In an outboard motor, a feed passage, through which a lubricating oil that flows upward from a gear mechanism due to rotation of the gear mechanism is fed upward from a gear chamber, includes a first feed passage, extending from the gear chamber to a connection passage via a first upstream passage, a spiral passage, and an interior of an upper bearing, in that order, and a second feed passage, extending from the first upstream passage to the connection passage while bypassing the spiral passage via a bypass passage. The bypass passage is positioned farther outward than the spiral passage in a radial direction of the driveshaft. A diameter of a cross section of the bypass passage that is orthogonal or substantially orthogonal to a center line of the driveshaft is smaller than a maximum diameter of the driveshaft.

An outboard motor includes an engine housed in a cowling and disposed above an upper case housing a driveshaft. A gear mechanism transmits a rotation of the driveshaft to a propeller shaft housed in a lower case disposed below the upper case. The gear mechanism is housed in an oil storage chamber of the lower case and is lubricated by a lubricating oil inside the oil storage chamber. An oil passage includes a lower oil port opening at the oil storage chamber, an upper oil port positioned higher than the lower case, and a longitudinal passage extending in an up/down direction inside the lower case.

The lubrication of a steerable thruster of a marine vessel is based on splash-type lubrication at the pod and full bath lubrication in the stembox and in the shank. The lubrication oil enters the pod both from the stembox and the shank via a constriction and directly from the oil tank. The oil is further circulated from the pod to the oil tank by means of pumps.

An outboard marine engine comprises an internal combustion engine; a lower gearcase, a set of gears disposed in the lower gearcase, the set of gears being configured to transfer power from the internal combustion engine to drive a propulsor to generate a thrust on the outboard marine engine, and a dipstick that extends into the lower gearcase. The dipstick is removable from the lower gearcase and configured to indicate a level of lubrication in the lower gearcase.

In a lubrication mechanism including a rotating shaft, the rotating shaft includes an external member and an internal member housed inside the external member, the internal member having an internal space extending in an axial direction, a horizontal hole is formed in the internal member, the horizontal hole for communicating between the internal space and an outer peripheral surface of the internal member, the horizontal hole communicates with a lubrication flow passage for communicating with a prescribed lubrication target portion, and the external member and the internal member are made of materials with a different hardness.

An outboard engine includes a steering mechanism having a pod propulsion device disposed in water outside a hull; a propulsive drive mechanism that is disposed in the hull and gives a propulsive drive force to the pod propulsion device; and a circulation cooling circuit which has an outward flow path that supplies a cooling oil to the steering mechanism and the propulsive drive mechanism, and an inward flow path which recovers the cooling oil from the steering mechanism and the propulsive drive mechanism, in which the inward flow path and the outward flow path of the circulation cooling circuit communicate with each other inside a case body of the pod propulsion device.

An outboard-motor closed-loop cooler system apparatus providing a retrofit substitute for the midsection and the lower unit of a standard outboard motor, having a substitute closed-loop cooling system with an exterior heat exchanger, a substitute oil reservoir, a substitute exhaust system, and a substitute propulsion system, allowing an existing standard outboard-motor powerhead to be used in conditions not conducive to standard open-loop water cooling, such as shallow-water, muddy-water, obstructed-water, seawater, or corrosive-water conditions.

A method for providing an outboard-motor closed-loop cooler system as a retrofit substitute for the midsection and the lower unit of a standard outboard motor, having a substitute closed-loop cooling system with an exterior heat exchanger, a substitute oil reservoir, a substitute exhaust system, and a substitute propulsion system, allowing an existing standard outboard-motor powerhead to be used in conditions not conducive to standard open-loop water cooling, such as shallow-water, muddy-water, obstructed-water, seawater, or corrosive-water conditions.

A drive assembly for a marine propeller drive unit has two concentric drive shafts for carrying a respective propeller. A space between the drive shafts is lubricated with liquid lubricant pumped into the space by a pump. The outermost drive shaft is provided with at least one protrusion protruding radially inwards from an inner surface of the outer drive shaft. The inlet of the secondary fluid channel is provided in said at least one protrusion at a first radial level offset radially inwards from the inner surface of the outer drive shaft such that liquid lubricant at said first radial level is able to lubricate bearings between the outermost drive shaft and the innermost drive shaft.

An outboard motor includes a power source disposed, a propeller shaft, a drive shaft, a gear mechanism, a lower case having an internal space in which gear oil is stored, a gear oil gauge configured to check a level or a state of the gear oil stored in the internal space, a gauge mounting hole provided configured to removably mount the gear oil gauge to the lower case such that one end side of the gear oil gauge is immersed in the gear oil stored in the internal space, a gauge insertion portion configured to insert the gear oil gauge into the gauge mounting hole, an oil supply and discharge passage provided in the lower case, and a pump connecting portion configured to connect a pump. The gauge insertion portion and the pump connecting portion are arranged side by side.