An engine device includes a water tank coupled to an engine to supply cooling water to the engine and having a mouth disposed in the upper portion. A separator housing is coupled between the water tank and the engine to receive heated water and vapor or air from the engine, the separator housing is coupled to the mouth with a tube to supply the vapor and the air from the separator housing to the upper portion of the water tank, and then to supply the vapor and the air to the engine. A lid is engageable onto the mouth for enclosing the orifice of the mouth and includes an aperture coupled to the tube, to receive the vapor and the air from the separator housing.