Trouble with water pump

I have been having problems with my 95 trans am lt1 it keeps running extreamly hot i never allow it to get in the red though the heater blows cold air i have replaced everthing the car store told me could be wrong then i was looking up on line that the water pump could be bad went to car part store had them check they told me as long as it is not leaking and the pulley is turning it is good is that true and could it be anything else???? HELP:screwy:

Hay mojo, I have a 01 impala with a 3.4 in it. I am working on it for someone. He brought it to me and said that its getting hot and he cant fix it. I went through it and replaced the radiator, thermostat, water pump and flushed the block. Still kept getting hot. I got to watching the radiator when it was running and it was bubbeling and pushing water up and out every couple seconds. I knew right then blown head gasket or cracked head. I had already ran a pressure test and it did not loose any pressure. I left it on for 30 minutes. The heater was the same way it would not blow warm air at all. Check your radiator and see if its bubbleing and or pushing coolant out. You can have a blown head gasket without it showing up in the oil. This is what was my problem. Maybe this will help.

I have not noticed abubbling sound one time it got hot and overflowed the overflow but i thought the water pump wouldleak if it was bad i have nothing leaking anywhere

lots of info on this. waterpump is driven by camshaft, tends to strip out. recomend a good shop or buying a manual