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How To Change Spark Plugs (A Step-By-Step Guide)

January 3, 2022

Spark plugs are crucial to keeping your car running smoothly. 

They’re responsible for the electric spark that ignites the air-fuel mixture in the combustion chamber. This is why it’s important to get routine spark plug replacements.

You may be thinking, can you DIY your spark plug replacement? 
And if yes, how can you change spark plugs?

In this article, we’ll go over the detailed procedure of changing spark plugs. We’ll also look at some helpful tips when replacing spark plugs and whether you can do it on your own

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Let’s begin! 

How To Change Spark Plugs (Step-By-Step Guide)

Spark plugs need to be inspected routinely to ensure that they’re in good shape. And if you ever discover faulty plugs or find a worn-out old plug, it’s best to get a prompt replacement to avoid further damage. 

But how do you do that? 
Let’s take a look:

  1. Clean The Engine
  2. Remove The Coil On Plug And Boots
  3. Unscrew The Spark Plugs
  4. Prepare The New Spark Plugs
  5. Repair The Spark Plug Wires And Clean The Plug Threads
  6. Install The New Spark Plug

Note: If you’re not confident about handling the repairs, it’s best to let your mechanic take over. Incorrectly installed spark plugs can lead to rough idling, poor acceleration, reduced fuel economy, damage to the combustion chamber, and even cause spark plug failure. 

Step 1: Clean The Engine

The first step in getting a spark plug replacement is to prep your engine and clean it. 

Start by parking your car on a flat, dry surface. Remove the engine cover if your combustion engine has one. Let the engine cool down and clean the surface to avoid the dirt and debris getting into the engine’s cylinder head before removing the old plug.

Label any vacuum hoses that you may remove so you won’t misplace them. 

Step 2: Remove The Coil On Plug And Boots

Locate the ignition coil near the spark plug boot and disconnect it from the electrical connector by gently pulling it up. Take the electrical connector off the coil.  

Modern cars can have a COP system with a detachable rubber spark plug boot and springs. If they don’t come off with the coil, use needle-nose pliers.

If your car does not have modern spark plugs with a COP ignition system, the spark plug boot will be attached to the spark plug wire and then the plugs. In this case, you can use a spark plug wire puller to take out the spark plug boot.

Step 3: Unscrew The Spark Plugs

Finally, you need to use a spark plug socket to remove the spark plugs from the engine. 

Using the socket wrench, turn the spark plug about half an inch in a clockwise direction. You can use a small amount of penetrant liquid to loosen up the threads and wires. 

If your spark plugs seem to be stuck, gently try to work them out in a back and forth motion using the spark plug socket. Repeat the procedure for the remaining spark plugs.

If you notice consistent resistance, reach out to your mechanic for help. Using a lot of force to disconnect spark plugs can damage the threads and cost you a fortune in repairs.

Step 4: Prepare The New Spark Plugs

Once you remove your old spark plug, you’ll need to prep your engine and new spark plugs for installation. 

Start by blasting compressed air around the ignition coil to eliminate residual debris. Next, ensure that you have the right spark plugs by consulting your vehicle manual and mechanic.

One important step in spark plug maintenance is the spark plug gap
Modern spark plugs are pre-gapped, meaning that they don’t need to be gapped using a spark plug gauge when installing them. 

But if you do need to gap them, refer to the manufacturers’ manual for the specified spark plug gap

Take the help of a gap gauge and slide it between the electrodes. Adjust the ground electrode (the piece of bent metal at the end) to narrow or widen the gap as per the spark plug gap gauge. Never put pressure on the center electrode.  

Step 5: Repair The Spark Plug Wires And Clean The Plug Threads

Before you install your new spark plugs, you’ll need to repair any worn-out spark plug wire and clean the spark plug threads. Replace any old spark plug wire with new ones. Use a wire brush to clean around the wire terminal. 

Rub some anti-seize lubricant or dielectric grease along the spark plug threads. This will help the spark plug from getting stuck in the cylinder head.

Step 6: Install The New Spark Plug

Once you have your spark plug gap set, you need to install each spark plug using a torque wrench. Reinstall the ignition coil and plug wire to each spark plug.

Next, reinstall any bolts your engine may have. Make sure any necessary electrical connector and other components are reattached. Reconnect the battery if you’d disconnected it in the beginning.

So what are some things to keep in mind when replacing spark plugs

6 Tips When Changing Spark Plugs

Here are some tips to help you with spark plug replacement: 

  1. Always work with a cool and clean engine. Wait for at least 30 minutes before you handle the engine for repairs, and get rid of any debris with the help of compressed air. 
  1. Never downgrade spark plugs. If your car came with a long-life plug or iridium spark plug, stick to them. 
  1. Additionally, always speak to your mechanic before upgrading your plugs
  1. When handling any spark plug wire, do not rush. The threads are very delicate and can easily get disconnected from the combustion circuit. Use a torque wrench or a socket wrench to handle spark plugs.
  1. Do not over-tighten the spark plugs with the torque wrench or the socket wrench. Always use dielectric grease when reattaching the COP boot or plug wire boot to a new plug.
  1. Most importantly, always refer to your vehicle manual. The vehicle manual is the blueprint for all your car repairs and is your best guide to preventing unfortunate mishaps due to misplaced parts.

Having said that, is it okay to replace your spark plugs by yourself? 
Let’s find out. 

Can I Change My Car’s Spark Plugs On My Own?

It should be okay for someone with decent mechanical knowledge to replace the spark plugs on their own. However, if you’re new to this or need help, please make sure to reach out to your mechanic. 

For assistance, why not try RepairSmith
RepairSmith is a mobile auto repair and maintenance solution with a wide range of services and competitive pricing.

Remember, incorrectly installed spark plugs can cause engine damage and affect your car’s gas mileage. Your car may have trouble starting, and experience poor acceleration, rough idling, and reduced fuel economy among other problems.

Avoid any of these issues by letting our certified mechanics come to your driveway and change your spark plugs for you!

Fill out this online form for a spark plug replacement cost estimate! 

Final Thoughts

Modern spark plugs are very low maintenance. Unlike oil changes, you do not need to replace your spark plugs very often. Regular replacement schedules and routine inspections should do the trick!   

But when the time comes to switch your old spark plug for a new plug, look no further than RepairSmith! We offer convenient online booking and a 12-Month, 12,000-Miles warranty on all our repairs. 

Contact us today to get started!