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Do You Have to Winterize an Outboard Motor? (Yes! And Here's How!)

Learn how to winterize your outboard motor to prevent damage during cold months. Essential tips for all boat owners to ensure peak performance next season.

Tobi Miles
October 25, 2022
Do You Have to Winterize an Outboard Motor? (Yes! And Here's How!)

If you want your vessel to run in top shape for the upcoming boating season, maintaining your outboard motor is essential to running smoothly. When you winterize your outboard motor, this will help prevent any damage to your boat. Before you begin the process, there are guidelines you should read up on to show you how to properly begin and complete this process.

It’s important to winterize your outboard motor to prevent any corrosion when sitting in storage during the winter months. When winterizing the outboard motor, it takes about four hours and you will stabilize the fuel, drain the water, and protect the internals. It takes an extended period of time under 32 degrees to experience any freezing conditions with your motor.

Sit back and relax as we go over some guidelines on how to safely and properly winterize your outboard motor for the next boating season.

Why Should You Winterize Your Outboard Motor?

Winterizing your outboard motor is important to do when not in use. Even if your outboard motor isn’t at risk from the cold weather, it’s still important that it receive a layup. In terms of maintenance, winterizing your outboard motor is one of the best things you can do as a boat owner to ensure safety and performance.

Doing this simple safety measure will ensure that your boat is up and ready to run in the spring. You’ll want to make sure that your boat and engine are cleaned also to preserve the ecosystems. If possible, you should always winterize your boat with the same company that you bought it from.

When the end of boating season approaches, your boat will need to be put away in storage and receive some extra care. Winterizing your outboard motor will be key to keeping your boat running in a top-notch shape. If you’re a new boater, winterizing your motor can seem like a challenging task.

Some of these tasks will include changing your oil regularly, fogging the engine, changing the gear lube, and other challenging tasks. Even if you’re an experienced boat owner, winterizing your motor can add up in costs over the years. If you don’t want to see engine corrosion, buildup, old fuel, or rust build-up, then yes, it is very important to winterize your outboard motor.

How Do You Winterize Your Outboard Motor?

As you probably already know, the winter months can be the most damaging to your boat. Cold winter weather can cause cracked blocks, cracked hoses, corrosion, and more. Spring is the busiest time for boat maintenance so you must winterize your boat at the end of the summer.

When beginning the process of winterizing your outboard motor, you’ll want to stabilize the existing fuel, drain the water, and protect the internals. This process is referred to as “winterization” and is done by completing these simple tasks. Below, we will go more in-depth about how to go about these three steps.

Step 1: Stabilize the Existing Fuel
When storing your boat, you want to make sure it has fresh fuel that has been treated with a stabilizer. The key is to make sure you plan late-season boating so you can use up the majority of the fuel in your tank and fill it with fresh fuel before you begin to put it in storage. Here are some things that you’ll need to do.

When stabilizing the fuel, you’ll want to use fuel that doesn’t use ethanol if you can find it in your area. As you begin to fill up your fuel tank to put your boat into storage, you’ll want to add a fuel stabilizer additive according to the instructions placed on the container. After that, you’ll want to take your boat for a short trip on the water to have the fuel distributed throughout your system.

Doing this is key for boat owners, especially boats that are powered by a gasoline outboard. Any fuel left in the untreated tank can become oxidized and can cause problems for your boat next season. You must stabilize your fuel all season long.

When the next boat season arrives, you can start with the stabilized fuel that is already in your boat.

Step 2: Drain the Water
Draining the water from your engine seems to be the most confusing step for boat owners. Pulling your boat won’t remove all of the water, as there’s usually water left behind in the systems. After you have your boat up, you’ll want to begin by running the pumps.

Once you have run the pumps, you’ll want to remove the supply lines from the seacocks. Once the water is drained you can pour in some antifreeze and run the pumps until you see the antifreeze come out of the wash-down hose. Next, you’ll want to replace the line so you don’t have any problems come the next boating season.

Now you’ll want to drain the water and run antifreeze through your outboard system and other systems such as freshwater systems, transom showers, etc. You’ll continue to use this same process to keep it flowing through the boat. If you have a bathroom on your boat, you’ll need to take some extra time on this step.

