Malfunctions of the diesel engine power system
Reduced fuel supply and decreased injection pressure are the main malfunctions of the diesel engine power system.
Signs of malfunctions are the impossibility of starting or difficulty starting the engine, a drop in power, smoking, knocking, unstable operation or “runaway”, i.e. when the engine is difficult to stop.
The reasons for a decrease in fuel supply, a decrease in injection pressure and the impossibility of starting the engine as a result are clogging of the fuel lines, the intake in the fuel tank or the filter elements of the fuel filters, freezing of water or thickening of the fuel in the fuel lines, the presence of air in the fuel system, violation of the fuel injection advance angle, malfunctions low and high pressure fuel pumps.
A decrease in fuel supply and a decrease in injection pressure, leading to a drop in power, smoking and engine knocking, occurs when: the gas exhaust system is clogged; malfunction of the governor lever drive (when the fuel pedal is fully pressed, the engine crankshaft speed does not increase); presence of air in the fuel system; violation of the fuel injection advance angle (knocking or smoking); water entering the fuel system (white smoke); excess fuel supplied to the cylinders (black or gray smoke); misalignment or clogged nozzles; wear of the plunger pair and nozzle nozzle holes; dirty air filter.
The uniformity of engine operation is disrupted due to the following reasons: the fastening is loose or the high-pressure pipe has burst, individual injectors are not operating satisfactorily, the uniformity of fuel supply by fuel injection pump sections is disrupted, the speed controller is faulty. The engine starts to peddle when the fuel injection pump rack is stuck, the spring of its drive lever is broken, or when excess oil gets into the combustion chamber due to wear of the cylinder-piston group
Methods for identifying malfunctions in the diesel engine power system
When troubleshooting the power supply system, you should keep in mind that their symptoms are also typical for malfunctions of other systems and mechanisms. For example, the reason for a decrease in engine power may be a violation of the clearance adjustment in the gas distribution mechanism. If it is difficult to start the engine, you must first check whether there is fuel in the tank, whether the valve of the fuel suction line is open, and whether the oil is appropriate for the given season.
Rice. 28. Device KI-4801: 1 -- pressure gauge; 2 -- frame; 3 -- three-way valve; 4 -- hose; 5 -- hollow bolt (fitting); 6 -- valve; 7 -- screw
After disconnecting the fuel lines of the injector fittings; fuel pumps, filters and fuel line openings must be protected from dirt with caps, plugs or wrapped with clean insulating tape. Before assembly, all parts must be thoroughly cleaned and washed in diesel fuel. The pressure in the low pressure fuel supply system can be measured with the KI-4801 device (Fig. 28). One of the tips of the device is connected to the discharge line of the priming pump in front of the fine fuel filter, the other - between the filter and the fuel pump. Before checking the pressure, remove air from the system by opening shut-off valve 6 and pumping the system with a manual fuel pump. The pressure is measured with the engine running. By setting the crankshaft rotation speed to 2100 rpm (maximum fuel supply), and using valve 3, using a pressure gauge / determine the fuel pressure before and after the fine fuel filter. The pressure in front of the filter should be 0.12... 0.15 MPa, and behind the filter - at least 0.06 MPa. If the pressure in front of the filter developed by the booster pump is less than 0.08 MPa, the pump must be replaced. If the pressure behind the filter is less than 0.06 MPa, the condition of the bypass valve should be checked. Having stopped the engine, install the control valve in place of the working valve and, having started the engine, measure the pressure behind the filter again at maximum fuel supply. If the pressure has increased, the removed valve is adjusted or replaced. If the pressure remains the same, this indicates clogging of the fine fuel filter elements. If the pressures before and after the fine fuel filter are equal or small, you should disassemble it and check the condition of the seals in the filter elements.
To replace the KI-4801 device, the KI-13943 device has been developed, which is distinguished by its simplicity of design, smaller overall dimensions and weight, and more rational technology for determining pressure. In the future it may find wide application.
If air gets into the fuel system, check its tightness. To check the tightness of the system to the fuel filter, unscrew the plug on the filter to communicate the internal cavity of the filter with the atmosphere and tighten all connections to the fuel filter. By unscrewing the handle of the manual fuel priming pump, pump the fuel system until clean fuel without air comes out of the fuel filter, after which the filter plug is screwed in. If after this check the engine power does not increase, check the fuel system from the fuel filter to the injection pump. Having unscrewed the air bleeder plug on the fuel pump and tightened all connections to the pump, pump the fuel system with a manual fuel priming pump until clean fuel without air bubbles comes out of the hole in the pump. After this, the plug in the pump is tightened.
