replace spark plug

How To Replace The Spark Plugs In Your Car

Daniel McDonald
Daniel McDonald8 min read
How To Replace The Spark Plugs In Your Car

How To Replace The Spark Plugs In Your Car

Do you want to replace a new spark plug in your car but do not know how? This article is for you. All our fellow drivers out there do not need to worry if they need to replace a spark plug in their car.

We offer some of the most straightforward how-to guides that adequately explain how to replace old spark plugs with new ones.

Cars need regular services and maintenance to serve you longer. Spark plug replacement is one of the ways to take care of the engine's performance and overall well-being.

Plug replacement is not a difficult task, and anybody can do it at home. However, you need at least basic knowledge of what is going on under the vehicle bonnet.

Also, it would be best to gather the equipment to replace the spark plug to avoid damage or accidents.

Read on to learn when it is time to change spark plugs and the easiest way to do it at home.

What Is A Spark Plug?

The spark plug is a device that delivers electric current. It plays a vital role in the vehicle's ignition system.

It uses high voltage electricity to make a spark in a cylinder combustion chamber. A spark is created in the middle of the center and ground electrodes. The spark ignites the fuel mixture and the air in the cylinder and makes ignition.

The spark plugs create an explosion which helps the engine make power. They are small and simple devices that ignite the mixture of air and fuel and thus produce electricity. They are small and simple and have a crucial role in ignition.

Usually, durable material is used to create spark plugs. They can go a long way and make countless explosions before they need replacement. However, as time goes by, the explosions make the sparks weaker. This is the moment when you need to replace the spark plugs.

When Should You Change Spark Plugs?

All vehicle's spark plugs are created for long-term durability, so spark plug replacement is not something you will do very often. Most spark plugs need replacement every 80,000 or 100,000 miles.

Of course, if you have trouble with faulty spark plugs, replacing spark plugs as soon as possible is the best thing. Likewise, if you deal with damaged spark plugs, invest in new ones sooner to avoid further damage and pricey repairs.

Signs You Need To Replace Spark Plug

It is easy to notice when you need to change spark plugs. However, focus on the mileage first. If the car has traveled more than 80,000 miles, it probably needs a spark plug replacement.

Otherwise, you might face poor acceleration, misfires, lower gas mileage, reduced fuel efficiency, and weaker engine performance.

Signs You Need New Plugs:

  • The vehicle cannot accelerate quickly.

  • You constantly top up the fuel (more often than before).

  • The 'check engine light shows up on the dashboard.

  • The engine has trouble starting.

  • Your engine is idling roughly and loudly.

  • Your engine misfires.

  • The vehicle is loud while driving.

The Equipment You Need To Replace Spark Plug

To change spark plugs, you need to be fully equipped. Although changing spark plugs is not complicated, you need the right tools to do the job successfully.

Installing a new plug without the necessary equipment is impossible.

The Equipment (Tools, Materials, Clothes)

  • Torque wrench.

  • Brush and rag.

  • Spark plug socket, ratchet.

  • Spark plug gap gauge.

  • Rubber hose.

  • Gloves, safety glasses, long pants, a long-sleeve shirt, and closed-toe shoes.

  • Vacuum/air compressor.

  • Spark Plug gap tool.

  • Wire brush.

  • Socket wrench extension bar.

  • Spark plugs.

  • Anti-seize compound.

  • Dielectric grease.

  • Owner's manual.

How To Change Spark Plugs

Once you are sure you have all the materials and tools, you can focus on changing spark plugs.

Find A Suitable Location

Park the vehicle and turn it off. The vehicle should be in a parking space, garage, or level driveway for you to have enough space to work.

Remove the keys and let the engine cool down, putting the brake on. To avoid any burns, ensure you give the engine enough time to cool off before you start working on it. Always wear gloves.

If you are sure the engine is cooled down, you can open the hood. Next, disconnect the negative battery terminal. Find 4-8 wires that lead to the engine compartment.

Suppose your vehicle has engine covers. Remove them to get to the spark plugs. If you are unsure about the location of the spark plugs, consult the owner's manual to find the exact position. Also, check the number of plugs, the socket size, and the gap size for plugs for that particular vehicle.

Another thing to do is use an air compressor or a vacuum cleaner to clean and blow out the space around the spark plugs. Do this to prevent dirt and debris from reaching the spark plug pocket.

Finally, do not forget to wear the clothes we suggested above, such as a long-sleeve shirt, long pants, closed shoes, and safety glasses since safety comes first.

Inspect The Leads When You Change Spark Plug Wires

When you change spark plugs and wires, it is essential to label them properly and not mix them up. Beware of this since the improper installation will not let the engine work and lead to cylinder misfires.

To avoid this, label the spark plug wire or lead to retain the correct order. When the engine fires, it fires in a specific order. That is why the labeling method is so crucial. You could use masking tape to note which wires are connected with which plugs.

Make sure the leads have no cracks or any other damages.

Remove The Ignition Coil And Say Goodbye To The Old Spark Plugs

When installing new spark plugs, you first need to remove the old ones. Next, remove the spark plug boots one by one. Then, again, see if they are correctly labeled.

