A marine engine has first and second banks of piston-cylinders, and first and second cooling water passages that convey cooling water in parallel alongside the first and second banks of piston-cylinders, respectively. A cooling water pump pumps the cooling water through the first and second cooling water passages. A first temperature-responsive valve is configured to discharge the cooling water from both of the first and second cooling water passages when the cooling water reaches a first temperature threshold. A second temperature-responsive valve is configured to discharge the cooling water from both of the first and second cooling water passages when the cooling water reaches a second temperature threshold that is greater than the first temperature threshold.

A water pump for a marine engine includes a drive flange for rotating a drive shaft, a housing having an internal cavity and a removable cap assembly. The removable cap assembly includes a cap lock ring secured to the housing, a cartridge extending into the internal cavity of the housing and an impeller rotatable inside the cartridge. The cap lock ring and cartridge are snap-fit together. The rotatable drive shaft has splines, which mate with a splined portion of an impeller to rotate the impeller. To replace the impeller, an operator twists the cap lock ring off the housing without any tools and pulls the cap assembly away from the housing disengaging the impeller from the drive shaft. A new cap assembly replaces the worn cap assembly.

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.

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.

Constraints on arrangement of catalysts are reduced, and early activation and long-term performance maintenance of the catalysts are both achieved. An exhaust pipe includes a first catalyst provided in a first exhaust pipe extending upward on the side of an exhaust manifold, and a second catalyst provided in a second exhaust pipe that extends downward from a bent pipe extending from the first exhaust pipe and that is adjacent to the first exhaust pipe. The second catalyst is disposed at a position offset to a higher location from an up-down middle position of the first exhaust pipe.

An outboard motor cooling induction system. A pickup assembly is attached to a boat's transom proximate the keel. An uptake hose from this pickup assembly carries cooling intake water to one or more inlets on the outboard motor's lower unit. An intake plane is provided on the pickup assembly. This intake plane is preferably positioned so that the intake flow is optimized.

A V-type engine in which exhaust pipe arrangement is easily performed and purification of exhaust gas can be performed by a single catalyst. Cylinders where pistons operate are arranged in a V-shape, a crankshaft driven by the driving of the pistons is disposed vertically, exhaust pipes communicating with exhaust openings in the respective banks of a cylinder head are included, rear exhaust pipes in the respective banks are merged outside on a side of the crankshaft, and a catalyst holder that holds a catalyst is provided in a merge portion of the rear exhaust pipes. Since the rear exhaust pipes in the respective banks are merged and the catalyst holder is provided in this merge portion, exhaust gas from each bank can be purified by the single catalyst, so that the number of catalysts installed is reduced to thus be able to reduce manufacturing cost.

A fuel module apparatus is for a marine engine. The fuel module apparatus includes a housing having a fuel cavity and a fuel pump in the housing. The fuel pump is configured to pump fuel through the fuel cavity from an inlet on the housing to an outlet on the housing. A cooling fluid sprayer sprays cooling fluid onto an outer surface of the housing to thereby cool the housing and the fuel in the fuel cavity.

A marine propulsion device includes an engine, a cylinder cooling pathway through which a cooling water passes, a water pump, an electromagnetic valve, a water pressure sensor, a water temperature sensor, and a controller. The engine includes a cylinder. The cylinder cooling pathway is disposed in an area surrounding the cylinder. The water pump supplies the cooling water to the cylinder cooling pathway from outside. The electromagnetic valve restricts a flow of the cooling pathway in the cylinder cooling pathway. The water pressure sensor detects a water pressure of the cooling water in the cylinder cooling pathway. The water temperature sensor detects a water temperature of the cooling water in the cylinder cooling pathway. The controller is configured or programmed to control an opening degree of the electromagnetic valve based on a detection value of the water pressure sensor and a detection value of the water temperature sensor.

A cooling system for a marine engine has a cooling jacket disposed in thermal communication with a heat-emitting portion of the marine engine. The cooling jacket has a water inlet, and a water outlet on an upper portion of the cooling jacket. A pump is connected in fluid communication with the water inlet and/or the water outlet that causes water to flow through the cooling jacket in order to cool the heat-emitting portion, wherein a flow velocity of water in the cooling jacket is low such that debris sinks to a lower portion of the cooling jacket. A debris outlet is in the lower portion of the cooling jacket that expels the debris from the cooling jacket.