The moment the fuel pump sections begin to pump fuel can be determined using a KI-4941 momentoscope (Fig. 29). To do this, disconnect the high pressure fuel line from the section of the fuel pump being tested. Having unscrewed fitting 5 from the fuel pump head, remove the discharge valve spring and install in its place the process spring included in the momentoscope kit. Having screwed fitting 5 into place, screw the union nut onto it 4 momentoscope. After pumping the fuel system with a manual booster pump until air bubbles are completely removed, turn on the full fuel supply. The engine crankshaft is then manually cranked until the glass tube/torque scope is filled with fuel.
By squeezing connecting tube 2, remove part of the fuel and, continuing to turn the crankshaft, monitor the fuel level in glass tube 1. The beginning of an increase in the fuel level in the tube is the moment the fuel pump section begins to pump fuel. This moment should occur 20° before altitude. At the moment the first section begins to pump fuel, the marks on the injection advance clutch and the pump housing must coincide. If the angle of rotation of the pump camshaft is taken as 0°; then the remaining sections should begin supplying fuel in the following order: section No. 2 at 45°; section No. 8 at 90°; section No. 4 at 135°; section No. 3 at 180°; section No. 6 at 225°; section No. 5 at 270°; section No. 7 at 315°. Inaccuracy of the interval between the start of fuel injection any the pump section relative to the first should be no more than ±30".
The injectors are checked for the quality of fuel atomization, tightness and pressure at the start of injection (lifting the nozzle needle). To find injector malfunctions, stop the fuel supply to the injector being tested by loosening the union nut connecting the fitting of the pump section to the High Pressure fuel line. If after this the crankshaft rotation speed decreases and the smoke does not change, then the injector being tested is operational. If the rotation speed does not change and the smoke decreases, the injector is faulty.
The injector can also be checked using a maximeter (Fig. 30). Using fitting 3, the maximeter is connected to the fitting of the fuel injection pump section, and the injector being tested is connected to fitting / through a short fuel line. Using micrometer head 2, the required lifting pressure of the spray needle 4 is set on the maximeter scale (for the ZIL-645 engine this pressure is 18.5 MPa). Then loosen the union nuts of all high-pressure fuel lines and turn the engine crankshaft with the starter. If the timing of the start of fuel injection through the maximeter and the injectors coincides, the injector is working. If fuel injection through the injector begins earlier than through the maximeter,
then the pressure at which the nozzle needle begins to rise is lower than the maximum pressure, and vice versa.
To check the injectors and precision pairs of the fuel pump, use the KI-16301A device (Fig. 31). When checking injectors, adapter 4 is attached to the injector fitting. The drive handle / pumps fuel into the nozzle, making 30...40 strokes per minute. The fuel injection start pressure is determined by pressure gauge 3. The tightness of the injector is checked at a pressure 0.1... 0.15 MPa less than the pressure at which the needle starts to rise. Within 15 s there should be no passage of fuel through the nozzle shut-off cone and seal points. The tip of the sprayer can be moistened without dripping.
Rice. thirty.
To check the precision pairs of the fuel pump, handle-reservoir 2 of the device is connected to a high-pressure fuel line coming from the pump section being tested. When the fuel is fully supplied, turn the engine crankshaft with a starter and use a pressure gauge to determine the pressure created by the plunger pair of the fuel pump.
Rice. 31.
Rice. 32.
The tightness of the discharge valves is checked with the pump not running and the fuel supply turned on. Under a pressure of 0.15...0.20 MPa, the valves should not allow fuel to pass through for 30 s. The condition of the air filter is determined by the clogging indicator (Fig. 4.32). The indicator is connected to the control hole on the intake manifold using a rubber tip 2. The degree of air filter clogging is determined when the engine is running at maximum idle speed. The indicator is turned on by pressing cap 5, which opens valve 7 and connects chamber 3 to the inlet pipeline. Chamber 4 communicates with the atmosphere, therefore the position of piston 6 relative to the viewing window of the housing characterizes the resistance of the air filter. Complete blocking of the window by the piston occurs when the vacuum in the intake pipe is more than 70 kPa and signals that the air filter is extremely clogged.
