About 13 years ago I was trying to get some more time out of my radiator in the 27 and dumped in some Barrs Leaks. Later on when I tore the engine down there was this cement like goop in the heads and intake manifold cooling passages that I had to chisel out with a screwdriver. In defense, I had put in two cans of the stuff, but I shy away from that one now. I have used Alumaseal, both in the powdered and liquid form and it seemed to be ok. Also, I had my radiator cleaned and fixed after I tore the car down and the radiator guy asked what the h*** I had used in there. He said he had a hard time getting it out.

Don