A piston for an internal combustion engine and method of construction thereof is provided. The piston has a piston body including an upper part and a lower part. The upper part has an upper combustion surface configured for direct exposure to combustion gases within a cylinder bore with an undercrown surface beneath the upper combustion surface. The body has a ring belt region configured for receipt of at least one piston ring adjacent the upper combustion surface with an annular cooling gallery configured radially inwardly from the ring belt region. The cooling gallery has a floor, wherein the floor has at least one through opening. A coolant medium is disposed in the cooling gallery, and a sealing member is disposed in the at least one through opening to seal off the coolant medium in the coolant gallery.