I just put a different motor in my stang, with a new 160 deg. thermostst, newer stock water pump, new perma-cool 16" electric fan, and the stock radiator. I didn't think it would overheat, but whenever I run it for about 30 mins, the temp gauge will get past 210. And this is in 50 degree weather. I know the thermostat is opening, and the fan is on all the time. Plus, it does this in traffic and cruising on the freeway (about 2400 RPM). It also has the A/C ratio water pump and crank pulleys. It's not leaking any coolant. So why is it overheating?!?!? Aaargh. Anything would really help. Thanks.