Diesel driver's headache. What are glow plugs needed for and why do they fail?

After a discharged or completely dead battery, non-functioning glow plugs are the second main reason that in winter will not allow you to start a diesel engine using the starter, even if the compression in its cylinders is normal.

In other words, when glow plugs fail, the absence of any other faults that can complicate a cold start may not be enough to start a diesel engine without problems. Sergei Boyarskikh reports.

Glow plugs: when to change, how much they cost and how to check on a diesel engine

As soon as the temperature drops to -10 °C, diesel drivers run the risk of encountering an unpleasant surprise: you turn the ignition key, and the engine treacherously shows no signs of life. According to the law of meanness, this happens at the most inopportune moment - either in the early morning before an important meeting, or at night somewhere far from civilization. Moreover, both owners of well-used and new cars may encounter this. One of the reasons why this “fiasco” occurs is glow plugs. If they are faulty, then the diesel engine may begin to “be capricious” even in very little frost, not to mention - 20 ° C. Today we’ll try to figure out how such a routine procedure as replacing glow plugs can prevent engine starting problems.

Last time, expert Andrei Trasko talked about when it is necessary to change spark plugs in an internal combustion engine and what consequences their improper operation can lead to. Today, a specialist will explain how the condition of the glow plugs affects the starting of a diesel engine and how to properly maintain them, so that in winter you don’t have to dance near the car, trying to somehow warm up the frozen fuel equipment.

— Andrey, let’s talk about a typical situation for “diesel drivers”: in the cold season, the engine is not always easy to start. What is this connected with? And what role do glow plugs play in starting a diesel engine?

— In modern cars, the difference in starting speed between a gasoline internal combustion engine and a diesel engine begins to be felt at temperatures below -10°C - this is an average figure. Unlike a positive-ignition engine, the fuel-air mixture in a diesel unit is ignited by compression. The intake air is heated in the cylinders by compression to a high temperature, approximately 700-900 °C, which leads to spontaneous combustion when fuel is injected.

Almost all features of winter starting are associated with starting the engine. Often heating alone is not enough to get it going. Without heat flow into the combustion chamber, a diesel engine does not reach the temperature required to ignite the fuel. It is at this moment that the glow plug comes to the rescue, which in a short period of time itself warms up to a high temperature - about 1000 ° C and, accordingly, heats the combustion chamber.

On modern engines, the glow plug is screwed into the cylinder head. Naturally, its main task is to generate additional energy to start the engine, but even after this, the glow plug (glow plug; note below CH) sometimes does not stop working. Thus, the glow plug not only helps the engine warm up faster, especially at low air temperatures, but also optimizes the combustion process, resulting in reduced smoke emissions and other emissions.

— What is the principle of operation of glow plugs? What types of candles are there and how do they differ from each other?

— Structurally, spark plugs and glow plugs are quite similar to each other. The fundamental difference is the presence of a heating element. The glow plug consists of elements such as an adjustment coil leading to the central electrode and a heating coil. The control coil helps maintain the operating temperature due to its properties: the higher the temperature, the higher its resistance, which in turn reduces the flow of current to the heating coil.

Depending on the material of manufacture of the heating element, inside of which the spiral is located, a distinction is made between glow plugs with a metal pin and ceramic glow plugs. In the second case, the heating element is covered with special ceramics, which allows the CH to heat up faster and reach the desired operating temperature. They have a longer service life. However, ceramic SNs are more fragile, so they should be handled very carefully. Moreover, both in the case of ceramic and pin glow plugs, a variety of shapes and sizes are possible. They are selected according to the make of the car, its year of manufacture, and engine type. If the cost of a spark plug varies from 3 to 60 rubles, then the price range for CH is on average from 9 to 100 rubles and above.

On the issue of fakes

Currently, you can often find fake glow plugs on the shelves of auto stores. They are mainly produced in China and the Russian Federation. Naturally, the quality of such products is much worse than the original ones. And, accordingly, they will not only be used for less time, but will also not meet the declared characteristics. Moreover, they can cause direct harm to the car engine. Therefore, when choosing certain glow plugs, it is necessary to use simple methods to minimize the likelihood of purchasing a counterfeit.

First of all, you need to use the services of trusted stores that have all the permits to conduct trade. It is also desirable that they have official permission from the manufacturers of certain goods to sell their original products, that is, they are their official representatives. You should not make purchases at small kiosks with a dubious reputation.

