How to Remove Spark Plugs That Are Stuck? – A Complete Guide

You’re in the middle of performing routine maintenance on your car but suddenly find the spark plug is refusing to come out. Frustration sets in as thoughts of expensive repairs start creeping into your mind. But don’t throw in the towel just yet, as every problem has a solution. 

So, how to remove spark plugs that are stuck? Luckily, there are several ways and tools to take out a stuck spark plug. As most common ones, you can use penetrating oil, apply leverage with a wrench, use a heat gun, or a vise grip. 

Now, the question still remains about how to establish the whole process efficiently, right? Don’t worry. Take a deep breath and stay with us till the end to arm yourself with expert advice on handling these sticky situations in detail. 

Read also: How To Fix Car Shakes After Ignition Coil Replacement: A Step-By-Step Guide

What causes spark plugs to be stuck?

Have you ever wondered why spark plugs won’t come out or be stuck inside the chamber? Before we step on how to deal with a stuck spark plug, it’s wise to put your attention on the root causes of the issue. Maybe this will help you to be more vigilant. So, let’s see. 


One of the most common causes of stuck spark plugs is corrosion. Over time, the metal components of the engine can be exposed to moisture and elements in the air that can lead to rusting. This rusting process is known as corrosion and can affect the threads of the spark plug, causing it to become stuck in its socket.

Corrosion occurs when a chemical reaction takes place between metals and their environment. In this case, when moisture contacts the metal parts of the spark plug, it reacts with them and forms oxide compounds. These compounds build up over time, making it difficult to remove the spark plug without damaging or breaking it.

Carbon Buildup

Carbon buildup is a common issue that can affect the performance of spark plugs, causing them to become stuck. This carbon buildup occurs when traces of fuel and oil create a residue on the electrodes, blocking the spark needed for combustion. 

While carbon buildup is usually caused by normal wear and tear over time, there are other factors that can exacerbate this problem. One such factor is using low-quality fuel or oil. Impurities in these substances can increase the rate at which carbon accumulates on the spark plugs. 

Additionally, short trips or excessive idling can contribute to carbon buildup as they prevent the engine from reaching optimal operating temperatures. This leads to incomplete combustion and more residue being deposited on the electrodes.

Heat Cycling

Heat cycling is a crucial factor that can cause spark plugs to become stuck. This process refers to the extreme temperature fluctuations experienced by the engine during operation. 

As the engine heats up and cools down, the metal components expand and contract, creating stress on various parts, including the spark plugs. Over time, these repeated expansions and contractions can lead to thermal cycling fatigue.

Thermal cycling fatigue occurs when materials are subjected to repetitive temperature changes, causing them to weaken over time. The repeated heating and cooling of the engine’s cylinders eventually takes a toll on the spark plug threads. 

As they go through cycles of expansion and contraction, microscopic cracks may develop in the threads’ surface, resulting in reduced strength and increased friction between the threads and cylinder head.

Over-tightening or Cross-Threaded Installation

Over-tightening or cross-threaded installation can cause spark plugs to become stuck in the engine. Over-tightening occurs when too much pressure is applied during installation, causing the threads on the spark plug and in the cylinder head to bind together tightly. This can make it difficult to remove the spark plug without damaging the threads.

Cross-threaded installation, on the other hand, happens when the spark plug is not correctly aligned with the threads in the cylinder head during installation. As a result, instead of smoothly sliding into place, the spark plug’s threads can become misaligned or stripped. This makes it challenging to remove later on.

Oil Deposition

In certain instances, the spark plug may be situated in an environment where a significant oil buildup is observed. Particularly when located adjacent to the valve cover, the spark plug can become coated with oil residue. 

As the day progresses, this oil accumulation gradually solidifies and ultimately results in what is commonly referred to as an oil-fouled spark plug. The presence of this hardened oil coating on the spark plug makes its removal a formidable task, requiring additional effort and expertise.

Common Tools and Necessary Items Used in Stuck Spark Plug Removal 

As you’re not bound to follow a single method to take out a stuck spark plug, the tools and necessary items can vary. However, below are the standard tools and items that can be used in the removal process. 

  • Penetrating oil
  • ⅜ inch ratchet
  • Never-seez
  • 2 to 6-inch extension
  • Spark plug socket wrench
  • ⅜ inch breaker bar
  • 2-inch length of pipe
  • Turpentine

How to Remove Spark Plugs That Are Stuck?

