How to Maintain a Boat

How to Winterize an Outboard Motor

To keep your outboard motor in top shape from year to year, prepare it carefully for winter storage.

Tools: owner's manual, freshwater flushing unit, garden hose, screwdriver, adjustable wrench, coffee can or other container, tarp, piece of scrap wood.


Materials: fuel conditioner, rust-preventive oil, lower-unit lubricant, soft cloths, replacement nuts and bolts as required, touch-up paint, car wax. Buy lubricant, oil, and fuel conditioner at a marine store.

Time: about 2 hours.

Whatever brand or size outboard motor you have, follow the specific recommendations and instructions given in your owner's manual. Use only specified lubricants and replacement parts; if you use different ones you'll void your warranty.

If you operate your motor in salt water, it must be thoroughly flushed to prevent corrosion. To flush the motor, use a freshwater flushing unit made to fit your motor. Attach the unit's fitting to the motor's cooling system as directed by the manufacturer; attach the coupling at the other end of the unit to a garden hose. Run the motor for several minutes at less than half throttle, exactly as directed, to remove all salt from the motor.

Whether you operate the motor in salt water or in fresh, you must protect it from corrosion. The last time you use the motor before storing it, add to the fuel tank 1 ounce of fuel conditioner for each gallon of fuel in the tank. Operate the motor for about 5 minutes to make sure the fuel conditioner has reached the carburetor. Then disconnect the fuel line or turn off the fuel, and squirt a liberal amount of rust-preventive oil into the air intake of the carburetor; use the type of oil recommended by your motor's manufacturer. The engine should sputter, smoke, and die. If it doesn't, squirt in more oil; then shut the motor off and shift it into neutral gear. Dismount the motor and let it cool.

With the motor disconnected, drain the fuel from the carburetor. Remove the cowling and disconnect the spark plug wires; be careful to note their location exactly so you'll be able to replace them correctly. Using an adjustable wrench, remove the spark plugs. Inject about 1 ounce of rust-preventive oil into each cylinder, and slowly crank the flywheel on the top of the motor to spread the oil over the entire cylinder surface. Then replace and hand-tighten the spark plugs; leave the ignition wires disconnected.

If your owner's manual recommends periodic lubricant changes for your motor's lower unit, remove the unit's top and bottom fill plugs and let the lubricant drain into a coffee can or other container. Replace the lubricant with the type recommended for your motor. Insert the lubricant applicator's nozzle into the bottom fill hole and squirt the lubricant into the gear case. When the lubricant starts to come out the top fill hole, replace the top plug; then remove the applicator nozzle and replace the bottom plug. Remove excess lubricant with a soft cloth.

Inspect the lower unit for loose or missing nuts or bolts; consult the drawings and follow the precise instructions provided in your owner's manual. Tighten loose screws, nuts, and bolts; replace missing hardware with the exact type recommended for use in your motor.

After lubricating and inspecting the motor, soak a soft cloth in rust-preventive oil and squeeze it out. Rub the cloth over all exposed parts of the motor to coat them with oil and prevent corrosion. Then replace the cowling.

Inspect the cowling for chipped or peeling paint; touch up bad spots with matching paint. Use a touch-up kit made for your motor, or any good enamel; follow the manufacturer's instructions for application and drying. When the motor is completely dry, apply a coat of car wax to the cowling, as directed by the manufacturer. For further protection, rub the cowling with an oil-soaked cloth to coat it lightly with oil.

Store the motor in a dry, dust-free place; cover it with a tarp to protect it from dirt. If the motor has a battery, remove the battery and store it separately; set it off the floor on a piece of scrap wood. Make sure the case is clean and the water in the cell is at the correct level.

During the winter, work the throttle control every few weeks to keep the moving parts from corroding; twist the hand throttle or move the control lever the throttle control cable is attached to. Gently pull the starter cord to engage the gears. If the motor has a battery, check the water level in the cell and add water as necessary to maintain the charge.

Storing your boat in an enclosed area is the best way to protect it from the elements. If you store your boat outside, a well-made cover can keep your boat from aging prematurely. Find out how to make a protective boat cover in the next section.

For tips on caring for and repairing other types of sports equipment, try the following links: