You need a radiator AND coolant..and under normal conditions if both are in good shape a pump is not needed. However, every car is different and most radiators are not in new shape, so sometimes a pump may help. I have one on my car..don't know if I need it or not..it has always been there..and I have never had an overheat. Some feel the pumps are totally worthless. It is one of those things which each driver must decide on his own. Also, while I would love a new radiator, they are a $600.00 item so one does not lightly replace them.