water circulation problem

[subjated]

so heres the situation, think the supra is having some water promblems...... the top radiator hose gets hot and the botom one stays cold, not actually let the engine run for long enough to over heat (still ok after about 25 mins of idling (not drove the car since i bought it yet)) but it doesnt sem it coling properly so i had a lok at the thermostat to see if it wasnt opening properly and its not there at all! so it wont be that, (or wil it) have taken the water pump out, although the gasket needs replacing the pump itself is fine, also tok the radiator out to check if it was blocked but thats fine, im thinking maybe a masive air lock or something? that posible? anybody had this problem and no what it is and or how to fix it?
thanks in advance alex