Many motorists, in order to save money, seek to purchase a car with a diesel engine, completely disregarding the fact that its repair or maintenance can easily negate such savings.
Although, it should be noted that for the most part, diesel engines are quite reliable, but, nevertheless, they periodically fail for various reasons, among which are the following:
- initial manufacturing defect;
- untimely maintenance and violation of operating rules;
- systematic use of low quality fuel, technical wear and tear of the fuel supply system and other parts during operation;
- and unqualified repairs with the installation of “left” spare parts.
1. We have already mentioned that, according to most experts, diesel internal combustion units are very reliable and their failure to operate, as a rule, is triggered by work under constant loads close to critical and distances exceeding the working life.
2. In addition, the “lion’s share” of breakdowns occurs through the fault of the users of diesel vehicles themselves, due to gross violations of vehicle maintenance regulations.
For example, in cars used in our country, due to the high percentage of sulfur content in diesel fuel, the oil must be completely changed after the car has driven 7,500 km, despite the technical instructions of the car manufacturer. The system is not flushed in order to avoid the formation of oxides.
Malfunctions of the diesel engine fuel system
1. Flushing the fuel system should be carried out twice a year, with the complete dismantling of the fuel tank and removal of sediment from the fuel filter. If someone thinks that doing this is pointless, let them try to remove the tank and see from personal experience how much dirt there will be in it.
2. Also, breakdowns occur when trying to start a diesel engine when it contains fuel that does not correspond to the operating season. Summer diesel fuel loses its fluidity at -5 C, it becomes waxed and the engine goes out of working condition. In this case, there is only one way out: place the car in a warm place and warm up the power system.
3. In addition, it should be remembered that starting a diesel engine from a pusher is not recommended, especially if the timing belt drive is used, otherwise this can lead to serious damage to the power unit.
4. And one more thing, you should not try to excessively add gasoline to diesel fuel (which some people “sin”) and drive a car at maximum speeds; this is unacceptable for a diesel engine. Before starting to drive, the engine must be warmed up for at least 3-7 minutes.
5. Try to refuel only at proven and well-established gas stations. After all, almost half of all diesel engine fuel system malfunctions are due to poor quality.
1. Due to wear of the engine piston group, compression decreases and therefore problems arise when starting the engine in winter, even despite the serviceability of the glow plugs and the fuel filled in for the season.
2. Another problem of engine wear is crankcase gas pressure and high fuel consumption. A major overhaul of the engine will only help here.
3. Increased fuel consumption and black indicates wear of the injector nozzles. It happens that the sprayer bites and a peculiar knock appears and white smoke comes out of the exhaust. You cannot drive for a long time on faulty injector nozzles; burnout of the prechambers and pistons of the diesel engine may occur.
4. If there is a problem starting a hot engine, this indicates wear of the injection pump plunger pairs.
Interesting video - valve malfunctions:
I wish everyone good luck! And fewer different problems.
Diesel engines of cars are characterized by high reliability; however, the possibility of failure of any components or systems for various reasons during operation cannot be ruled out. You should adhere to the rules that are regulated by the documentation of the manufacturer, otherwise, due to frequent breakdowns and improper repairs, the service life of the diesel engine is sharply reduced.
Malfunctions:
- difficult starting of a cold and hot engine;
- idle failures;
- reduction in engine power;
- fuel and oil consumption have increased;
- noises and knocking appeared in the diesel engine;
- the engine does not hold speed well;
- Blue or black exhaust occurs periodically.
Diesel problems can arise for a number of reasons. For example, due to unqualified maintenance and improper use. We must remember that it is better to carry out diagnostics, repairs of diesel engines, as well as adjustment of their components and mechanisms in a trusted service center, where experienced technicians will provide competent maintenance of your car’s engine both during the warranty and post-warranty periods. They will also provide you with all the necessary information.
It is recommended to change the oil no more than after 7-7.5 thousand km. mileage This is primarily due to Russian realities: domestic diesel fuel contains many impurities, including sulfur, as a result of which the oil tends to oxidize. The quality of the oils used must also meet the standards stated by the manufacturer.
The quality of diesel fuel greatly affects the service life of the engine. According to statistics, half of all engine malfunctions in general and the fuel system in particular are directly dependent on fuel. Imported fuel is “cleaner” than Russian fuel and contains less various mechanical impurities and water. However, refueling with foreign fuel will cost significantly more.
