The powerhead contains the outboard's engine, so for any problems with that definitely start here. Under the cowling there is also plenty of ancillary equipment such as the starter motor, fuel pump, ignition coils, etc. The outboard's telltale to show you if cooling water is pumping also exits from here.

The powerhead attaches to the top of the mid-section and the mid-section attaches to the swivel bracket via a series of engine mounts. The driveshaft from the gearbox passes up through the mid-section to connect with the bottom of the crankshaft in the powerhead. The pipe carrying cooling water from the water pump to the powerhead also travels up through here. The exhaust and the bulk of the cooling water that comes out of the engine passes back down through the mid-section to exit though the centre of the propeller.

The swivel bracket attaches the outboard to the transom of the boat and allows it to tilt up and down and swivel to steer the boat.

The lower unit contains the driveshaft down from the powerhead, the gearbox and dog clutch, propellor shaft, gear selector and water pump. There are oil seals that go around the propeller shaft, drive shaft and gear selector to stop water getting into the gearbox.

The propeller ("prop") is critical to getting the correct thrust from the engine. The pitch and diameter of the blades must be correct, the blades must not be bent, and the bushing attaching the propeller to the shaft must not be slipping ("a spun hub"). Propellers also have differing numbers of blades and splines inside the hub. These factors, and others, affect performance and handling, and must be considered when choosing or servicing your outboard.

Outboards need routine servicing to prevent damage and ensure efficient, safe performance, across seasons. Special care must be taken when an outboard is to be left unused for extended periods.