How Long Does It Take to Change Spark Plugs? (Expert Answered)

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On my first day as a mechanic attempting to change spark plugs, it took me several hours or at least more than an hour—I can’t recall exactly. I had trouble locating the spark plugs and figuring out how to loosen them, making the task all the more difficult.

It may sound crazy but I was tightening the spark plug instead of losing it. Thank goodness, this was my first experience changing spark plugs on cars but for generators, it depends on the model you’re dealing with. 

I acknowledge that everyone who is changing their spark plug also goes through this same process, but some prefer taking their car or generator to a professional for help. 

In that case, they would like to know the exact time it takes for them to change their spark plug, whether they intend to do it themselves or if they want to invite a professional for assistance. 

Therefore, in this blog post, I will explain to you the factors contributing to changing spark plugs, how long it takes to change a spark plug, how often you should change your spark plug, the best type of spark plug you should go for and the estimated cost of changing a spark plug. 

Let’s get started! 

Factors Affecting Time-Changing Spark Plugs

how long does it take to change spark plug
Image of a man holding a fouled spark plug in his hand.

There are a lot of factors affecting the time you change your spark plug. Some of these factors include engine type, accessibility, experience level, and complications. Let me explain better!

Engine Type

Firstly, the type of engine you want to change its spark plugs for matters a lot. That is to say, the number and arrangement of cylinders in an engine can have a significant impact on the time it takes you to change spark plugs. 

For instance, four-cylinder engines, which are typically found in smaller cars, generally have a more spacious engine bay, allowing for easier access to spark plugs. 

This translates to a quicker replacement time compared to those using V6 or V8 engines, which may have spark plugs nestled away in tight corners or obscured by other parts in the engine. Just like cars, generators can also vary in difficulty depending on their design, such as the Honda 2200i generator

Conversely, some generators do provide easy access to the spark plug for easy changing, while others may require you to remove the panel of the generator or maneuver around bulky parts before you can access the spark plug.

Accessibility

Secondly, apart from the engine time, you are not also allowed to access the engine spark plug fast, which can also affect the time change of your spark plug. Most times, spark plugs are usually located at the head of the cylinder, which can be buried deep in the engine bay.

Apart from the spark plug buried in the engine bay, how the engine parts are tightened can be a real challenge when it comes to changing your spark plug. In most cases, a mechanic might need to remove the air intake components, coil packs, or even brackets just to get enough clearance to reach the spark plugs.

This extra disassembly adds significant time to the process. Furthermore, the wiring harness and other hoses or lines might be routed in a way that makes it difficult to access the spark plugs.

In these situations, you might need to carefully unplug connectors or gently move the components aside to create a working space. While some engine designs offer good clearance around the spark plugs, others can be quite cramped, turning a seemingly simple task into a time-consuming one.

Experience Level

As I mentioned in the introduction of this article, I found it easier to change my spark plug this time around compared to the first time I tried. This applies even to someone new to the task.

This is because, over the years, I have worked with various types of vehicles, generators, and engine setups, which has given me the experience I need to work in tight spaces, remove parts efficiently, and deal with unexpected challenges.

Furthermore, I have also perfected my skills over time, unlike someone new to repairing engines. This enables me to work quickly without compromising precision. 

Additionally, I have all the necessary tools at my disposal and know how to use them effectively, which is not the case for someone with less experience. 

Unexpected Complicated

Even the smoothest spark plug change can hit a snag. Seized spark plugs, for instance, can be a real problem for you, requiring extra time and patience to coax them out without damaging the threads in the engine head. In these cases, a special tool called a spark plug extractor might be what you need. 

Additionally, broken spark plug wires can also derail the process, potentially leading to the replacement of the entire wire set, which adds extra time and expenses to the job.

Furthermore, stripped threads are another complication that can significantly extend the repair time. I have encountered this in many cases. If the threads in the spark plug hole are damaged, a thread insert might be needed to create a secure fit for the new spark plug. In the worst scenario, the cylinder head itself might require machining to repair the threads, which is also time-consuming.

ALSO READ: Reasons Why Your Spark Plug Tips Are White: The Best Way to Fix It

How Long Does It Take to Change a Spark Plug?

HOW LONG DOES IT TAKE TO CHANGE SPARK PLUG
Image of a man changing his vehicle spark plug with spark plug extractor.

Now that we have understood the factors affecting the time, let’s talk about the time duration for changing spark plugs. So, here is a breakdown of how long it might take to change spark plugs under different circumstances.

Ideal scenario (4-cylinder engine, easy access, experienced mechanic)

First, we have the ideal scenario where everything is perfect. If you are a mechanic working on a well-maintained 4-cylinder car or a similarly designed generator with plenty of space to reach and you have done it countless times before and know exactly what to expect,. 

In this perfect scenario, you can swiftly replace the spark plugs and get back on the road, or back to using your generator, in a flash. If this is a scenario you find yourself in, you can easily change your spark plugs between 30 minutes and 1 hour.

Average scenario (including some complications)

In this scenario, things often aren’t perfect like in the first scenario. In this case, you might be with a car that has a cramped engine bay, a V6 engine with spark plugs tucked in a corner, or an obstruction before accessing the spark plug. 

Trust me, these aren’t insurmountable challenges but they do add some time to the spark plug-changing processes. This is because you might need to remove some components to create a working space or you might encounter a spark plug that’s a bit stubborn to remove, which in most cases is a normal phenomenon for mechanics. 

