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).
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.
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.
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.
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.
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.
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://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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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:
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.
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.
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.
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.
Please, no "crowbar"
We will not go into details of how this is done, no matter how fascinating such a story may seem to those who want to find out for themselves the condition of the glow plugs in their car.
We will not delve into the issues of replacing spark plugs with our own hands, despite the fact that this seemingly simple procedure can easily turn into an exciting thriller if it turns out that the old spark plugs do not want to get out, and after applying force they break off completely.
Let’s just say that if you happen to encounter a candle that cannot be twisted out, the “no trick against crowbar” method is contraindicated. Service station specialists, who know how this usually ends, recommend not sparing WD40, and unscrewing the spark plug on a well-warmed engine, turning it back and forth. If it doesn’t work, let the engine cool down, use WD40, warm up the engine again, turn the spark plug back and forth again, and so on ad infinitum. Sometimes it helps.
What if this doesn’t help or the spark plug breaks, leaving one part of it in the cylinder head? In order not to aggravate the situation, which will complicate further actions to remove the candle or its fragment, it is better to contact specialists who have tools and devices designed for this work. There are masters, you just need to find them.
Considering the issues of dismantling, as well as the subsequent installation of a new spark plug, means running far ahead of the locomotive, because in order to replace a spark plug, you first need to buy a replacement for it. And spark plugs come in different types - for pre-chamber and swirl-chamber diesel engines, for engines with direct injection - and differ in power and heating time to operating temperature.
Therefore, the replacement must be adequate. Otherwise, the candles will only partially heat up or will not work at all.
Exact information about which spark plugs are used in a particular engine should be found in the maintenance and repair instructions, in the interchangeability catalogs of spark plugs produced by different companies. In the absence of data, a candle for which a replacement is being sought can serve as a sample.
Although if one spark plug malfunctions, it is not necessary to change all the spark plugs in the engine as a set, it is still advisable not to skimp on the purchase. If, as a result of long-term use of a set of glow plugs, one of them fails, this can be considered a signal that the resource of the others is most likely almost exhausted, they will not last long, which means you will have to get into the engine again.
How much in rubles it will cost to purchase glow plugs of individual brands for some common cars can be found in the table. It also shows the price range from the minimum to the maximum of the candles found in the offers for sale.
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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.
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.
