89 prelude engine to hot...?

can any one help me why is this car engine come to hot... and then when it is to hot my ALTERNATOR cant handle it, dropping the power to nearly 11.39,, and i know for fact it is not my .A.L.T., i change it two times already... please help me, how to tell if the water pump is broken or i need anew radior or what is worng with it...