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Keep Your Boat Engine Running With New Spark Plugs

Improve your boat’s performance – change your spark plugs

Changing the spark plugs is an easy way to improve the performance of your boat’s engine. A straightforward job, changing marine spark plugs is a repair job that you can tackle in your own garage.

What do I need to know before I start?

To prevent the possibility of electric shocks, be sure to disconnect the battery from the engine.

Make sure your boat’s engine is cold before you start. Spark plugs get very hot – only remove the spark plugs when the engine is cool.

Make sure you have the correct spark plugs for your boat’s engine. Consult your owner’s manual for the correct part number or visit our Champion part finder to find the correct Champion boat plug for your marine engine.

Change marine spark plugs one at a time – spark plugs fire in a specific order and crossing a wire to the wrong plug can damage your engine.  If you are going to remove all the spark plugs at once, label each wire using a marker and masking tape.

Before starting the job, clean the spark plug area with compressed air to prevent dirt from falling into the cylinder area.

Be sure to examine your boat’s spark plugs on an annual basis as a part of a maintenance routine. Replace them when they show signs of deterioration.

What tools do I need?

You need just a couple basic tools to do spark plug maintenance:


To combine the two opposite motions on each end of the control arm, the arms are tied on the frame side to pivot up and down on the control arm bushings. On the opposite end, the control arm is tied to the spindle and front wheel with upper and lower ball joints. The coil spring supports the weight of the car and dampens the shock of road surfaces.

How do I remove the old spark plugs?

Start by removing the cover to the motor and locate the spark plugs. Grab the spark plug boot and turn it 90° counterclockwise. Gently pull the boot and cable away from the spark plug.

After the wire is removed, use your socket wrench with the spark plug socket to remove the spark plug. Place the socket around the spark plug and turn the socket counterclockwise.


Do I have to set the gap?

In the past, it was necessary to use a gapping tool to make sure the gap in the spark plugs was the correct size. Today, many spark plugs come gapped, eliminating the need for this step. To double check that the gap is correctly set, check your owner’s manual to find the measurement for the spark plug gap and use a gap gauge or feeler gauge to check the gap.

 Today, many spark plugs come gapped, eliminating the need for this step. 

If you find that the gap needs adjusting, select the correct measurement on your gap gauge or feeler gauge. If you can’t get the feeler gauge through the gap, the gap needs to be widened. If the tool runs through the gap without touching the electrodes, the gap is too big and must be narrowed.

Use your spark plug gap tool to adjust the gap. Gently bend the bottom electrode in to narrow the gap or bend it out to widen it.  You can also bend the electrode in by using a flat surface to apply pressure.

How do I install the new spark plug?


Examine the threads, if they are dirty; clean them with a clean rag and some rubbing alcohol.

If the spark plug shows signs of damage or fouling, it is time to replace it. Set the old spark plug aside.

Seat the new spark plug by hand; turn it clockwise at least two turns. Use the socket wrench with extension and spark plug socket to tighten it turning the plug clockwise.

Next, replace the spark plug’s wire boot. A plastic boot should click into place while a rubber boot may require a coat of dielectric grease on the inside of the boot for easy removal next time.

Repeat the process for each spark plug, put the engine cover back on and get ready for a day on the water!

Learn more about Champion spark plugs for boatsfind your boat part, or find where to buy your boat part today.

The content contained in this article is for entertainment and informational purposes only and should not be used in lieu of seeking professional advice from a certified technician or mechanic. We encourage you to consult with a certified technician or mechanic if you have specific questions or concerns relating to any of the topics covered herein. Under no circumstances will we be liable for any loss or damage caused by your reliance on any content.

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