How to Properly Flush a Boat Motor

Flushing a boat motor is a crucial maintenance task to prevent damage. Ensure you attach a hose to the motor's water intakes before running it out of water.

Before starting the motor out of water, consult your manual to locate the intakes and determine if built-in attachments are available. If not, use motor flusher muffs. Always follow the manufacturer's recommendations.

Attach the hose directly to the motor's built-in attachment. If your motor has a built-in attachment, screw the hose nozzle into one of the water intakes on the lower unit. Follow the manual's instructions, which may include covering the other intake with tape.

Obtain motor muffs from a boat supply store or online. You can buy motor muffs for less than $10 (USD) at a marina, outdoor gear store, or online. These muffs resemble earmuffs connected by a V-shaped rod.

Moisten the muffs for a tighter seal. Wetting the inside of the muffs before attaching them to the motor can improve the seal and prevent them from slipping off during operation.

Secure the muffs to the motor and avoid the propeller. Position the muffs over the water intakes on the motor's lower unit, ensuring the connecting rod is in front of the motor, away from the propeller. Exercise caution to prevent injury or damage.

Connect the garden hose to the muffs. Screw the garden hose into the nozzle-equipped muff securely. Confirm that the connection is tight and that the muffs fit snugly over the motor's water intakes.

Turn on the water supply. Once you've attached the garden hose, head to the faucet and turn on the water. Refer to your manual for any specific water pressure recommendations, typically around half pressure.

Engage neutral gear. Ensure that the gearshift or throttle is set to neutral before starting the engine. The engine must be in neutral to initiate startup and should remain so during operation.

Initiate engine startup. Depending on the engine model, either insert the key or pull the starter to activate the engine. For electric engines, you may also need to press and release a button after turning the key.

Verify the functionality of the motor's water pump. Look for a steady stream of water flowing out of the motor's top. If there's no stream, it indicates a problem with the water pump.

• If no water flows, immediately switch off the engine. Use a thin wire to check for debris in the outflow tube. Restart the engine to see if the issue is resolved. If not, consult a mechanic to replace the water pump.

Operate the engine for 10 minutes, or as directed in the manual. For flushing purposes, most manufacturers advise running the engine for 5 to 10 minutes. If running the engine for other tasks, adhere to the recommended duration specified in your maintenance guide.

• Never leave the engine unattended during operation. Monitor the muffs to ensure they remain securely attached to the water intakes.
• In most cases, running the engine for 10 to 15 minutes should be sufficient for any task.

Switch off the engine before cutting off the water supply. After approximately 10 minutes, deactivate the engine by turning the key or closing the throttle. Only turn off the water supply after shutting down the engine. Even a brief period of running the engine without water can result in damage.

Disconnect the hose from the muffs or built-in attachment. Following the engine shutdown, detach the garden hose from the muffs or the motor's water intake. Coil the hose and store it properly.

Remove the muffs if in use. If applicable, slide the muffs off the lower unit of the motor. Store them in a convenient location such as your boat house or garage for future use during motor flushing.

Allow the water to drain before tilting the engine. Keep the engine in the downward position for 30 to 60 minutes to facilitate water drainage from the powerhead. Once drained, lift the motor to the tilted position. Cover the boat and transport it to your garage, boat house, or preferred storage location.