Engine Troubleshoot

How To Remove A Stripped Spark Plug (In 7 Easy Steps)

How To Remove A Stripped Spark Plug

Removing a stripped spark plug is a delicate process that can easily go wrong if you're not careful. 

How do you remove a stripped spark plug? The best way to remove a stripped spark plug is by using a special nut extractor socket that is designed to grip the stripped spark plug nut as you turn it.

Spark plugs are notorious for getting stuck and being difficult to remove, especially if they haven't been replaced recently. 

A stripped spark plug can be difficult to grip with a pliers or standard socket wrench. This is because spark plugs are often located at the back of the engine or deep down in hard to reach areas. 

How To Remove a Stripped Spark Plug in 7 Easy Steps

It's important to use the right tool and correct procedure to remove a stripped spark plug. If the plug breaks, leaving the bottom part in the cylinder head, it makes the job much more difficult.

The two most important things that you will need are a bolt/nut extractor and some penetrant spray such as WD-40. The extractor set that I use are the Irwin Bolt Extractor Set For Deep Well Bolts (link to Amazon.com). 

These extractors have reverse spiral flutes that are designed to grip the outside of the spark plug (or any nut) as you push down and turn on the wrench. So far, I've had a 100% success rate with these extractors, and I've also used them to remove rusted sway bar bushings, so they've been well worth the investment.

Here's a video that illustrates how to remove a stripped spark plug with the Irwin bolt extractors.

When it comes to successfully removing stripped spark plugs, the secret is to take your time and be gentle.

Here is a description of the steps that should help you to remove any stripped spark plug successfully.

1. Remove any engine covers 

Before you start, remove as many engine covers and any nearby engine ancillaries such as the air filter box and hoses if they are in the way.

This will make it much easier to access the spark plugs and will ensure that you can hold the wrench at the correct angle and with the right amount of pressure. This is important to help ensure that the spark plug does not break.

2. Remove the spark plug wires 

It's also a good idea to move all of the spark plug wires to give more access to the spark plug pits.

Make sure you mark each spark plug wire as you remove them so that you can reconnect them correctly later.

3. Clean the area around the stripped spark plug

Using a slightly damp cloth, gently wipe around the the spark plug to remove any loose debris. If you have a portable vacuum cleaner with a narrow head you can use this to remove any lose dirt.

Don't be tempted to use a blower or power washer as this will damage the spark plugs and nearby engine parts.

4. Spray lots of penetrant spray and wait

This is probably the most important step in the entire process. Spray lots of penetrant (WD-40 works just fine) around the base of the spark plug where it meets the cylinder head.

Leave the penetrant to do its job for at least an hour. If you really want to increase your chances of successfully removing the spark plug, then I'd suggest leaving the penetrant fluid applied for at least 4-6 hours or even overnight. 

5. Gently attach the extractor tool

The next step is to correctly attach the extractor tool to the top part of the spark plug. It's vital that the tool is attached properly so as not to break the spark plug. 

Start by attaching the correct sized extractor tool to an extension bar. Most spark plugs require a 5/8" or 16mm socket for removal. You will need the extension bar so that the extractor can reach down to the spark plug and to allow you to attach it correctly. 

Locate the top of the spark plug and push the extractor socket gently on to the top of it. Try to stand directly over the spark plug so that you naturally apply direct downward pressure and not sideways pressure that may cause the spark plug to snap.

6. Slowly try to turn the tool anti-clockwise

Now attach the wrench handle to the top of the extension bar. Gently apply a direct downward pressure whilst turning the wrench slowly anti-clockwise.

This first turn of the wrench will allow the extractor flute to grip the spark plug and it's important that it sits square and pushed down as far as possible onto the spark plug.

7. Slowly Continue to Remove the Spark Plug

Once the spark plug has loosened from the cylinder block, then continue to turn the wrench slowly in an anti-clockwise direction whilst applying even pressure. Take your time, and keep turning the spark plug until is is completely unscrewed. 

Once the spark plus has been removed use a torch to inspect the spark plug socket in the cylinder head for damage. Before you fit the a new spark plug, clean around the opening ensuring that nothing falls into the top of the engine.

5 Tips for successfully extracting a stripped spark plug

  1. Use penetrant fluid such as standard WD-40 or a specialist penetrant such as Kano AeroKroil (Amazon.com Link). It's vital that you allow the penetrant to sit for at least an hour and don't be afraid to soak the spark plug to ensure it works.
  2. Attach the spark plug extractor carefully. It's very important the the extractor sits as far down on the spark plug as possible and is sitting squarely. You don't want to put any strain on the spark plug as this may increase the chances of it snapping.
  3. Clean around the spark plug before you start. Make sure to clean the area around the spark plug so give the extractor the best chance of gripping the damaged nut. You also want to make sure that no debris falls in to the top of the engine when the spark plug is removed.
  4. Use the correct size extractor. Most modern spark plugs need a 16mm or 5/8" socket to remove them. The Irwin extractor set has exact sized extractor for the job.
  5. Take your time. This is a delicate process that requires patience and care. Let the penetrating fluid do its job, and take care when turning the wrench so as to ensure an even pressure is applied to the spark plug.