Learn How To Change Spark Plugs And Save Money!

With all of the amazing components and skilled machining processes that are required to build a modern day engine. The combustion process all starts with a mixture of porcelain and metal. The spark plug is the most important piece of your car’s ignition system, it is what creates the spark to ignite the air fuel mixture to create the power to move your car. 

The spark plugs main purpose is to produce a spark to ignite the air-fuel mixture in the cylinder to produce that power. 

Despite the engineering marvel of porcelain, steel and other precious metals that are in a spark plug, engineers have not been able to prevent wear. Over time the spark plugs electrode will wear, this requires you to change the spark plugs to keep your engine running smoothly and efficiently. 

How do spark plugs work?

Through a multitude of components such as the ignition coil, ignition rotor, distributor cap, spark plug wires it is the spark plug that completes the job of creating a spark.

The end piece of the spark plug known as the electrode has a specified air gap before it reaches the ground electrode. The components I mentioned above create a large voltage and when the ignition system commands it, the voltage “jumps” over the spark plug gap and creates a spark. This spark causes the air fuel mixture to combust and force the piston downwards. 

Every time the spark plug fires it creates a small amount of wear between the two electrodes. Over time this causes the electrodes to erode. If left long enough the spark plug will not fire correctly, resulting in poor performance or possibly not firing at all. 

Spark plug with all the parts listed

This is why it is important to ensure that you change your spark plugs when required by your engine manufacturer. You can find this type of information with a google search or a good quality automotive service manual. 

How often to change spark plugs?

You need to change spark plugs between 40,000 – 100,000 miles. This is a large amount of difference but depends on the type of spark plug electrode your engine uses. 

A simple copper plug lasts about 40,000 miles while new plug materials such as platinum, iridium and even double platinum can last as long as 100,000 miles. So how will you know if your vehicle is ready for spark plug replacement?

There are many things that can happen if you do not change your spark plugs. If however, you make sure you follow the proper manufacturers recommendations on replacing your spark plugs this should never happen. 

When Should You Change Your Spark Plugs?

Putting off certain important steps in your vehicle’s maintenance schedules because of a tight budget is understandable, but replacing the spark plugs when needed should be a priority. There are many advantages to ensuring your vehicle is maintained correctly, the largest reason for me is ensuring that I am never left stranded on the side of the road. 

Symptoms of Faulty Spark Plugs

  • Sometimes, you will observe that your car’s engine doesn’t start easily anymore. It may produce a rough sound, or the acceleration might be slower, especially in cold weather.
  • Your car may have an engine misfire when the spark plugs are old or worn out. A misfire is a cylinder that is not firing correctly, misfires can cause reduced power. For example, if a four cylinder engine has one cylinder misfiring, it can reduce the power of the engine by 25%

If your engine shakes, works roughly, or exhibits reduced power, it may indicate an engine misfire. The check engine light may blink in this case.It is a good idea to consider replacing the old spark plugs with new spark plugs at such a time to fix the misfire and improve your fuel economy. 

  • The ignition coil might fail if you decide to drive your vehicle with  worn-out spark plugs. The ignition coil generates a large impulse of voltage to produce the spark. If spark plugs are worn out it causes the ignition coil to output more voltage reducing its lifespan.

Benefits Of Replacing Your Spark Plugs:

Spark plug replacement can bring about certain benefits that include the following:

  • New spark plugs keep your engine working smoothly. This will ensure that your vehicle is running as good as it was the day it left the factory. This will result in less wasted gas, less exhaust emission, and increased power.
  •  New spark plugs are your vehicle’s catalytic converter best friend. Even a single misfire can dump enough fuel into the vehicle’s exhaust that it could cause damage to the catalytic converter. A load of unburned gasoline in the combustion chamber will eventually cause a meltdown of the catalytic converter. This will result in a repair bill that far exceeds the cost of simply replacing your spark plugs. 

Tools Needed to Complete the Job

If you are concerned about the tools you will need to change the spark plugs at home, we have a complete list of spark plug replacement tools for you. Check if your toolbox is missing any essential equipment before you start!

Spark Plug Swivel Socket

The special spark plug swivel is built with the correct size to ensure that it can fit in tight places to remove the spark plugs. It can be used with an extension bar to reach hard to access spark plugs. 

Spark Plug Boot Puller Pliers

Spark Plug Boot Removal Tool removing a spark plug boot

Spark plug boots can get stuck on the plug over time. Directly pulling on the spark plug boot may cause  damage to the wires. Spark plug boot pliers will help you remove the rubber boot without causing any harm, making sure you can reuse the spark plug wires.

