1999 Chevy Cavalier antifreeze leak

Engine Cooling problem
1999 Chevy Cavalier 4 cyl Front Wheel Drive 170000 miles

I have a leak running on ground on the left side of motor, cannot find where its coming from. I was about to put a new thermostat in and when I took the old one out and reconected the hose antifreeze just ran out. I put the old thermostat back in and it doesnt leak as bad.
thank you