What Does A Glow Plug Do In A Diesel Engine?

To get started, let’s start at the beginning: what is a glow plug? What is the purpose of a glow plug?

In a diesel engine, a glow plug is a heating element that warms entering fuel and air to promote efficient fuel combustion. The burning of fuel starts your engine, allowing you to drive. Your engine has one glow plug in each cylinder, either in the pre-chamber (pre-chambered engines) or in the combustion chamber (combustion chamber engines) (direct-injection engines).

  • BERU glow plugs use three-phase technology to provide maximum performance.
  • When the ignition is turned on, the first phase is pre-heating. BERU glow plugs heat up quickly to 1300°C Celsius (for Ceramic Glow Plugs) and can sustain that temperature independent of the outside temperature.
  • Post-heating is the third phase. BERU glow plugs stay hot for around 3 minutes after the engine is started. As the combustion chambers heat up, this extended glow plug operation period aids in the completion of the combustion process and the reduction of noise production.
  • Beru glow plugs are manufactured by BorgWarner, which also provides glow plugs that match original equipment (OE) manufacturer specifications, so you can be confident that you’re getting high-quality parts. Beru glow plugs account for 95% of the glow plug market in Europe for diesel cars.

Glow plug systems

The starting process of an engine has a significant impact on a vehicle’s exhaust gas values. Glow plugs and its associated components (glow plug control modules, glow plug relays, and glow plug combustion sensors) work together to reduce emissions and help safeguard the environment.

What are the symptoms of bad glow plugs?

The dashboard’s engine warning light is frequently the first indication that something is wrong. Vehicles with this light should be taken to an authorized workshop as soon as possible for a full diagnosis and service. The engine warning light might come on for a variety of reasons; we’ve outlined the signs that indicate to damaged glow plugs below.

1. A difficult start

The most common sign of damaged glow plugs is a difficult start. Without properly functioning glow plugs, the combustion chamber may not reach the proper temperature to ignite the gasoline and start the engine in cold temperatures. Glow plugs should be checked if there are no problems with the gasoline or the battery.

2. Misfiring of the engine

In diesel engines, the combustion process necessitates a high rate of compression, as well as fuel supplied at the right moment and in the right volume. The diesel fuel is ignited, resulting in combustion. Fuel quality, compression, and fuel injection difficulties can all lead to misfires.

Compression pressure and glow plug heat provide heat to the combustion chamber. For ignition to occur, it must reach a temperature of at least 450° F / 232° C. The engine chamber will not attain the requisite temperatures if the glow plugs are defective.

3. Idling in a rough manner

If one or more glow plugs have burned out, become carbon fouled, or have been damaged, the engine will become increasingly difficult to start as the temperature drops, and it will idle rough and emit white smoke from the exhaust for many minutes once it does start. Check the fuel injection timing if all of the glow plugs are burned at the tips.

4. A reduction in fuel efficiency

Fuel efficiency is usually determined by temperature and fuel, not glow plug performance. Glow plugs, on the other hand, do have a place in specific situations.

During the cold months, diesel may be combined with appropriate additives based on the local climate to lower its freezing point. The combined fuel will almost certainly be lower in energy and deliver lower fuel economy. To guarantee that all of the injected gasoline is thoroughly burned, the engine’s operating temperatures should be regulated. Glow plugs contribute to the extra heat in the combustion chamber.

The engine’s performance will be harmed if the required temperature is not attained owing to malfunctioning glow plugs, and it will have to work harder to satisfy the demands of the road. The vehicle’s fuel efficiency will suffer as a result.

If the car exhibits any of the other symptoms indicated below, as well as lower fuel efficiency, it should be sent to an authorized workshop as soon as possible for a proper diagnosis and treatment.

5. Smoke that is white

When there isn’t enough heat to burn the fuel, white smoke appears. Unburned gasoline particles escape out the tailpipe as smoke, giving off a strong fuel odor. During cold weather, white smoke from the exhaust is common until the engine has warmed up.

When an engine starts up, white smoke might be caused by damaged glow plugs or a malfunctioning glow plug control module. Low engine cranking speed, low compression, and air in the fuel system are all probable reasons of an excessive amount of white smoke. If white smoke persists after the engine has warmed up, the problem could be one or more defective injectors, delayed injection timing, or a damaged injection pump.

6. Smoke that is black in color

An imbalance in the air-fuel ratio – too much fuel and not enough air – causes black smoke. This indicates that either too much fuel is being added to the mix or not enough oxygen is being given to allow the fuel to burn. Faulty glow plugs can disrupt the delicate diesel combustion process, causing the engine to produce black smoke from the exhaust pipe. This is a warning indicator that something is wrong with the glow plugs or other important combustion components.

DENSO has been a leader in OEM automobile technology for a long time. As the world’s leading automotive component producer, we continue to invest in R&D to assist the world’s top automakers create vehicles that are more responsive, efficient, and reliable.

DENSO Aftermarket offers OEM-quality glow plugs for all makes and models. DENSO Glow Plugs provide a wide range of options, from excellent start-up performance to longer post-heating temperatures. All contemporary glow plug technologies are covered in the program, including single coil, double coil, extended post-heating, ceramic, and immediate heating.

Can you drive a diesel with a bad glow plug?

