Winterizing Your Inboard Boat Engine: Step-By-Step Guide

Winterizing your inboard boat engine is essential to prevent damage during the colder months. The process involves several simple tasks, including flushing the engine with fresh water, changing the oil and oil filter, and adding antifreeze to the system. This guide will take you through the steps to properly winterize your inboard boat engine, ensuring it stays in good condition until the boating season starts again.

How to Winterize a Boat Engine

Fill the tank with gas to prevent air from entering

Filling the tank with gas is a crucial step in winterizing your inboard boat engine. This is because gas in the tank leaves less room for air, which can be detrimental to the engine.

Air in the tank can cause moisture to enter, leading to condensation when temperatures drop. This condensation can cause severe problems for your engine, including corrosion and the formation of deposits. By filling the tank with gas, you displace any air and reduce the possibility of condensation forming.

It is recommended to fill the tank with fresh, non-ethanol gasoline, as ethanol can cause issues with your fuel system. After filling the tank, be sure to add a marine-specific fuel stabilizer additive and follow the instructions on the product.

Another benefit of filling the tank is reducing the risk of fire. Gasoline vapors, not liquid gasoline, can ignite and cause a fire. By minimizing the air space in the tank, you also decrease the space available for vapors to collect, reducing the risk of fire.

Additionally, filling the tank helps keep your gas dry. Moist air can enter the tank through the vent, and the moisture can be absorbed by the fuel or condense on the tank walls. This can lead to water accumulation in the fuel tank, causing issues with your engine.

By filling the tank with gas and taking the necessary steps to stabilize the fuel, you can help ensure that your inboard boat engine stays healthy and performs well when you take it out on the water again in the spring.

Add antifreeze to the engine to prevent condensation from freezing

Adding antifreeze to your boat engine is crucial to prevent condensation from freezing during winter storage. When water freezes, it expands, which can cause cracking and severe damage to your engine. Therefore, taking the necessary steps to winterize your inboard boat engine is essential.

To add antifreeze, you must first drain the engine block and manifolds of all water. This step is crucial, as any remaining water could freeze and cause damage. Once drained, you can add the antifreeze solution. It is recommended to use a marine antifreeze solution, specifically one that is propylene glycol-based. Propylene glycol is odourless, tasteless, biodegradable, and non-toxic. It is a safer alternative to ethylene glycol, which is poisonous and can be harmful to the environment.

After adding the antifreeze, you should run the engine for a few minutes to circulate the solution throughout the engine. This ensures that the antifreeze reaches all parts of the engine, providing protection against freezing. Finally, turn off the engine and disconnect the battery to prevent accidental starting.

It is important to follow the manufacturer's recommended winterization procedures for your specific boat make and model. If you are unfamiliar with the process, it is best to consult a professional mechanic.

Additionally, it is worth noting that the antifreeze solution should be mixed with water. This mixture will help to save on cost and make draining easier. You can determine the appropriate ratio by referring to the manufacturer's instructions and considering the winter temperatures in your location.

Change the engine oil

Changing the engine oil is an important step in winterizing an inboard boat engine. This is because residual acids and moisture left in the crankcase over the winter can pit bearings and other vital engine parts.

To change the oil, start by warming up the engine. Find the freshwater intake and attach a motor flush tool, such as the Fake-A-Lake, to make sure the engine doesn't overheat. Attach the tool to the intake and a hose to a source of freshwater. Add Sea Foam at a rate of 1oz per gallon of gas and fill your gas tank with non-oxy gas. This will ensure that the tank and hoses don't have any air gaps. Now you are ready to start the boat and get the engine up to idle temperature (usually the centre of your temperature gauge).

Next, hook up an oil vacuum pump. Attach the hose from the extractor to the oil drain on the engine, then remove the oil check cap to prevent the vacuum from stopping the oil from draining. You are now ready to pump the oil out of the engine. Continue pumping until you are only getting air and no more oil. Replace the check oil cap and remove the hose from the oil drain, replacing the oil drain cover as well. Now, remove the old oil filter. Place a ziplock or watertight bag over the filter and unscrew it, being careful not to let oil drip into your boat.

