How do you know you really sealed the water pump ?

[vrooom]

i got paranoid about water pump leaking after doing the water pump. Is there any way to test water pump while head and rad is off.

[Cooperman]

If you cleaned both faces - pump and block, used a new gasket and tightened the bolts up correctly it won't leak. It's not really possible to test this until the pressure gets up as the water heats (yes, I know you can block off all the holes, fit a pressure hose and turn it on, but that's a bit unnecessary really).