To sum up, there are a few points I’d want to emphasize. Keep in mind that glow plugs are required for some engines but not for others. They’re especially useful if you have a vehicle with a HEUI injection system, such as a 7.3L Powerstroke or a 6.0L Cummins, because those engines are difficult to start in the cold. It’s also quite acceptable to run a diesel with defective glow plugs if it starts easily. If it starts easily, then driving it will cause no damage to the engine. I sincerely hope that this little primer on glow plugs was beneficial to you and your cause. If you enjoyed it, please share it, and thank you for taking the time to read it.

Are glow plugs only used for starting?

Model engine glow plugs are not the same as those found in full-size diesel engines. Only the glow plug is used to start full-size engines. Because of the catalytic impact of the platinum wire on the methanol-base fuel they are supposed to run on, model engines employ glow plugs as an essential part of the ignition system.

In theatrical pyrotechnics and the special effects industry, model engine glow plugs are also employed as re-usable igniters to remotely ignite pyrotechnic devices using flash and smoke composition powders.

How often should you change glow plugs in a diesel engine?

Glow Plugs: How Long Do They Last? A glow plug in a diesel engine has an average life of 100,000 kilometers. As a result, it is not something you should be concerned about on a regular basis. They can, however, break before then, especially if you hard start your pickup frequently or use a lower-quality glow plug than the manufacturer recommends.

Can glow plugs cause loss of power?

Engine misfires are one of the first signs that the vehicle’s glow plugs are failing. If the glow plugs fail, they will not deliver the additional heat required for diesel combustion, which could result in misfires in the engine. Misfires can result in a reduction in power, acceleration, and even fuel efficiency.

Do glow plugs affect power?

While vehicle engines are separated into two types, diesel and gasoline engines, each has its own set of advantages and disadvantages. While we will not go through the distinctions between the two types of engines, we will focus on the diesel engine and a very prevalent problem that many diesel engine owners have or may face in the future: malfunctioning glow plugs. We’ve all experienced that moment when our engine’s performance abruptly deteriorates and we begin to despise the entire concept of a diesel engine.

What is a glow plug, exactly, before we go any further? When a diesel engine is started, it requires heat to start and maintain a constant flow of heat in order to remain running. Diesel engines employ a component known as a glow plug to do this purpose. This glow plug provides the necessary heat to keep the engine running, especially in colder climates. This heat is also transferred to and absorbed by the engine’s cylinder. In order to return this heat to the engine, the glow plug must be installed inside the vehicle’s combustion chamber. However, the glow plug will show indications of wear and tear as well as constant use. So, let’s take a look at some of the most prevalent signs that your glow plugs are bad or failing.

Black smoke from the exhaust:

This is the first indicator of a glow plug that has been damaged. If the combustion of a diesel engine is improper, the car will emit black smoke from its exhaust. The combustion process will be hampered by a damaged or incorrect glow plug. The main reason for the black smoke emitted by the exhaust is that the fuel combustion process is faulty, and the exhaust throws out all of the residual carbon.

Engine misfire:

A glow plug is required for the operation of a diesel engine, as previously stated. Unlike a petrol engine, which uses a spark plug to start the engine, a diesel engine uses a glow plug to provide a constant source of heat to keep the engine pumped up and running. This steady flow of heat will break down if the glow plug is defective.

The entire combustion process of the fuel is harmed as a result of this heat loss. As the combustion process begins to undergo momentary pauses, the vehicle’s overall operation suffers from misfires. This has an impact on the engine’s power, the vehicle’s acceleration, and its fuel efficiency. It’s all due to a malfunctioning glow plug!

Improper fuel combustion has a direct impact on vehicle performance, and by simply replacing the broken glow plug, one can extend the life of their diesel engine while also avoiding performance concerns. So, the next time you have a misfire while driving, take it to your nearest service shop to get the glow plug checked to avoid any additional issues or breakdowns.

Difficulty starting:

When the glow plugs are damaged, hard starting is a very common problem. A diesel engine, unlike a gasoline engine, requires a glow plug and chamber pressure to ignite the fuel. As a result, a diesel engine must start with equal power from the glow plug while preserving cylinder chamber pressure.

The engine puts extra load on the cylinders to start if the glow plug is damaged. This will cause the engine to start slowly. While this may appear to be a minor issue, a damaged glow plug might lead to more serious problems and breakdowns in the future. If your vehicle is having trouble starting, you should visit an expert to determine the extent of the damage and how to avoid more engine problems.

How much does it cost to replace diesel glow plugs?

If you’ve been putting off replacing your glow plugs due to the cost, you should know that glow plug replacements are rather inexpensive. A replacement glow plug might cost anywhere from $25 to $50, depending on the quality and brand.

You can save money on labor by changing the plugs yourself if you have the necessary tools. You can pay a mechanic labor cost of $90 to $200 to replace your glow plugs if you want to emphasize convenience and get the job done right.

The job could take up to two hours depending on the design of your engine and the mechanic’s expertise. The more time the project takes, the more money you’ll spend on labor.

What is the function of glow plug?

Glow plugs’ primary function is to heat the air in a diesel engine’s combustion chamber to the required temperature. There could be up to ten glow plugs in the engine, one for each cylinder.