How to change spark plugs?

Has your vehicle been driving rough lately? Spark plugs ignite the fuel mixture within the combustion chamber, which allows your car to drive. If your spark plugs have worn out or malfunctioned then – you guessed it – you’re not going anywhere.

Given their importance to the overall function of your car, it’s a good idea to get spark plugs replaced when your vehicle manufacturer recommends. Make sure to check your owner’s manual to be sure. Most will suggest every 100,000 kilometres.

Sometimes it can be hard to tell when they were last replaced if you are not the car’s original owner. If this is the case, there may be signs of wear or problems with starting that indicate it’s time for a change.

If you’re feeling confident in tackling the change over yourself, it is possible to inspect and replace your own spark plugs. We’ve put together some handy tips to help you.

Does your car require replacement spark plugs? Natrad’s range of spark plugs caters to a huge variety of vehicles, so talk to your nearest store today.

How to change spark plugs

Depending on your car, spark plugs may be a relatively easy thing to access. This can make it feasible for you to inspect your spark plugs and change them over.

Spark plugs are usually situated at the top of the cylinder head, making them visible and simple to reach. You can tell them apart by the wires leading back to the ignition coils. If your spark plugs are not visible, it’s probably better to let a qualified professional handle the replacement.

If you have chosen to tackle the replacement yourself, some recommended tools are:

• A torque wrench
• Dielectric grease
• Anti-seize lubricant
• Spark plug socket (ideally magnetic)
• Hose ring pliers
• Gap tool

If you don’t have these tools handy, nip into your nearest Natrad today where a specialist can help. Technicians at Natrads across the country can inspect your ignition system and replace spark plugs when needed.

Failure signs and symptoms

If you’re not sure when to replace your spark plugs, look out for these signs of failure:

• Slow acceleration
• Poor fuel economy
• Rough idling
• Refusing to start or hard starting
• Misfiring

Changing your spark plugs

*Note: this process may vary depending on the vehicle.

Step 1: Clean up the work area

Firstly, make sure your car is turned off and cooled down. Secondly, remove the spark plug boot by pulling directly from the boot, not the wire. This is where hose ring pliers can come in handy if the boot is tricky to remove.

Be sure to clean the area around the spark plug before removing the spark plug itself. Using compressed air for this can be really helpful to dislodge any tough dirt or debris. Without this, it could mean debris falls into the engine.

Step 2: Unscrew the plug and inspect

Using the spark plug socket and torque wrench, unscrew the spark plug from its well by turning anticlockwise. You can then lift the plug out. Sometimes you may need an extension to gain additional leverage or easier access.

From here you can inspect the plug and see if it needs changing. Even if they are in good condition, your service manual may still recommend they be changed. This is called preventative maintenance.

Check and see if the spark plug displays any of the following:

• Cracked insulator
• Heavy corrosion or charring
• Rust or dirt
• Wearing or derivation of the plug tip

If so, it’s a good idea to change your spark plug.

Step 3: Check the gap

Some spark plugs come pre-gapped, but others don’t. It is best practice to check the gap before installation to ensure optimal performance. You can do this with a gap tool. There are several different types of gap tools depending on the kind of spark plug you have and they are pretty easy to find.

Use the gap tool to see whether the tip is the correct distance away from the electrode. You can find the correct distance in the owner’s manual of your car. Sometimes your car may have an information sticker located in the engine bay.

Be sure to make only small incremental adjustments if the gap needs to be changed. Bending the tip too far can render it useless.

Step 4: Install the new plug

Before installing, it is a good idea to check whether the particular spark plug needs anti-seize lubricant. You can check this in the owner’s manual or by contacting the specific spark plug manufacturer. Some plugs do not require anti-seize.

Secondly, you should use dielectric grease. This helps prevent fusing with the spark plug boot, prevents moisture from entering and high voltage from leaking out. As it is an insulator it is imperative to only place it on the ceramic part of the plug. Placing a small amount of dielectric grease inside the boot can also help.

Finally, install the new plug.

• Place the plug inside the well and tighten with a torque wrench. Be sure to match the manufacturer’s torque specifications.
• Place the boot back onto the spark plug until it clicks.

Repeat as necessary. And you’re done!

What next

If you’re not comfortable carrying out this process yourself, contact your nearest Natrad workshop. Natrad specialist technicians can inspect, supply and install brand new spark plugs for a large range of vehicles.