Engine Cooling problem
2001 Chevy Tracker 4 cyl Two Wheel Drive Automatic 120000 miles

I just changed out the radiator. All the hoses are connected as they should be, I put in a gallon of half water/ half coolant in before I started up. It took for ever for it to reach normal temp. I took it for a spin and it shot up to the RED zone and stayed there till I got it back to the house about 3/4 of a mile away.

I was thinking maybe the thermostat is messed up, but really not sure. Any idea of what could be the problem?

Thanks,

T