How to Clean Spark Plug Hole – Step by Step Guide

Spark plugs are essential in an engine’s smooth running, so you should keep them in clean working order. Cleaning your spark plug is an easy and quick way to keep them working optimally, but it’s also essential to find out why you often have to clean your spark plugs.

Some car owners always clean their spark plug when they notice any little oil or debris in the spark plug tube which is not the right thing to do when you find oil or debris in the spark hole. This article will show you the exact thing to do, which is cleaning the spark plug tubes and the spark plug itself. Hence, I will show you how to clean spark plug hole to get off the gunk or oil in the spark plug hole.

How to clean spark plug hole step-by-step guide

If you see oil in the plug wells when you take off the spark plugs, you may want to take it off because if it stays there for long, it will cause an engine misfire which you don’t want it to happen. Follow this guide to remove loose materials or oil from your plug wells.

how to clean spark plug hole threads

Things Needed

  • Sandpaper
  • Giant screwdriver
  • Air gun
  • Carb cleaner
  • Spark plug cleaner tool
  • A clean rag
  • Spark plug wrench
  • Extension
  • Safety glasses
  • Underhood work light

Step 1. Disconnect the negative battery terminal

You can find the car battery either in your trunk or engine bay. It looks like a rectangular plastic box with two terminals on top. Take off the negative terminal by loosening the bolt holding the cable on the terminal, and then pull it off. If you can’t find the battery, visit your owner’s manual.

Step 2. Locate the spark plugs

Find the ignition coils or high tension lead cables. (Thick wires that come from the distributor) trace the wires to track down the spark plug tubes. There will be one coil/cable and one spark plug for each cylinder.  If you’re finding it difficult to track down the spark plug tubes in your car, visit your owner’s booklet or service manual.

Step 3. Use your air gun or can air to blow out debris around the surface

Once you find the spark plug holes, the next thing you want to do is to clean all the gunk and dirt to prevent it from falling into the tubes. If it does, you’re going to get it out anyway since this article is all about how to get out the gunk in the spark plug hole. Use your air gun to blow out loose materials around the hole. Ensure you put on your safety glasses.

Step 4. Disconnect the ignition coils or lead cables one at a time

To prevent adding more debris and gunk into the spark plug holes rather than removing them, you have to remove the ignition coils one at a time. Grip the ignition coil firmly and gently pull it off by turning and pulling it.

Step 5. Use a spark plug socket to lose the spark plug

Fix the spark plug socket on an extension, and then fix your ratchet on the extension. Put the socket on the spark plug tube and break free the spark plug by turning it counter-clockwise. Once you break it free, you can take off the ratchet and unscrew it by hand.

Step 6. Clean the spark plug well with an air gun

Cleaning your spark plug hole with an air gun is the surest way to remove dirt, debris, or any loose material that finds its way into the spark plug tubes. This step requires fixing your air gun tip into the spark plug hole to send compressed air to blow out any debris and gunk inside.  Several air guns come with different tip sizes. You have to use a long tip that will get close to the bottom of the well. An extended tip will do a perfect blow job than a short one. 

Step 7. Clean the spark plug well with a screwdriver, clean rag, and carb cleaner

You can choose either the previous step or this one. If you see oil on the spark plug or ignition coil with the spark plug out of the hole, it indicates you have oil in spark plug tubes. To clean oil from the spark plug holes, you have to spray carb cleaner in the spark plug hole and then take a giant screwdriver and a clean rag and dip it into the spark plug Wells to clean off the oil in it. To avoid spraying too much carb cleaner in the spark plug tubes – spray the carb cleaner on a clean rag rather than spraying the cleaner inside the plug wells.  Do the cleaning multiple times to ensure you have thoroughly wiped out all the oil.

Note: oil in spark plug wells is abnormal, which indicates a faulty valve cover gasket. The only way to prevent oil from getting in again is by replacing the bad valve cover gasket.

Step 8. Clean your spark plugs and set the spark plug gap

After cleaning the spark plug holes, you have to clean the spark plugs with a spark plug cleaning tool, wire brush, or sandpaper. Whichever option you want to take, ensure you clean the spark plugs very well.

Visit your owner’s booklet to see the recommended measurement for your spark plug gap. Then, insert the gap tool in-between the spark plug and the plug electrode. Measure the gap, either press down the electrode or pry it till the gap matches the vehicle’s specifications. Suppose you can’t find the gap spec. for your car, visit the manufacturer’s website.

Step 9. Place the spark plug in the plug wrench facing the thread out and tighten it with a socket wrench

The spark plug wrench has a rubber grommet inside that will hold the plug, so you can easily fix back the spark plugs without closing the gap. Suppose your plug wrench does not have the rubber grommet inside. You will have to gently put the spark plug back by hand.

Snug the spark plug by hand using a socket and extension. Once you have snugged the spark plug by hand, connect your ratchet handle to tighten the spark plug properly. Ensure the spark plug is secure. However, you don’t have to over-tighten it. Overtightening can cause the spark plug to break, so only apply moderate pressure while tightening the spark plugs.

Step 10. Reinstall the ignition coils or plug wires

Grab the ignition coil or plug wire and reinstall them using the reserve process. You have to fix everything in place – including the battery terminals. Then, start your engine and allow it to run on idle so you can check out for any error.

how to clean spark plug hole without compressed air


Q: Can you put gas in the spark plug hole?

A teaspoonful of fuel in the plug well is enough to make it fire. It is generally advisable to put the gas in the intake manifold instead. Too much gas in the spark plug hole will help wash out oil on the catalyst too, but you’ll be causing severe damages to your entire engine system.

Q: Why should you vacuum around spark plugs before removing them?

It is necessary to clean the spark plug surface before removing it. This helps to prevent dirt, grime, debris, and any loose materials around the spark plug surface from getting into the spark tubes. The best way to remove these loose materials is by using canned air or air gun.

Q: Can I spray carb cleaner into the spark plug hole?

Yes, you can spray carb cleaner into spark plug tubes to dissolve hardened debris and loose materials in the well and afterward take them out using an air gun. However, I recommend spraying the carb cleaner on a clean rag, then dip it inside the plug holes rather than directly pouring the cleaner into the spark plug holes.

Q: Can you spray WD40 in the spark plug hole?

All automotive cleaners are specifically made to clean one component in your car. For instance, a brake cleaner is specifically made for cleaning brake systems, and a throttle body cleaner for the throttle. Although, some of these cleaners can work on other car components. Like WD40, you can spray it into spark plug tubes to dissolve moisture and then take them out using an air gun.

Q: How do you clean a spark plug socket?

Cleaning a spark plug socket could be difficult, especially when the socket looks so scrappy. It requires spraying a carb cleaner or engine degreasers and allow it to stay for 10 minutes, then blow it out using an air gun.

Final word

It might surprise you to know that spark plug tubes require some cleaning after hundreds of thousand miles – and yes, some really need some cleaning either due to oil in spark wells or gunk on spark plug tube threads. Cleaning the spark plug hole threads will prevent possible spark plug seizures and make the plugs a lot easier to remove when replacing them in the near future. Hence, follow this how-to clean spark plug hole guide to remove oil in the spark plug hole and prevent plug seizure.

Read More:

Osuagwu Solomon

Osuagwu Solomon is a certified mechanic with over a decade of experience in the mechanic garage, and he has over five years of experience in the writing industry. He started writing automotive articles to share his garage experience with car enthusiasts and armature mechanics. If he is not in the garage fixing challenging mechanical problems, he is writing automotive repair guides, buyer’s guides, and car and tools comparisons.

Leave a Reply

Your email address will not be published. Required fields are marked *

Recent Posts