Various types of problems can appear after poorly carried out repairs of a diesel power unit, because in order to correctly eliminate all problems, mechanics are required to have knowledge of all the design features of the engine. Only high-quality original spare parts should be installed and components should be replaced in a timely manner. All this will extend the operation of the engine, as well as save money.
The main signs of malfunctions include: difficulty starting the engine. Typically the culprit is poor compression. For the same reason, the engine begins to operate intermittently, the fuel is poorly atomized, and noise occurs.
Natural wear and tear of the engine can be caused by high mileage of the car, after which defects in the fuel equipment components are noted. Compression decreases and the piston group wears out. In cold weather, it becomes increasingly difficult to start the engine. Signs of natural wear of the diesel engine are indicated by an increase in oil consumption, as well as crankcase gas pressure.
If the injector nozzles wear out, black smoke appears from the exhaust pipe and fuel consumption increases. The normal lifespan for a sprayer is from 60 to 80 thousand km. Long-term operation of the motor with this type of malfunction will ultimately lead to burnout of the prechambers.
Quite often, the plunger pairs of diesel injection pumps wear out. A sign of their defects is poor starting of a heated engine.
Diesel engines are widely used in engineering vehicles, trucks and route vehicles. This type of engine is less common in passenger cars, however, due to the general increase in their popularity, diesel engines are increasingly being installed on them.
The design of the combustion chamber of a diesel engine is divided into a separate combustion chamber and a direct injection chamber. In the first situation, the combustion chamber is connected to the cylinder using a special channel. During compression, the vortex-type air entering the chamber is swirled. This improves the self-ignition that occurs in the main chamber. Such diesel engines are most often found in passenger cars, since their noise level is much lower compared to other engines and the speed range is larger.
In the second case, the combustion chamber is located directly in the piston, and the fuel enters the space above the piston. Low-speed engines with large volumes most often have this design. Such engines initially made a lot of noise and vibration, but consumed a small amount of fuel. Gradually, high-pressure fuel pumps for diesel engines appeared with optimization of the combustion process. Stable engine operation was achieved at a range of up to 4500 rpm. Noise and vibration have also been significantly reduced.
Diesel or gasoline?
The pros and cons of different types of engines often worry car owners. Despite the fact that the noise and vibration levels of diesel engines have significantly decreased as a result of their modernization, many car owners are concerned about the question: how to start a diesel engine faster in frosty weather? Indeed, the diesel engine and car interior warm up more slowly due to lower engine operating temperatures. The issue is resolved by installing additional heaters on the engines. This option is widely used on modern engines.
It would seem that that’s all, but no. Many motorists buy cars with diesel engines due to the relative cheapness of diesel fuel. Wanting to save on fuel, they do not take into account that diesel engines are much more demanding on fuel quality than gasoline engines. Gasoline engines are more demanding in terms of the required octane number.
Diesel engines are wrongly considered unpretentious, since their demands on the quality of fuel and consumables are quite high. It is no secret that domestic diesel fuel is far behind imported European fuel in quality. Using good old diesel fuel can adversely affect engine performance. However, leading Russian oil companies are trying to solve this problem.
Euro 4 diesel fuel fully complies with the standards and allows the engine to remain operational for a long time. Some also try to use auto chemicals (anti-gel agents), which can increase the quality of fuel, but it is recommended to use them only if the warranty period has already expired.
Thus, by purchasing cars with diesel engines that are not officially supplied to Russia, you risk quickly rendering the engine, designed for European fuel, unusable.
Maintenance of a diesel engine is almost always more expensive than a gasoline engine. This is due to the higher cost of spare parts (air, fuel filters, etc.). Oil changes are carried out more often than with its gasoline competitor (on average every 7.5 km).
A good advantage of a diesel engine compared to a gasoline engine is more economical fuel consumption with a long vehicle mileage. An older gasoline engine does not consume gasoline as economically as a new one. There is practically no such problem in a diesel engine.
Summarizing all of the above, we can conclude that modern diesel engines are not inferior to gasoline engines in terms of reliability. But purchasing them in order to save money on fuel is justified only if the car is used for a long time.
Principle of operation
Like gasoline engines, diesel engines are divided into four-stroke and two-stroke depending on the principle of operation. Two-stroke engines are quite rare. Read on to learn more about the operating principle of a four-stroke diesel engine.
