How to Clean Spark Plugs Effectively?

Spark plugs need to be cleaned after certain periods to eliminate grime, oil build-up, and dirt. Dirty spark plugs cause reoccurring problems such as slow acceleration, bad fuel usage, and deposits sitting on the cylinder head. However, is it possible to clean spark plugs, or should I get new ones? In the comprehensive article below, we have covered various methods of cleaning spark plugs the cleaning materials and described the process of re-installing spark plugs.

Before you clean a spark plug, it is vital to disconnect the spark plug from the battery by breaking the contact between the battery and the negative terminal. There are two ways of cleaning spark plugs effectively; the blow torch method and cleaning with abrasives.

How to Clean Spark Plugs Effectively

Method 1: Cleaning With Abrasives

Step 1: Remove the Spark Plug Wire and the Battery Plug by Unscrewing it

The most effective way of cleaning spark plugs while remembering where each spark plug wire connects to and to reduce the extent of debris falling into the combustion chamber is by cleaning each spark plug before proceeding to the nest spark plug. Handling all the spark plugs at once makes sit easy for you to get confused and risk materials falling into the empty spark plug hole.

Dirt and debris falling into the cylinder when the spark plug is being cleaned would cause severe damage to the engine. The battery is found on the engine bay or in the trunk. In case you have trouble finding your battery, the service manual can provide further instructions.

Detach one spark plug wire safely by pulling it away from the plug. The spark plug wires are the thick cables organized by connecting the spark plugs and the opening of the cylinder head. Again, refer to the service manual if you can’t find the spark plugs.

However, use considerate force as you could destroy the inside of the spark plug, making it stop connecting with its connector for the plug. If the spark plug wire seems complicated to remove, consider twisting it to make it lose, then pull gently.

Use a spark plug socket to remove the plug after removing the spark plug wire securely. Turn the plug in an anticlockwise direction till it gets loose, then use your hands to unscrew it. The spark plug socket is equipped with a rubber grommet that keeps the plug in place during ignition removal. Again, ensure no loose dirt or debris fall into the engine before disconnecting the spark plug.

Step 2: Clean the Spark Plug Electrode Using 220-grit Sandpaper

After you have secured the spark plug, examine the firing end or tip, which is essentially the part connected to the engine. You will see a small piece of metal poking out of the spark plug known as the electrode on the side that connects to the engine on the firing end. If the electrode looks dark, discolored, and does not resemble bare metal, you can use sandpaper to clean it. Essentially, you move the sandpaper back and forth until you get clean metal.

Additionally, check the spark plug electrode and the ceramic insulator for traces of damage or dirt. You are advised to take precautions and wear eye protection when using sandpaper due to the loose debris.

Step 3: Clean the Dirt on the Electrodes Using a File

In cases where the spark plug electrode has extreme dirt build-up and carbon deposits, and the sandpaper does not seem to deliver desired results, then you know it’s time to get a new spark plug. However, we may not replace spark plugs that often because of many financial burdens. Therefore, finish cleaning the spark plug electrode using a small file to eliminate the carbon build-up.

Step 4: Scrub the Threads With a Wire Brush

Dirt and oil build-up on the threaded portion can make it impossible to re-install them. Therefore, the solution is cleaning the threads thoroughly using a wire brush. When cleaning the spark plug threads, the wire brush should be inserted at an angle and in the same direction as the threads. This tactic helps effectively get rid of most dirt off the dirty spark plug.

Then, you should position the wire brush at a perpendicular angle to thoroughly clean the spark plug threads. However, note that the threads don’t need to be extremely clean to work efficiently. Exercise caution by wearing protective gloves when scrubbing; spark plug threads can poke your skin.

Step 5: Wash the Spark Plug With a Brake Cleaner

Brake cleaners come in handy when cleaning various car parts, such as the spark plugs. A brake cleaner makes an ideal car parts cleaner because it evaporates rapidly. In addition, brake cleaner contains compressed air that helps blow debris off services. To clean the plug and its threads, spray brake cleaner on them and wipe them clean with a clean cloth.

To be more thorough, use the brake cleaner in combination with the wire brush to remove stubborn deposits. Ensure you are thorough in wiping extra brake cleaners that may have mixed with the grease and grime.

Step 6: Re-install the Spark Plug and Carry Out the Process for the Other Plugs

Once you achieve a clean spark plug, you can replace it and reconnect the ignition coil. Using a spark plug gap tool, set the gap on the clean spark plugs before re-installing them. You can then place the clean plugs into the spark plug socket with the firing tip facing in and threads facing out.

