Abstract: In an outboard engine, an upstream oil return path is connected to an oil passage upstream of an oil filter to return lubrication oil that is accumulated in the oil passage upstream of the oil filter to an oil pan. A downstream oil return path is connected to an oil passage downstream of the oil filter to return lubrication oil that is accumulated in oil passages and a main gallery downstream of the oil filter to the oil pan. The lubrication oil accumulated in a portion of an oil passage downstream of the oil filter is hindered from flowing to the outside even if the oil filter is removed when the engine is stopped.

Abstract: In an outboard engine, an upstream oil return path is connected to an oil passage upstream of an oil filter to return lubrication oil that is accumulated in the oil passage upstream of the oil filter to an oil pan. A downstream oil return path is connected to an oil passage downstream of the oil filter to return lubrication oil that is accumulated in oil passages and a main gallery downstream of the oil filter to the oil pan. The lubrication oil accumulated in a portion of an oil passage downstream of the oil filter is hindered from flowing to the outside even if the oil filter is removed when the engine is stopped.

Abstract: An engine has a crankshaft. The crankshaft has a set of steps formed at one end. A drive pulley for a cam drive arrangement is positioned on one of the steps. A set of holes are formed in the end of the crankshaft adjacent to the steps. The holes has axes that are substantially parallel with a rotational axis of the crankshaft. Threaded fasteners that screw into the holes couple the crankshaft and the drive pulley. An alignment pin also extends between the drive pulley and the crankshaft. A position sensor component such as a washer is interposed between the crankshaft and the drive pulley.

Abstract: A marine drive includes an oil pump assembly circumferentially mounted on a rotating shaft. The pump assembly defines a pump chamber. An upper seal member is provided above the pump chamber to effectuate a seal with the shaft so that foreign matter will be inhibited from passing downwardly past the upper seal. An intermediate seal member is provided below the pump chamber and also effectuates a seal with the shaft. The intermediate seal member minimizes leakage of oil from the chamber downwardly past the intermediate seal, and is more specifically directed to inhibit invasion of foreign matter, such as water, upwardly past the seal member. A lower seal member is provided below the intermediate seal member and also effectuates a seal with the shaft. The lower seal member acts as another barrier to inhibit leakage of oil downwardly past the lower seal and invasion of foreign matter upwardly past the lower seal.

Abstract: An engine for an outboard motor includes an engine body, a crankshaft and one or more camshafts. A camshaft drive mechanism is arranged on a top surface of the engine body. The camshaft drive mechanism includes a timing belt to rotate the camshafts with the rotation of the crankshaft. A belt tensioner is arranged to adjust tension of the timing belt. The tensioner includes a shaft unit mounted on the engine body. A peripheral unit is swingably carried by the shaft unit and abutting on a portion of the timing belt. A swing axis of the shaft unit is offset from a center axis of the peripheral unit. The tensioner further includes a hydraulic damping mechanism to damp a vibration of the timing belt. The damping mechanism has a piston rod that urges the peripheral unit toward the timing belt. The piston rod is positioned at a location which can be generally the highest of the damping mechanism when a drive unit of the outboard motor is tilted up about a tilt axis.

Abstract: A marine drive includes an oil pump assembly circumferentially mounted on a rotating shaft. The pump assembly defines a pump chamber. An upper seal member is provided above the pump chamber to effectuate a seal with the shaft so that foreign matter will be inhibited from passing downwardly past the upper seal. An intermediate seal member is provided below the pump chamber and also effectuates a seal with the shaft. The intermediate seal member minimizes leakage of oil from the chamber downwardly past the intermediate seal, and is more specifically directed to inhibit invasion of foreign matter, such as water, upwardly past the seal member. A lower seal member is provided below the intermediate seal member and also effectuates a seal with the shaft. The lower seal member acts as another barrier to inhibit leakage of oil downwardly past the lower seal and invasion of foreign matter upwardly past the lower seal.

