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.
Glow plugs for diesel - types
Glow plugs produced today for cars with a diesel engine can be divided into two groups - open and closed.
- Open glow plugs - they are also called rod or pin. During operation, fuel enters the heated part. They are less durable and more susceptible to various contaminations. During operation, these candles can oxidize and become unusable. To extend their service life, the cuff rod should be secured as tightly as possible.
- Closed glow plugs - consist of a spiral and a shell, the internal space is filled with ceramic powder. Spare parts are characterized by durability and a high degree of strength; parts rarely suffer mechanical damage and operate stably for a long time. These candles do not oxidize.
Properties of diesel glow plugs
The spark plugs heat the fuel-air mixture in the injection zone in seconds. The heating temperature ranges from 850-1000°C. At the same time, glow plugs for a diesel engine continue to operate even after the power unit is started, until the coolant is warmed up to the required temperature (at least 75°C).
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 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:
- Metal body.
- Heating tube.
- Connecting bolt and nut.
- Adjustment spiral.
- Ceramic filling.
- Central electrode.
- 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.
The glow plugs continue to work after the engine is turned on, continuing to warm up and ensuring the most complete combustion of the air-fuel mixture, reducing harmful emissions.
How do glow plugs work on a diesel engine and their design?
Glow plugs have a slight visual resemblance to their gasoline counterparts, but they are not used for sparking. The main part of the product is a heating element made in the form of a spiral made of metal or ceramic materials.
It is important to know that the highest permissible temperature to which the working coil is heated is 1350 C.
A modern heating tip may contain a pair of spirals, one of which is adjustable, and the other is heating. The first of them is used to protect against overheating. The main factor is that due to an increase in operating temperature, electrical resistance increases.
The designers provided for the presence of space in the gap between the heating pipe and the spirals. This cavity is filled with a special insulator, which performs several functions:
- efficiently transfers thermal energy;
- protects the spiral from external influences;
- creates comfortable working conditions.
In devices with metal spirals, the tip can heat up to 1000C. Heating takes slightly longer than ceramic.
Methods for checking spark plugs
You can check the voltage in the elements using a multimeter or car battery.
In order not to dismantle the device, just connect it to the battery. The connection diagram is as follows: the minus is connected to the spark plug body, and the plus to the terminal, respectively. In a working unit, the coil heats up within a few seconds. The absence of heat indicates the need to replace the device.
When checking the spark plugs in the injectors, you need to unscrew the elements and examine the glow of the pins, which should glow. A difference in the glow intensity of at least one element indicates the need for additional verification by measuring its resistance. In order to avoid rapid failure of the remaining elements, the entire set is replaced at once, regardless of how many parts turned out to be defective.
It rarely happens that more than two devices fail, in which case it is necessary to check the electrical wiring or electronic control unit.
Using a multimeter, the performance of a dismantled spark plug is determined by the “diagnosis” method.
In modern cars, these components can be checked through self-diagnosis, additionally using an indicator located on the instrument panel, which gives a signal when a spark plug breaks.
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.
Description of signs of malfunctions of incandescent elements
Failures of glow plugs are manifested by the following defects:
- The engine does not want to start.
- Uneven operation of a cold engine.
- 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.
Glow plugs for diesel engines in Yekaterinburg
Glow plugs for a diesel engine are significantly different from spark plugs for gasoline, as they operate according to completely different patterns. The glow plug for a diesel engine is not used to ignite the mixture of air and fuel, as happens in a gasoline unit; the mixture will ignite due to compression. When diesel fuel enters the chamber, the sucked air mass, due to compression, heats up to 900 degrees. Which starts the combustion process. But! Such an engine is very sensitive to frost, while the “winter period” begins at quite warm +5. It is because of this factor that there is a need for a source that will help the mixture ignite at low temperatures. If we remember about spark plugs for a gasoline engine, then everything is simple. Depending on the characteristics of the engine, different “warmth” and heat ratings are required. A diesel engine has 2 types of glow elements:
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.
Why do spark plugs fail?
The service life of modern diesel glow plugs is 60 thousand kilometers, subject to operating conditions. If damage to the shell of the spiral occurs, the entire device will fail earlier, because dirt and moisture penetrate into the resulting crack, and the spiral closes to the housing. The shell may fail for the following reasons:
- failure to observe thoroughness and accuracy when installing the glow element into the motor;
- the appearance of electrochemical corrosion over a long period of time;
- installation of spark plugs that do not correspond to the models of this type of diesel engine.
These devices are very important - they ensure both uninterrupted starting of a diesel engine at sub-zero ambient temperatures and significantly reduce the amount of exhaust harmful gases.
Useful tips
- Before the onset of the cold season, the glow elements should be checked regardless of whether the diesel engine starts well or poorly.
- 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.
- If a malfunction is detected, it is optimal to replace the entire set, rather than one or two failed elements.
- 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://avtodvigateli.com/detali/svecha-nakalivaniya-dizelya.html
- https://HyperAuto.ru/articles/poleznaya-informaciya/zimniy-zapusk-dizelya-svechi-nakalivaniya/
- https://my-zenit.ru/remont/kak-proverit-svechi-nakala-ne-snimaya
- https://service-vao.ru/articles/zamena-svechej-zazhiganiya-dizelnogo-dvigatelya/
- https://voditelauto.ru/%D1%81%D0%B2%D0%B5%D1%87%D0%B8-%D0%BD%D0%B0%D0%BA%D0%B0%D0%BB% D0%B0-%D0%BD%D0%B0-%D0%B4%D0%B8%D0%B7%D0%B5%D0%BB%D0%B5/
- https://mashinapro.ru/1819-kak-proverit-svechi-nakalivaniya.html
- https://AutoTopik.ru/diagnostika-neispravnostei/1535-proverit-svechi-nakala-na-dizele.html
- https://InfoSort.ru/remont-avtomobilya/385-kak-vyibrat-svechi-nakalivaniya-dlya-dizelya-otzyivyi-xarakteristiki-i-sovetyi-speczialistov
- https://KrutiMotor.ru/kak-proverit-svechi-nakala-na-dizele/
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.
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:
- Make of your car;
- Engine capacity;
- Year of issue;
- 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.
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.
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.
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.
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.
