Our Tips to Prevent Outboard Corrosion


Marine enthusiast on any level will probably be familiar with saltwater corrosion and the damage it can cause. However, did you know that corrosion can happen just about anywhere in your outboard? This includes inside the fuel system or in the internal cooling water passages as well as on the outer electrical connections and various exposed metal components. Fortunately, there are several corrosion prevention methods and Coast Road Motors provide some essential information below to help with your maintenance techniques.

What Is Corrosion Prevention and Why Is It Important?

Corrosion prevention involves taking excellent care of your outboard as well as knowing the first signs and what steps to take when they appear. You can start by paying close attention to the surface of the paint. This is usually the first place where signs of corrosion will appear. If you notice any blisters or bubbles, you’ll need to take some corrective steps to avoid further corrosion to your outboard. Some corrosion is unavoidable due to basic use of the outboard, especially in saltwater environments. A sacrificial anode, which is a small chip made of highly active metal, can come in handy. This can be implanted into your motor and helps prevent less active metals from corroding.

What Is Dry Corrosion?

Dry corrosion occurs in the areas that don’t come into direct contact with the water, such as the exhaust systems, where the outside components are cooled by raw water to prevent overheating. When ethanol-enhanced fuel is burned, it produces sulfate salts that are highly corrosive when exposed to hot temperatures. You can avoid dry corrosion by flushing your engine with fresh, clean water for about 15 minutes after each boating trip. This helps your cooling system run at maximum efficiency by keeping the cooling water passages clean and clear. As a result, the heat inside the engine is minimized thus, less susceptible to dry corrosion.

How Do I Flush My Outboard?

There are a few ways to go about flushing your outboard. The first option for performing this type of maintenance is to use the built-in flush attachment. All you need to do is connect the garden hose to the inlet side of the attachment, turn the spigot on full blast, and allow the water pressure to do all the work. Be sure to let the water run for 15 minutes so it can fully circulate through the whole cooling system several times. If your boat is out of the water, the fresh water will trickle down and help clean the water pump and lower unit’s cooling water passages.

Another option is the flush muff method. Connect a garden hose to clean fresh water on one end and a “flush muff” attachment to the other end. You’ll slide the attachment around the lower unit to provide water to both ends of the raw water inlet. Turn the water on until you see water coming out of the sides of the flush muff and then start your outboard in neutral. Set the outboard to no more than a fast idle and run it for 15 minutes in neutral. Next, increase the water pressure enough to maintain a bit of squirting out from under the flush muffs the entire time while your outboard is running.

The last option you’ll have is the flush bag method, which can be used when your boat is on a trailer or when it’s moored. When a flush bag is filled with water, it simulates the outboard idling in its normal state but immerses the lower unit in fresh, clean tap water. Place the bag around the motor, attach the hose, and fill the bag. You’ll want to make sure the water level reaches the height of the outboard’s water pump, which is about 1” above the lower unit separation seam. Start the engine and run it for 15 minutes while in neutral. Allow the hose to run throughout this process. When it’s finished, stop the engine, stop the hose, and drain the bag.

We hope you find this guide helpful. For more information please contact us at Coast Road Motors. Our team will be happy to answer your questions and help you.

We’re located at 4133 Yorke Hwy ARDROSSAN SA 5571

Phone us on (08) 8837 3202

Researched and formatted by a staff member for our requirements.