How do they work and why are glow plugs needed in a diesel engine?

What kind of glow plugs install in the engine? This question is often asked by owners of cars with diesel engines, regardless of the time of year. After all, replacement is necessary not only when the spark plug has already completely or partially failed, but also according to the regulations. The question of which glow plugs to install is especially pressing for car owners during the cold season, when the air temperature drops significantly.

Choosing a good glow plug starts with determining its type. They are divided into metal and ceramic. The next stage in the selection is the choice of its manufacturer. Currently, products from different brands are sold on the market, so the answer to the question of which glow plug brand is better is quite complicated. At the end of this material there is a list of popular candles, compiled on the basis of reviews of the actual use of these products found on the Internet.

Working principle and functions of a glow plug

Installation options for glow plugs The main purpose of a glow plug is to warm up the internal space of the combustion chamber.
Therefore, each cylinder has its own spark plug. Unlike gasoline engines, it does not generate a spark, but only warms up the air to start the engine. Depending on the design of the diesel engine itself, these spark plugs can be installed in various places:

• in a vortex chamber;
• in the prechamber (prechamber);
• in the combustion chamber.

When the ignition is turned on, voltage is supplied to the glow plugs from the battery. This allows the air space in the fuel injection zone to be heated to high temperatures of 850-1350°C. When heating occurs, the status indicator of the heaters (plugs) lights up on the car's dashboard.

If the indicator light goes out, this means that the required temperature has been reached and the engine can be started. After starting the power unit, the glow plugs continue the warm-up cycle until the engine coolant temperature sensor shows 75 ° C. In standard mode, this takes no more than 3 minutes from the moment the engine starts.

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The main characteristics of glow plugs are the following parameters:

• heating rate;
• heating volume;
• dimensions;
• adaptation to combustion chamber parameters.

How to start a diesel engine correctly

Diesel does not like haste - not only when driving, but also when starting. To ensure the engine starts confidently, let the glow plugs run a full cycle, and only then start turning the starter.

The glow plugs begin heating when the ignition is turned on, and their operation is indicated by a special indicator on the dashboard - a yellow spiral. The colder it is outside, the longer the glow cycle lasts. Wait until the spark plug indicator goes out before starting the engine. And in severe frost, you can do two warm-ups in a row: turn off the ignition after the first glow and immediately turn it on again to restart it. This will significantly increase your chances of a successful launch.

How to replace glow plugs?

These parts are located in the upper parts of the cylinder head. To replace, you need to disconnect the wires that are located under the head cover. Remove the wires connected directly to the spark plugs.

Then use a wrench to unscrew all the parts. You need to work carefully. After this, thoroughly clean the contacts, battery terminals, and spark plug wires. The holes into which the candles were screwed also need to be cleaned. You can use a scan for this.

After replacement, you should tighten the spark plugs, but not too much. If the tightening is tighter than necessary, the part may break during the next replacement. And this is already an expensive repair. But you shouldn’t tighten the part too loosely, as there is a risk that it will simply unscrew while moving. Now all that remains is to connect all the wires back. That's it, the replacement of diesel glow plugs has been successfully completed.

Reviews

Many car owners note that glow plugs are not expensive and do not require frequent replacement. At the same time, it is still better to purchase products in the mid-price category and take extra care of them (this applies to cleaning). Many car owners note the good quality of Japanese parts - they rarely fail.

Candle manufacturing companies are also not standing still, using new technologies that significantly increase the service life of the product. But you should definitely choose original products and not fake ones.

Checking the condition of the glow plugs

The condition of the glow plugs must be carefully monitored and changed in a timely manner, especially if the car is operated in winter (how often the car manufacturer will indicate how often to change). Firstly, before winter you need to check their performance, since even one non-working spark plug will not allow you to start the engine at sub-zero temperatures. If the check reveals one, then it is better to change the entire set, since the rest may soon fail.

There are two safe ways to check spark plugs. The first requires the participation of two people. You will need to unscrew the nozzles, after which one person will look into the wells, and the second will turn the key to the pre-start position. Working spark plugs will turn red from heating. However, this method is not suitable for everyone, because... On some engines, spark plugs are simply not visible through the injector wells.

