An outboard motor includes a power source, a drive shaft, a propeller shaft, a propeller attached to the propeller shaft, a case covering the power source, the drive shaft, and the propeller shaft, a water intake passage provided in the case, through which water is taken into the case from an outside of the outboard motor, a first pump configured to be driven by rotation of the drive shaft and to supply the water taken in from the water intake passage to the power source as cooling water, and a second pump configured to be driven by rotation of the drive shaft and to supply the water taken in from the water intake passage to the power source as the cooling water. The first pump and the second pump are arranged in a distributed manner in the outboard motor.

A cooling structure for an outboard motor comprises an oil case which has an oil chamber for storing lubricant oil for an engine. Said cooling structure further comprises: a main exhaust gas passage which guides exhaust gas to a lower side; a cooling water outbound path which guides cooling supply water taken from outside the outboard motor to an upper side, and cools the periphery of the main exhaust gas passage in the oil case by means of the cooling supply water; a cooling water inbound path which guides cooling discharge water that has cooled the engine to the lower side and cools the oil chamber by means of said cooling discharge water; and a mixed fluid passage which, on a side below the oil case, cools the exhaust gas by mixing the exhaust gas and the cooling discharge water.

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.

An open loop cooling water system is for a marine engine. A cooling water inlet receives cooling water from a body of water. A cooling water outlet discharges the cooling water back to the body of water. A cooling water circuit conveys cooling water from the cooling water inlet, through the marine engine, and to the cooling water outlet. A cooling water pump that pumps cooling water from upstream to downstream through the cooling water circuit. A recirculation pump that is located in the cooling water circuit downstream of at least one component of the marine engine and upstream of the cooling water outlet. The recirculation pump is configured to pump cooling water from downstream of the marine engine back into the cooling water circuit upstream of the marine engine. Methods are for cooling a marine engine using an open loop cooling system.

An outboard motor includes an engine, a supercharger that compresses air to be supplied to an air intake of the engine, and a cooler that cools the air compressed by the supercharger. The compressed air is cooled by spraying water obtained by condensing water vapor produced by combustion in the engine to the cooler.

An outboard motor is provided with an upper separator disposed on the lower side of an oil case for storing a lubricating oil of an engine, and an extension case which is separably connected on the lower side of the upper separator. The upper separator has a central exhaust passage through which exhaust gas flows, and a cooling water flow part through which cooling water flows on the outside of the central exhaust passage, the central exhaust passage and the cooling water flow part forming an integrated structure. The exhaust gas and the cooling water are caused to mix in the extension case.

An outboard motor includes an engine, a first cooling water passage to cool a first cooling target including the engine and through which first cooling water including water from outside an outboard motor body passes, a first pump to pump the first cooling water from outside the outboard motor body to the first cooling water passage, a second cooling water passage to cool a second cooling target different from the first cooling target and through which second cooling water different from the first cooling water passes, and a second pump to pump the second cooling water to the second cooling water passage.

The cooling device for a power source for a ship propulsion device that pumps up cooling water, from which foreign matters with sizes that cause clogging of a cooling water route have been removed, supplies the cooling water to a cooling water passage (30), and discharges the cooling water to outside after cooling a power source (10) includes: a cartridge-type filtration device (40, 73) that is provided at a midpoint of a first water passage (36, 71) in the cooling water route and incorporates a filter (45, 46) for filtrating foreign matters remaining in the cooling water; and a second water passage (38, 72) that is branched from the first water passage and adapted such that a valve member (53) is opened to cause the cooling water to flow in a case in which clogging occurs in the filter.

The cooling device for a power source for a ship propulsion device that pumps up cooling water, from which foreign matters with sizes that cause clogging of a cooling water route have been removed, supplies the cooling water to a cooling water passage (30), and discharges the cooling water to outside after cooling a power source (10) includes: a filtration device (40, 40A, 40B) provided in the cooling water route to filtrate foreign matters remaining in the cooling water, and the filtration device is of a cartridge type that incorporates a filter (45, 72) for filtration disposed in a main water passage (P1) and a valve member (46, 66) configured to open and close a bypass water passage (P2) and that is configured such that in a case in which clogging occurs in the filter, the valve member opens to cause the cooling water to flow via the bypass water passage.

A marine drive is for propelling a vessel in body of water. The marine drive has a powerhead, a crankcase on the powerhead, and a cooling system that pumps a first flow of cooling water from the body of water through a powerhead cooling conduit for cooling the powerhead and in parallel pumps a second flow of cooling water from the body of water through a crankcase cooler for cooling the crankcase and lubricant in the crankcase. A valve controls the second flow of the cooling water to the crankcase cooler. The valve is normally positioned in a closed position, which inhibits the second flow of cooling water to the crankcase cooler and thereby reduces condensation of water from the lubricant in the crankcase. The valve is moved into an open position upon operation of the powerhead at or above a threshold speed, which permits the second flow of cooling water to the crankcase cooler and thereby cools the lubricant in the crankcase. Corresponding methods of operating the marine drive and cooling system are provided.