As we mentioned in the beginning, there are various methods to take out a stuck spark plug. However, not all methods will be equally effective or feasible at a given time. 

So, based on the availability of tools, elements, your skill, and ease of work, you have to decide which method is suitable for you. Let’s explore all these methods in detail. 

Method 1: Using Penetrating Oil

The most common and convenient method to remove a stuck spark plug is using penetrating oil. This handy substance has the ability to seep into tight spaces and break down the rust or corrosion that may be causing the plug to become stuck. It works by lubricating the area and reducing friction, making it easier for you to remove the plug without damaging your engine.

One popular type of penetrating oil is WD-40, which can be found in almost any hardware store. Simply spray a small amount onto the stuck spark plug and let it sit for a few minutes. 

The oil will work its way into any crevices or gaps, loosening any rust or debris that may have accumulated over time. As it sits, try using a proper socket wrench with an extension bar to turn and gently remove the spark plug.

Another alternative you can use is PB Blaster, which is specifically designed as a penetrating catalyst. This product contains special solvents that penetrate through rust and corrosion while simultaneously breaking down harsh residues like carbon deposits. It’s important to note that these products are flammable, so exercise caution when working near hot engine parts.

Method 2: Heating the Spark Plug

Heating the spark plug can expand the metal and break the bond between the threads, making it easier to unscrew. One method of heating the spark plug is using a blowtorch. Apply heat directly to the spark plug body for 10–15 seconds, ensuring you don’t overheat and damage any surrounding parts.

Another effective way to heat the spark plug is by using an induction heater. This innovative tool uses electromagnetic fields to generate heat within metallic objects without direct contact. 

Place an induction coil around the stuck spark plug and let it do its magic. The advantage of using an induction heater is that it heats only the desired area while keeping everything else cool, minimizing potential damage.

Both methods are highly effective for removing stuck spark plugs but require caution. Always ensure you work in a well-ventilated area and follow safety guidelines when handling open flames or electrical equipment. Remember that excessive heat can cause damage, so take your time and be patient throughout this process.

Method 3: Applying leverage with a wrench

Applying leverage with a wrench can be an effective method. This technique allows you to use the rotational force the wrench provides to loosen the plug from its position. 

Choose a wrench that fits snugly over the spark plug’s hexagonal nut. Once in place, apply steady pressure and turn the wrench counterclockwise with gentle but firm force.

It’s important to remember not to rush this process or exert excessive force, as it could potentially damage the spark plug or even break it off inside the engine. If you encounter resistance, stop and assess the situation before proceeding further. 

Sometimes, penetrating oil on the threads can help lubricate and loosen any stubborn debris causing resistance. Additionally, short bursts of force instead of sustained pressure can often be more effective in gradually loosening a stuck spark plug.

Method 4: Tapping with a rubber mallet

Sometimes, a little brute force is needed to loosen a stubborn spark plug when all else fails. One method worth trying is tapping the spark plug gently with a rubber mallet. The idea behind this technique is that the impact created by the mallet can help break any corrosion or rust that may be causing the plug to stick.

To use this method, spray some penetrating oil around the base of the stuck spark plug and let it sit for a few minutes. This will help lubricate and loosen any debris or grime that may be jamming it in place. 

Next, take your rubber mallet and give the top of the spark plug an assertive tap. Be careful not to hit it too hard, as you don’t want to damage anything, but at the same time, make sure you’re providing enough force to try to dislodge it.

Remember that safety should always come first when working on your vehicle’s engine. Be cautious not to hit other nearby components while tapping with the rubber mallet, as you could cause further damage. 

Method 5: Use A Vise-Grip

In dire circumstances where all other alternatives have been exhausted, employing a vise grip becomes an option worth considering for detaching a firmly lodged spark plug. One can exert enough force to unscrew it from its position within the engine by firmly clamping onto the spark plug’s body.

To start, manage a pair of vise grips with large jaws, a socket wrench, and an extension bar. Gently position the vise grip around the body of the stuck spark plug while ensuring a firm hold without over-tightening it; maintain enough pressure for stability but not so much that you risk damaging or breaking anything further.

With a swift yet controlled motion, turn the vise grip counterclockwise. Remember that steady pressure and continuous movement are preferable over exerting sudden force.

Cautions While Dealing with A Stuck Spark Plug

When faced with a stuck spark plug, there are several important cautions to remember. Being patient and employing these cautions ensures a safer approach when dealing with stubbornly seized spark plugs, reducing risks of damaging components and facilitating smoother removal procedures even in challenging situations. 

