21-Point Outboard Motor Spring Maintenance Checklist

When springtime rolls around, it’s time to prepare your outboard engine for another year of boating action with some necessary de-winterization. 

Run through this 21-point spring maintenance checklist to make sure your outboard is ready for its return to the water after winter storage. 

Under the Top Cowling

1. Electrical Wiring: Inspect all the wires and cables for wear or signs of rodent bites. Also, look for and clean any corroded connections, and check that all the connections are secure.

2. Hoses: Inspect every hose for cracks or bulges, and worn out connections. Replace any worn out hoses. Check that all hose clamps are in place and secure, and replace any loose or corroded clamps.

3. Spark Plugs: Remove the spark plugs, and check that the gap between the electrodes is set correctly. Clean the electrodes with a wire brush, and reset the gap if necessary, or replace the spark plugs with new ones.

PRO TIP: If you're replacing the spark plugs, change them after you’ve run the motor to clear out any fogging oil residue from last year’s winterization.

4. Engine Oil (4-stroke outboards only): The engine oil should have been changed as part of the winterization process last year, so simply check the oil level and top it off if necessary. If the oil wasn’t changed during winterization, drain and replace it now.

5. Oil Filter (4-stroke outboards only): If you’re changing the engine oil, be sure to change the oil filter too.

6. Fuel Filters: Your outboard’s owner’s manual will tell you how often the fuel/water separator filter and any other fuel filters your outboard has should be replaced. If you haven’t replaced the fuel filters since last spring, you should definitely replace them now. 

Lower Unit

7. Lower Unit External: Inspect the outside of the lower unit for scratches or damage from underwater strikes. Remove any resulting corrosion, and prime and paint the affected areas.

8. Water Intakes: Inspect the water intakes, and clear out any debris or marine growth within them.

9. Zincs/Anodes: Inspect the zincs or anodes, and replace any that have corroded beyond half of their original size and mass.

10. Lower Unit Oil: The lower unit oil should have been changed as part of the winterization process last year, so simply check the oil level and top it off if necessary. If the lower unit oil wasn’t changed during winterization, drain and replace it now.

11. Propeller: Inspect the prop for distorted or damaged blades. Also, look for excessive pitting and corrosion, and replace the propeller if it’s damaged or badly corroded. Make sure the prop nut is tight, and the nut’s cotter pin is securely in place.

Inside the Lower Unit

12. Impeller: Your outboard’s owner’s manual will tell you how often the water pump impeller should be replaced. An impeller should last a couple of years, but if you can’t remember when it was last changed, replace it now. Inspect the water pump housing while you’re changing out the impeller, and replace any other worn parts.

13. Internal Zincs/Anodes: If your outboard has internal zincs or anodes, your outboard’s owner’s manual will tell you how often they should be inspected. Replace any that are corroded beyond half of their original size and mass.

Controls

14. Control Cables: Inspect the control cables for cracking or swelling to their outer jackets, and replace them if necessary. Lube the ends of the cables with marine grease.

15. Steering Cables and Lines: Inspect the steering cables for signs of wear. Check that the cables are taught and operate smoothly. Inspect hydraulic lines for cracking, bulges or leaks, and ensure all connections are tight.

16. Trim/Tilt Mechanism: Test that the trim/tilt mechanism operates correctly, and that it can raise the outboard all the way up and lower it all the way down.

17. Zerks: Grease all the zerk fittings on the trim/tilt mechanism. 

Electrical Power and Fuel

18. Battery: Inspect the battery terminals for corrosion, and ensure the battery wires are securely connected. Clean the battery terminals if necessary, and cover the terminals and wire ends in dielectric grease. Charge the battery up and test it to make sure it’s holding the charge. If the battery won’t charge or hold a charge, replace it with a new one.

19. External Fuel Tank: Inspect the outside of the tank for damage, cracks and leaks.

20. Fuel Lines: Inspect all the fuel lines for cracks, bulges, kinks or damage, and replace them if necessary. Make sure all clamps and connections are secure and there are no leaks. Replace any loose or corroded clamps.

21. Bulb and Feed Line: Inspect the fuel bulb and feed line for wear and leaks, and replace them if necessary.