Replaceing Freeze Plugs or Block Plugs. If they show signs of leaking they should be replaced. Knock it out with a hammer and a chisel or large screwdriver. Do not worry if you knock it into the cooling channel or jacket but try not to. I like to use vise grips and pull it out after knocking it. Sand down the block port and clean it free from grease and particles. Brake clean works well. Fit your new plug with nondrying silcone into the port and drive it into the port. Some Freeze plugs are difficult to replace and extremely diffulicult to create enough force to drive the plug into the port. ONLY drive the plug from the outside lips so it doesnt get warped. They sell expandable plugs but those are only temporary solutions. Keep your eye on the temp gauge if you go this route. I also read that cleaning it out and a light sand then packing it with Epoxy might work. I cant ever remember being taught that method.