Many modern auto parts manufacturers use modern methods to protect their products using online verification. So, there are several similar methods. This may involve checking the packaging using the code on it through the manufacturer’s official website. Or scanning the QR code printed on the packaging and obtaining the relevant information on the same website of the candle manufacturer. Manufacturers are getting creative in this niche.

If you are sure that your car's engine originally had an original spark plug that failed, it makes sense to take a photo of it. This will help to visually compare the original and the product offered in the store.

Don't forget to visually check the spark plug. Its body must be of high quality, the metal must be well processed, the body must not have chips, burrs, poor-quality engraving, and so on. Same with packaging. Famous manufacturers spare no expense in producing high-quality packaging, including for their protection. The printing must be of high quality, the pictures must be clear, and there must be no errors in the product description.

Conclusion

Glow plugs are an important part of a diesel engine, and their selection must be approached with all responsibility. First of all, it is necessary to consider their dimensions so that they are suitable for a particular engine. Secondly, their type. It is better, of course, to buy ceramic glow plugs, but they are quite expensive, so it is better to install them on expensive foreign cars. In most cases, metal candles are quite suitable. As for specific brands, it all depends on the price-quality ratio, as well as the availability of certain candles in a particular region of the country, since logistics have a significant impact on availability. If you have had positive or negative experience using certain glow plugs, write about it in the comments.

Are there spark plugs in a diesel engine?

Almost every driver knows that a diesel engine does not have an ignition system like a gasoline internal combustion engine. Then the question arises of how a diesel engine starts. The answer to this question is quite simple. In order to ignite a diesel fuel mixture, it requires compression, not a spark.

The principle of operation is based on the fact that the air is heated due to strong compression, and when fuel enters it, it ignites. The problem with such a motor is that in the cold season, in order to heat the air in the cylinders, external heat is also required. It is worth noting that a diesel engine does not have spark plugs, but it does have glow plugs.

Characteristic symptoms

You should think about how to check glow plugs in a diesel engine if there are the following characteristic signs:

• The engine can be started with great difficulty.
• At idle speed, the power unit operates unevenly.
• There is a white tint in the exhaust.

If the spark plugs were changed not so long ago, this may indicate a defect on the part of the manufacturer. Otherwise, you can be sure that one of the elements is faulty. In any case, it is necessary to carry out diagnostics by visiting a service station or doing everything yourself.

It is worth considering that problems with spark plugs manifest themselves well in the cold season (autumn or winter), while in summer it is quite difficult to determine the malfunction.

Chamber heating

As everyone already knows, a gasoline engine has spark plugs. The ignition process is simple. The spark plug produces a spark that ignites the gasoline. Solar oil (diesel fuel) does not ignite from a light spark, so it was invented that the diesel would immediately enter the hot air and ignite.

The main work of a glow plug occurs in the cold season. The fact is that it heats up both the fuel and the air that enters the cylinders for compression. It really helps to start a diesel engine in the cold season.

Description of signs of malfunctions of incandescent elements

Failures of glow plugs are manifested by the following defects:

1. The engine does not want to start.
2. Uneven operation of a cold engine.
3. The appearance of white exhaust gases.

If the car owner has recently replaced all the spark plugs, then the reason may lie in a malfunction of the element due to the fault of the manufacturer. The defective part must be unscrewed and replaced with a new copy. Malfunctions of incandescent elements are most noticeable in winter. A decrease in ambient temperature causes more signs of faulty filament elements to appear.

To facilitate the dismantling process, a special diesel engine glow plug puller is used. It must be used in conjunction with a tool adapted for a square or hexagonal head.

Location

Almost everyone knows where the spark plugs are located, but the glow plugs are located depending on what brand of engine it is.

If a diesel engine consists of one auxiliary combustion chamber, then it is installed directly in this combustion chamber. If it is divided into cylinders, then it is installed in a pre-chamber or vortex chamber.

Modern engines have direct fuel injection, which means that swirl chambers are no longer installed. The glow plugs heat the cylinder itself directly.

How do they stand it?

In addition to glow plugs, one for each cylinder, the preheating system also consists of a control unit, a switching relay and a temperature sensor, but it is the glow plugs that most often fail. Why?

When starting, the tip of the candle heats up to 1000 degrees in a few seconds, and in ceramic candles - up to 1350 degrees. What material can withstand such heat indefinitely?

