Abstract: An improved liner particularly useful for the prevention of pitting and corrosion of portions of an internal combustion engine, particularly a diesel engine, which contact a circulating coolant, the invention provides a coating over at least those portions of a "wet" cylinder block liner normally in contact with a coolant liquid, the coating being comprised of a polymerized resin, particularly the reaction product of a free radical catalyzed oxidatively coupled polyester resin. The polymeric coating of the invention is disposed over, conforms to, and adheres to those surfaces of a "wet" cylinder block liner normally in contact with a coolant liquid.