it's not difficult to repair or swap it out.
x what everyone else has said - water pump.
gasket around $20, water pump if needed - around $125- $ 230 depending on where you get it (I'd get CROWN replacement, they tend to be cheaper)
just don't over tighten - that'll be your nightmare :beer:
Just got the pump replaced, they said it was the problem. Now when I shut off my car I have lots of steam coming through the passenger side headlight out the grille