Properly winterizing your Yamaha 115 outboard motor prevents corrosion, fuel issues, and engine damage during the off-season. Follow this step-by-step guide to keep your motor in top condition.

Step 1: Flush the Engine with Fresh Water

• Connect a garden hose and flushing muffs to the motor’s water intake.
• Start the engine and let it run for 10–15 minutes to remove salt and debris.
• Turn off the engine and disconnect the hose.

Step 2: Drain and Stabilize the Fuel System

• Add a marine-grade fuel stabilizer to the gas tank.
• Start the engine and let it run for a few minutes to circulate the stabilizer.
• Turn off the fuel supply (if available) and let the engine burn off remaining fuel.
• Alternatively, drain the fuel system completely if storing for an extended period.

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Step 3: Change the Engine Oil and Filter

• Run the engine for a few minutes to warm the oil.
• Remove the drain plug and let old oil drain into a pan.
• Replace the oil filter and refill with fresh Yamaha 4-stroke marine oil.
• Check the oil level and tighten the drain plug.

Step 4: Fog the Engine Cylinders

• Remove the spark plugs and spray fogging oil into each cylinder.
• Turn the flywheel manually a few times to distribute the oil.
• Reinstall the spark plugs securely.

Step 5: Check and Change Gearcase Oil

• Remove the bottom drain screw and top vent screw to let old oil drain.
• Refill with fresh Yamaha lower-unit gear oil using a pump.
• Replace the screws and ensure there are no leaks.

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Step 6: Grease All Moving Parts

• Apply marine grease to the steering mechanism, throttle linkage, and prop shaft.
• Remove the propeller, clean the shaft, and apply grease before reinstalling.

Step 7: Remove and Store the Battery

• Disconnect the battery cables, starting with the negative (-) terminal.
• Store the battery in a cool, dry place and charge it periodically.

Step 8: Cover and Store the Motor

• Use a breathable outboard motor cover to protect against dust and moisture.
• If possible, store the boat in a dry, sheltered area.

Conclusion

Winterizing your Yamaha 115 outboard motor protects it from cold weather damage, fuel degradation, and corrosion. By following these steps, your motor will be ready to run smoothly when boating season returns.

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FAQs

1. Do I need to fog a fuel-injected Yamaha 115 outboard?

Yes, but instead of spraying fogging oil directly, use a fuel stabilizer and run the engine to coat internal components.

2. Can I skip changing the gearcase oil?

No, old oil can contain water, which may freeze and damage the lower unit.

3. How often should I grease the outboard motor parts?

At least once a season or after extended storage.

4. Should I remove the outboard motor from the boat for winter?

Not necessary, but if stored outdoors, use a full cover and tilt the motor down to drain water.

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5. Can I winterize my Yamaha 115 without a hose or flushing muffs?

No, proper flushing is essential to prevent internal salt buildup and corrosion.