The second way to check the serviceability of the spark plugs is with a multimeter. You need to select the circuit check mode, then touch the spark plug body with one probe and its cap with the other. If the circuit is closed, then it works, otherwise it needs to be changed.

Under normal operating conditions, glow plugs need to be changed on average once every 60 thousand km. If the machine is constantly operated under extreme conditions, then it would be a good idea to check their performance at least once a season, and change them either at frequent intervals or when they fail.

Glow plugs must be changed with caution. They are quite fragile and often break when trying to unscrew them.

If this happens, you will have to take the car to a service station or remove the cylinder head yourself to drill out the broken spark plug and cut a new thread.

Main malfunctions and their symptoms

A working spark plug ensures stable engine operation, but no matter how durable it is, various types of malfunctions inevitably arise. As some car enthusiasts note in reviews of NGK 11 spark plugs, this can be detected by a number of signs:

• The car engine does not start the first time and runs with great difficulty.
• There is an increased fuel consumption, which is accompanied by an increased content of CO and CH.
• Upon visual inspection, one of the spark plugs turns out to be wet from gasoline that has fallen on it, which indicates its malfunction.
• There is a clear “triple movement”, which is reflected in the twitching of the car while driving. This indicates that the engine is not developing full power.

Design features of various types of candles

These structures can be made of either closed ceramics or open metal. The heating element is made in the form of a spiral.

Metal pin structures have spirals: heating and adjustment. Thanks to the first, rapid heating occurs, the second serves to protect the structure from overheating.

The composition of ceramic parts is more complex:

1. Metal body.
2. Heating tube.
3. Connecting bolt and nut.
4. Adjustment spiral.
5. Ceramic filling.
6. Central electrode.
7. Threaded part.

Ceramic parts are preferred due to their ability to produce heat quickly and provide very high temperatures.

Under the influence of electric current, the coil heats up. The high temperature in the motor prevents the element from heating above 850°C; heating lasts for a short time: from 4 seconds to 2 minutes. The duration of heating is monitored by an electronic control unit, which monitors the temperature of the coolant through special sensors.

While heating continues, the control light located on the instrument panel lights up. Turning off the lamp indicates that the engine is completely ready to start.

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?

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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.

Which glow plugs are best to buy?

This section provides a list of glow plugs that are best to buy for your car in order to ensure not only normal heating of the fuel before starting, but also to be sure of their durability. It is worth noting that the list is not of a commercial nature and does not endorse any of the brands featured on it. The rating is based on reviews of their operation that were found on the Internet.

NGK

The Japanese company NGK Spark Plug Co., Ltd is the world's leading manufacturer of glow plugs for various types of automotive equipment. NGK glow plugs are designed to operate in the lowest temperatures, so they can be used even in the extreme north. The advantages of NGK candles include:

• the company's many years of experience in the production of glow plugs for a wide variety of equipment, and constant updating of the assortment due to new developments;
• the company produces glow plugs for more than 260 models of European automobiles (which is about 86% of the market);
• the highest quality of manufacture and operation of NGK spark plugs;
• unique design of the spark plug body, which implies the use of a protective layer against corrosion, effective heat transfer, gas-tight seal, housing strength, high resistance to deformation, high reliability;
• production of various types of candles, including those with a metal rod and ceramic high-temperature glow plugs, capable of developing a temperature of +1350°C, which the candle reaches in two seconds.

Reviews and tests found on the Internet suggest that, in fact, NGK glow plugs are one of the leaders in this market. They have extremely high performance characteristics. However, they have two disadvantages. The first is the high price. However, in many ways it is justified, since the candles are guaranteed to work reliably and for a long time. The second disadvantage is the large number of counterfeit products. Accordingly, you must carefully check the product before purchasing.

What to look for when choosing

In order to answer the question of which glow plugs are best for diesel, you need to decide on what characteristics you need to make your choice. There are several criteria.

