Plug up the water inlet and outlet and adapt a garden hose to the block drain. With pressure applied from the average household water system, the crack will definitely show up. Just be sure the radiator and heater core are disconnected from the engine!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!