The operating cycle of such an engine consists of four strokes:
- Intake (injection). During this stroke, the crankshaft rotates from 0 to 180 degrees and reaches bottom dead center. Air enters the cylinder through the open intake valve. At the same time, the exhaust valve opens only 10-15 degrees, forming an overlap.
- Compression. The piston, moving upward from 180 to 360 degrees, reaches top dead center. The air is compressed more than 16 times, and the intake valve closes at the beginning of this stroke. The air temperature in the engine can reach from seven hundred to nine hundred degrees Celsius.
- Working stroke, expansion. The crankshaft rotates from 360 to 540 degrees, again reaching bottom dead center. As we know from physics, highly compressed air heats up to very high temperatures, causing the fuel coming from the intake valve to spontaneously ignite. At this stage, an important difference between a diesel engine and a gasoline engine appears. Diesel fuel begins to be supplied even before the crankshaft reaches top dead center (ignition timing). Combustion products push the piston down. During the working process in a diesel engine, the gas pressure is constant, and thanks to this they are able to develop greater torque. The proportion of the air-fuel mixture in a diesel engine differs from that of a gasoline engine in the large amount of air.
- Release. When the crankshaft rotates 720 degrees, the piston pushes the exhaust gases into the open exhaust valve. The gases exit through the exhaust pipe, and the whole cycle repeats.
Power supply system of a diesel internal combustion engine
Purpose
The power system in a diesel engine is a whole complex of special devices. Its main task is not only to supply fuel to the injection nozzles, but also to ensure high pressure during supply. The power system also performs other important functions:
- dosing a precisely defined amount of fuel, taking into account the load on the engine in different operating modes;
- ensuring effective fuel injection at a fixed period of time with the required intensity;
- spraying and uniform distribution of fuel throughout the combustion chamber in the cylinders;
- preliminary filtration of diesel fuel before supply to the power system pumps.
The power supply system provides the supply of purified fuel, and the injection pump (high pressure fuel pump) of the diesel engine compresses it to the required pressure. The injectors supply finely atomized diesel fuel into the combustion chamber
As an example, a diagram of the ZMZ-5143.10 diesel engine installed on UAZ vehicles with an electric fuel pump is given.
Main elements of the system
The diesel engine power system consists of basic and additional elements. The main elements are: a fuel tank, diesel fuel coarse and fine filters, a fuel priming pump, an injection pump, injection nozzles (through which fuel is injected), a low pressure pipeline, a high pressure line and an air filter.
Additional elements may vary. These include electric pumps, exhaust gases, particulate filters and mufflers. The diesel engine power supply system is divided into two groups depending on the installed fuel equipment: diesel fuel supply equipment and air supply equipment.
In fuel supply equipment, as a rule, injection pumps and injectors are implemented as separate devices. Fuel is supplied to the engine through high and low pressure lines. In the high-pressure line, the injection pump increases pressure to supply and inject the required portion of fuel into the working combustion chamber.
In addition to the injection pump, the diesel engine is equipped with a fuel priming pump. It supplies fuel from the fuel tank and passes fuel through fine and coarse filters. The pressure created by this pump allows fuel to be supplied through a low pressure pipeline to the injection pump.
The fuel injection pump of a diesel engine supplies fuel to the injection nozzles under high pressure. The flow depends on the operating order of the diesel engine cylinders.
Diesel injectors are located in the cylinder head. Their main task is precise atomization of fuel in the combustion chamber. There is also a drainage system that removes excess fuel and air through separate pipelines. Nozzles come in open and closed types, but the closed type is used more often. The nozzle of such an injector is a hole closed by a shut-off needle. The key element of the nozzle is the atomizer. It receives one or more nozzle holes, which form a torch at the time of fuel injection.
There is also a non-separate type power supply system, in which the high-pressure fuel pump and the injection nozzle together form a pump-injector device. The service life of such engines is short, and the noise generated often exceeds specified standards.
Features of the turbodiesel power system
The turbocharging system is used in both diesel and gasoline engines. It is designed to increase their power without increasing the volume of the combustion chamber. The fuel supply system in turbocharged diesel engines remains virtually unchanged, while the air supply system undergoes significant changes.