The boot is at the end of the plug wire and is silicone-made. Therefore, you prevent lead to damage when you pull the boot and not the wire itself.

Depress the locking tab to disconnect the ignition coil connector. Take the connector off the coil. Pull out the entire coil with the boot assembly when you remove the ignition coils.

Next, to take out the plugs, take a spark plug socket and a ratchet socket wrench (with a socket wrench extension bar). It would help if you had the spark plug socket because the spark plug will be secure when installed or removed due to its magnetic base. In addition, it speeds up the removal process.

Clean The Wire Terminal

When you remove the spark plugs in your vehicle, check the wires to see any signs of damage, wear, or cracking.

Next, check the wire terminals, and clean any dirt or debris from the terminal with a fine brush. Cleaning will not allow any foreign material to fall into the cylinder head.

Since thread damage in the cylinder head can be costly, please keep it clean and neat. It will also ensure the new plugs work as they should when you install them.

See If The Old Spark Plugs Are Old Enough

Inspect the old plugs. Are they good enough, or do they all need replacing? Each plug's center electrode needs to be even and correctly shaped. Take a spark plug gap tool. Measure the gap within the center and side electrodes.

Consult the owner's manual to determine the correct distance between two electrodes. Remove the plugs if they are old, worn, uneven, and misshapen.

Time For Newly Installed Spark Plugs

Take the spark plug gap tool to check the gaps on the new spark plugs. Before you install the new spark plugs, adjust the correct gap distance.

A little bit of anti-seize compound should be added to the plug threads. Next, take the spark plug socket and an extension bar to install the new spark plugs into the cylinder head. Hand thread them with your hands gently.

If the plugs do not thread quickly and smoothly, loosen the plug and try again. You must not cross-thread the plugs.

Next, use a torque wrench and tighten the plugs according to the manufacturer's torque specification. Be sure to gap the spark plugs properly.

Although today most spark plugs are pre-gapped, double-check the recommended setting. Finally, check the labels to attach the right boot to the correct spark plug. Remove all the tools you used and clean the area.

Lubricate The Boot

Before reinstalling the coil, add a thin coat of dialectic grease to the inside of the spark plug boot. When you add grease, the engine will not misfire as often as before, and next time you need to remove the boot, it will help you do it more leisurely.

Reinstall the hold-down bolt and the electrical connector with the ignition coil.

Test The Plugs

Time for a test! Before you close the hood, remove all the equipment you used. Next, turn on the car and test the newly installed spark plugs.

Turning on the engine will show you if you correctly installed the plug and the spark plug wire. If the engine misfires, it means the plugs were not tightened enough, or they were not installed in the correct order.

If you suspect incorrect installation, turn off the engine again, and once it has cooled down, double-check your work. Then, go over the process again and test the plugs once more. Of course, if you repeat this a couple of times and still cannot correct your mistakes, call professional help.

Regular Maintenance

Regular maintenance has a key role in the longevity of any part of the vehicle. You must take care of your vehicle if you want higher gas mileage and better engine performance. Cars need many parts replaced throughout their lifetime, which applies to plug replacements.

Each plug should be replaced according to the manufacturer's specifications, but if you notice some of the signs mentioned above, do not hesitate to replace the plug even before the book says so.

In addition, to extend the life of the spark plug wires, conduct regular maintenance. Regular repairs will prevent further damage. For example, if you notice any fluid leaks, take care of them as soon as possible because they can easily contaminate the spark plugs. Then, fix the leaks to avoid constant replacement of the spark plugs.


How Much Will I Pay If I Change Spark Plugs At Home?

If you decide to do this at home and DIY (do it yourself), you might expect to pay about $50. Since the only thing you need money for is the new parts you need, this is the cheapest way to do any vehicle repairs.

However, you need at least some basic knowledge and experience in cars before you decide to do the job yourself. Otherwise, you may end up paying much more than the initial price.

Do I Have To Disconnect The Battery When Changing Spark Plugs?

Disconnecting the battery whenever you do anything related to electrics is best. Always disconnect the battery's negative terminal before you touch anything in the hood.

First, let the car cool down, and then disconnect the battery. Disconnecting will make the process of plug replacement much easier and safer.

Why Do You Have To Use A Spark Plug Socket To Replace Plugs?

Spark plug sockets are the tools used to remove spark plugs or fit them into engines. The spark plug socket is specifically designed to loosen or tighten the plugs, so you must use it if you want to replace them correctly.

How Often Should I Replace A Spark Plug?

Always change spark plugs at about 90,000 miles. If you notice any signs and damages earlier, replace them in the same instant to avoid further costs and damages.

Final Thoughts

A car's hood has a whole system under it working together. All the parts need to be in good condition for the car to work correctly and have a long life span.

Your vehicle will take you places only if you care for it and never neglect its needs. Therefore, replacing the car's spark plugs means taking care of its most crucial firing part.

Each car misfire comes from old and damaged plugs. You can change the plugs by yourself if you follow this simple guide and if you have some basic car knowledge. Just put on the safety gloves and put your head under the hood.