Abstract: An outboard motor includes an engine, a cooling water passage, a pump that is driven in conjunction with the engine, an inlet water passage that branches from the cooling water passage, an oil cooler, an outlet water passage, a first thermostat located in the cooling water passage, and a second thermostat. The pump takes outside water into the cooling water passage. The oil cooler includes a water-storing space into which water in the inlet water passage is taken. The outlet water passage is connected to an outlet of the oil cooler. The first thermostat increases and decreases the flow rate of water flowing through the engine. The second thermostat is located at the outlet or at the outlet water passage, and increases and decreases the flow rate of water flowing through the outlet water passage.

Abstract: A thermostat includes an annular flange extending in radial directions and surrounded by a cylindrical large-diameter portion of a housing inner surface, and a frame extending in axial directions from the flange. The thermostat further includes a sealing member that hermetically seals the gap between the flange and the inner surface. The sealing member includes an annular outer peripheral portion sandwiched in the axial directions by the inner surface and a thermostat cover inside the large-diameter portion, and a plurality of protruding portions extending outward in the radial directions from the outer peripheral portion toward the large-diameter portion. The thermostat is disposed inside a housing that defines a portion of a cooling water passage, and opens and closes the cooling water passage according to the temperature of cooling water inside the cooling water passage.

Abstract: An outboard motor includes an oil cooler, an engine cooling water passage, an oil cooling water passage, and a water discharge passage. The oil cooler is disposed forward of a crankshaft. The engine cooling water passage is disposed inside an engine. The oil cooling water passage is connected to the oil cooler and branches from the engine cooling water passage. The water discharge passage is connected to the oil cooler. The water discharge passage is disposed lower than the oil cooler and forward of a center axis of the crankshaft.

Abstract: An outboard motor includes an engine including a plurality of cylinders, a drive shaft, an oil pan portion provided below the engine and including an oil storage region, an oil pump configured to be driven by a drive portion of the drive shaft passing through the oil storage region and located in the oil storage region, and a supply path configured to supply oil from the oil pump to the engine.

Abstract: A vessel propulsion apparatus includes a water pump that is driven by an engine, and supplies water from an water inlet to the engine via a cooling water supply passage. The vessel propulsion apparatus includes an auxiliary cooling passage branching from the cooling water supply passage to extend to an oil pan. A water pressure control valve disposed at a branch position from the cooling water supply passage to the auxiliary cooling passage limits the flow rate of water flowing to the auxiliary cooling passage when a water pressure inside the cooling water supply passage is less than a set pressure. The water pressure control valve is configured to allow a portion of the water inside the cooling water supply passage to flow to the auxiliary cooling passage when the water pressure inside the cooling water supply passage is the set pressure or more to maintain the water pressure to be less than the set pressure while supplying water to the oil pan via the auxiliary cooling passage.

Abstract: An outboard motor includes an engine including a crankshaft that is rotatable about a rotation axis extending in an up-down direction, and a crank chamber that houses the crankshaft. The outboard motor includes an oil pan disposed under the engine to retain lubricating oil to be supplied to at least the crank chamber. The outboard motor includes an oil recovery passage and a first blowby gas passage separate from the oil recovery passage. The oil recovery passage extends downward from the crank chamber to the oil pan and is configured to lead lubricating oil inside the crank chamber to the inside of the oil pan. The first blowby gas passage extends downward from the crank chamber to the oil pan and is configured to lead a blowby gas inside the crank chamber to the inside of the oil pan.

Abstract: In a spacer case for an outboard motor, a rear portion includes an upper fastening hole opening to the upper surface of the spacer case, into which a first fastening member is inserted, and a lower fastening hole opening to the lower surface of the spacer case, into which a second fastening member is inserted. At least one of the upper fastening hole and the lower fastening hole connects to a lateral opening inside the spacer case.

Abstract: An outboard motor includes an exhaust pipe that includes an outer wall section, an inner wall section, a coolant passage, and a constricted section. The inner wall section is arranged inward of the outer wall section. The coolant passage is arranged between the outer wall section and the inner wall section. The constricted section is configured to constrict a flow cross section of the coolant passage. A catalytic converter is housed in the exhaust pipe. A temperature sensor is installed in the constricted section and measures a temperature of a pipe wall of the exhaust pipe.

Abstract: An outboard motor includes an engine including a cylinder body and a crank case, an engine holder configured to come into contact with both the cylinder body and the crank case along a second bonding surface, a power transmission shaft passing through a hole between the engine holder and both the cylinder body and the crank case, and a first sealing member between a portion of the power transmission shaft above the second bonding surface and above both the cylinder body and the crank case to separate an oil region above the first sealing member from an external water entering region below the first sealing member.

Abstract: An outboard motor includes an engine including a cylinder body and a crank case, an engine holder configured to come into contact with both the cylinder body and the crank case along a second bonding surface, a power transmission shaft passing through a hole between the engine holder and both the cylinder body and the crank case, and a first sealing member between a portion of the power transmission shaft above the second bonding surface and above both the cylinder body and the crank case to separate an oil region above the first sealing member from an external water entering region below the first sealing member.

Abstract: An outboard motor includes an engine including a plurality of cylinders, a drive shaft, an oil pan portion provided below the engine and including an oil storage region, an oil pump configured to be driven by a drive portion of the drive shaft passing through the oil storage region and located in the oil storage region, and a supply path configured to supply oil from the oil pump to the engine.

