1992 Mercury Sable Still leaking coolant

Other Category problem
1992 Mercury Sable 6 cyl Front Wheel Drive 140, 00 miles

Hello Guys,
My dilemma is this I have a 1992 Mercury Sable with a 3.0 engine. Problem starts I noticed smoke coming from under the hood when I checked it out I smelled antifreeze and saw a small leak dripping onto the pipe that connects to the catalytic converter. Which is causing the smoke. I had the water pumped changed and for a week everything was fine then the smoke re-appeared so now I change the hose underneath the car it still smokes.I've now bought a thermostat and before I have that installed I want to know if the problem could be that the water pump isn't on tight or that I do need to go ahead and put the thermostat in. It's driving me nuts by the way the car has never overheated and the temperature has always stayed in the normal range that's why this is so baffling.

I need advice and help in the worst way can you guys help me out
Thanks.