  • Ensure the engine is cooled down completely before starting the removal procedure. This reduces the risk of burns from hot engine parts and minimizes the potential for thermal expansion, further complicating the removal task. 
  • Gently spray penetrating oil around the base of the spark plug before starting any removal attempts, as it helps lubricate and loosen any built-up debris or rust that might be causing the plug to stick. 
  • Use appropriate tools during the removal process. Choose a high-quality spark plug socket and ratchet that fits well with the size of your spark plugs. 
  • Avoid excessive force or makeshift tools that may increase the risk of breaking off fragments within the cylinder head.
  • Do not overtighten or wrench too forcefully on stubborn plugs, as this could damage threads or break off parts inside the cylinder head.
  • Consider rotating (to break free) and turning counterclockwise slowly to release any thread binding gradually. While turning counterclockwise, maintain even pressure and carefully monitor resistance levels.

How Do I Keep My Spark Plug From Sticking To The Socket?

We often hear a common saying: “Prevention is the best solution.” Before you find yourself in a frustrating situation like dealing with a stubborn spark, it’s good to take preventive measures early on. So, keep the following tips in mind. 

Choose the Right Spark Plug

Selecting the right spark plug, one that is the correct size and of high quality is of utmost importance when it comes to the car engine. Opting for an inappropriate spark plug can lead to various complications, including plugs getting stuck. 

It is essential to verify that the spark plug gaps are correctly positioned. An excessively large or small gap can result in ignition problems.

Keep the Spark Plug and the Socket Clean

Make sure that both the spark plug and socket are clean and in proper working condition before attempting to install or remove them. Besides, ensure that the spark plug and socket are dry before connecting them. 

Apply Dielectric Grease

Dielectric grease is a basic mixture of oil and silica filler, possessing strong hydrophobic properties that effectively block moisture and hinder the occurrence of corrosion. 

It’s used as an insulator or dielectric in stuff like batteries, power outlets, light bulbs, and spark plugs – but people often don’t know how to use it correctly. You shouldn’t put anti-seize or lubricant on NGK spark plugs because it’s pointless and could mess things up instead.

Avoid Over-tightening

It’s important to avoid over-tightening during installation; instead, follow torque specifications specified by your vehicle manufacturer. Moreover, ensuring correct torque values are applied during installation will aid in keeping the spark plug securely in position without excessive force.

Ensure Regular Inspection

Regularly maintaining and inspecting the ignition system remains vital for smooth operation. In particular, paying attention to signs of wear or damage on the socket and replacing it when necessary can help prevent any potential sticking problems. 


How do you remove a stuck spark plug from an aluminum head?

One method is to use penetrating oil or lubricant to loosen the grip of the stuck spark plug. Applying a generous amount around the base of the plug and allowing it to soak for several minutes can work wonders. With some careful maneuvering using a socket wrench or spark plug removal tool, you may find that the plug loosens up enough for removal.

How do you remove a spark plug from a metal boot?

Applying heat to the boot can help loosen it. Use a heat gun or propane torch to warm the metal boot gently. Be careful not to overheat and damage any surrounding components. Once heated, try twisting and wiggling the boot while pulling it off the spark plug. Another method is using penetrating oil or silicone spray lubricant. 

What should I do if the spark plug still won’t come out after applying penetrating oil?

In this case, you may have to apply some rotational force while gently tapping the end of the wrench with a rubber mallet or a similar tool to help break the rust or corrosion seal.

Is there any risk of breaking the spark plug while removing it?

Yes, there is always a possibility of breaking off part of the spark plug if it’s severely corroded or overtightened. In such cases, it’s best to seek professional assistance.

Final Words

Removing a stuck spark plug might seem like a piece of cake at first glance from this guide. But hold up! Don’t get too carried away, or you’ll find yourself pulling your hair out in no time flat. If you want to make things easier on yourself, let that penetrating oil do its thing overnight. 

To be honest, not everyone can take the stuck spark plug out on their first try, and they’re stubborn little buggers. So don’t be surprised if you have to give them a few good tugs before they loosen up enough to come out.

It is imperative to approach this task with a mindset of diligence and patience, as it demands both qualities. Ultimately, armed with perseverance and the appropriate tools, you will eventually triumph in liberating your seized spark plugs.

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