Gmc Safari van take a lot of water in radiator

Hello,
The water has to be going some where! You should check the van's parking spot for any obvious water puddles, as that will tell you roughly where the leak is.You should check the oil and make sure it is a dark color and not white as that would indicate a blown head gasket (and water is now going into the oil). Another possibility is that the radiator is leaking when it gets hot and the water is being boiled off and evaporating before it hits the ground in which case you should see steam coming from the hood and smelling the coolant.
Good Luck!
Rich Lilja

3 possibilities:
1) Leaking (you should see coolant on the ground)
2) Going into your oil (sign of blown head gasket)
3) Going out your exhaust (sign of blown head gasket)
anyway you look at it, it's bad.