Secure the spark plug by twisting it by hand till it’s snug. FUse a spark plug or socket wrench to tighten the spark plug. The last step involves reconnecting the spark plug wire and the spark plug.

Method 2: Using a Blow Torch

If you find the above-explained method tedious, you have no shortage of options. You can try this other method instead.

Using a Blow Torch

Step 1: Secure the Spark Plug With Pliers

For this method, you will need to hold the spark plug with pliers to prevent the heat from the blow torch from reaching your bare skin. Be careful not to use extreme force with the pliers and end up damaging your spark plugs. Note that this is a mandated safety measure, and it should be taken very seriously. However, while securing the spark plug with pliers, be gentle; otherwise, you will damage the spark plug. Let the pliers hold the plug while you clean spark plugs. A bench vice can act as a good alternative to pliers.

Step 2: Wear Gloves and Switch on the Torch

To use the propane torch, you have to first switch it on, allowing the gas to flow and get to the ignition button, where the blow torch then switches on. Ensure that your propane torch produces a blue flame for maximum effect. Ensure you put on eye protection to protect your eyes from the heat.

Step 3: Direct the Flame to the Spark Plug

A blow torch works by burning all the carbon and dirt build-up, making the spark plug ineffective. Keep rotating the spark plug until all sides are covered, and both the electrode and the tip of the plug turn glowing red hot. These high temperatures in the engine are why the spark plug is designed to survive. Depending on how hot your propane torch is, the process might be done within a few minutes. Take extra caution with fire to avoid accidents.

Step 4: Wait for the Spark Plug to Cool Down

Since the electrode and spark plug are red burning hot, it is necessary to let them cool down for a while. Once you have completed this procedure, your spark plug will be clean and will function better. Note that the spark plug may appear normal long before it has cooled down. Wait for approximately five minutes for the spark plug to be ready for reinstallation.

Step 5: Follow the Same Procedure for the Other Spark Plugs

After successfully cleaning the clean spark plug using a blowtorch, you can proceed to re-install it and connect it back to the ignition coil. It is very important to clean all spark plugs to ensure that they run at the same capacities.

Re-installing Spark Plugs

Step 1: Apply the Gap Tool to Apply the Correct Distance Between the Plug and Electrode

Refer to your service manual to confirm the exact gap measurements for your spark plug. The gap is essentially given in Millimeters. To use the gap tool, insert it between the electrode and the spark plug body. Use the gap tool to estimate the distance between the spark plug and the electrode, then adjust the electrode to close or extend the gap until it matches your car’s specifications.

By applying pressure using a gap tool, you should be able to easily adjust the electrode by squeezing it shut or opening it wider. If you find it hard to find the gap specifications, you can alternatively check the vehicle-specific repair manual.

Step 2: Re-install the Spark Plugs so That Their Threads Face Outward in Their Sockets

Make sure to properly re-install the spark plugs back into the spark plug socket. Typically, the threads and the electrodes appear on the same side, and the electrode essentially sticks out of the spark plug socket.

Step 3: Return the Spark Plug and Twist it in a Clockwise Manner

It is essential to ensure that you do not cross-thread your spark plugs if you forcefully tighten them before it sits properly in the spark plug socket. Ensure that the spark plug does not get screwed at an angle; ensure it seats evenly on the engine. Stop twisting the spark plug once it becomes snugly seated.

Step 4: Use a Socket Wrench to Tighten the Spark Plug

Upon successfully securing the spark plug into place, you should use a ratchet wrench to finish tightening it. However, do not use extreme force to tighten the spark plug.

See AlsoHow to Clean an Engine


Spark plugs are likely to get fouled after continuous use; therefore, when replacing them is not an option, you can clean them using easy methods. The spark plugs can be cleaned either with a blowtorch or with abrasives. The blow touch primarily cleans the spark plugs by burning the dirt and carbon build-up, while abrasives work to scrape off the dirt and build-up.

When it comes to cleaning spark plugs, wire brush and brake cleaning fluid are definitely the tools to go with. These methods ensure a smooth finish, leaving the spark plugs and electrodes working at an optimum level. When cleaning spark plugs, ensure that you don’t blow debris into the engine, attracting long-term engine issues. Additionally, ensure that you clean the electrode till they resemble bare metal.

This comprehensive guide will help you manage your vehicle right at home with easy-to-follow instructions. All the best.

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