Had similiar issue. Tried adding a few added to the radiator,waterglass,and a few othrers, none worked and had to flush the system a number of times to try and remove it all. Will never us those things again. Used an AB 2 part epoxy by Moroso sold by Summit and it worked fine.I removed the manifolds and ground it clean, heated with a gun, applied and heated again to help cure. Area must be super clean or it won't hold.