Material of manufacture

Comparison of the glow of metal and ceramic glow plugs

Currently, glow plugs are divided into two main classes based on the material used. The most common and cheapest are metal ones, they are also called pin ones. They have a metal shell made of a resistant alloy of iron, chromium and nickel. Their heating element is insulated from the body with thermally conductive powder (usually magnesium oxide). This material not only insulates the spiral, but also reliably protects it from harmful vibrations that can mechanically damage it.

Another type of glow plugs are the so-called ceramic ones. Their heater is made of a refractory ceramic alloy, which is capable of withstanding operation at maximum temperatures for a long time while maintaining the specified performance characteristics. Their protective shell is made of silicon nitrite. This is a ceramic material that has extremely high thermal conductivity. The design of the ceramic candle allows it to warm up to operating temperature in a record time - about 2 seconds. Thus, the driver can often start the engine immediately without waiting for a warm-up time.

Interestingly, only ceramic glow plugs meet the requirements of Euro-5 and Euro-6 environmental standards, since they ensure optimal combustion of diesel fuel almost from the first seconds. That is, with minimal emissions, with a minimal amount of carbon monoxide.

Many car enthusiasts cannot make a choice: should they buy ceramic or metal glow plugs for their car? There is no clear answer in this case. Ceramic candles have much higher performance characteristics and need to be changed extremely rarely. However, they have a significant drawback - high price. Therefore, it makes sense to install them on new and/or expensive imported cars that are demanding on individual engine parts, in particular, glow plugs. In other cases, there is no point in overpaying, and you can use standard metal candles. However, their selection must be made based on additional parameters.

Number of spirals

The most common are candles with one heating coil. They belong to the first generation. Their heating time is about 10 seconds. However, recently spark plugs with two incandescent coils have become increasingly popular. They are designed to last longer on a cold engine. The second spiral is the so-called regulatory one. Its use allowed us to achieve two advantages. The first is a short warm-up time, about 2...5 seconds. Secondly, the load on the main spiral is reduced, which extends its service life.

The use of self-regulating spark plugs (with two spirals) promotes better combustion of diesel fuel, reducing the amount of carbon monoxide and other harmful substances into the atmosphere. European environmental standards Euro-4, Euro-5 and others strictly regulate these requirements. This is what caused the appearance of spark plugs with two filament coils.

Therefore, before choosing glow plugs, you need to further clarify in the documentation which type of spark plugs is suitable for your car’s engine. And purchase the appropriate unit. Please note that the geometric dimensions, seating and fastening elements for first and second generation candles may be the same. And they will differ only in the number of spirals.

They cannot be replaced with each other. The fact is that a candle with two heating coils lasts longer in a heated state. That is, it is designed to operate in long-term thermal conditions. And if instead of it you install a candle with one incandescent spiral, it will simply burn out. It is this fact that often becomes the reason that some car enthusiasts very often burn out new spark plugs within a short period of time after installation. The situation is aggravated if the ambient temperature outside is significantly below zero (severe frost). In this case, if instead of a double-stranded glow plug a single-stranded one was installed, then the likelihood of its rapid failure increases significantly.

There is another type of spark plugs - for easier starting. Their design involves the use of one spiral, but with variable resistance. Its value changes as the engine warms up, which ensures not only easy engine starting in the cold season, but also less load on the spark plug and the vehicle’s electrical system as a whole.

Accordingly, when choosing a particular glow plug, you need to know not only the geometric dimensions of the plug, but also its characteristics. And it’s better to choose from the electronic catalogue. Ideally, of course, buy original spare parts, but due to the fact that most of them are unreasonably expensive, you can also find cheaper analogues.

Number of poles

Modern glow plugs can have one or two connection poles. Single-pole connection is simpler. In this case, the “plus” of power is supplied to the spark plug, and the “minus” (ground) is output to the housing. More complex double-pole spark plugs have separate contacts for plus and minus.

Voltage consumption

Various glow plugs are available for different operating voltages - from 6 to 24 Volts. For most passenger cars this value is 12 Volts. There are glow plugs with an afterglow function. They are mounted complete with additional electrical resistance. This ensures that the spark plug operates at maximum power before starting the engine, and after starting the engine, this power is reduced in order to reduce the load on the adjusting spiral.

