What Causes Spark Plug Electrode To Bend (List of Reasons)

What Causes Spark Plug Electrode to Bend

Just when you thought your day couldn’t get any worse, your spark plug electrode gets bent. A bent electrode can cause an engine to misfire as the spark plug gap is either too small or too big.

Before you attempt to fix the bent electrode, it is wise to find out what causes the spark plug electrode to bend. If you know the cause, you might be able to prevent it. Thus, avoiding the hassle of fixing the spark plug in the first place.

What Causes a Spark Plug to Bend – Here’s the Reasons

Here is a list of reasons why a spark plug electrode might bend. Make sure to go through all the causes to find out why your spark plug electrode is bent.

Installing the Wrong Spark Plug

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One of the major causes of having a bent spark plug electrode is using the wrong plug in your vehicle engine. You have to make sure the spark plug fits perfectly inside the engine. Not even a millimeter of measurement should be incorrect.

If the spark plug is too long or deep inside the engine, it will hit the piston/rod assembly. This physical contact with the piston will cause the electrode to bend.

It might be the major cause, but it is also very uncommon. Nowadays, everyone uses the correct spark plugs, so these plugs are unlikely to hit the piston.

Maybe Something Dropped in the Cylinder?

It sounds harsh, but this might happen during carelessness. During maintenance, when something drops and finds its way to the cylinder, it may get stuck between the spark plug and the piston.

Thus, the piston will hit the spark plug, bending the electrode right away. Remember that the electrodes are very small and narrow. This is why they get bent so easily.

If the piston contact is good, the gap between the electrodes will shrink, sometimes they might even end up touching each other. One electrode touching the other will cause major problems for the engine.

Rod Bearing Failure

Rod rod-bearing failure will cause the piston to go deeper/higher inside the cylinder. The deeper the piston gets, the higher the chance it will hit the spark plug electrode.

You might have guessed the pattern already. Due to rod bearing failure, the piston hits the electrode. Thus, causing the electrode spark plug to bend or even get smashed. You wouldn’t want a smashed spark plug electrode, would you? In this case, immediate engine repair is required.

Dropping The Spark Plug

Well, dropping the spark plug may sound laughable, but you will be surprised by the number of people who drop their plug unintentionally.

The whole body of the plug is very strong and durable, except for the electrodes. They are very fragile compared to the body.

Dropping your spark plug on the floor during installation can cause the electrode to bend or even crack. This is why it is crucial to cross-check the spark plug before installing.


It isn’t a surprise that the temperature inside the cylinder and piston is very high. During ignition, the temperature suddenly goes through the roof. This sudden temperature change can make the electrodes soft.

Due to extremely high temperatures, this softening can cause the spark plug electrodes to bend. Yes, even metal can bend under high temperatures. But, high temperature alone isn’t the culprit here. It could be that your spark plug’s heat withstanding range is too high. Meaning, it isn’t suitable for your engine.

Try using a spark plug with a lower range and colder than the previous one. You may have to play with the range and experiment before hitting the right one.

Carbon Buildup

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A big amount of carbon building up inside the combustion chamber can be a reason behind your spark plug gap getting closed. The carbon coming loose and blowing through the cylinder can close the plug’s gap.

This is pretty rare for new vehicles, but it can often happen to older vehicles without modern functions. Your engine’s throttle body can also cause something to open up, bend your electrode, and close the gap of your spark plug.


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This one is related to overheating. When detonation (explosion of air-fuel) happens inside your cylinder, it launches an overwhelming heat. Is your spark plug getting bent too often? Detonation might be the cause.

In this case, it’s likely that your spark plug is unable to handle the extremely high temperature and becomes malleable. Thus, causing the electrodes to touch each other. The pressure is so intense that it causes the plug to slam shut.

For the detonation bent spark plug, you should take your vehicle to a professional who can inspect it further. All of these reasons/causes apply to any type of spark plug like a two-stroke spark plug.


There are several reasons why a spark plug electrode gets bent. All the reasons are somewhat similar. The piston hits the plug, bending or cracking it in the process. It should give you a clear idea of what causes the spark plug electrode to bend.

Here’s a quick reminder: when you’ll see a bent spark plug electrode, it will be better to fix the problem first before replacing the spark plug. Getting a new spark plug won’t fix the problem; it will just delay it.

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