If you have a larger boat and feel uneasy doing this step, you can always take your boat to a professional for them to complete it. Sometimes things like this are just easier if we let someone else do it, too!

Step 3: Protect the Internals
Protecting the internals of your boat is easier said than done. Having a cover on your boat that is poorly fitted can do a lot of damage to the inside of your boat. It can even begin to wear away the finish of your boat as the stiff winter weather approaches.

Two things you can do to protect the internals are to get a custom-fitted cover or have your boat shrink-wrapped. One of the downsides to shrink-wrapping is that if there is an unseasonably warm day and you want to take your boat out, you can’t. For the shrink wrapping approach, we recommend getting it done by a professional so you don’t ruin your boat.

If you decide to get a fitted cover, don’t go with the cheapest one. The cheaper covers that you get from Amazon normally don’t last a long time. When looking for a cover you’ll want to get the six to the ounce cover.

When putting your cover on, make sure you have chosen one that fits around the windows and transom corners so you can prevent any internal damage. Internal damage is one way that you will delay your upcoming boating season.

What Happens If You Don’t Winterize Your Outboard Motor?

As you can imagine, if you don’t winterize your motor, it can cause harm to your engine and other parts of your boat. Failure to winterize your outboard motor will cause the engine to freeze and expand. This could lead to cracks and maybe even worse, your engine might start to split open.

When you don’t winterize your motor, you may also have problems with mold, mildew, or even battery discharge that could affect your boat in harmful ways. If you don’t take the proper steps, failure to winterize your motor could cause you to miss the start of the boating season. This could also cause your boat to need extensive repairs that would cost a lot of money.

One of the worst things that could happen is that your engine could corrode and break. If you leave dirty oil unflushed before placing it into storage it could ruin the life of your engine, which would affect your boat’s efficiency. Additionally, you could also experience mechanical system corrosion from unflushed oil.

If you don’t winterize your outboard motor and cover your boat, it could also get mold, mildew, or other dirt buildups. Even if you’re storing your boat in dry storage, it can still collect a considerable amount of dirt, so it’s important to cover it once you winterize it. The last thing you want or need is for your vessel to rot.

Do I Need to Winterize My Boat If I Keep it In the Garage?

Yes, you still need to winterize your boat if you are keeping it in a garage. For the most part, the answer is always yes, unless you are storing it in a heated environment. If you live in an environment where your outdoor temperature doesn’t drop below 32 degrees, then you can get away with not winterizing your boat.

This is an important question because you want your boat and its engine to last as long as possible. Many boat owners live in a climate where they can’t sail all year long, so winterizing their boat, even in a garage is needed.

How Do I Keep My Outboard Motor From Freezing?

In many areas, boat owners have to deal with below-freezing temperatures. In order to prevent damage, your outboard motor needs to be properly drained when exposed to temperatures that are less than 32 degrees. To keep your outboard motor from freezing, there are certain steps and precautions you should take.

The first thing you’ll need to do is make sure your fuel tank is almost filled, to leave just enough space to a add fuel stabilizer to it. This needs to be done because water can sneak into the fuel engine along with the fuel and freeze it. Afterward, you’ll need to stabilize the fuel.

Once you have stabilized the fuel, you’ll need to drain out all of the water by trimming the motor to a downward position. Next, while your motor is in a downward position, you’ll want to let your motor rest. Some boat owners even recommend doing a dry run.

Once you have done your dry run, you’ll want to add antifreeze into the system. Next, you’ll want to remove the cover and spray fogging oil to prevent water penetration in the insides along with rust. Lastly, you want to disconnect everything so you don’t get any accidental water inside before changing your oil.

How Long Does it Take to Winterize an Outboard Motor?

As autumn fades and winter approaches, you’ll need to start thinking and taking the steps to winterize your outboard motor. Depending on what kind of experience you have with your vessel, it should take you around four hours to winterize your outboard motor. If you’re a new boat owner, it may take you longer depending on how well you’ve researched the steps.

Here are some tips you can take on winterizing your outboard motor to help the process move along. While your boat is in the water, you’ll want to warm up the engine to drain out dirty fuel and other impurities. The next thing you’ll want to do is dispose of all the water in the machine to avoid freezing.