Electrical resistance

As a rule, the resistance value of the spiral is in the range of 0.5...1.8 Ohms. It depends on the specific candle model, as well as its type. So, for ceramic candles the corresponding value is lower, and for metal candles it is higher. The value of electrical resistance directly affects the efficiency of the spark plug.

Operating temperature

On average, the operating temperature of glow plugs is within the range of +1000°С…+1350°С. This depends on the specific brand of candle. Metal samples will have a lower temperature, while ceramic samples will have a higher temperature. The choice of temperature conditions must be carried out in accordance with the requirements of the car manufacturer. Typically, the documentation indicates a specific temperature range for glow plugs.

Standard Features

We are talking about geometric dimensions and other technical parameters. In particular:

• diameter and pitch of fastening thread: from M10×1.0 to M18×1.5;
• key size: 12, 14, 17, 21 mm;
• cone slope: 63°, 93°, 123°;
• total length: 58…137 mm;
• working part length: 17…35 mm;
• working part diameter: 4…6 mm.

Information about spark plugs suitable for a particular engine can be found in its technical documentation. And make a choice, be sure to take these parameters into account.

Spark plug life and reasons for failure

According to experts, it is very difficult to speak clearly about the life of glow plugs. They are changed every year or two, depending on the quality of the product itself. If we talk about the service life of spark plugs based on mileage, we can come to the following pattern:

1. Products with a metal spiral become unusable after 50-80 thousand kilometers;
2. Products with a ceramic spiral last twice as long as metal ones - up to 160 thousand kilometers;
3. Some Japanese glow plugs for premium cars can last 240 thousand kilometers.

Let us only note that the breakdown of one spark plug will not have a special effect on the engine. Two working candles guarantee operation in the warm season. However, in all cases, it is advisable to change them as a whole set, since even one non-working part will affect the consistency of diesel fuel, and, accordingly, the operation of the engine.

The glow plug will work long enough if the following conditions are met:

• Fuel injectors are working properly. A clogged injector does not spray fuel, but streams it directly onto the spark plug, causing it to burn out;
• The candle is clean. Combustion products can be deposited on the working part, which is why the part can eventually close on the “minus”, that is, the car body, and fail forever;
• The installation was carried out incorrectly. The candle is a rather delicate detail. Excessive force on the key will simply break it;
• Tightness of engine components. Oil contamination is a common cause of failure of many car parts. For example, oil leaks also burn spark plugs in gasoline/gas engines.

A serviceable part is clean, its tip has no swelling. External damage usually indicates excessive tightening during installation, and a broken tip indicates problems with fuel injection. We advise you to check the spark plugs every year for these changes.

As practice shows, most often failure occurs due to incorrect selection and subsequent overheating. We did not describe this point above simply because the rule applies to all consumers of energy from the vehicle’s on-board electrical network: always choose a spare part that meets the vehicle’s parameters. If the rule is not followed, any candle fails very early.

Consequences of untimely replacement

No matter how good the glow plugs are used in a particular car, sooner or later they will fail. Untimely replacement (that is, replacement not according to regulations) can lead to very sad consequences for the engine, and accordingly, this can result in expensive repairs for the car owner. Therefore, it is necessary to change these units on time.

So, if you drive on spark plugs alone for 50...70 kilometers, then the spark plug rod is corroded from the sealing cone to the thread, and even beyond the thread. This leads to the “accretion” of the spark plug body to the cylinder head body. Accordingly, when you try to unscrew it from its seat, it often breaks either in the thread area or immediately behind the hexagon. Because of this, a large piece of the spark plug remains inside the cylinder head, and removing it from there is very problematic. To do this, you need to dismantle the head and use additional machines and equipment (jig boring machine). To reduce the likelihood of such cases, it is recommended to lubricate the spark plug threads with a special lubricant.

The second common problem associated with long-term use of a glow plug is that the heating element itself may fail. Moreover, failures can be very different. For example, it can burn out and fall into the combustion chamber. And this can lead to very serious consequences, such as destruction of the piston, destruction of the valve mechanism and other critical and expensive engine elements.

