Over here in aus you can get stuff called chemiweld, it can clog radiators, and chances are you will never get the engine apart once you've used it but does work, my engine had really bad blown head gaskets, water in the oil, blew all the water out of the system, etc and it fixed it and lasted for 18mths till I could replace the engine.
But once it was out I couldn't get the heads off, not even bashing them with a hammer.
Jordan.