Next, you’ll fuel your tank with fresh gasoline to prevent any corrosion from occurring. Doing these steps at the beginning with save you a lot of time when beginning to winterize your outboard motor. Being prepared with a cheat sheet, especially if you’re a new boat owner will help take a lot of the stress off at the end of the season.

Taking the proper steps and planning will not only help save you a lot of time in the process but will make the beginning of your boat season more enjoyable.

Do You Have to Winterize a 2-Stroke Outboard Motor?

To ensure your boat is ready for next season, it’s always important you winterize your vessel. Your 2-stroke outboard motor must also be winterized. The great thing is, is that the 2-stroke outboard motor will only take you around twenty minutes to do.

To start this process, you’ll need a flat-head screwdriver, gloves, a grease gun, a hand pump, and an oil pan. You’ll want to complete the lower unit oil change first by changing the gear case lube which should be changed every 100 hours. Next, you’ll want to address your fueling system, followed by the cylinders.

After protecting the powerhead portion of your motor from corrosion, you’ll want to address the same with the engine by spraying it with a corrosion guard. Finally, even though it’s not a part of your outboard, the battery still needs to go through its charging cycles to stay healthy for the upcoming boating season.

Do You Have to Winterize a 4-Stroke Outboard Motor?

The end of boating season means it’s time to winterize your outboard motor in preparation for the next boating season. As soon as you’re done with your outboard for the year, winterizing your 4-stroke outboard motor is crucial to prevent any corrosion from happening. Some of the tools you will need to do this are a ratchet and extensions, a socket set, screwdrivers, and a torque wrench.

The first step in winterizing your 4-stroke outboard motor is changing the lower unit and the engine oils. Next, you’ll want to address your fuel system and add a fuel stabilizer to prevent breakage and going stale. After that, you’ll want to focus on the combustion chambers and spray fogging oil on them which will give them a protective coating.

Finally, you’ll want to spray the powerhead with a corrosion guard to give it a coating that will protect any metal parts from rusting. Also, even though the battery isn’t a part of the outboard, you’ll want to winterize that as well. As you can see, the process for a 4-stroke outboard and a 2-stroke outboard is very similar.

Should I Leave My Outboard Motor Up or Down?

If you plan on leaving your boat in the water, you’ll want to leave your outboard motor in an upward position. This position will help you avoid any unwanted growth. If you plan to leave your boat out of the water, you’ll want to leave your outboard motor down to trim out the water and protect the seals from the sun.

Where you live also plays a factor in what kind of water you’re in, such as freshwater, salt water, or hot water. It also depends on how you plan to use your boat. If you plan on using your boat back to back, then obviously you can leave it in an upward position.

If you plan to let your boat sit for a couple of weeks, your best bet is to keep it down.

How Cold Does it Have to Be to Freeze a Boat Engine Block?

When winter approaches, so do the freezing temperatures, so worrying about your boat’s engine block freezing is natural. A boat engine block can freeze any time the temperature is below 28 degrees for an extended time. With coolant and antifreeze, you can prevent your engine block from freezing unless you live in an arctic climate.

One of the shocking things is that it’s not your engine that actually freezes. When water freezes, it expands, which can cause the hoses in your engine to crack and split. Your engine has hollow parts where the coolant can flush away the heat.

If there is water left in these hollow spaces, this is when the water can freeze. When the water expands, it can crack your engine block. To keep your engine block from freezing, you’ll want to remove all of the water and replace it with anything that will lower the freezing point below typical outdoor temperatures.

If you come across freezing temperatures over one night, you won’t have a problem with your engine block. It’s only when exposed to freezing temperatures over an extended amount of time is when you’ll start encountering problems. This is why it’s important to get your winterizing done ahead of time.

How Long Does it Take Your Outboard Motor to Freeze?

Once freezing temperatures arrive, it will take around 24 hours for your outboard motor to freeze. For the temperatures to crack a block, it has to be below freezing for an extended amount of time. No matter what the degree is outside, it will also stay around 3 to 4 degrees warmer on the inside.

To avoid freezing, make sure you winterize your boat at least a couple of months ahead of temperatures falling below freezing. The last thing you’ll want to do is wait last minute and end up with a cracked engine and prolong your next boating season.

Tobi Miles
Article updated:
March 28, 2024
A nomadic wordsmith savoring the world's flavors and penning stories that turn every journey into an epic.
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