I think Cletis had a craked block and used JB weld to fix. I will suggest the same thing to you as I did to him. Drain the cooling system and then hook up the shop vac to one of the hose fittings (waterpump or Thermastat). This way there will be some negative preasure to draw the jb weld into the crack. Make sure to leave the other end of the cooling system open just a bit, you don't want to suck the JB weld Through the cooling system. But just draw in into the crack. I would make sure you clean the crack out very well.
Good Luck!
