Winterizing Your Outboard Engine: A Boat Owner's Guide

Winterizing your boat's outboard engine is essential to protect it from cold weather damage and to ensure it's ready to go in the spring. In freezing temperatures, water left in the engine can cause significant and costly damage. Even in milder climates, winterizing is a great time for annual maintenance to keep your outboard running reliably. This includes changing the engine oil and oil filter, checking the gearcase lubricant, changing fuel filters or spark plugs, and testing the batteries. Basic steps to winterizing your outboard engine include greasing lubrication points, applying a corrosion barrier, and preparing the engine for storage.

Flushing the engine with fresh water

Flushing your boat's engine with fresh water is a crucial step in maintaining your boat, especially if it has been used in saltwater. Saltwater can be extremely damaging to your boat's engine if left inside for long periods. When saltwater is trapped inside an engine, it becomes oxygen-deprived and turns acidic. This acidic water is highly corrosive and can cause significant damage to the engine's cooling tubes, heat exchangers, and coolers. Therefore, it is essential to flush your boat's engine with fresh water after each use to prevent costly repairs.

The process of flushing a boat engine with fresh water involves using a garden hose or a flushing bag/bucket to pump fresh water through the engine's cooling system, removing any salt, silt, mud, sand, shells, or brackish water that has accumulated. This helps to prevent corrosion and maintain the engine's performance.

There are a few methods for flushing a boat engine with fresh water:

• Using a built-in flush connection: Modern outboards often have a built-in flush connection that allows you to connect the motor to a garden hose. This method may not require starting the motor.
• Using flushing muffs: These are rubber cups that fit over the cooling water intake ports and are held in place by a spring or clamp. A garden hose is attached to one of the cups, and the engine is started to circulate fresh water.
• Using a flushing bag or bucket: This method involves fitting a bag or bucket around the gearcase and filling it with water to cover the cooling water inlets. The engine is then started, and the water is pumped from the reservoir.

It is important to refer to the owner's manual for specific instructions on flushing your particular brand and model of the engine. Additionally, it is crucial to ensure that all fresh water is drained from the motor after flushing, especially if the temperature will drop below freezing to avoid engine damage.

Benefits of Flushing with Fresh Water

Flushing your boat engine with fresh water after each use offers several benefits:

• It removes salt and other debris from the engine, preventing corrosion and maintaining performance.
• It helps prevent the formation of acidic water, which can be highly corrosive and damaging to the engine.
• It ensures the engine's cooling system is free-flowing, allowing for efficient cooling and preventing overheating.
• It is a relatively quick and easy procedure that can save you time and money on costly engine repairs.

When to Flush with Fresh Water

It is generally recommended to flush your boat engine with fresh water after each use, especially if the boat has been used in saltwater or brackish water. Additionally, if the boat has been used in freshwater that is silty or muddy, flushing is advised. Regular flushing helps maintain the engine and prevent the build-up of corrosive materials.

Steps for Flushing with Fresh Water

• Consult your owner's manual for specific instructions and safety precautions.
• Prepare the necessary equipment, such as a garden hose, flushing muffs, or a flushing bag/bucket.
• If using a garden hose, connect it to the built-in flush connection on the motor or the cooling water intake ports.
• Ensure the boat is either in the water or on a trailer to provide a water supply to the engine.
• Start the engine and let it idle in neutral to circulate the fresh water.
• Run the engine for approximately 10-15 minutes to ensure thorough flushing.
• Turn off the engine and then the water supply.
• Drain all fresh water from the motor to avoid freezing and potential engine damage.

Changing the oil and oil filter

Gather the necessary tools and materials:

You will need an oil extractor (manual or electric), catch pans and oil-absorbent pads, a new oil filter, a funnel, and the correct type and amount of fresh engine oil. For a four-stroke outboard, you may also need a remote oil change pump and a grease gun with a Zerk fitting. It is important to consult your owner's manual or a factory service manual for specific recommendations and procedures.

Prepare the engine:

Before changing the oil, it is recommended to bring the engine up to operating temperature. Warm oil drains more easily and holds more contaminants, ensuring a more thorough removal of abrasive gunk and chemical impurities. If your boat is not in the water, you will need to use muffs.

Drain the old oil:

Place catch pans and oil-absorbent pads beneath the engine to prevent spills. For inboard marine engines, you will likely need an oil-evacuation system to transfer oil from the engine into a separate container. As for four-stroke outboards, while some models have a drain plug, it is often easier to use an oil extractor that goes through the dipstick tube. Allow the oil to drain completely into a catch pan.

Inspect the old oil:

Before replacing it, it is important to inspect the old oil for any signs of issues. Oil that appears milky may indicate the presence of water, antifreeze, or fuel, which could be due to a blown gasket or a cracked block. Rubbing a small amount of oil between your fingers can also help identify issues; if it feels abrasive or has a burnt odour, it could be a sign of bearing wear.

Remove and replace the oil filter:

Place oil pads or a catch pan beneath the filter to catch any spills during removal. You may also want to wrap the filter with a thick cloth or place a large zip-top bag around it to reduce the chance of spills. Remove the old filter carefully and install the new one, ensuring you lubricate the O-ring at the top with a bit of fresh oil. Tighten the new filter by hand.

Refill the engine with fresh oil:

Using a funnel, add the specified type and amount of fresh engine oil as per the manufacturer's recommendations. Once you have added the oil, start the engine and let it idle for a short period (around 15-30 seconds). This will distribute the new oil throughout the engine and fill the filter. Stop the engine and check the oil level, adding more if needed.

