Abstract: A steam from a water jacket of the engine is pressurized to form a pressurized steam. The steam thus pressurized is then cooled and condensed by air-cooled condenser to form a pressurized water. The pressurized water is then decompressed to have a normal pressure and then introduced into the water jacket for recirculation.

Abstract: A fan arrangement has a rotatable fan, a plurality of blades formed on the fan, and a shroud. The blades extend radially and are spaced circumferentially. The blades also extend perpendicularly to the radial direction. The base angle of each blade is set at a value of 55.degree. to 75.degree.. The shroud is located on the periphery of the fan so as to cover a part of the fan in such a manner that the fan is partially exposed at its downstream part and a clearance is formed therebetween. The covering percentage of the shroud relative to the fan is set at a value of 50% to 90%. The covering percentage is defined as 100.multidot.L.sub.2 /L.sub.1, where L.sub.1 is the axial width of the outer edge of each blade and L.sub.2 is the axial distance of the shroud from the downstream end thereof to a point in the same axial position as the upstream end of the outer edge of each blade.