How Do You Winterize a Boat Motor

As the chill of frosty air starts to settle in, it’s time to give your boat motor the care it needs to withstand the harsh winter months. Winterizing your boat motor is a crucial step in boat maintenance, whether you have an outboard or inboard motor.

In this guide, we’ll explain why winterizing is essential and provide you with a step-by-step breakdown of how to winterize both types of boat motors.

The Importance of Winterizing Your Boat Motor

Properly winterizing your boat motor is not just a matter of convenience; it’s a critical step in preserving its functionality and preventing damage. Here’s why it’s essential:

1. Protecting Against Freezing:

When water is left in certain components of your motor, freezing temperatures can cause it to expand, exerting immense pressure on those parts. This can lead to cracks, breaks, or other forms of damage.

2. Preventing Corrosion:

Winter weather often brings higher humidity levels, which can lead to rusting of the metal parts of your motor. Corrosion can weaken your motor and cause other issues down the line.

3. Extending Lifespan:

Winterizing your boat motor can significantly extend its lifespan, ensuring that it continues to serve you well in the coming years.

4. Saving Time and Energy:

When spring arrives, and boating season returns, you’ll be grateful that you took the time to winterize your motor. It will save you from unexpected repairs and delays.

Now, let’s dive into the step-by-step process for winterizing both outboard and inboard boat motors.

How to Winterize an Outboard Motor

Outboard motors are the self-contained units mounted outside the transom of your boat. Follow these steps to properly winterize your outboard motor:

1. Flush with Fresh Water:

Use a flusher or run the motor in a tank filled with clean water. This flushes out any residual saltwater or debris.

2. Clean the Motor:

Remove dust and debris from the powerhead and exterior surfaces of the motor.

3. Change the Oil:

  • Fill the oil tank with the type of oil recommended in the engine manual.
  • Replace the oil filter.

4. Service the Gear Case:

  • Change the oil in the gear case and replace the seals on the drain plugs.
  • Spray the gear case with fogging oil to prevent rust.

5. Fuel System:

  • Drain the fuel from the fuel filter and replace it with new fuel.
  • Replace the fuel water separator filter if your motor has one.
  • Drain the fuel from the vapor separator tank or carburetor if applicable.

6. Lubricate:

  • Grease all pivot points and seals inside and outside the motor.
  • Grease the prop shaft.

7. Disconnect Battery:

  • Disconnect the battery and remember to charge it at least twice over the winter.

8. Prevent Rust:

  • Spray the powerhead and rubber components with fogging oil.

9. Cover and Store:

  • Cover the engine with a waterproof tarp or canvas.
  • Store the engine in a dry place if possible.

How to Winterize an Inboard Motor

Inboard motors are enclosed within the hull of your boat. Here’s how to winterize an inboard motor:

1. Flush with Fresh Water:

  • Flush the motor with fresh water to remove any salt or debris.

2. Change Oil:

  • Use an oil vacuum pump to drain the oil from the engine without allowing any oil to drip into your boat.
  • Replace the oil filter.
  • Refill with the type of oil recommended by the manufacturer.

3. Water Pump:

  • Place the water pump intake hose in a bucket of clean water and run the motor for about 10 minutes to ensure water is drained from the system.

4. Transmission Fluid:

  • Change out the transmission fluid.

5. Spark Plugs:

  • Remove the spark plugs; replace them if they’re in poor condition. Add some motor oil inside the cylinders.

6. Antifreeze:

  • Fill the cooling system with antifreeze to prevent freezing.

7. Cover and Store:

  • Cover the boat with a tarp or canvas designed for winter storage.


By diligently following these steps, you can rest assured that your boat motor will weather the winter months without any undue stress or damage. When spring returns, you’ll be ready to hit the water without delay, knowing that your boat motor is in excellent condition.

So, don’t wait until winter’s chill sets in. Take the time to winterize your boat motor, and you’ll enjoy many more seasons of smooth sailing and aquatic adventures. And 

With proper winterization, your boat motor will be raring to go when the warm weather returns, ready to propel you on new voyages and memorable experiences on the water.

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