Another option for a heating element to fail is when it “swells up” in the shape of a pear. This leads to the fact that when the spark plug is removed from its seat, such a “pear” breaks off and falls into the engine cylinder. The situation is similar to that described above.

Another common problem associated with replacing glow plugs with diesel is caused by incorrect tightening torque when installing the spark plug. Most often this is expressed in the fact that the technician who installed it did not use a torque wrench, but chose the tightening torque “by eye,” usually exceeding the required value. Often, in this case, the spark plug body breaks and a microcrack appears in it. The spark plug continues to work normally, but the process of corroding the metal begins at the fractured area. And this leads to the fact that when the spark plug is removed from its seat, it usually breaks precisely at the fracture point formed. As a rule, the value of the corresponding tightening torque is about 15...20 Nm (it differs for different cars, so look for additional information in the car manual). Tightening must be done using a torque wrench.

If the glow plugs on your car have been running for over 30...40 thousand kilometers, and they were installed without using a torque wrench, then it is better not to dismantle them yourself, but to seek help from a specialized service. In such organizations, glow plugs are dismantled using special vibration pullers, which not only directly unscrew the spark plug, but also transmit vibration to its body, thereby loosening it in its seat and preventing breakage of its body. Vibration neutralizes the effect of rust, which causes the spark plug to stick to the body.

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.

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.

Understanding ceramics

Owners of modern diesel cars in many cases can replace worn-out metal glow plugs with ceramic ones. Having overpaid, they receive a whole set of “bonuses”. Namely:

• The ability to start driving almost immediately after starting the engine. Ultra-fast heating contributes to this;
• An almost eternal life of a glow plug, especially if it was produced by one of the companies that we will talk about later;
• The probability of burning out the heating coil is close to zero.

Here we can draw an analogy with iridium spark plugs used in gasoline and gas engines. The price is steep, but there is an opportunity to save for yourself something that is very difficult to translate into monetary equivalent: your own nerves. A high-quality ceramic product is either not replaced at all, or at most only once during the entire life cycle of the car. Of course, if you take care of it properly. Then, most likely, you will not have to check the spark plugs at all for carbon deposits and mechanical damage - set it and forget it.

Design Features

Diesel engines, of course, do not have such colossal differences as the Wankel rotary piston engine, the design of which is absolutely not similar to the “anatomy” of a traditional internal combustion engine, but it has a number of features that draw a line between it and gasoline engines.

The diesel engine also has a crank mechanism, but its compression ratio is significantly higher - 19-24 units versus 9-11 units, respectively. The fundamental difference between a diesel engine and a gasoline engine is how the fuel-air mixture is formed, ignites and burns.

A diesel internal combustion engine does not have spark plugs and, accordingly, ignition of the fuel-air mixture occurs from compression. At the same time, air and diesel fuel are supplied separately. It should also be noted that almost no modern diesel engine can do without a supercharging system, which is used to improve the performance of the unit. Variable geometry turbochargers are used to optimize boost over the widest possible speed range. A diesel unit has a higher efficiency, but it is heavier and produces more torque at low speeds than a gasoline internal combustion engine.

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.

What you need to know before starting work

An urgent need to replace glow plugs with your own hands may arise in the cold season, since the candles increase the temperature inside the cylinder for effective self-ignition of the mixture of diesel fuel and compressed air when the internal combustion engine warms up. If more than one spark plug fails, the diesel engine will no longer start in winter. Glow plugs also affect the efficiency of fuel atomization in the cylinders.

To replace it yourself, you need to have a minimum set of available tools: a wrench, a socket wrench and a screwdriver. A complete set includes gloves, wrenches and socket wrenches (which have extensions and ratchet locks), a reamer and pliers. You will also need some graphite and high temperature grease.

Is it possible to save money on fakes?

Remember: buying fake glow plugs is actually more expensive than buying original ones. Such products do not provide high-quality fuel heating, quickly fail and can damage your engine.

