When Spark Plugs Should be Changed

This short post explains when spark Plugs should be changed. If you drive a car with a petrol or gasoline engine, then you should know spark plugs are reason why fuel combusts in the first place. Without spark plug, there would be no spark. Without spark, fuel no burn. If fuel no burn, car no move.

What are the signs of bad spark plugs?

When a car is all new and dandy, its engine parts are fresh, clean, and working flawlessly. After driving several thousand kilometers, we get build up of gunk and residue of dust, carbon, and burnt fuel all around the engine. This build up is barely noticeable until it becomes noticeable in the form of engine vibration, sluggish acceleration, and increased fuel consumption. In severe cases, we may get engine knocking caused by “misfiring” of spark plugs. It feels like your car’s heart skips a beat, but in a bad way.

In the image below we have a side by side comparison of a 40 thousand kilometer old spark plug and a brand new spark plug. Notice how black and dirty the old one has gotten due to exposure to gas, emissions, and heat. At this point, the spark plug still works and produces sparks as usual. However, there is all this gunk in the way that comes in contact with the gasoline vapor and makes its burning let effective. This overall causes the engine to burn more gas than necessary. To learn more about how to minimize fuel consumption, check out this article.

When Spark Plugs Should be Changed

How do you know if spark plugs need changing?

Now that you know that in addition to oil changes, battery replacement, tire changes, and other maintenance activities, spark plugs also need replacement, be sure to do this in a timely manner.

A good time to change or replace your spark plugs is around 35,000 kilometers or 20,000 miles. By this point, the plugs would be reaching the end of their usable life.

At the 15,000 kilometer mark, it is a good idea to get your plugs cleaned. During this process they are simply unscrewed from the engine head and the black gunk buildup is scraped away till the metal parts become metallic shiny again. This extends the life of the spark plug and allows it to continue delivering a clean, fuel efficient, burn.

Additional tip when you get new plugs

While you’re getting your spark plugs changed, ask your mechanic to also clean up the throttle body of your engine. This is the part that sucks in air to mix with gasoline. This too gets all dirty with time and sneaks in micro-contaminants into your engine, affecting its performance and fuel economy. Most mechanics offer a throttle body cleaning with a spark plug replacement.

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