It was weeping on the main water jacket, drivers side about an inch from the top. Must have frozen at some point, but couldn't see anything till water was in it the first time. Really bummed me out at first, but then I realized that I basically had no money into this engine, and it was a placeholder until I get the real one back from the machine shop. Figured I'll just try what I can, and maybe get to drive it before the rebuilt motor is ready. This one will be good to have as a back up, and for any other projects that come along.