In addition to harsh working conditions, the service life is affected by the brand, which reflects the quality of the candles. However, even if high-quality products are used, the risk of spark plug failure increases significantly if they have worked for 80-100 thousand km.

The design of candles cannot be called complex. In general terms, this is a housing, a heating element, or - another name - a glow tube with a spiral inside, a terminal for connecting electrical wiring.

The spiral in the glow tube is tightly packed in compressed powder, which insulates the coils from short circuits and protects against vibrations. Such a device reduces to a minimum the number of reasons that lead to premature spark plug failure.

Principle of operation

Unlike conventional spark plugs, it ignites the fuel not with a spark, but with the help of a heating coil. The glow plug is started by turning the ignition key. At this time, all the relevant indicators about its operation light up on the dashboard. They start only to warm up to operating temperature, which happens in less than 4 seconds.

It is worth noting the fact that if the glow plugs are faulty, then it will be possible to start a diesel car only with a properly functioning starter. After the engine has been successfully started, electricity is still supplied to the glow plug for some time. This is necessary so that the diesel engine burns out completely without any residue. Complete combustion of the fuel ensures a quiet start of the engine, and also reduces the amount of harmful emissions into the atmosphere.

Consumer Opinions

Spark plugs NZhK If a car enthusiast can determine the parameters of the SZ thanks to the manual, then with the brand the situation is more complicated, since the range of well-known and not so well-known brands is quite large. To simplify the selection, we suggest that you familiarize yourself with consumer opinions about NLC spark plugs.

Review 1

I tried many well-known brands of spark plugs, but decided on NLC. When using them, virtually no carbon deposits are formed, the spark is stable, and its power is sufficient for normal engine starting. I have been using consumables from this manufacturer for 7 years, the main thing is to buy from trusted people so as not to buy a fake. Using them, I did not have to unscheduledly change the spark plugs; they fully served out their entire service life. I change all consumables at the same time: oil, filter, spark plug kit.

Review 2

All car enthusiasts will whine about how difficult it is to find a good set of spark plugs. There are a lot of offers on the car market, a lot of brands, but the quality almost always leaves much to be desired. In one store they offered me a set of NLCs, the seller praised it so much that I decided to buy it. To be honest, I didn’t expect any special effect. Among the advantages I can highlight is that the main electrode is made of copper for quick cooling of the spark plug, and the body is completely sealed, that is, it prevents moisture from entering. This spark plug set lasted much longer than standard spark plug sets from other manufacturers. I recommend to everyone.

Review 3

I bought a used car and decided to immediately change consumables. When I took out the spark plugs, they were in perfect order, although the owner assured me that he had not changed them for 2 years. It was a set of NLCs, I didn’t think twice about it, bought exactly the same ones and installed them on the car. The car has been running on them for six months now, the engine starts perfectly even at sub-zero temperatures, the engine does not hesitate, the car drives smoothly. The only disadvantage I see is the cost, it is higher than that of other manufacturers. I recommend this brand.

Review 4

During the planned change of spark plugs, I decided to try not the original spark plugs, but the NLC ones. I sincerely thought that this was a Japanese brand, but in the end they were made in France. This did not upset me, since I know that most brands operate all over the world and this does not affect the quality of their products. Before purchasing a spark plug kit, I familiarized myself with the manufacturer’s markings and selected products on the car market with the designation I needed. I was pleased with the result, the engine runs smoothly, does not stall, and starts in any weather.

Advantages and disadvantages

A diesel engine, like any other, has its drawbacks.

• The main one is that in winter the car takes a long time to warm up, which is why the speed qualities of the car are lost.
• The second disadvantage is the difficulty of starting the engine in winter. That's where the cons end.
• Another disadvantage is that in order to refuel the car’s tank, you will need to choose the “right” fuel, especially in winter. The fact is that diesel can be used in summer, winter and off-season.

It is worth noting that all the disadvantages of a diesel engine appear only in winter, since many diesel engines will not start without glow.

• Positive aspects include low fuel consumption, which is already cheaper than gasoline.
• The second advantage is the durability and endurance of the diesel engine.
• There is one more plus, but buyers rarely pay attention to it. This means that a diesel engine is environmentally cleaner than its gasoline counterpart.

Self-replacement

Please note that when replacing, it is advisable to immediately replace all spark plugs with new ones, regardless of their visual condition. Glow plugs are selected according to their suitability for installation on a particular type of diesel engine.