Abstract: An outboard motor cooling system includes an improved construction to enhancing cooling of the lubrication system, and more particularly, an oil pan of the lubrication system. The oil pan depends from an engine of the outboard motor and into a driveshaft housing. A periphery coolant jacket is provided around the oil pan. A water pool is defined between the oil pan and the driveshaft housing. An exhaust manifold passes through in a hollow of the oil pan and a water curtain is defined between the hollow wall and the exhaust manifold. An upstanding water passage is also disposed through the oil pan. At least one of an upper and lower transverse water jacket extends transversely above or below the oil pan. No drain water from the engine flows through these jackets or passages. The oil pan therefore is sufficiently cooled. In addition, the upper transverse water jacket increases protection of engine components from heat deterioration.

Abstract: A lubrication system for an outboard motor engine includes a pump housing includes an inlet port through which lubricant enters the pump housing and an outlet port through which the lubricant is discharged from the pump housing. Both the crankshaft and the driveshaft extend through an opening defined at the pump housing and are couple with each other within the pump housing. A first seal member is disposed around the crankshaft for sealing a first location between an outer surface of the crankshaft and a first inner surface of the pump housing that defines at least a portion of the opening. A second seal member is disposed around the driveshaft for sealing a second location between an outer surface of the driveshaft and a second inner surface of the pump housing that also defines at least a portion of the opening.

Abstract: An outboard motor is configured for steering by a tiller arm. The tiller arm is moveable relative to the outboard motor about a transverse axis and is arranged to steer the motor about the vertical axis. The outboard motor further has a power head that contains a vibration engine and is comprised of a protective cowling and lower tray. A tiller arm mounting bracket is secured to the power head and a mounting structure extends from the tiller arm. A resilient member is juxtaposed between the mounting bracket and the mounting structure. A gap is defined between a face of the resilient member and the tiller arm such that the resilient member may freely vibrate within the gap without that face of resilient member contacting the tiller and directly translating vibrational energy to the tiller arm.

Abstract: An outboard motor includes an improved engine layout to provide a compact power head while simplifying the arrangement of components on the engine. In one mode, an induction system of the engine includes a carburetor that is arranged over a cylinder head. An intake pipe connects the carburetor to an intake port of the cylinder head. The pipe has generally a U-shape and loops around the upper side edge of the cylinder head. An air intake device is arranged upstream of the carburetor to supply air thereto. The air intake device includes a downward facing air intake opening that is located along a side of the engine below the upper end. This arrangement of the induction system that extends over the upper side of the engine produces a compact assembly without overly complicating the arrangement of other components on the engine, such as, for example, a manual starter device.

Abstract: An improved and simplified outboard motor construction wherein the exhaust system for the engine is formed with a minimum number of components and sealing joints. The exhaust system includes an elongated expansion chamber formed in the drive shaft housing. In addition, the drive shaft housing has a cylindrical section that is journaled within a swivel bracket for its steering movement. The volume between the external portion of the drive shaft housing and the internal portion of the swivel bracket forms a second expansion chamber that is employed for the low speed above the water exhaust gas discharge. The flow of cooling the water to and from the engine is controlled so that the exhaust gas interchange area between the power head and the drive shaft housing will be well cooled, as will the oil reservoir for the engine.

Abstract: An improved and simplified outboard motor construction wherein the exhaust system for the engine is formed with a minimum number of components and sealing joints. The exhaust system includes an elongated expansion chamber formed in the drive shaft housing. In addition, the drive shaft housing has a cylindrical section that is journaled within a swivel bracket for its steering movement. The volume between the external portion of the drive shaft housing and the internal portion of the swivel bracket forms a second expansion chamber that is employed for the low speed above the water exhaust gas discharge. The flow of cooling the water to and from the engine is controlled so that the exhaust gas interchange area between the power head and the drive shaft housing will be well cooled, as will the oil reservoir for the engine.

Abstract: An outboard motor incorporating a unitary mounting assembly for resiliently connecting the steering shaft to the driveshaft housing. The mounting assembly also closes an upper portion of the driveshaft housing and has an opening that passes a water tube for supplying cooling water to the engine of the outboard motor.