Where To Put Dielectric Grease On Spark Plugs : A Detailed Guide

If you own a car, you might have to use a dielectric substance on the spark plug to prevent accidental short circuits or electric arcing. But do you know where to put dielectric grease on spark plugs?

Well, to put it simply, you have to apply the dielectric grease on the spark plug boots. To be specific, you should use a thin layer of dielectric on the top portion of the spark-plug boot. Plus, you can also apply dielectric on the ceramic part of the spark plug itself.

Now, if this answer doesn’t clarify this matter enough, then read on because a detailed image-based guide has also been provided below. If you consider going through this post till the very end, you will surely get a full understanding of this matter.

So, let’s dive down below right now!

Where To Put Dielectric Grease On Spark Plugs?

It’s been already said that, you will have to apply the dielectric grease in two places:

  • Inside the spark plug boot
  • On the ceramic of the spark plug itself

Now, let’s see a detailed guide on putting dielectric gel on these particular spots.

A) Applying Dielectric Into The Spark Plug Boot:

To better understand the process of how to put a dielectric on the spark plug boot, let’s see an image of it below:

Applying Dielectric Into The Spark Plug Boot
Applying Dielectric Into The Spark Plug Boot

In the above picture, focus on the “green mark” area which is the tip of the spark-plug boot. Remember, you only have to apply the dielectric gel on this particular area and not on the metal body (terminal) above it.

Now, let’s see the steps of correctly applying the dielectric material on the spark plug boot:

1. First off, you need to understand that you have to only apply the dielectric grease in a thin layer. To do that, you can use a cotton-made ear swab as a fine applicator.

2. So, go ahead and take a cotton swab and apply a small portion of dielectric on it. (See the image below for better understanding).

apply dielectric with a cotton

3. Next, put the cotton swab inside the spark plug boot. But, don’t put it too much inward to make sure it doesn’t touch the metal body inside the spark plug boot.

Remember, you must refrain from applying the dielectric material on the metal here. Otherwise, your spark plug will create a misfire or accidental spark when you start your car.

You can use the below image as your guide:

don’t apply dielectric material on the metal part

4. Finally, all you have to do now is apply the dielectric grease in a thin layer.

B) Applying Dielectric On The Spark Plug Body:

In the spark plug body, there are two major portions: a metal terminal and a ceramic portion. Here, you only have to apply a very thin dielectric layer on the ceramic part.

In addition, you must also ensure that you do not apply any dielectric on the metal part. Now, notice that “green marked” portion in the below image to get a better understanding of where you should apply the dielectric:

What Happens If You Incorrectly Apply The Dielectric?

If you mistakenly apply the dielectric grease on the metal body (terminal) of the spark plug or the metal inside the spark plug boot, it will increase the resistance of the spark plug. As a result, the flow of electricity will be hampered, and it will generate a huge amount of heat.

Consequently, you might see misfiring or accidental sparks inside the spark plug boot. Remember, an accidental misfire is the main reason what causes spark plug electrode to bend and break. So, incorrectly applying the dielectric will damage your spark plug in no time.

Is Dielectric Grease Necessary for Spark Plugs?

Many people wonder whether they need to use dielectric grease when installing spark plugs. While it is not absolutely necessary, dielectric grease can provide several benefits that make it a worthwhile addition. Dielectric grease is a non-conductive lubricant that helps to protect electrical connections from moisture, dirt, and other contaminants. When used on spark plug connections, it can help to prevent misfires and other electrical issues by ensuring a secure, moisture-free connection.

However, it’s important to note that dielectric grease should only be used in the right places. While it can be applied to the inside of the spark plug boot and the outside of the spark plug porcelain, it should never be applied to the electrode or the threads of the spark plug, as this can interfere with the spark and cause damage to the engine.

Overall, while dielectric grease is not essential for installing spark plugs, it can be a useful addition to help protect the electrical connections and prevent potential issues.

Also Read: What To Do With Old Spark Plugs : Except Recycling

Why Should I Apply The Dielectric Grease In The Spark Plug?

To understand why you have to apply the dielectric grease, you need to have a clear idea of what a spark plug does. In short, a spark plug uses high voltage electricity to create a spark flame so that the engine can start burning the fuel.

But, such a high voltage of electric flow will naturally create some electric arcing and short circuits. So, how to stop spark plug wires from arcing? Well, in this case, you have to apply dielectric substance on particular spots inside the spark plug boot and on the spark plug body.

That way, the electricity flow will be conducted in a much more controlled manner. Plus, if you apply dielectric correctly on the right spots, electricity will not get short-circuited.

Moreover, due to the heat created by the spark plug, the spark plug boot often melts and gets stuck to the spark plug ceramic. In turn, when you pull off the spark plug boot, it comes apart by tearing itself.

To prevent this, you must apply spark plug dielectric grease, which will act as a lubricant between the spark plug boot and the spark plug ceramic. So, when you pull the spark plug boot, it will come off easily without tearing.

Last Words

Well, there you have it, people. That was my take on this query, where to put dielectric grease on spark plugs? In short, you have to put dielectric gelly on the spark plug boot and the spark plug ceramic.

As you can see, applying dielectric in the spark plug boot is indeed an intricate process. Plus, it’s an extremely necessary step as well. In fact, you must do this every time you set up a new spark plug.

So, use my guide above to finish this job neatly and quickly. Best of luck! 

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