coolant leak...help.

1996 chevy s-10 pickup.
My engine coolant began leaking slightly about three weeks ago. It only leaked after I drove (hot engine). I added coolant directly to the radiator and it kept my truck from overheating but the fluid leak is worsening. Today it overheated to the point where I had to pull over and let it cool down so I could add more coolant. I will be taking it to a shop to have it examined and fixed as I am not very knowledgeable about engines an stuff. But, I am curious as to what exactly is leaking though.
I added more coolant today about two hours after it overheated. Much of it drained back out from somewhere behind and below the flywheels that the belts are on. (the belt assembly located just behind the radiator).
Any ideas on where it is leaking from and why? How much $$ will it take to fix?
Thank you for any help.

Krab

Sounds like the water pump. I couldn't tell you how much $$ because I replaced my own but can't think it would be too much. Took me like 4-5 hours with a lot of beer breaks.

i agree with vt sounds like water pump i cant imagine much more then 300 if that high

it could also be a hose with a small leak and it only is noticeable when on because the system is pressurized forcing fluid out

vtmecheng don't you mean a lot of beer with some waterpump breaks?

an hour should be lots of time, if you really try

yep waterpump and hoses

Hey, after a few breaks it can be hard to tell which of the two water pumps you see is the real one.