To prepare the new oil filter, fill it halfway with fresh oil, then spread a small amount of oil around the top to ensure a proper seal. Screw the new oil filter into place. Using a funnel, add most of the oil to the engine. For example, if you are using 5.5 quarts, add 5 quarts, start the engine, stop the engine, check the oil, and add the remaining amount. Adding too much or too little oil can cause issues, so make sure to check the manufacturer's specifications and check the oil level after adding oil.

Finally, restart the engine and let it run for about a minute to circulate the fresh oil to the internal parts. While the engine is running, check to make sure the oil filter is not leaking.

Clean the boat and cover it

Once you've winterized your inboard boat engine, it's time to clean the boat and cover it for the winter season. Here are the steps you should follow:

Clean the Boat

Start by removing any debris, such as leaves, bugs, grass, and dust, from the boat. Use gloves and paper towels to ensure you're not spreading contaminants and to reach all the nooks and crannies. Next, fill your gas tank with non-oxy gas to ensure there are no air gaps in the tank and hoses. It is also important to check your engine's filters, such as the fuel filters, and inspect the rubber hose connections to ensure they are in proper working condition.

Now, it's time to wash the boat. Use soap specifically intended for washing boats, as dish soap, household cleaners, and industrial cleaners can harm the boat and the environment. Wash the exterior of the boat, including the engine, and be sure to rinse the powerhead with freshwater, especially if you boat in saltwater. Avoid using high-pressure spray, as it can force water into electrical connections. For a very dirty engine, spray it with a light degreaser before rinsing.

Cover the Boat

After the boat is clean and dry, it's time to cover it up. Invest in a quality winter boat cover that fits your boat properly and is ventilated. This will keep out contaminants and deter small animals and insects. Make sure the boat is securely covered and consider using support poles to keep the cover in place.

Additionally, take care of the battery. You can either remove it and keep it indoors or leave it installed and hook it up to a trickle charger. It is also important to consider pest control measures and invest in theft prevention, such as regularly checking on your boat during the winter.

Check the exhaust system for corrosion

Winterizing your inboard boat engine is essential to prevent gunk from building up, to keep condensation out of the fuel tank, and to maintain a healthy engine. Here are some detailed steps to check the exhaust system for corrosion:

Understand the Exhaust System:

Start by understanding the basic components of your boat's exhaust system. Most marine exhausts are water-cooled, using water from the engine's raw water cooling system to cool the hot exhaust gases. The water and exhaust gases mix in the injection bend, turning into steam before cooling and condensing back into water, which is then discharged through the exhaust system.

Inspect the Exhaust System:

With the boat out of the water, carefully inspect the exhaust system for any signs of corrosion or damage, especially around the injection bend. This area is critical as it cools the exhaust gases to prevent the flexible rubber sections of the exhaust from melting. Look for any signs of deterioration, such as cracks, leaks, or white crystals, which indicate seawater leaks.

Check the Exhaust Piping:

Pay close attention to the flexible rubber piping, connections, and clips. Check the condition of the double clips along the system. If you notice any signs of corrosion or deterioration, it's important to replace them. Exhaust piping in good condition should be free of any external signs of damage and securely clamped to prevent leaks.

Inspect the Engine:

Before starting the engine, drain the water from the engine's risers and manifolds to perform a thorough visual inspection. Unclamp the exhaust hoses and remove the bolts securing the risers and/or elbows to inspect the inside for any signs of heavy corrosion or material dislodgement. Use a screwdriver or similar tool to check for any loose material.

Check for Leaks:

Look for signs of water leaks around the cooling water injection nipple or any other areas where leaks may occur. Leaks can lead to water seeping into sensitive engine components, causing corrosion and potential engine damage. If you find any leaks, address them promptly to prevent further issues.

Regular Maintenance:

Even if your boat is used in freshwater, it's important to regularly inspect the exhaust system. Risers and manifolds in freshwater may have a longer lifespan, but annual checks for gasket condition and bolt torque are still recommended. Corrosion can occur over time, so staying proactive can help prevent unexpected issues.

Frequently asked questions