coolant gush

I have a 2000 Blazer 4.3 4wd that has alot of coolant (now water) leaking badly from behind the a/c above and right of water pump. The filled radiator will lose water, then stop after a few minutes all while the engine is off. Leaking too much to drive it. Any ideas? Thanks

Sounds like a bypass tube leaker.. should be easy to find once you remove a few things.