In order not to buy a fake candle, it is better to once again take advantage of the benefits of our time. Find the original candle and take a photo of it. Surely your car already has one of these, which means you won’t have to go far. By comparing a potential purchase with a photo, you can quickly identify a counterfeit:

• The metal of the original spare part is well processed: there are no chips, burrs, poorly worked parts, poor-quality engraving, etc.;
• The dimensions of both parts are identical.

Also don't forget to study the packaging. Large companies spend a lot of money on materials and packaging design. On the packaging with the original candle you can always find information about the product, verification codes, and everything is well printed and does not contain errors.

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.

How to check products before purchasing?

When choosing glow plugs for a diesel engine, the price of which depends on the manufacturer and variety, you should definitely check these details. You should not buy fake items, they will not last long. It is better to immediately pay attention to the original parts.

To distinguish the original element from a fake, you should pay attention to the metal with which the candle is processed. It should not have poor-quality engraving, burrs or other defects. When purchasing a kit, both units must be identical. It is also worth paying attention to the packaging: it should contain all the information about the candle, without any errors.

Checking diesel glow plugs is done using a voltmeter, ohmmeter or multimeter. The appropriate operating mode is configured. You can also check the performance of the spark plug without connecting it to the car's electrical network. To do this, you need to connect the positive probe to the electrode, and the negative probe to the frame or engine block. Even a non-working element has resistance, although it should be small. If it is not there at all, this indicates a malfunction of the glow plug.

In some instructions, the manufacturers themselves write about how to check the glow plug. There are several ways.

How to extend the work period?

Replacing a diesel glow plug, as experts note, should happen every two years or even more often. It all depends on the quality of the chosen product. If a spark plug has a metal spiral, it will last no more than 80 thousand km, while a ceramic analogue will last up to 160 thousand km. But there are also “premium class” spark plugs made in Japan, which can be used for up to 240 thousand km without replacement.

If the glow plug fails, and there are two of them in the car, this will not greatly affect the operation of the car. But in any case, according to the recommendation of experts, it is worth changing the entire set at once.

In order for the glow plug to work for a long time, the following conditions must be observed:

• replace fuel injectors if they malfunction (the clogged part does not spray fuel, and it falls directly onto the spark plug, thereby contributing to its burnout);
• do not allow the candle itself to become clogged, so you should periodically clean it;
• install the parts correctly (a candle is a rather delicate element; sharp or strong pressure on the key can break it);
• engine components must be sealed (oil leakage leads to contamination of many car components, including spark plugs).

If you pull the glow plug too hard during installation, you will see that it is bent, which means it will not work for a long time. It can also burn out if you choose the wrong model for the car brand.

Checking the removed spark plug

Apply voltage from the battery positive to the spark plug terminal, and the spark plug body to ground. With a working spark plug, the glow tube heats up immediately. After 10 seconds it becomes hot and begins to glow, otherwise the candle should be replaced.

While glow plugs on passenger diesel engines are found everywhere, more efficient pre-heaters that are so necessary in winter are extremely rare. And this is understandable, because most diesel foreign cars are designed for the climate of Central Europe and are absolutely not adapted to our winters. Cars from Scandinavia, as well as German and French ones, aimed at our market, are much better prepared for operation in winter conditions and have a number of “highlights” in their design in this regard, including pre-heaters. Even if they are installed for an additional fee, but paired with a timer, such a heater works wonders - the car “comes to life”, as if an alarm clock is ringing. When the owner arrives, everything is ready for the trip: the engine is warm, the interior is warm, there is no need to scrape ice off the windows, etc.

