Glow Plugs: Essential Components for Diesel Engines

Spark plugs are the top-most essentials for gasoline-powered engines. They initiate the combustion of fuels at the engine. Now, if you have a diesel truck, you might wonder about the number of spark plugs you need.

To answer the question quickly, a diesel truck doesn’t require spark plugs. Engines of the diesel trucks typically inject the atomized fuel into the cylinder. While inside the cylinder, ignition is initiated by the engine’s compression that heats the air-fuel mixture.

Spark Plugs play no role in diesel truck engines; therefore, you don’t need any for your truck. Instead, the diesel truck engines use glow plugs for combustion. Every engine cylinder should have one glow plug. For example, if your truck has a 6-cylinder diesel engine, it means that you should have six glow plugs.

With that in mind, let’s get deep to understand better how spark plugs work and how they’re made different from glow plugs.

What is a Spark Plug?

A spark plug is the combustion element for gasoline-powered engines. One spark plug is usually found in each of the engine cylinders. Therefore, if you have a six-cylinder vehicle, its engine should have six spark plugs.

Uniform electric sparks at the car’s engine are produced by the engine firing each spark plug in an orderly manner. The spark plugs are meant to create a spark to start the combustion of the fuel-air mixture. It’s the common cause of small explosions heard inside the engine’s valves. The explosion is the one that forces the engine’s piston downwards and creates energy that makes the car move forward.

Diesel engines tend to operate in a different mechanism compared to gasoline engines. They don’t need the spark; rather, they heavily rely on the heat drawn from the glow plugs. Glow plugs are similar to spark plugs in size and shape, but each serve through a different mechanism. Diesel fuel needs pressure for ignition. Therefore, the heat for fuel-air combustion is produced from pressure exerted by the glow plug, which is later transformed to heat.

What is a Glow Plug?

A glow plug is a heating component found in diesel engines. As stated above, each engine cylinder should have only one glow plug.

When you want to start a diesel engine, air needs to flow from the intake pump to be compressed. When the piston is raised, pressure increases, making the diesel fuel mix with air. Eventually, when the intense pressure causes too much heat, the mixture ignites.

Under warm conditions, combustion from diesel engines happens without the help of a plug. When it’s cold, it’s difficult for the diesel-air mixture to burn down. Significant heat is needed to help in the ignition process. Such heat is derived from the glow plugs.

Diesel trucks need glow plugs for a quick start. The same heating device helps in maintaining the engine at optimal temperatures for the vehicle to function effectively. Glow plugs are set to operate through three phases.

First, the pre-heating step ensures that it’s easy for the engine to start. Secondly, temperature maintenance helps in maintaining the ideal combustion condition for the engines. Lastly, the post-heating phase maintains the engine’s heat after the combustion process, and the vehicle can now move.

Types of Glow Plugs

Several considerations must be taken into account when selecting glow plugs for your car. Hot, medium and cold plugs are the three main types. When acquiring new glow plugs, consider the proportion of nitro, the engine type, the engine size, and the acceleration.

Three types of glow plugs include:

PSG (Pressure Sensor Glow Plugs)

These plugs include an embedded pressure sensor that can help your engine run more efficiently. The sensor sends data to the engine control unit about cylinder pressure.

PSG plugs can help you start your car in the cold and save money on gas. They’re also helpful for cutting your vehicle’s emissions.

• Steel Glow Plugs

Steel plug is also efficient and reliable like PSG. However, they tend to take slightly longer to start. Luckily, you will not go through the same problem with the same Steel glow plug in extreme cold.

• CPG (Ceramic Glow Plugs)

Ceramic glow plugs are heated up quickly. In addition, it’s also easy for them to reach higher temperatures than the steel and pressure sensor glow plugs.

Since the Ceramic glow plugs heat up faster, your vehicle is likely to start up quickly, even in the coldest conditions. When you use the Ceramic glow plugs, the diesel fuel undergoes optimal combustion giving more efficiency to your truck.

How Often Should You Change the Glow Plugs of your Truck?

To enjoy the peak performance of your truck, you need to consider doing routine changes to the glow plugs. Replacing the glow plugs is quite easy and inexpensive. It’s recommended that after every 12,000 miles, you should turn your vehicle in for the inspection of the glow plugs.

Notably, different vehicles have specific maintenance schedules. Therefore, you need to consult the owner’s manual to know the appropriate time for servicing and maintenance of your vehicle.

Most glow plugs last for an average of approximately 100,000 miles. When you decide to replace the damaged plugs, you should also replace the other plugs in the engine even if they are still working. The tip ensures that the cylinder is working at its best from all edges.

Trouble Shooting the Glow plugs

If you have a problem with starting your truck, the main culprit that might be causing the problem is the plug. Here are some of the things that you should look out to know whether the glow plugs are malfunctioning:

• Activated car warning lights might indicate glow plug problems.
• Damaged plugs can cause vehicle misfiring.
• Glow plug difficulties can occur in vehicles that cannot accelerate or have insufficient power.
• Glow plug failure is the cause of poor fuel economy.
• Glow plugs that aren’t working properly might result in poor fuel economy.
• Plug failures are a common cause of diesel knocking noises.
• Smoke coming from your engine might indicate a problem with your glow plugs.
• Your car won’t start, especially if it’s chilly outside.

Finally, you now have some insights into how diesel engines work. As the diesel truck driver, you don’t need a spark plug; instead, you need the glow plug.