Outboard motor

An outboard motor comprising:

• an engine holder;
• an engine disposed above the engine holder in a state of the outboard motor being mounted to a hull;
• an oil pan disposed below the engine holder;
• a drive shaft housing disposed below the oil pan;
• an exhaust passage means formed in the engine, the engine holder and the oil pan and adapted to exhaust an exhaust gas from the engine into the drive shaft housing, said exhaust passage means having a downstream side end opening;
• an exhaust tube provided for a bottom surface portion of the oil pan so as to align with the downstream side end opening of the exhaust passage means, said exhaust tube having a downstream side outlet positioned, in a plan view, at a substantially central portion of the drive shaft housing;
• a water pump disposed at a bottom portion of the drive shaft housing for pumping up a cooling water;
• a cooling water passage means formed in the engine holder and the oil pan;
• and
• a cooling water discharge passage means formed in the engine holder and the oil pan for discharging the cooling water after cooling the engine inside the drive shaft housing,
• wherein the cooling water pumped up by the water pump is guided to the engine through the cooling water passage means, said cooling water passage means includes a passage portion formed in the oil pan, a relief valve is provided for said passage portion directly above the downstream side outlet of the exhaust tube, said relief valve having a structure for relieving an excess pressure of the cooling water before the cooling of the engine, said exhaust tube is disposed in a vicinity of the relief valve, and a return water guide is further arranged integrally with the exhaust tube, said cooling water discharge passage means having a downstream side end opening with which said return water guide is aligned, and said return water guide has a box-shaped cross section having an opened side portion which is disposed so as to face a vertical wall section formed in the drive shaft housing.