Final checks:

After running the engine for several minutes, check the new filter for any signs of leaking around the seal. You should also grease all fittings on the outboard with marine waterproof grease using a grease gun with a Zerk fitting. Refer to the service manual for the locations of all Zerk fittings.

Dispose of waste oil and filter properly:

Used engine oil and filters should be disposed of and recycled properly. Many marinas, automobile repair shops, or auto parts stores offer waste oil recycling. You can also search for local recycling drop-off locations online.

Draining the fuel from the fuel filter

Step 1: Prepare the Fuel

Before beginning the draining process, it is essential to ensure that the fuel in your tank has been treated with a fuel stabilizer. Fuel stabilizers help prevent the fuel from breaking down and oxidizing, which can lead to the formation of gum-like substances in the engine's fuel system. This step is especially crucial for boats equipped with carburetors.

Step 2: Run the Engine

Run your boat's engine, either in the water or while connected to a garden hose, for about 10 minutes. This step ensures that the treated fuel circulates throughout the entire fuel system, including the fuel filter. It is important to refer to your boat's owner's manual for specific instructions and safety precautions.

Step 3: Remove the Fuel Filter

Locate the fuel filter in your boat's engine. The fuel filter is typically found on the front, side, or rear of the powerhead and is usually made of transparent plastic. Refer to your boat's manual or seek assistance from a marine technician if you are unsure about the location. Once located, remove the fuel filter carefully, as it may contain fuel.

Step 4: Drain the Fuel

Place the removed fuel filter in a safe and secure location and allow it to drain completely. Ensure that you have a suitable container to catch the draining fuel. This step ensures that all the fuel is removed from the filter, reducing the risk of fuel degradation and engine issues during storage.

Step 5: Dispose of the Fuel

Properly dispose of the drained fuel in accordance with local regulations and guidelines. Fuel is a hazardous substance, and improper disposal can pose environmental and safety risks. Contact your local waste management authorities or marine service facilities for guidance on responsible fuel disposal.

Step 6: Clean and Replace the Fuel Filter

After draining and disposing of the fuel, it is important to clean the fuel filter thoroughly. Use a suitable cleaning solution or solvent to remove any residual fuel, debris, or buildup from the filter. Once the fuel filter is clean and dry, replace it with a new, compatible fuel filter. Refer to your boat's manual for specific recommendations on fuel filter replacement.

By following these steps, you can effectively drain the fuel from your boat's fuel filter as part of the winterization process. Remember to consult your owner's manual and, if necessary, seek assistance from a qualified marine technician to ensure a safe and effective winterization of your boat's outboard engine.

Applying a corrosion barrier

• Clean your boat's engine: Start by giving your engine a thorough cleaning. Use a good external boat engine cleaner to remove any dirt, grease, or residue. This step is essential as it creates a clean surface for the corrosion barrier to adhere effectively.
• Flush the engine: After cleaning, flush your boat's engine with fresh, clean water. This step is crucial, especially if you have been boating in saltwater. Flushing removes any salt buildup and other contaminants that can accelerate corrosion.
• Dry the engine: Once flushed, ensure that the engine is completely dry before proceeding. Use a soft cloth or chamois to wipe down the engine and remove any remaining moisture.
• Apply a corrosion inhibitor or protectant: Choose a corrosion inhibitor or protectant specifically designed for marine use. Look for products such as Mercury Corrosion Guard or Yamashield, which are designed to protect against corrosion in saltwater and freshwater environments. You can also use a high-quality silicone spray as an alternative.
• Spray the engine: Liberally spray the corrosion inhibitor or protectant onto the engine, covering all metal surfaces, electrical connections, and rubber cowling sealing gaskets. Ensure you follow the product instructions and safety guidelines during application.
• Reinstall the cowling: Once you have applied the corrosion barrier, carefully reinstall the cowling, ensuring that it is properly sealed and secured.
• Store the boat: After applying the corrosion barrier, store your boat in a dry, covered area to protect it from the elements. If possible, store the boat in a climate-controlled environment to minimize the risk of condensation and moisture buildup, which can contribute to corrosion.

By following these steps and applying a corrosion barrier, you can effectively protect your boat's outboard engine from corrosion during the winter months or extended periods of inactivity. Remember to refer to your engine's owner's manual for specific recommendations and instructions for your particular make and model.

Storing the engine upright

Storing your boat engine upright is an important step in winterization. Whether the boat is stored on a trailer or a rack, the engine should be trimmed down to its vertical position so that any water remaining in the engine can self-drain. If water trapped in the engine freezes, it could cause serious damage.

In some situations, mice can be a problem. They may be able to get under the motor cowl and chew on the wiring. Some dealers recommend using fabric softener sheets, or dryer sheets, to repel mice. Just remember to remove the sheet before taking the boat out on the water again.

If you have a self-draining outboard, it may be fine to take advantage of warm weather during the winter. Just be sure to return the boat to its long-term storage state—fuel treated, engine drained, battery maintained—after your warm-weather outing. It may be weeks or months before you use the boat again.

If you live in a climate where the lake is annually certain to be covered by ice, prepping the boat for the freezing off-season is almost mandatory. If left to freeze, water trapped in an engine block, water tank or other on-board plumbing can cause significant and very expensive damage.

Even if you live in a more temperate climate, winterizing your boat engine is a good idea. This is a great time to take care of annual maintenance that will keep your outboard engine running reliably.

Frequently asked questions