Spark Plug Gap Gauge

You must gap the new spark plugs according to the manufacturer’s instructions before installing them. You will find the spark plugs available for modern vehicles are come out of the box already gapped. I always suggest checking them with a automotive feeler gauge before installing them. The spark plug gap gauge is inserted between the ground electrode and the plug’s center to form the required gap.

Torque Wrench

Properly torqued spark plugs reduce the risk of major engine damage. You can use a torque wrench (or the socket wrench) to tighten the spark plugs to the correct torque without over-tightening them.

Wire Loom Spacers

Spark plugs are installed at a distance to prevent crossing over,  wire loom spacers help route the spark plug wires to get this job done. Most vehicles that need these have them already equipped in the engine bay. Just make sure you do not throw them out when you are removing the old spark plugs. 


Even a single drop of anti-seize on the spark plug threads will help prevent the plugs from sticking to the cylinder head threads permanently. Be careful, using anti-seize can affect the torque procedure. Use with caution.

Spark Plug Boot Grease

Apply a liberal amount of this dielectric boot grease before installing the spark plug boot. It protects the engine’s ignition components by preventing high-voltage flashovers.

Steps to Replacing Your Own Spark Plugs

Replacing your own spark plugs will require between 1-4 hours depending on the vehicle. It will save the hefty amount you would otherwise spend at your local garage to get this job done.

We recommend you keep your vehicle’s owner’s manual with you if you are doing it for the first time. Once you have changed a few sets of spark plugs following the correct procedure you will start to feel more confident.

Follow this specific order to to make sure that your spark plug replacement procedure goes well:

  • Remove the engine cover if equipped and label any equipment you remove from your engine when removing. Blow off ignition coil packs, spark plugs and wires to prevent dirt from falling into cylinders when removing the spark plugs.
  • Trace the location of the spark plugs, and remove the spark plug boot. If necessary use the spark plug boot pliers to remove them to prevent any damage that you may cause. 
  • Find the correct size socket and place it over the plug. Rotate to loosen, and remove.
Spark plug socket and extension removing a spark plug
  •  Use the manufacturer’s specifications to gap the new spark plugs before installation. Slide the gap gauge between the two electrodes, so the wire drags slightly between them. Open it if the gap is too small, and lightly tap the side electrode if the gap is too large. Use an anti-seize compound at this point if necessary.
  • Install the spark plug by hand into the cylinder head making sure that it goes in smoothly. If it is tight you may be cross threading the spark plug, remove and try again.
  •  Using the torque wrench and manufacturer’s spark plug torque specifications. Torque the spark plug to the correct specification.
  • Apply a thin layer of dielectric grease inside the spark plug boot before you install the spark plug wire. It makes the boot easier to remove when needed and prevents misfires. Reinstall the ignition coil as you hold down the coils electrical connector and the hold-down bolt.
  • Reinstall any removed components and the engine cover. Start up the engine and verify that the check engine light is not on and the engine is running smoothly. 
  • Crack open a nice cold beer. (This is, after all, one of the best parts of the job.)

Beginner’s Tips

Certain tips will make the spark plug replacement process a little easier in old as well as modern cars; some of them are as follows:

  • Before removing any part from the engine, you should be able to identify the engine part. 
  • Some systems have removable rubber boots and springs. You may need to retrieve them with needle-nose pliers and replace them with new parts before re-installing.
  • Keep extensions of various lengths with the swivel to help it reach the otherwise inaccessible hard to reach areas.
  • The spark plugs of most engines are not very accessible. Because of this, the more compact car engines require more force and power to get the spark plugs out. Nonetheless, all spark plugs can be removed and replaced with the right amount of cursing and tool throwing. 
  • When using an anti-seize compound on the spark plug threads make sure you torque the spark plugs correctly. Anti-seize can cause spark plugs to become torqued tighter than they should have been. 

How Much To Change Spark Plugs

The cost to replace spark plugs can change a lot depending on the vehicle and engine. Some four cylinder engines require at most 1 hour of labor and copper spark plugs will cost roughly $200-300 depending on the shops labor rate.

A V-8 engine that is equipped with two spark plugs per cylinder, a Hemi engine in a Dodge for example can cost up to $800 to complete a tune up.

Some engines also require removal of the intake manifold to gain access to change the spark plugs which can also increase the cost of how much to change spark plugs on that vehicle.

There are many things that can change the cost. If you are going to get this repair done by a mechanic make sure you get quotes from multiple locations to ensure that you are not getting taken advantage of.


While repair costs are rising daily; taking a few hours and learning how to change your spark plugs to save some extra money can really reduce your costs of owning a vehicle. 

Staff Writer
Staff Writer
Our team of staff writers goes above and beyond in creating material that our readers love. They bring unique skills to the team that always provides a fresh perspective on the automotive industry.

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