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Video:Why Spark Plugs Need to Be Changed

with Matt Ediger

If you don't know how spark plugs work, you probably also don't know when the best time to change them is. Here's a quick guide on when to change spark plugs and how they work.See Transcript

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Transcript:Why Spark Plugs Need to Be Changed

Hi, I'm Matt Ediger from DownForce Motoring for About.com, and this is why your spark plugs need to be changed. In this video, we'll discuss what the spark plug does, how they wear out, and why it should be changed at regular intervals.

What Does a Spark Plug Do?

Your car's spark plug is what ignites the air fuel mixture inside your combustion chamber. This happens thousands of times a minute. Times that by the hundreds of hours you drive your car over the years, and you can begin to see that the little guys are getting quite a work out. This is why it's important to change or at the least inspect them regularly. Your average spark plug lasts for about 10,000 to 20,000 miles. High end spark plugs with platinum or iridium tips can last upwards of 60,000 miles. So if you can't remember the last time you checked or replaced your spark plugs, then it probably means that an inspection is due.

Checking to See if You Should Change Your Spark Plug

This a simple task that takes less than 10 minutes and can be done with simple hand tools. As the car ages, the tolerances between the engine parts like piston and cylinder become greater, this is just a fact. As these gaps increase, so does the amount of oil that can leak into the cylinder, which is detrimental to the overall life of the spark plug. You may have heard the term "fouled plug" before. If you're not sure, or have no idea what that means, it's when some sort of deposit, usually carbon, is interfering with the spark plug's ability create spark, adversely affecting your vehicle's performance. This can be felt as a misfire, or a general lack of performance.

Changing the Spark Plug

With the spark plug out, you'll be able to tell what's going on in your engine by "reading the plugs." You'll be able to tell if your car is running rich or lean, or if you have excess oil entering into the cylinders. There are several web pages that can help you diagnose why your spark plug looks the way it does. In the old days, you'd have to adjust what's known as the spark plug gap. Not so anymore; most cars built recently do not need this done. They will run perfectly fine with the spark plugs installed straight out of the box. It's not a bad idea to spend a few extra dollars and buy a quality spark plug at your local parts store. Quality spark plugs produce a better spark, thereby increasing the fuel economy and performance of your car.

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