Lower Unit

The lower unit transfers power from the engine to the propeller. Routine maintenance keeps it reliable.

Role & Maintenance

The lower unit of an outboard motor plays a critical role in the boat’s operation. Maintenance must be routine to the area where power is transferred from the top called the powerhead to the propeller sticking out the backside of the most lower section. Gear oil reduces friction on the lower unit, thus reducing the likelihood of failure.

How It Works

The lower unit transfers the energy generated by the engine, otherwise known as a powerhead, to the propeller. When transferred, the propeller spins in a clockwise or counter-clockwise motion moving the vessel forwards or backward.

A rod mounted to the base of the motor spins at a rate determined by the position of the throttle. The shaft connects to the lower unit by a series of gears called pinion, reverse, or forward gear. Energy from the powerhead spins the forward or reverse gear, thus turning the propeller depending on the direction the operator pushes the throttle.

When to Change Lower Unit Oil

Lower unit oil should be changed every 100 hours or if it looks burnt or milky, in which case you may need new seals.