A system for flushing a cooling water pathway of a marine propulsion device with water supplied from a water source includes a water control device and a controller. The water control device is connected to the water source and the cooling water pathway of the marine propulsion device. The controller controls and causes the water control device to supply the water from the water source to the cooling water pathway so as to perform the flushing. The controller obtains propulsion device data including at least one of a pressure of the water, a flow rate of the water and a concentration of salt contained in the water in the cooling water pathway. The controller determines whether or not to stop a supply of the water by the water control device based on the propulsion device data.

An outboard motor has a powerhead that causes rotation of a driveshaft, a steering housing located below the powerhead, wherein the driveshaft extends from the powerhead into the steering housing; and a lower gearcase located below the steering housing and supporting a propeller shaft that is coupled to the driveshaft so that rotation of the driveshaft causes rotation of the propeller shaft. The lower gearcase is steerable about a steering axis with respect to the steering housing and powerhead.

An outboard motor includes a cooling water passage structure, in which a combustion chamber periphery water jacket through which the cooling water flows around the combustion chamber and an exhaust port periphery water jacket through which the cooling water flows around the exhaust port are formed in the cylinder head, a cylinder periphery water jacket through which the cooling water flows around the cylinder is formed in the cylinder block, and an exhaust passage periphery water jacket through which the cooling water flows around the exhaust passage is formed around the exhaust passage. The water jackets are connected such that the cooling water from the water passage will flow through the combustion chamber periphery water jacket, the exhaust port periphery water jacket, the cylinder periphery water jacket, and the exhaust passage periphery water jacket in order.

A fan is suitable for an air-guiding system of an outboard motor including an internal combustion engine and a covering hood bounding an engine interior space. The engine drives the fan, which is connected to an upright shaft journal projecting beyond an upper side of a housing of the engine. The covering hood has air flow openings, and the fan influences the air flows in the covering hood interior space. A flywheel, fixedly attached to the upright shaft journal, carries a fan wheel of the fan. The fan wheel is set in place from above, and the flywheel carries the fan wheel for conjoint rotation. Airflows enter the interior space via an inlet opening and a first conducting device, and the airflows, under the action of the fan, act upon at least parts of surfaces of the internal combustion engine and the auxiliary units to cool the internal combustion engine.

An internal combustion engine for an outboard motor for driving a vessel has an air guide system acting by way of a covering hood surrounding surfaces of the internal combustion engine and ancillary units. Covering hood inlet and outlet openings permit airflows to move in an interior space of the covering hood, and a fan driven by the internal combustion engine influences the airflows in the covering hood interior space. Airflows enter the interior space of the covering hood via an inlet opening and a first routing arrangement. Assisted by the fan, part of the airflows acts on the surfaces of the internal combustion engine and of the ancillary units. A second routing arrangement routs another portion of the airflows, as intake air, to an engine suction system. Airflows heated by engine and ancillary unit surfaces are conveyed by the fan and a third routing arrangement outside the covering hood.

Embodiments of outboard motors and related systems and components thereof, as well as arrangements of marine vessels implementing same, as well as related methods of operation, use, assembly, and manufacture, and related improvements, are disclosed herein. In at least some embodiments, the outboard motor includes a cowling system in which at least one divider portion separates an interior region into first and second portion, with the transmission and engine respectively being situated in the first and second portions, respectively. Additionally, in at least some embodiments, the outboard motor includes a water pump system in which a water pump is integrated with the transmission. Further, in at least some embodiments, the outboard motor includes a fuel vaporization suppression feature, or an oil tank feature that allows for desirable oil drainage from the engine of the outboard motor particularly when the outboard motor is in particular (e.g., storage) positions.

An outboard motor includes a first cooling water passage through which first cooling water including water from outside an outboard motor body passes to cool a first cooling target including at least one of an electrical component other than an engine and fuel in a fuel tank, and a first pump that is an electric pump that pumps the first cooling water from outside of the outboard motor body and flows the first cooling water into the first cooling water passage.

An outboard motor includes a bracket, an upper case, a lower case, a drive shaft, a propeller shaft, a cooling water passage, a water pump, and an electric motor. The outboard motor is attached to a watercraft via the bracket. The upper case is below the engine. The lower case is below the upper case. The drive shaft is in the upper case and the lower case. The propeller shaft is connected to the drive shaft. The propeller shaft is in the lower case. The cooling water passage is connected to the engine. The cooling water passage is in the upper case and the lower case. The water pump is below a lower end of the bracket to deliver cooling water to the engine through the cooling water passage. The electric motor is operable to drive the water pump.

A cooling device for a power source for a boat propulsion apparatus includes a cooling water passage. The cooling water passage includes a passage provided in the power source, in which an engine or an electric motor is used as the power source of the boat propulsion apparatus that propels a boat. Water from outside the boat is taken into the cooling water passage as cooling water to cool the power source, and the cooling water after cooling the power source is drained from the cooling water passage. From the cooling water flowing through the cooling water passage, foreign substances having a size that clogs the cooling water passage are removed. The cooling water passage is provided with a filter device which can filter residual foreign substances remaining in the cooling water.

A cooling system is for cooling a marine engine having an engine block and a cylinder head, and a supercharger configured to provide charge air for combustion in the marine engine. The cooling system has a charge air cooler configured to cool the charge air prior to combustion in the marine engine. The cooling system is configured to circulate cooling water from a body of water in which the marine engine is operating to the marine engine and then back to the body of water. The cooling system is further configured to convey the cooling water in parallel to the marine engine and the charge air cooler. A sprayer is configured to spray the cooling water into exhaust gas discharged from the marine engine. The cooling system is configured to convey the cooling water in series to the charge air cooler and then to the sprayer.