Invention relates to an internal combustion piston engine provided with a heat shield for an exhaust gas duct (22). The body of heat shield forms a collar around the exhaust gas duct (22), and that the heat shield is provided with an aperture (26) extending from a first end of the body to the second end of the body, through which aperture the exhaust gas duct (22) extends (26), and wherein a gap (42) is provided between the exhaust gas duct (22) and the heat shield (24) collar, and that the first cooling fluid opening (36) is arranged to communicate with cooling channel (28) of the cylinder head and the second cooling fluid opening (34) is arranged at a radial distal end of the heat shield from a center line of the aperture (26).