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Boat Engine Maintenance:

How to keep your engine running smoothly

One of the most important aspects of owning a boat is keeping the engine well-maintained. Whether you own a new Mercury® Outboard or an old OMC® Sterndrive, Sierra Marine offers a vast selection of boat parts to keep you moving. A properly running engine is essential for a safe and enjoyable boating experience. Luckily, with a little bit of regular care, it's easy to keep your boat engine in good shape.

A few things to keep an eye on:

Fuel Lines

Check your boat's fuel lines regularly for cracks, leaks or other damage. Today's fuel can be hard on fuel systems. Regular checks can ensure that you do not run into any issues when you least expect them. If you notice any damage, replace the fuel line immediately.

Primer Bulbs

Check the primer bulbs on your engine before each use. Similar to fuel lines, primer bulbs may suffer from exposure to Ethanol based fuel. A quick replacement of an old primer bulb is a simple way to eliminate any potential problems. If the bulb is hard or cracked, replace it.

Fuel Filters

It's also important to check and replace your fuel filters regularly. Clogged or dirty fuel filters can cause all sorts of problems, including reduced engine power and poor fuel economy. Fuel water separating filters take engine protection to another level by removing water deposits that might enter the fuel system. Sierra's fuel water separating filters are a perfect solution for a fuel filter replacement.

Spark Plugs

Inspect your spark plugs yearly and clean or replace them as needed. Carbon build up on the electrodes limit the spark plug's ability to efficiently produce a spark. This could cause you to experience reduced gas mileage, poor acceleration, hard starts, engine misfires and rough idling. Checking your plugs in the spring to ensure they are ready for boating season and can possibly help identify hidden problems within your engine. This is an important step in keeping your engine running at peak performance.


One of the most important things you can do for your boat engine is to change the oil regularly. Check the oil level in your engine every time you take the boat out for the day. If it's low, add more oil. Also, keep an eye on oil quality. Using a high quality engine oil offered on you can be sure that you are giving your engine the best protection against the harsh marine environment. If the appearance of the oil turns milky in color, this could indicate that you have water intrusion into your engine and should be addressed immediately. Be sure to check your owner's manual to find out what type of oil is best for your engine.

Gear Lube

Another important aspect of boat engine maintenance is changing the gear lube. Your lower unit has several gears that rely on quality gear lubes to minimize friction and overheating. Over time, lower units can become susceptible to leaks and allow water to enter, and mix with the gear lube. This will greatly reduce the gear lube's ability to maintain proper lubrication and protect your gears from damage. Regular inspection can help you identify leaks early and reduce repair costs. This should be done according to the manufacturer's recommendations.


Boat batteries are essential for starting your engine and powering accessories. Most marine batteries are lead-acid batteries and require special care. Check the battery regularly for corrosion on the terminals, which can be cleaned with a mixture of water and baking soda. If the battery is more than three years old, it's probably time to replace it.

Keep your engine happy

By following these tips, you can help keep your boat engine in good working order. Regular maintenance will prolong the life of your engine and help ensure that it runs smoothly when you need it.

If you have any questions about boat engine maintenance, or if you need help troubleshooting an issue, feel free to contact us at for more information.