Abstract: In a spacer case for an outboard motor, a rear portion includes an upper fastening hole opening to the upper surface of the spacer case, into which a first fastening member is inserted, and a lower fastening hole opening to the lower surface of the spacer case, into which a second fastening member is inserted. At least one of the upper fastening hole and the lower fastening hole connects to a lateral opening inside the spacer case.

Abstract: An outboard motor includes an engine including a crankshaft that is rotatable about a rotation axis extending in an up-down direction, and a crank chamber that houses the crankshaft. The outboard motor includes an oil pan including an oil retaining portion, a cooling water passage disposed along an outer wall surface of the oil retaining portion, an oil recovery passage extending downward from the crank chamber to lead lubricating oil inside the crank chamber to the inside of the oil retaining portion, and a guide member. The guide member includes a shielding portion disposed inside the oil recovery passage so as to be located over an opening of the oil retaining portion, and a guide hole disposed inside the oil recovery passage so as to be located over an inner wall surface of the oil retaining portion.

Abstract: An outboard motor includes an engine including a crankshaft that is rotatable about a rotation axis extending in an up-down direction, and a crank chamber that houses the crankshaft. The outboard motor includes an oil pan including an oil retaining portion, a cooling water passage disposed along an outer wall surface of the oil retaining portion, an oil recovery passage extending downward from the crank chamber to lead lubricating oil inside the crank chamber to the inside of the oil retaining portion, and a guide member. The guide member includes a shielding portion disposed inside the oil recovery passage so as to be located over an opening of the oil retaining portion, and a guide hole disposed inside the oil recovery passage so as to be located over an inner wall surface of the oil retaining portion.

Abstract: A vessel propulsion apparatus includes a water pump that is driven by an engine, and supplies water from an water inlet to the engine via a cooling water supply passage. The vessel propulsion apparatus includes an auxiliary cooling passage branching from the cooling water supply passage to extend to an oil pan. A water pressure control valve disposed at a branch position from the cooling water supply passage to the auxiliary cooling passage limits the flow rate of water flowing to the auxiliary cooling passage when a water pressure inside the cooling water supply passage is less than a set pressure. The water pressure control valve is configured to allow a portion of the water inside the cooling water supply passage to flow to the auxiliary cooling passage when the water pressure inside the cooling water supply passage is the set pressure or more to maintain the water pressure to be less than the set pressure while supplying water to the oil pan via the auxiliary cooling passage.

Abstract: An outboard motor includes an engine including a crankshaft that is rotatable about a rotation axis extending in an up-down direction, and a crank chamber that houses the crankshaft. The outboard motor includes an oil pan disposed under the engine to retain lubricating oil to be supplied to at least the crank chamber. The outboard motor includes an oil recovery passage and a first blowby gas passage separate from the oil recovery passage. The oil recovery passage extends downward from the crank chamber to the oil pan and is configured to lead lubricating oil inside the crank chamber to the inside of the oil pan. The first blowby gas passage extends downward from the crank chamber to the oil pan and is configured to lead a blowby gas inside the crank chamber to the inside of the oil pan.

Abstract: A thermostat includes an annular flange extending in radial directions and surrounded by a cylindrical large-diameter portion of a housing inner surface, and a frame extending in axial directions from the flange. The thermostat further includes a sealing member that hermetically seals the gap between the flange and the inner surface. The sealing member includes an annular outer peripheral portion sandwiched in the axial directions by the inner surface and a thermostat cover inside the large-diameter portion, and a plurality of protruding portions extending outward in the radial directions from the outer peripheral portion toward the large-diameter portion. The thermostat is disposed inside a housing that defines a portion of a cooling water passage, and opens and closes the cooling water passage according to the temperature of cooling water inside the cooling water passage.

Abstract: An outboard motor includes a cooling water passage that guides cooling water to cool an exhaust passage and a cylinder unit. A cooling water intake port draws external cooling water into the cooling water passage. A water pump draws cooling water into the cooling water intake port and supplies the cooling water to the cooling water passage. A thermostat is arranged in the cooling water passage downstream of the catalytic converter and the cylinder unit. A first bypass passage is connected to a first connecting section provided on the cooling water passage. The first connecting section is provided along the cooling water passage at a position farther downstream than the catalytic converter and farther upstream than the thermostat.

Abstract: An outboard motor includes an exhaust pipe that includes an outer wall section, an inner wall section, a coolant passage, and a constricted section. The inner wall section is arranged inward of the outer wall section. The coolant passage is arranged between the outer wall section and the inner wall section. The constricted section is configured to constrict a flow cross section of the coolant passage. A catalytic converter is housed in the exhaust pipe. A temperature sensor is installed in the constricted section and measures a temperature of a pipe wall of the exhaust pipe.

Abstract: An outboard motor includes an exhaust pipe that includes an outer wall section, an inner wall section, a coolant passage, and a constricted section. The inner wall section is arranged inward of the outer wall section. The coolant passage is arranged between the outer wall section and the inner wall section. The constricted section is configured to constrict a flow cross section of the coolant passage. A catalytic converter is housed in the exhaust pipe. A temperature sensor is installed in the constricted section and measures a temperature of a pipe wall of the exhaust pipe.