming from under the block it looked like, my temp gauge was completely topped out, but i felt the radiator and it was cold, i could even take off the cap and nothing happend, the coolant was full and i just replaced the water pump whats happenin

 

Was the thermostat opening up? im gonna guess no since the rad is cool to the touch.

 

it was the thermostat, $3.49 to replace

 

Figured as much from what you said. Glad its running good now.