is their a special technic to purge the water pump

Need to purge the cooling system from air pockets. Have the radiator full and the cap off. Run the car until the thermostat opens up, it may push fluid out the radiator until the thermostat opens. The top radiator hose will get hot. Have the heater set on hot so it can circulate threw the heater core. Once the coolant level drops in the radiator add coolant until it is pretty full. Let the thermostat open up again so it can push out any other air trapped. Fill the radiator, install the cap while it is running, then you can turn it off.