NGK candle range

• NGK Laser Iridium are spark plugs with a service life of up to 100,000 km
  . The central electrode is made of noble metal - iridium.
• NGK Laser Platinum - high-quality spark plugs with a central electrode coated with platinum
  . The precious metal helps reduce spark plug wear. Special corrugated ribs prevent fire.
• NGK Platinum VX are platinum-coated spark plugs for conventional petrol engines. High ignition efficiency is combined with a long service life. The diameter of the central electrode of such a spark plug is only 0.8 mm
  .
• NGK Standard - inexpensive spark plugs with a nickel
  central electrode. Standard series with a high service life at a low price.
• NGK V-Line are spark plugs with a V-
  . This solution promotes more efficient ignition.
• NGK V-Power - spark plugs with V
  -shaped notch.
  Fast ignition
  is possible even with reduced voltage. The copper core provides high-quality heat dissipation.
• NGK Racing - professional spark plugs
  for high loads. Used in racing cars.
• NGK LaserLine - spark plugs for cars with gas engines
  . Just a few modifications cover 95% of the market for such cars.
• NGK Glow - glow plugs with a special heating coil
  . Used in cars with diesel engines.
• NGK D-Power is a series of glow plugs. The engine can be started even at low temperatures. This series includes ceramic candles
  designed for extremely high temperatures; their article numbers begin with the
  
  letter C.

Useful tips

1. Before the onset of the cold season, the glow elements should be checked regardless of whether the diesel engine starts well or poorly.
2. Checking on a diesel engine by assessing the spark is recommended only for older cars. You should not test heating solutions in this way on a “fresh” model, which is equipped with a complex electronic engine control system.
3. If a malfunction is detected, it is optimal to replace the entire set, rather than one or two failed elements.
4. Try to purchase products from well-known manufacturers, since cheap solutions have a noticeably shorter service life and often demonstrate low efficiency of the heating element.

Finally, we would like to add that in order to reliably start a diesel engine in winter, it is necessary to correctly select, charge and maintain a diesel battery, refill high-quality diesel fuel according to the season, and use anti-gels if necessary. Also, in the case of diesel engines, it is advisable to install a diesel fuel pre-heater or a Webasto-type engine pre-heating system.

Sources

• https://instapie.biz/blog/svechi-dlya-dizelnogo-dvigatelya-kakie-luchshe/
• https://automobile-zip.ru/systems-and-nodes/sveci-nakalivania-dla-dizela.html
• https://etlib.ru/blog/1035-horoshie-svechi-nakala–kakie-luchshe-stavit
• https://eldomo.ru/avto/top-8-luchshih-svechej-nakalivaniya-dlya-dizelya-kakie-svechi-luchshe-vybrat
• https://avto.pro/autonews/kak_vibrat_svechi_nakala-20170216/
• https://FB.ru/article/426401/kak-vyibrat-svechi-nakalivaniya-dlya-dizelya-harakteristiki-tsena-i-otzyivyi
• https://orsarm.ru/pochinka/svechi-podogreva-dizelnogo-dvigatelya.html
• https://gil-service.ru/ts/svechi-nakala-dlya-dizelya.html

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The principle of switching on a diesel engine

The fuel-air mixture, which is under pressure in the cylinder, is heated to 900°C.
To ensure fire conditions, the structure is highly durable. The combustible mixture is ignited by the compression ratio, and not by the spark plug. At ambient temperatures below plus 5°C, down to severe frosts, the combustion chamber requires forced heating using ceramic or pin glow plugs. The glow plug in a diesel engine is capable of heating the injection zone to 1000°C in a matter of seconds. When the diesel engine is turned on, these devices operate until the coolant temperature reaches plus 75°C.

Due to the increased demands of environmentalists, thanks to their unique properties, spark plugs begin to function at idle speed. The design of these parts helps reduce the amount of harmful emissions from a diesel engine into the atmosphere.

Starting a diesel engine: differences from gasoline engines

A diesel engine starts completely differently than a gasoline engine. Volatile gasoline, even at a temperature of -40° C, is ready to ignite from one spark, which is created in the cylinders by spark plugs. Due to its low volatility, diesel fuel - even winter fuel - needs the same 40 degrees for ignition, but with a plus sign (and summer fuel - +62° C). It’s not for nothing that diesel fuel is called heavy fuel.

The high temperature required for diesel combustion in the cylinder is created by air compression by the piston. Like any gas, air is compressed reluctantly, but its pressure and temperature increase. When an injector injects a portion of diesel fuel, it ignites on its own from contact with hot compressed air - because of this, it is often said that a diesel engine is started by pressure or explosion. Old diesel engines, not equipped with electronic injection and sensors, can easily operate without a battery, since the ignition of the fuel in the cylinders occurs mechanically, without any sparks or spark plugs.

