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How Many Spark Plugs Does A Diesel Have

SOLVED! How Many Spark Plugs Does A Diesel Have?

Diesel engines are an important tool inside cars, trucks. This part ignites fuels such as gasoline, oil inside the combustion chamber and thereby helps the vehicles operate. Thanks to this engine, the performance of the components is many times higher than that of a conventional gasoline engine.

Not only that, many people choose to use diesel engines because of their safety and durability when using. However, there are many questions related to this department.

The most common question is How many spark plugs does diesel have?. To answer this question, let’s find out and explain this problem together.

What Are Spark Plugs?

What Are Spark Plugs


A spark plug is a part inside the ignition system. You can see the spark plug in the cylinder head inside the engines.
The internal design of the spark plug includes:

  • Connector: It is used to ignite the coil.
  • Center conductor: consists of an insulator and an outer sheath.
  • Gasket: Used to prevent electrical leakage during ignition.
  • Electrode: It is the site where ignition occurs.

Currently, on the market, there are many different types of spark plugs. Depending on the purpose of use, you can choose the types of parts you want. By far the most popular products are copper and silver as both are the best conductors of electricity.

How it works

A spark plug is an important part of the process of creating sparks inside the engine. This device has the role of creating an electric spark, helping to ignite the fuel to pass into the combustion chamber.

From there, the vehicle’s components will receive fuel and operate. In order for the internal engines to work properly, the spark plug must run continuously to recharge the fuels.

Read more: Who Makes Motorcraft Spark Plugs?

Specifically, after filling in gasoline or oil from the outside, the spark plug will receive the task of emitting an electric spark. This unit then ignites the fuel and transfers it to the engines. The process of creating sparks and burning will often happen and repeat thousands of times.

How Many Spark Plugs Does A Diesel Have?

How Many Spark Plugs Does A Diesel Have
There are many people wondering about the question, “how many spark plugs does a diesel have?”. The answer is no.

Specifically, diesel engines and gasoline engines have completely different ways of working. This type of engine does not use any spark plug but only a glow plug.

Read more: Things To Know About Ruthenium Spark Plugs

When you add a spark plug inside the diesel, that part will not work because they do not help the other engines receive fuel to conduct the normal operation. Therefore, the spark plug does not play any role inside the diesel engine.

Why Does A Diesel Engine Not Need A Spark Plug?

Why Does A Diesel Engine Not Need A Spark Plug

Diesel engines and gasoline engines work almost the same way. But these 2 engines use 2 different types of fuel. Here are the reasons why diesel engines don’t need spark plugs.

Self-ignition system

First, diesel-powered vehicles will be fueled with diesel to operate the engine.

Inside the diesel engine system, there will be a compression ignition system. Therefore, after loading fuel from the outside, the combustion chamber will automatically generate sparks and ignite those fuels.

In particular, when the machine has generated a high enough temperature, the fuel that has just been loaded will automatically ignite without ignition. Diesel oil can burn at the right temperature, so it will be injected directly into the ignition chamber, and fuel combustion will occur immediately.

Almost no effect related

Gasoline engines use gasoline as fuel, so a spark plug is needed to ignite the fuel. Unlike gasoline engines, diesel engines can only use diesel oil to operate.

Not only that, the engines all have a certain compression ratio. For gasoline, there will be a ratio of 8:1 or 10:1. Meanwhile, diesel has a ratio of 16:1 and can go up to 20:1. A high compression ratio will help fuel burn more and operate better. Thanks to such a high compression ratio, the fuel does not need a spark plug to ignite.

Not only that, diesel molecules are heavy and require pressure from the piston to ignite. So using a spark plug to ignite diesel won’t work.


What kind of diesel engine uses a spark plug?

What kind of diesel engine uses a spark plug

Because the fuel of the diesel engine can ignite itself without a spark plug, we can replace it with a glow plug. This part does not help the engine burn fuel, but it can warm the engine when the engine is idle.

If you don’t regularly use the vehicle, the internal motors will not be able to run normally in the long run as before. Therefore, you should use a glow plug to maintain the temperature inside the engine so that other parts can work properly.

What is the difference between a spark plug and a glow plug?

In general, both of these parts have the function to help the car’s engine work properly. But there are still some differences:

The spark plug has a short and large design, while the glow plug is long and thin. Specifically, it has the role of ignition to help ignite the fuel, while the glow plug can only keep the engine warm in all weather.

A glow plug works only during ignition while spark plug works continuously while the vehicle is running.

What happens if I use spark plug to diesel?

A lot of people think that using a spark plug to ignite diesel will help fuel get to the engine faster. However, this part can only be used with gasoline to generate power for the vehicle and has no effect on diesel.

So, even if you use a spark plug to ignite diesel, nothing will happen.


Each part inside the engine has a specific function to help the vehicle operate properly. However, not every device can be used in every vehicle. Hopefully, the above article has answered your questions about diesel engines and helped you choose the right parts for your vehicle.

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