Removing protection

Glow plugs are often located at the top of the cylinder head (usually near the diesel injectors). They may not be visible if the motor is covered on top with a plastic cover or protective casing. This protection must be removed to provide access.

Disconnecting the battery terminals

Since glow plugs are an electric heating element, you will need to disconnect the negative terminal from the battery. Then the small nuts are unscrewed, which secure the tips of the high-voltage wires to the contact rods of the glow plugs. The wire connects to the top of the spark plug. This nut must be unscrewed with a wrench, and the wire itself can be moved slightly so that it does not interfere with further removal of the glow plugs.

Unscrewing glow plugs

The next step is to unscrew the spark plugs using a ratchet wrench. It is necessary to unscrew it very carefully so as not to damage the threads in the cylinder head. There is also a risk of breaking the spark plug itself, which may result in additional difficulties with subsequent drilling of the rod and restoration of the thread.

Cleaning contacts

Next, it is necessary to clean the contacts on each high-voltage wire of the glow plug from contamination. This is necessary for the new spark plugs to be fully operational after they are installed on a diesel engine. If the contact is “stuck”, then it can be removed without much difficulty using a flat-head screwdriver.

Removing dirt from spark plug holes

Separately, it is worth noting the procedure for cleaning the holes for installing candles from carbon deposits. To do this, you will need a special reamer, the length of which will allow you to effectively clean the spark plug wells. Before screwing in, the reamer must be lubricated. The specified reamer must be screwed into each hole. For the procedure, it is better to use a standard scan rather than a universal one. If this is possible, it is additionally necessary to remove deposits from the channels using compressed air.

Summary

Every interested person, after reading this article, will be able to deduce for himself several important facts. Many people did not know that a diesel engine does not have an ignition system, and now they understand why owners of diesel cars often tinker with the hood of their cars in winter.

The article also describes the pros and cons of such an engine, and how such a low level of environmental pollution is achieved.

Source

One of the best

Often, due to the wide range of spark plugs, it is not easy for car enthusiasts to make the right choice. As experts advise, it is worth taking a closer look at the following companies, which are considered one of the best:

• BRISK.
• BOSCH.
• DENSO.
• CHAMPION.
• NGK.

Moreover, almost every manufacturer has its own characteristics. This can be understood from reviews of NGK V Line spark plugs.

They are suitable for drivers who drive Volvo, BMW, Ferrari, Ford or Volkswagen. The Champion brand cooperates with equally popular car manufacturers such as Alfa Romeo, GM, Suzuki, Jaguar, Volvo.

Making the right choice

Glow plugs are selected based on the characteristics of the car engine and its electronic unit. The easiest way to search is to have the vehicle's VIN code. You can do without it, guided by the following data:

1. Make of your car;
2. Engine capacity;
3. Year of issue;
4. Body type.

Of the main characteristics of the product, you need to pay attention to the following:

• Diameter, thread pitch, and turnkey size;
• Linear size of the working part;
• Connection type. There may be two poles or one. If there is only one pole, then the spark plug is brought out onto the car body. Bipolar ones are connected to a separate wire;
• Rated voltage;
• The rate at which heating occurs. The car’s electronics are “adjusted” to a certain heating rate;
• Candle material. Coming from the previous point. Ceramic candles heat up quickly, but if the heating time, which is recorded in the control electronic unit, is, say, 25 seconds, even ceramics will be unsuitable.

In fact, in your choice you should rely on the geometry, the brand of the car manufacturer, the characteristics of the engine and the ECU. The choice of spark plug for a car whose automatic system does not have a heating sensor must be scrupulous. The situation for owners of new cars without modifications is simpler: immediately buy an OEM spare part or a close equivalent.

A brief tour of brands

As already mentioned, original candles are a priority. You will buy exactly what suits your vehicle.

You can save significantly by purchasing candles from Japanese brands Denso and NGK or German Beru. All three options are very good. We are especially pleased with NGK products - this company produces the most advanced parts for ignition systems, and a significant part of them is supplied directly to the factories of large automakers.

One cannot help but pay attention to the American company Champion and the German Bosch. These are clear winners of the “audience choice”, because their products make up the majority of the glow plug market in Russia and Ukraine.

Also, if you decide to save money, pay attention to the Danish company JP Group and the Polish Maxgear - their products are inferior to those of the above brands, but meet all quality standards. The best option for new diesel cars.