A pile driving ram for driving piles into subaqueous ground, during which a heavy piston operating as a hammer is each time lifted by fuel explosion in a cylinder, comprises a considerable and expensive cylinder piece, which has inlet and outlet ports and which comprises at least two guide girdles for supporting guide members co-operating with at least one guide stay of a guide frame. In order to increase the lifetime of the cylinder piece, the core is moulded from precious steel according to the fling moulding method.