But the diesel idyll is destroyed by Mother Nature: when the temperature drops to sub-zero temperatures, the air compression in the cylinders is no longer enough to heat the fuel until it ignites spontaneously. Therefore, it is impossible to completely abandon spark plugs in a diesel engine. It’s just that spark plugs are needed here not to ignite the fuel-air mixture, but to heat it.

Checking with a multimeter (tester)

The tester for checking diesel glow plugs is used in three modes:

1. Measurement of resistance readings;
2. Dialing method (if supported);
3. Measurement of current consumption readings.

All methods can be applied without removing the product from the engine. But in this way we will only answer the question - “is the spark plug working or not.” It will not be possible to find out what condition it is in and the reasons for its breakdown.

Chain ringing

To check using the dialing method you need to:

1. Disconnect the supply wire from the glow plug;
2. Set the regulator on the tester to the desired position;
3. Press the negative probe to the engine block, the positive probe to the electrode.
4. The presence of sound indicates that the spiral is intact.

If you are using an analog tester, then you need to follow the arrow; its deviation indicates the integrity of the circuit.

This can also be done on a removed spark plug, only instead of a block, the probe must be attached to the body of the product.

The first and third methods are more informative, but they have their own characteristics that are important to know

Resistance measurement

Here it is important to understand the principle of the relationship between the ECU unit and the resistance of the spiral, which in a new glow plug should be in the range of 0.7-1.8 Ohms. The ECU is guided by the current consumed by the heating elements (A), which changes depending on their warming up

The amount of current is inversely proportional to the amount of resistance

The ECU focuses on the current consumed by the heating elements (A), which changes depending on their warming up. The amount of current is inversely proportional to the amount of resistance.

Those. Glow plugs are turned off when their resistance increases as a result of heating, and the current passing through the coil decreases. When a certain current value is reached, the ECU receives a signal that the spark plugs are warm and need to be turned off.

If the resistance, as a result of a malfunction of the heating elements, is too high (more than rated), then the current strength decreases earlier than necessary.

At this moment, the ECU receives a signal (premature in our case) that the glow plugs are warmed up and need to be turned off, which is what happens. At the same time, the air temperature in the cylinders remains insufficient for reliable engine starting.

Current consumption measurement

The most informative method, which involves starting a still cold engine. Those. There is no need to remove the glow plugs.

By measuring current consumption, you can quickly identify a faulty heating element. In this case, the reliability of the result obtained will approach 100%.

But here it is important to understand what types of glow plugs are installed in the engine and what their standard current consumption is. For example, if we take rod products, they can be single-pole and double-pole

For example, if we take rod products, they can be single-pole or double-pole.

The first ones are connected according to the classical scheme - ground on the body, one terminal coming off. Consume from 5 to 18 A.

The latter are determined by the presence of two terminals and can consume up to 50A.

To measure the current consumption, it is necessary to connect the tester in series in the “ammeter” mode into the electrical circuit that supplies the glow plug.

For this:

1. Disconnect the power cable from the product;
2. We switch the multimeter to ammeter mode;
3. We connect one probe to the power wire, the second to the central terminal of the glow plug.
4. An assistant will be needed. We start the car (the engine must be cold) and take readings from the device.

In the first seconds, the resistance on the electrode will be minimal, since the engine is still cold, and accordingly the tester will show the maximum current.

As the spark plug warms up, its resistance will increase and the current will drop. This will be displayed on the device. The reduction should take place without sudden changes, gradually. And then, at some stage, the current must stabilize.

It is better to write down the results of checking each spark plug so that they can be compared later. They should be as identical as possible.

If the behavior of a certain glow plug differs from others, then most likely only its middle or tip warms up. The absence of current will indicate an open circuit.

Here you will have to unscrew the product and recheck it, but visually observing the heating process. Typically this is already done using a directly connected battery (see below).

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.