[Mike Pearson]

clean the water jacket the best you can using a caustic cleaner like Purple Stuff. Let it dry real good. Go to your local craft store and get some Enviro-Tex epoxy. That's the stuff they pour bar tops with. Mix it up and pour it in the water jacket and position the head so the epoxy will run to the area that you suspect it is leaking. I have fixed several heads this way and it has been permanent on them. Of course if you can see where it is leaking hit the area with some weld and then the epoxy treatment