What Size Socket Is Used For Spark Plugs? (Easy 5 Step Guide)

Not sure what size socket is used for spark plugs in your engine? You're in the right place!

In this ProperMechanic.com guide, you'll learn:

  • What you need to know about spark plug sockets
  • How to assess your spark plug sockets
  • Supplies you'll need

And much more!

What Size Socket is Used for Spark Plugs?

We're here to teach you a few things you didn't know about spark plug sockets.

Servicing your spark plugs is a simple task that most people can handle without any problem. 

Most spark plugs these days are made with a 5/16"(16mm) or 13/16"(20mm) hex, and most all of them are deep sockets. 

So, before you do replace your spark plugs, I recommend you read through this guide for some additional information about what size socket to use on the spark plugs that will help you with your service.

What You Need To Know About Spark Plug Sockets

Servicing your spark plugs is an easy task when you have all the right tools. On small engines such as lawnmowers and go-karts, you might find that you can service the spark plugs with just a couple of simple hand tools. 

When servicing the spark plugs on a vehicle's engine, you will most definitely want to use a spark plug socket. You are also going to want a torque wrench for reinstalling the spark plug to perfection, and to prevent any operating problems.

A spark plug gapping tool or feeler gauges are arguably necessary to set the distance between the electrodes on your spark plug for the best results.

Although a lot of spark plugs are pre-gapped, it is a wise decision to double-check before installing brand new spark plugs.

In the case of doing professional work, you should double-check the gap no matter what if you have the tools on hand.

Did you know: If you notice your spark plug's tip is shiny it can indicate that your fuel mixture is too rich, or that your heat range is set too low.

Accessing Your Spark Plugs

To access the spark plugs on a vehicle you will have to remove the ignition coils/spark plug boots and possibly other parts like air pipes and electrical chords. You can find plenty of videos online of someone performing the repair on your specific vehicle to give you a good idea.

Servicing spark plugs is a relatively easy task, but general mechanical knowledge is recommended before digging into an engine that you care about; go to town on all those small engines. 

Empower yourself to learn more about spark plugs by reading more.

Supplies You’ll Need For Servicing Your Spark Plugs

Here are is a complete list of tools and equipment you may want when servicing the spark plugs in any engine/vehicle. 

  • spark plug socket/wrench
  • spark plug gap tool/feeler gauges
  • torque wrench
  • pliers/spark plug boot removers
  • screwdriver 
  • swivel/universal joint
  • ratchet and extension
  • anti-seize(optional)
  • basic socket set
  • flashlight
  • magnet extension(optional but always helps)

How To Choose The Right Socket For Your Spark Plugs (5 Step Guide)

  1. Can I get away with just a wrench?
  2. Find out what size spark plug your specific engine uses
  3. Locate and purchase/borrow the correct socket/socket set
  4. Decide between rubber insert or magnet style
  5. Service your spark plugs

Step 1: Can I Get Away With Just a Wrench?

Some small engines don't require a spark plug wrench; you can simply remove the spark plug wire boot and use a box-end or crescent wrench to remove the plug. But if your spark plug is deep down into the engine head of your car's engine then you are going to need a deep socket and possibly an extension.

Step 2: Find Out What Socket Size to Use

Use the internet to find out what is the appropriate size spark plug for your specific engine model and year. It shouldn't be too hard to do.

The two most common size spark plug sockets that are essential for servicing most engines are the 5/16-inch and 13/16-inch, or if we are speaking in metrics then 13 and 20 mm sockets - as you could imagine, engineers have created different sizes of spark plugs, but these two standardized sizes will get you through most projects. 

And if you come across one of those weird BMW or another design where the spark plug socket is a weird size, don't worry. Use a deep socket that isn't meant for a spark plug; just be careful not to damage the plug upon removal.

You could even use calipers to measure the bolt yourself if you are feeling ambitious!

Step 3: Locate and Purchase/Borrow the Correct Socket

Whether you decide to purchase or borrow the spark plug socket, there will also be plenty of price ranges and options.

If you are willing to wait a couple of days for shipping, then Amazon is a good marketplace for purchasing parts for your vehicle. 

Sometimes you need the part right away, and that's when you visit places like the dealership and local auto parts stores.

Do you want high-quality? Then buy a high-quality spark plug socket set.

If you are going to work on more than one vehicle in your life, then why not always have the right tool on hand? Searching for the right tool for the job can be a huge part of the wild goose chase that is engine repair.

Thinking ahead of time isn't always the most convenient option, but you will thank yourself the next time you need a spark plug socket with a good socket set.

Step 4: Decide Between Rubber Insert or Magnet Style

When you are ready to purchase the spark plug socket, you should consider the quality of your purchase.

For example, most spark plug sockets have a rubber insert that protects the ceramic insulator of the plug when installing and reinstalling, and there are even magnet style sockets that make the spark plug hard to drop and break on the ground.

It all depends on what you want. You can also try a magnet extension for successfully removing the plug from the engine.

Step 5: Remove You Spark Plugs

You are now ready to remove those spark plugs! So pull off those spark plug boot cables/coil packs, stick that spark plug socket down in there, and get ripping on that engine tune-up.

Just remember to use a torque wrench when reinstalling if you are working on something you care about. 

A quick tip:

Avoid dropping anything down into the spark plug hole while you have the spark plugs removed, and blow each hole out with compressed air before installing new spark plugs to prevent debris from knocking around inside the combustion chamber.

Now Your Spark Plugs Are Out

What's next? Inspection. Read our page about how to properly check a spark plug for proper operation.

Other Valuable Resources On Spark Plug Sockets 

Websites like Amazon have great deals on spark plugs on brands like NGK, Bosch, Autolite, and ACDelco that are great purchasing options.

Asking Google questions is the best way you can successfully navigate your situation when finding parts or working on your engine.

You would be surprised at the quantity of information you can find these days concerning simple items like spark plug sockets.

Now that you know what size socket for spark plug removal, you should be able to quickly and efficiently get the job done. And don't forget to take your time!

Preventing Fouled Spark Plugs

To successfully service your spark plugs, you must take care of any outstanding services your vehicle needs first.

For example, if the valve covers are leaking oil all over the spark plugs then the new plugs will foul again shortly after installation.

There are plenty of other reasons why your engine is misfiring, or why your spark plugs are fouling.

Don't get discouraged when you replace the plugs and the engine still isn't right; you'll find out sooner or later what the problem was because there is a reason for everything.

Read More >> How to Clean a Spark Plug

About Your Mechanic

About Ryan Nichols

Ryan here! My pro mechanic career began as a technician for Mercedes-Benz. After two years of that great experience, I went out on my own in both the automotive and construction fields. I've since pulled my share of salvage yard parts and fixed more vehicles than I can count.

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