a flat gasket for a reciprocating engine or a driven machine including at least one metal sheet 0 . 05 to 0 . 5 mm thick which is provided with a coating of an elastomer film at least on the sides facing outward in at least one sealing area and has an edge area , formed by the outer contour and / or at least one cylinder bore and / or a water and / or oil passage in the cylinder head , adjacent to at least one peripheral self - contained cavity , and the cavity is filled completely with a hydraulic medium .