Updated at: 05-03-2022 - By: micdot

The engine’s performance is directly influenced by the thread on the spark plug. As a result, you must take care of it and keep it in good working order. Furthermore, if a correction is required, it is preferable to do so as quickly as feasible. As a result, you may be wondering what steps you should take and how much time you should set aside for this. Thus, you may wonder:

What is the procedure for repairing a spark plug thread, and how much does it cost? If you’re going to get your spark plug rethreaded, you’ll need to budget at least $1000. You may also do it yourself for a fraction of the price by acquiring some basic tools. However, you must first ensure that you understand what you’re doing. Spark plugs wear out as a result of continuous use over a long period of time. As a result, it is possible for the thread to develop holes that require repair. Leaving these damages unattended could result in further degradation of your engine’s performance. As a result, taking care of these issues as soon as possible will save you money and headaches in the long run.

Repairing a spark plug thread and the associated costs are both covered in detail in this article. This way, you’ll know what to do if something like this happens to your engine, and you’ll be prepared.
Let’s get started, shall we?

How Much Does It Cost to Rethread a Spark Plug Hole?

It’s recommended to get a spark plug hole rethreaded by a professional rather than try to do it yourself. But if your spark plug needs to be repaired properly (if it was stripped with crossed and pulled-out threads), it can be expensive. If this happens, the mechanic will have to remove the engine’s head. It may sound straightforward, but it’s a lot more involved and time-consuming than you may expect. You can rapidly fix the threads with a thread repair kit. Tsp holes are bigger in this variant, as are the stainless steel thread substitutes that fit in them.

Attempting to do this without removing the head could result in irreversible damage to the cylinder from cutting new threads for the thread replacements. Repairs of this complexity can run up to $1000 on the average. It is possible to do the work yourself if you know what you’re doing.

Can You Rethread a Spark Plug?

There are various tools you can use to replace a spark plug’s threads. Insertion of a Helicoil is a common repair technique. Helicoils can be used to rethread a spark plug hole that has been damaged. Tracking old threads is another option.

You can accomplish this by purchasing a thread chase that matches the diameter of your thread. You can then wash and re-use your spark plugs after tracking down the old thread and tapping it to the proper size. Make sure you understand how to get around the spark plugs in order to avoid any future issues from developing.

How Do You Fix Spark Plug Threads?

There are two ways to correct spark plug holes: inserting a Helicoil or using a thread chaser. However, removing the cylinder head may be necessary if the damage is severe. Spark plug threads can be repaired using these simple methods:

Basic repairs

Thread repair kits or insert kits can be purchased and inserted into the spark plug hole as the initial step in fixing the hole. Thread repair kits may be found at most automobile dealerships and on Amazon.com. A chisel, a tap, and other installation tools are included in these kits. For the repair of your spark plug hole, you’ll need the following things.

Spark plug hole repairs

For starters, you should take out the spark plug to see whether there are any damaged threads therein. After that, wash the threads that are stained using the pressure tool.

In order to avoid aluminum fragmentation during retapping threads, lubricate the thread. Because aluminum fragments might cause engine harm if they get inside, lubrication is necessary. To begin cutting the replacement threads, gently insert the tap into the hole and spin it slowly and steadily. Remember that you don’t want to damage anything inside the hole, so proceed with caution. For accurate alignment while reattaching threads, use the old broken threads as a guide to cut the new threads. As you insert the tip of the tap into the spark plug pit, cut larger threads and fasten the tap in the remnants of your prior spark plug threads. Keep the new threads parallel to the broken ones to prevent them from unraveling. In addition, the new threads must be stitched over the old ones, which must be left intact. The tap should be removed from the hole in the same place it was installed after threading the entire length of the screw.

Finishing steps

The thread insert must be screwed onto the mandrel during installation and then tightened. Use the installation mandrel that came with the recoil kit to insert the new and replacement threads into the spark plug hole..

