Actually I would take the radiator cap off (of course when the car is cool) and start the car. You may have some left over bubbles in the system causing the coolant not to circulate correctly. Since you just installed a new radiator.
__________________
Sponsored by: KAM Racing Sports, Falken Tires, Progress Technology, Brady's High Performance, Taggart Performance Engineering, Rotora Brakes
Autocross is: 90% driver, 5% car, & 5%
CRAZY MOJO!
Autocross Help Page