A few months ago my radiator had a crack and kept overheating replaced the radiator and the thermostat and still overheating. I opened the cover of the radiator and tried to start and water shot out someone suggested replacing the waterpump. Looked at the oil is fine no water spots so hopefully not the head gasket any suggestions?

 

so you tried to start it and as soon as you started cranking it water started surging out of the radiator? if that's what happened, it sounds like a headgasket to me.

 

waterpump is a centrifugal pump and usually what fails are the bearings so I doubt that is your issue.

start simple:

-did you flush the rest of the cooling system when replacing the rad?
-did you make sure to get all the air bubbles?
-is the pressure cap in good shape?
-radiator fan, and shroud?

under what conditions does it overheat? normal driving? highway? idling?

edit: if you want to check the headgasket try doing a compression test

 

There is not water in the oil and when draining the radiator comes out clean. It overheats when running for aprox 15-20 min. Can one do a compression check do I have to have a professional do it?

 

Try bleeding it. I nearly overheated mine years ago because I didn't properly bleed the system. I just left the radiator cap off, filled with coolant (keep checking the level it takes like 2 gallons or more), and let the engine run until your lower radiator hose gets hot. In the meantime I would snap the throttle several times to expel any air pockets and it also seemed to help if I cranked up the heater after the engine runs for several minutes. I have always used this method and no problems.