How to clean a spark plug

Spark plugs are a life source for your car’s engine and it is crucial to keep them in top shape at all times. If your engine won’t start, a dirty spark plug can be one of the possible causes. 

As such, you need to clean these essential components in your car regularly to keep them working. On average, a set of spark plugs will offer you around 20k to 30k miles but by cleaning them, you can add a couple thousands of miles to them. 

So, just how do you clean a spark plug?... This is where we come in! 

There are various ways to clean your car’s spark plugs and this post will tell you how to do just that!

How Do Spark Plugs Get Dirty

Before we get to the finer details of cleaning a spark plug, you need to understand how it gets dirty in the first place! There are multiple reasons for this, one of them being a gas-to-air ratio that’s too rich. This usually happens as a consequence of a wrong carburetor setting.

Another reason for a dirty spark plug is damaged valve seals that allow engine oil to leak and find its way into the combustion chambers. Prolonged periods of idleness cause the spark plug to operate at a temperature that is not sufficiently high to burn the air-fuel mixture.

Over time, the spark plugs start to accumulate oil or carbon deposits that get them dirty. Although you need to replace your spark plugs once they've run the course of their lifespan, sometimes you may not have a new plug around. In such a case, cleaning and firing the tip of your old spark plug will come in quite handy.

This should be able to get your car engine roaring as usual!

Cleaning a Spark Plug

So, the next time your car’s spark plugs require maintenance, following the guide below:

Removing the Spark Plugs

Step 1: Disconnect the Negative Terminal

Locate the car battery, which is usually either in the trunk or engine case (you can consult the vehicle’s manual if you’re having trouble finding it). Go to the negative terminal (this features a (-) sign on it), loosen and slide off the bolt holding the cable to the battery’s terminal.

Remember to tuck the cable away so that it doesn’t connect to the terminal by accident!

Cleaning the plug

Step 2: Find the Plugs

The spark plug wires are thick cables that run from the car’s ignition coils, ending up at the top of the engine. These will lead you to the openings in the cylinder head. Here, you’ll notice one cable and one plug for each engine cylinder. If it’s taking you too long to find the spark plugs, you can always consult the car manual.

Step 3: Remove Any Dirt on the Spark Plugs

Once you have located the spark plugs, you must first get rid of all the dust and dirt so that they don’t find their way into the cylinders when you remove the plugs. You can do this using compressed air so that any dirt and loose material is blown off completely. 

Step 4: Disconnect the Plugs

Disconnect the wires on each spark plug one at a time. This will prevent any confusion when you refit the plugs later. Hold the cable low and firmly, and pull it off the plug. If you pull too high on the cable, you could easily separate the inside of the cable from its plug connector.

Step 5: Unscrew with a Spark Plug Socket

Take a spark plug socket and put it on the end of an extension before connecting it to your ratchet. Place the socket over the plug then unscrew it by twisting the socket in an anti-clockwise direction. When you feel that it’s loose enough, you can finish the job using your hands. 

Before pulling out the plug, be sure to look around for any objects to avoid the risk of contaminating the engine with such. 

Cleaning the Spark Plugs

Cleaning your vehicle’s spark plugs can be done in multiple ways. Let us look at a few methods you can use to achieve this:

Cleaning with a Blow Torch

The first method of cleaning your spark plugs features the use of a blow torch. Use a  pair of pliers to hold the plug as it can get extremely hot. Make sure the pliers are long enough so that your hands are a safe distance from the heat. Grip the plug with the pliers but do this gently so as not to damage it. 

We recommend to use a pair of gloves to add a layer of protection before you start the process.

Cleaning with a Blow Torch

Ignite the blow torch by turning the knob that allows the air to flow in. When the torch has ignited and starts to burn, move the end of the plug inside the flame and hold it till it turns red.

The heat will burn any deposits and dirt on the spark plug without affecting it as the plug is designed to cope with high temperatures, the same way it does inside the engine when you ignite your car. Try to rotate the plug from side to side so that the grime burns evenly and until the electrode glows red. 

Finally, remove the plug from the frame and turn off the torch once you see the electrode glowing red hot. Let it sit down for a couple of minutes before you can continue. You can wait five to ten minutes for the plugs to cool down before trying to reinstall them. 

Cleaning with Abrasives

Use 220-grit sandpaper for this method. At the end of your spark plugs, you should be able to locate the electrode (the piece of metal extending from the plug). This is usually black or discolored and it is exactly what you want to work on. Slide your sandpaper under the portion of the electrode and file it until you expose clean metal on both sides.

Remove any grime and dirt on the electrode until you feel it is clean enough. You can also use a tiny file to grind away any carbon build-up you see on the electrode. Just position the file in the gap between the electrode and the plug then move it back and forth to clean the metal.

Move to the threads on the plugs and scrub using a wire brush. There is a possibility of grime and oil build-up in the threads and this can complicate the reinstallation process. While scrubbing, make sure you do this from a perpendicular angle to the plug to remove as much gunk as possible. 

Spray the spark plugs with brake cleaner and wipe them down. You can find a can of brake cleaner in your local automobile store and this does a great job of eliminating the grime. Not only that, but it is also quite volatile and quickly vaporizes to ensure the parts dry quickly. Remember to use a clean piece of cloth to wipe off any remaining dirt on the plugs.

When you’re done with the first spark plug, move on to the next and follow the same procedure to ensure you clean them uniformly. 

Reinstalling the Spark Plugs

The first thing you need to do when reinstalling the spark plugs is to set the gap. If you can access a gap tool, this will help you correct the gap separating the plug and the electrode. Check the manufacturer’s manual to determine the accurate gap measurement for your plugs.

Electric gap

Insert the gap tool between the spark plug and the electrode sticking out to measure the gap. Pry the electrode further if you want to enhance the gap or press it closer to the plug body to reduce the gap until the right measurement is achieved.

The plug should be placed into the socket with its threads facing out. There is a rubber grommet on the socket that holds the spark plug in position as you lower it into the engine, making it easier for you to thread the plug. 

Use your hand to turn the spark plug clockwise and screw it into the engine. This will ensure that the plugs do not cross-thread, which you might not realize when you forcefully screw the plugs using a socket. 

gap opener

Once you have the spark plug screwed in as desired, you can now use the socket wrench to tighten it.

With the spark plug snugly in position, connect your ratchet so that it is tight enough. You don’t need to apply too much force on the socket; just make sure the spark plug is secure. At this point, the only thing remaining is to reconnect the spark plug cables.

Grip the plug cable by the boot and press it into the exposed end of the plug sticking from the engine. Make sure it is firmly in place, which will be confirmed when you hear a notable "pop". Finally, your plugs are now ready to be put in use again!

Final Thought

The next time your engine won’t ignite, be sure to consider dirty spark plugs as one of the possible causes. Luckily, you don't need to go to a professional if that’s the case. The guide above provides you with all the knowledge you require to clean a spark plug effectively. 

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