Afterwards, after withdrawing the installation tool from the hole, thoroughly clean the installation tool. Finally, put the spark plug back in its socket.

What Is the Best Spark Plug Thread Repair Kit?

When it comes to fixing spark plug threads, you may want to check out these five kits. Observe each one to see which one best meets your demands.

Helicoil 5521-4 1/4-20 Inch Coarse Thread Repair Kit

A 1/4-20mm thread repair kit is included in this package. It’s an easy-to-use kit that includes 12 inserts and a slew of instructions.

A Helicoil tap and an installation tool are also included in the package. It’s composed of high-quality materials, so you can count on it to work when you need it to. As with the other Helicoils, this one also comes packaged in carded form and is typically used to fix tapped holes.

Helicoil 5521-5 5/16-18 Inch Coarse Thread Repair Kit

Inches long, this Helicoil is 5/16-18 inches in diameter. The repair kit is easy to use and comes from China.

A complete set of instructions, a Helicoil tap, and an installation tool are included with the kit. Using such materials, you may fix tapped holes, and you can rely on their great quality. To make things even simpler, the kit is packaged in a carded format.

OEMTOOLS 25649 14mm Cylinder Head Re-threaded Kit

In order to fix your spark plug, you’ll need this 14 millimeter threading kit. You don’t need anything extra to utilize this kit, and anyone can do it. The main drawback is that it only works with aluminum-headed spark plugs.

High-quality materials are included in the repair kit, which may be used for a long time. It has a variety of inserts to fit your spark plug’s specifications. Included are the following:
Insert a 3/8″
Insert a 7/16″
a half-insert
In the third quarter, insert
A tap or reamer that functions as both. It’s worth noting that the device comes with a one-year warranty, so you won’t have to stress about anything. It’s also really compact, so you can put it in your drawers without any problems.

CalVan Tools 38900 Two Valve Ford Triton Tool Kit

Ford engine two-valve modular cylinder heads were the target of this product’s development. It’s made of high-quality materials and has an easy-to-use repair mechanism. Thus, it allows for cost-effective and speedy fixes to the threads of your spark plugs

Use this item to fix heads that have been damaged by blown-out spark plugs. To replace the shattered components, the inserts offered are bigger. Additionally, you may reuse the inserts multiple times, which saves you money in the long run.

ABN Spark Plug Thread Repair Kit

A time-saving feature of this tool is that it allows you to cut threads to mend a broken spark plug hole. It also aids in the repair of spark plug configurations, but only for those constructed of aluminum. It’s also a product that anyone can use because of how simple the directions are. A 14mm reamer with 12 points is included in the kit. It is 2.5 inches long and can be used with a 3/8-inch wrench or drive ratchet. There are four different depths of inserts included in the kit for your convenience.

Where Can You Get Your Spark Plug Thread Repaired?

If you don’t know how to fix your spark plug thread on your own, it’s always advisable to seek the advice of a professional. Spark plug thread repairs may typically be found in standard vehicle repair shops. As a result, you can take your car to a repair shop and request assistance with the threading of the spark plug.

Your spark plug would be examined by the mechanic to determine the optimum technique of repair. A lot will depend on how bad the damage is and how much work needs to be done to fix it. The cost of having it done will be higher than if you were to do the repair yourself. Even so, it’s a good approach to ensure that your engine is running smoothly and that you don’t have any future problems owing to unresolved spark plug threads.


Basically, the cost of repairing a spark plug thread depends on your negotiating style. For the tools you’ll need to repair it, you’ll just need to spend a few hundred dollars. For the greatest treatment, though, you’ll need thousands of dollars. To summarize, repairing a spark plug thread is not an easy task, but it is straightforward if you follow these instructions. Despite the fact that this may seem like a basic and uncomplicated task, if you lack the necessary skills, you should have your specialist handle it.

Repairing a spark plug hole with the help of experts can be done swiftly and professionally. Check the condition of your engine and plugs before anything else. Rethreading your plugs is as simple as following these simple steps.