Best Practices for Storing an Outboard Motor Long-Term

Properly storing an outboard motor during the off-season or extended periods of non-use is essential to ensure its longevity, reliability, and performance. Whether you’re putting your boat away for the winter or anticipating several months before your next outing, taking the right steps to prepare and maintain your outboard motor can prevent costly repairs and preserve the engine’s condition. This article will guide you through the best practices for long-term storage of your outboard motor, covering key aspects such as cleaning, fuel system treatment, lubrication, and protection from environmental damage.

Why Long-Term Storage Maintenance Matters

Outboard motors are exposed to harsh conditions during operation—water intrusion, salt buildup, corrosion, fuel degradation, and mechanical wear all take their toll over time. When left idle for long periods without proper care, engines can develop problems like:

• Corrosion inside the engine and lower unit
• Fuel system clogs from gum and varnish deposits
• Deterioration of seals and gaskets
• Freeze damage in cold climates
• Rust on exposed metal parts

Taking deliberate steps to winterize or store your outboard motor helps prevent these issues. It minimizes downtime, keeps maintenance costs down, and ensures your motor starts easily when you’re ready to use it again.

Step 1: Clean the Engine and Lower Unit Thoroughly

Before storing your outboard motor for an extended period, start with a thorough cleaning. Saltwater exposure or even freshwater use can leave mineral deposits, grime, algae, and contaminants on the motor’s surfaces.

• Rinse with fresh water: Use a garden hose or a specialized flushing device to rinse all external parts of the engine and lower unit. Run fresh water through the cooling system as well by attaching a flushing device to the water intake ports while the engine is running at idle.
• Remove debris: Scrub away any barnacles, algae, or dirt using a soft brush or sponge. Avoid high-pressure washers which can force water into sensitive areas.
• Dry completely: After rinsing and cleaning, dry the engine thoroughly with towels or let it air dry in a well-ventilated space. Moisture left on metal parts can accelerate corrosion during storage.

Step 2: Treat the Fuel System

Fuel is one of the most common sources of problems during long-term storage. Gasoline deteriorates over time, forming varnish and gum deposits that clog carburetors or fuel injectors. Residual moisture in fuel can cause corrosion inside fuel tanks and lines.

To protect your fuel system:

• Use fresh fuel: Start with a full tank of fresh gasoline mixed with the appropriate amount of marine-grade fuel stabilizer. The stabilizer prevents oxidation that leads to fuel breakdown.
• Run the engine: After adding stabilizer, run the engine for about 10–15 minutes at operating temperature to circulate treated fuel through the entire system.
• Drain carburetors if applicable: For carbureted engines, draining the carburetor bowls prevents stale fuel from causing blockages.
• Consider fuel system fogging: For long-term storage beyond a few months (especially in carbureted engines), use fogging oil sprayed into the carburetor or intake while the engine is running at low RPMs. This coats internal components with a protective film that prevents rust and corrosion.

Step 3: Change Engine Oil and Gearcase Lubricant

Engine oil degrades over time as it collects moisture and contaminants. Changing oil before storage ensures that these impurities don’t cause internal corrosion during inactivity.

• Change engine oil: Warm up the engine to operating temperature to thin the oil for easier drainage. Replace with fresh manufacturer-recommended oil.
• Replace gearcase lubricant: Remove old gear lube from lower unit housing and refill with fresh lubricant. Check for water intrusion by inspecting old lubricant for cloudiness or milky appearance—a sign that seals may need replacement.

Step 4: Fog Internal Engine Components

Fogging involves spraying a special fogging oil into the engine’s combustion chambers via spark plug holes or carburetor/intake while it’s running at low RPMs. The oil coats internal metal surfaces like pistons, cylinders, and valves with a protective film that prevents rust during storage.

Steps for fogging:

1. Remove spark plugs.
2. Spray fogging oil into each cylinder until you see oil coming out of spark plug holes.
3. Turn over engine by hand several times using motor handle or starter.
4. Reinstall spark plugs but do not start engine again until after removal from storage.

Step 5: Inspect and Maintain Battery Care

If your outboard motor relies on an electric start system powered by a battery:

• Disconnect battery cables: Remove battery cables to avoid slow discharge during off-season.
• Remove battery if possible: Store battery separately in a cool dry place.
• Charge periodically: Regularly maintain battery charge with a trickle charger or battery maintainer throughout storage to prevent sulfation which shortens battery life.

Step 6: Protect Against Environmental Damage

Environmental exposure causes many long-term storage issues such as corrosion, UV damage, mold growth on seats/covers, and rodent infestations.

To minimize these risks:

• Store in a dry location: Keep your motor indoors in a well-ventilated garage or shed if possible. If outdoor storage is unavoidable:
• Use a high-quality waterproof cover designed specifically for outboard motors.
• Elevate motor off ground on a stand to avoid moisture accumulation from below.
• Cover cooling water intakes: Plug water intake holes to prevent animals or debris from getting inside but ensure some ventilation remains.
• Lubricate external moving parts: Apply marine grease or corrosion inhibitor spray on pivot points and external linkages to keep them moving smoothly.

Step 7: Regular Checks During Storage Period

Even while stored long-term, periodic checks are crucial:

• Inspect covers and protectors for damage.
• Check for signs of pests nesting inside covers or around motor components.
• Verify battery condition if left connected.
• Look for any leaks or fluid drips.

Conducting these inspections every few weeks helps identify potential problems early rather than letting damage grow unnoticed over months.

Step 8: Prepping for Restart After Storage

When it’s time to bring your outboard motor back into service after long-term storage:

1. Reconnect battery cables if removed; fully charge battery beforehand.
2. Replace spark plugs if corroded or worn.
3. Change engine oil again since condensation may have formed internally during off-season.
4. Inspect fuel lines for cracks/damage; replace if necessary.
5. Use fresh gasoline without stabilizer before firing up engine.
6. Start engine carefully; listen/monitor for abnormal noises or leaks.
7. Test run at idle and gradually increase throttle; check cooling water flow.

If you notice any performance issues after restart such as hard starting or sputtering, consider having your motor professionally serviced before returning it to normal use.

Conclusion

Proper long-term storage of your outboard motor requires careful preparation before putting it away as well as ongoing maintenance during storage itself. Basic but critical steps like cleaning thoroughly, treating fuel systems with stabilizer and fogging oil, changing fluids, protecting against corrosion and pests, plus periodic inspections are key best practices that preserve engine health.

By following these recommendations tailored for outboards—whether two-stroke or four-stroke—you reduce potential repair costs down the line while ensuring reliable starts every boating season ahead. Proper care today means more years of smooth operation tomorrow with fewer headaches along the way!