water jacket
 

how hard would it be to repair this? on a na s4 motor? came across a motor on craigslist and its almost free for the motor but the water jacket is said to be damaged. i was just htinking about pickin this up and jumping into one head first so i can get a good feel for how everything inside works... is it fixable without a rebuild?

If the problem is a bad coolant seal then I've got a fix for you. If the engine actually has a crack in the metal somewhere then that's a different story...