Many people do simple maintenance on their own cars. Not only is regular maintenance important, but it can save you a lot of trouble and money in the long run. Aside from changing the oil and filters, there are a few more wear items that need to be replaced often. Spark plugs are amongst these parts and in most cases, it’s a straightforward job that doesn’t require a lot of time. Unless you end up with a broken spark plug in the cylinder head. This is where things get complicated.

In this article, we’ll go through some of the most common things that cause damage to spark plugs, what can be done if you experience a broken spark plug, and the procedure of how to extract a broken spark plug.

Article updated on 12/03/21. Original publishing date 05/18/16.

What Causes a Spark Plug to Break?

There are a couple of reasons why a spark plug breaks when you try to remove it from the engine. In most cases, human error is to blame. That being said, a broken spark plug can mean there’s another issue with the engine that you might not know of just yet.

When it comes to human error, the most common reason why you have a broken spark plug is overtightening. Each vehicle has precise specifications when it comes to tightening spark plugs.

When torque is exceeded, it’s far more likely that you’ll have a broken spark plug once you try to replace it during regular maintenance. When not enough torque is applied, you’ll likely notice misfire or uneven idling of your car. This is why it’s important to use proper tools such as a torque wrench when working on your car, even if you’re doing simple maintenance such as replacing spark plugs.

Dirty threads usually occur if there was previous engine damage where the gasket was leaking coolant to the engine. It’s a fairly uncommon cause for broken spark plugs, but it is possible to overlook.

If coolant reached the spark plugs and wasn’t cleaned off from the cylinder head properly, it can seize up the spark plugs and cause them to break when trying to remove them.

Another reason for a broken spark plug is that it wasn’t replaced recently. The longer the spark plug sits in the cylinder head, the more it gets glued to the thread due to constant differences in hot and cold. Spark plugs should be replaced every 30,000 miles or sooner if you notice any issues. It’s important to choose manufacturer-recommended spark plugs for your vehicle.

Symptoms Of Bad Spark Plugs

When it comes to the symptoms of bad spark plugs, there are a couple you should look for. They include:

• Your car won’t start or is struggling to start
• You notice rough or uneven idling
• Misfiring
• Increased fuel consumption
• Lack of power when accelerating

What Happens When a Spark Plug Breaks?

A few scenarios are possible when it comes to a broken spark plug. The least dangerous scenario is that the plug breaks above the nut used to torque the spark plug. We’ve written a separate piece on the anatomy of a spark plug, which can come in handy for this guide. Unfortunately, this rarely happens.

What is much more likely is a breakpoint right under the nut, leaving the thread and electrode in the cylinder head. At that moment, removing the rest of the spark plug becomes pretty difficult and will likely result in the need to remove the cylinder head as well.

If the broken spark plug gets shattered, especially the ceramic part, under no circumstances should you try to start your engine. This can instantly cause irreversible damage and instead of just removing the cylinder head, you’ll need to rebuild the entire motor.

How to Extract a Broken Spark Plug

Because a broken spark plug is something a lot of people experience, we’ll go through the process of extracting a broken spark plug from the cylinder head. You’ll need an easy out tool and a lot of patience.

If you’re not afraid to tinker around the engine, and you want to save some money on labor, here’s what you’ll need to do.

Knock Out The Inner Parts Of The Spark Plug

If and when you have a broken spark plug in your engine, the first thing you’ll need to do is to break the remaining insulator from the plug. This is done by brute force. You’ll need a hammer and a long punch or a screwdriver.

When you start working the spark plug, the inner part will start breaking off. The problem is that the debris will end up in the engine itself, which means you’ll have more work cleaning all the debris.

Install The Easy Out Tool

Before trying to jam in the easy out tool to the broken spark plug, make sure you soak the spark plug with penetrating oil and let it sit for a few minutes. Penetrating oil will help you remove the broken spark plug with less trouble.

There are two types of easy out tools – a spiral cut or square cut tool. We recommend using the square cut easy out tool because it’s less likely you’ll expand the spark plug shell more than you should.

By using a hammer, you should lightly tap the easy out tool into the hole. Once you feel the easy out tool is pushed deep enough, it’s time to try and remove the broken spark plug. When hammering the easy out tool, make sure you don’t overdo it because you can also break the tool and at this point, you’ll need to take the cylinder head to professionals to take care of the issue.

Slowly Try To Remove The Broken Spark Plug

When you have the easy out tool properly placed, it’s time to attach a socket wrench and try to remove the broken spark plug by turning it counter-clockwise. Make sure the easy out tool is sitting correctly, so it won’t slip the moment you try to remove the spark plug.

Depending on how stuck the broken spark plug is, just using a socket wrench wouldn’t let you apply enough force to nudge out the spark plug from the chamber.

In our specific case, just attaching a socket wrench to the easy out tool wasn’t possible. We had to get creative to attach the socket wrench, so we welded two 3/8” sockets together end to end in order to use the socket wrench to remove the broken spark plug.

If you feel that you need to apply more force to remove the spark plug, you can use a breaker bar to have some more leverage. Using a heat gun can also help to remove the stuck spark plug, but make sure not to overheat the cylinder head and cause additional damage.

We ended up having to use ½” drive breaker bar and a lot of force before we could remove the broken spark plug from the cylinder head.

When the threads start turning, this means you’ll be successful in removing the broken spark plug from the cylinder head. Some say that blowing compressed air in will clear all the debris, but we recommend removing the cylinder head to make sure every single piece is out, making sure no additional damage will occur.

On this photo, you can see our home-made adapter we used to remove the broken spark plug with a spiral easy out tool.

How To Find OEM Spark Plugs For Your Car?

If you own an older car, it would be amazing to have a manual that came with the car. The manual usually includes codes of OEM parts, and you’ll be able to find information about original spark plugs that came with the car, and of course, information about how to replace them. Many owners down have car manuals, so searching the internet is the only option.

Either way, it’s worth doing the research to find the perfect spark plugs that will make your car work perfectly. But where to find the spark plugs for European cars?

Here at eEuroparts.com, we offer a wide variety of genuine OEM spark plugs for European vehicles as well as other parts you’ll need for regular maintenance. Visit our store today and find all the parts you need to make your car perfect!