white smoke and water from tail pipe

hi i have a 91 lumina...v6 3.1, no temperature light ever came on, but the low coolant light has, i checked the radiator and coolant reservoir and it was full, then when i would check the water level it started being a gallon low each time , now there is white smoke coming out the exhaust, water and antifreeze pouring from the muffler and exhaust when the car is running, and the engine runs rough, could anyone please send any information.

thank you,
lin :banghead:

Probably a blown head gasket or lower intake gasket. Get a compression test done on all six cylinders to rule out a head gasket issue. If it is a gasket, you're lucky. If its a warped or cracked head, you're not so lucky.

When's the last time a coolant flush was done?