In these scenarios, it’s expected that you spend at least 1 to 2 hours on the spark plug change as a result of the extra time it took to deal with the unexpected hurdles that show up during the job. 

Worst-case scenario (difficult access, seized plugs)

As it says, the worst-case scenario is accompanied by a lot of hurdles you can’t think of, such as seized plugs, difficulty accessing the spark plug, worn spark plug thread, damaged cylinder head, and many more.

Let’s say you have a car known for its tight engine spaces or a generator with a poorly designed spark plug placement. To top it off, you also encounter seized spark plugs that require extra effort and patience to remove without damaging the engine.

If you found yourself in this scenario, the job might take more than 2 hours, unlike others, because of the challenges you are facing. If this is the first time, I will recommend you consider seeking help from a professional mechanic or a generator repair specialist at this point.

For a better understanding of the time range to change your spark plug, this table summarizes all I’ve said in the paragraphs above. 

Scenarios Reasons Duration 
Ideal Scenario The perfect kind without any hurdles.30 minutes to 1 hour
Average ScenarioAverage is perfect with hurdles like stuck spark plugs, limited space to remove the spark plug, etc.1 hour to 2 hours
Worst-Case Scenario Worst case as a result of the damaged spark plug, worn spark plug thread, damaged cylinder head, and many more. 2 hours until you are done changing the spark plugs.

ALSO READ: Why Is Spark Plug Covered in Oil? Common Causes of Spark Plug Oil Fouling

How Often Should You Change Your Spark Plug?

man holding burnt spark plugs
A man holding burnt spark plugs that need changing.

I have always advised my readers on how important the spark plug is to the function of your engine, whether you are using a vehicle or a generator, if they don’t want their engine to break down when they need it the most.

Just like every other component that can be damaged at any time, spark plugs can also wear out or become fouled, leading the engine to misfire, not start, reduced acceleration, and rough idling, which are signs that it might be time for you to replace your engine’s spark plug. 

There’s no actual timeline on how often you should replace your engine’s spark plug. In short, every manufacturer has a different timeline for spark plug replacement, but as a general guideline, automotive experts suggest changing spark plugs every 30,000 to 100,000 miles for vehicles and every 100 to 150 hours of use, or at least once a year for generators.

ALSO READ: Oil in Spark Plug Holes: Causes, Symptoms, and Solutions

The Best Type of Spark Plug You Should Go For 

For every engine manufactured, there’s a recommended spark plug for that engine in the owner’s manual, and if you can’t find yours, you should consult with a professional mechanic. 

There are 3 types of spark plugs: the copper spark plugs, the platinum spark plugs, and the iridium spark plugs. 

For a standard copper spark plug, they are budget-friendly and more affordable. However, keep in mind that this kind of spark plug wears out faster than the rest and does need frequent replacement compared to them.

Unlike the copper spark plugs, the platinum and iridium spark plugs are usually the best and most recommended by manufacturers for their durability and performance, although they may be more costly than you can imagine. 

Based on my experience, for vehicles that are performance-oriented, the iridium and platinum spark plugs are a good choice for you. Apart from being costlier than their counterparts, they tend to boost longer lifespans, improved efficiency, and a more reliable spark under high-performance conditions.

However, generators typically require spark plugs with specific gap sizes, which you can only find in your owner’s manual. However, if you can’t find your way around your manual, you can check out my previous articles where I talk about spark plug gaps

ALSO READ: How To Fix Black Spark Plugs in 7 Easy Ways

How Much Does It Cost to Change Your Spark Plug?

HOW-LONG-DOES-IT-TAKE-TO-CHANGE-A-SPARK-PLUG

Okay, let me put it like this: Spark plugs are very important to the engine, right? Especially for petroleum or gas engines, if there’s no spark plug or a better one, the engine won’t start at all. Just like the human body, when one part is affected, the whole body feels the heat, so we need to always take care of our body. The same goes for your engine. 

There’s a need for you to constantly repair or replace any part of your engine that wears out. For both cars and generators, the biggest factor influencing cost is the spark plug itself. 

Standard copper spark plugs are the most affordable option, just like what I said earlier; they typically range from $2 to $5 each. So if you are budget-minded, they are a good choice for them but know that their bad side includes you frequently replacing the spark plugs.

Iridium and platinum spark plugs offer a longer lifespan and better performance, but one thing about these spark plugs is that they have a higher price tag, costing from $5 to $30 per spark plug. 

Apart from the cost of spark plugs, the number of spark plugs in your generator or vehicle has also played a critical role in determining the cost of changing your spark plugs. For instance, cars typically have 4 to 6 spark plugs, while v8 engines might have 8. Generators usually only have 1 spark plug, which means that the more spark plugs, the higher the overall part cost will be.

Additionally, the labor cost also has its part to play, especially if you are not into DIY (do it yourself). The mechanic or generator specialist will charge you for their time to replace the spark plugs. Depending on your location, the shop rate could, in total, cost you between $40 and $200 per hour. 

On a general note, for both generators and vehicles, it is not just about the spark plug price tag but also about who does the job and how tricky it is to get it done depending on how long it takes. 

ALSO READ: Generator Repair Cost Estimation: How Much Does it Cost to Repair Generator?

Final Thought

Changing spark plugs is one of the easiest things you can do for your generator or vehicle, and at the same time, it might also be the hardest if you do not have any experience with the whole process. 


While the normal duration, according to my experience, of changing spark plugs for both vehicles and generators is between 30 minutes and 1 hour, it’s important that you also consider other factors that might hinder you from replacing the spark plug in time.

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