DIY Boat Motor Maintenance

By Devin DeLuca

July 8, 2019 - Wrenching on your boat is not only rewarding to the spirit; it can save your wallet from a beating as well.

There is just something about doing your own outboard engine and boat maintenance that makes an outdoorsman’s heart sing. Applying your mind to a problem, making a correct diagnosis, executing the correct repair and then listening to your outboard run like a top is an endeavor that boosts pride and confidence. Plus, it can be a great way to spend quality time with your father, son, daughter, wife, buddy or anyone in your life.

Maintaining Your Boat Motor
Seasonal services and common mechanical fixes cost hundreds of dollars at a marine mechanic, but performing these yourself will cost significantly less. Besides boosting your mechanical competence, servicing your motor allows you to become more familiar with its current condition. This allows you to perform preventative maintenance or put together a service plan based on your motor’s current condition. This is especially important for anyone buying a used motor. Establishing a baseline for your motor will allow you to diagnose future problems, or identify a problem soon to happen.

For example, while overhauling and cleaning my carburetors on my ’97 Evinrude Ocean Pro, I noticed a slight warp in one of the plastic carburetor bowls where it connected to the carb body (causing a leak). Upon taking a closer look, I realized that all 6 of my bowls had started to warp! Instead of a costly amount of labor hours at a mechanic, I replaced all 6 of them in one morning, which prevented a huge headache and fuel system problems down the road.

I challenge you to do your own seasonal service this year on your boat motor. Here’s a list of easy to moderate level maintenance that is easy and rewarding to learn:

1. Change your spark plugs

Changing spark plugs is recommended about every 50-70 hours. Learning to “read” your plugs can also tell you a lot about how your cylinders are firing. Check the gap on your plugs using a spark plug gap tool (costs about $2).

2. Check the resistance in your HT leads

While looking at those spark plugs, why not check your leads? Check resistance in your leads with a multimeter, and make sure they conform to the manufacturer’s specs.

3. Replace the impeller and inspect the water pump housing

Suggested as yearly maintenance by most manufacturers, changing your impeller regularly is a great way to prevent your motor from, well, blowing up. The water pump and circulation system on your motor is essential for preventing overheating. Look at the water pump housing; you might have more corrosion down there than you thought. This is a great opportunity to check the health of your lower gear seals, grease your drive shaft, and remove any corrosion.

Do It Yourself Boat Motor Maintenance
4. Change your lower gear oil (and your top end too, if you have a four-stroke)

Top that oil off, and look at the old oil. See any weird colors, consistencies, water, or metal flakes? These could be an indicator of other problems that need to be addressed.

5. Rough idle? Clean your carburetors and/or throttle bodies

There is usually no better fix than a carburetor clean for a rough idling engine. This is also a good preventative maintenance since needles, valve seats, gaskets, and float mechanisms wear over time. Additionally, all the little passages and jets in your carbs and throttle body need to be cleaned every so often.

6. De-Carbon your engine

This can be as simple as putting a fuel additive in your gas tank. Run your motor and watch all that carbon burn off!

With years of forums and videos readily available, most of these procedures and knowledge are at your fingertips. That being said, buying the service manual to your engine (usually around a $20-$40 cost) is a great investment. You’ll need it for model-specific instructions, diagrams, and specs. What’s especially useful in these manuals are the torque, timing, and synchronization specs. You don’t want to freestyle those!

Keep yourself productive and sane this off-season by wrenching on that outboard, whether you’re learning yourself, teaching your kids of friends, or spending time with buddies. Get after it!

Hit the water after you boat maintenance

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