Supercharging occurs using a turbocharger. The turbine consumes the energy released by the exhaust gases (read also,). The air in the turbocharger is compressed, cooled and fed into the combustion chamber of the diesel engine. The value of this pressure classifies compressors according to the degree of boost (low, medium, high).
Diagnostics of the diesel engine power system
Diagnostics of the diesel engine power system is carried out in special service centers aimed at identifying and eliminating the following faults: wear on the surface of cylinders, gears, sprockets, crankshaft, injection pump, clogging of the radiator, air filter, cooling channels, oil channels, damage to the flywheel, valves, etc. d.
A variety of malfunctions can occur. Their timely identification will allow the engine to last longer. The main signs by which you can understand that there is a malfunction are the following: the engine does not start, does not develop the declared power, smokes heavily, and knocking noises occur during operation.
Troubleshooting the diesel engine power system
If the engine does not start, the first thing to do is check for fuel. At low temperatures it can thicken, so special heating of diesel fuel will help to start the engine in cold weather. The next reason may be the presence of excess air in the power system. Such situations arise due to leaks in the system. To eliminate excess air, it is necessary to bleed the system and eliminate its leaks.
The lines, tank pickup and fuel filters may be clogged. The water in them may freeze. It is necessary to warm them up and clean them thoroughly with a rag soaked in hot water. If the injection pump does not work, then you must first warm it up with warm air or steam, and if this does not help, then the filter elements must be replaced.
If the engine does not develop the declared power and smokes heavily, then it is necessary to check the air filter for clogging, check the content of excess air in the fuel system, adjust the fuel supply angle, adjust and clog the injectors, and check the malfunction of the high and low pressure pumps. The malfunction can be eliminated by cleaning the filters, pumping and removing excess air, adjusting the injection advance clutch at the injector, replacing or repairing the high and low pressure pumps if warming up does not help.
Uneven engine operation occurs due to loss of performance of the injectors, malfunction of the injection pump or regulator. Faulty injectors must be replaced immediately, and the pump should be sent for repair.
Knocking in the engine occurs due to too early fuel supply or, conversely, increased supply. This occurs due to the rack lock becoming disengaged. To eliminate it, it is necessary to adjust the angle at which the fuel supply begins or replace the fuel injection pump rack.
Now, in order, about the troubleshooting process. The sediment from the fuel filters is drained provided that the engine is warm. The drain plugs are unscrewed and the sediment is drained until clean fuel begins to flow. Then the plugs are tightened tightly, and the fuel system is pumped with a hand pump. After this, the engine starts. After 3-4 minutes, all air pockets will be eliminated. Sludge from fuel tanks is drained using special taps in the same way.
To wash the diesel fuel coarse and fine filter, the fuel is drained, the caps are removed and washed with clean diesel fuel. Then the old filter elements are replaced. After assembly, you must make sure that there is no air leakage when the engine is running. Otherwise, the bolts securing the cups to the bodies are tightened manually.
The air filter is removed from the car and the filter element is removed. The body and inertial damper are washed in diesel fuel or hot water, and the parts are blown with compressed air, and the air intake mesh is cleaned. Damaged parts are replaced.
The exhaust tract is checked for leaks. The filter element is cleaned by blowing with dry compressed air or washing. The filter element must be replaced if it has through-hole damage.
The average service life of a filter element is about 30,000 km. It should be washed no more than three times, and purged no more than six times.
The fuel injection advance clutch is lubricated through one of the holes until oil spills from the other hole. It contains 0.3 liters of motor oil.
To check the fuel injection advance angle, you need to turn the crankshaft to a position where the mark on the drive half of the clutch is at the top and the latch fits into the hole on the flywheel. If the marks on the coupling and the pump are aligned, then the injection advance angle is correct.
To set the injection advance angle, you need to unscrew the 3 bolts of the driven half-clutch and turn the crankshaft and the advance clutch until the marks align.
Checking the injectors for injection pressure is carried out on a special stand. The value should not deviate from the value of 18+0.5 mPa or 17 mPa for an injector that has worked for a certain period of time. The injector should inject mist-like diesel fuel, and the injected jet should be cone-shaped. If these parameters are not met, then repair of diesel injectors is required. Checking and adjusting the injection pump is also carried out by fuel equipment specialists.
Conclusion
We examined the main components and assemblies of the diesel fuel supply system and its main malfunctions. Timely maintenance will help identify and eliminate these faults and, as a result, increase the service life of your car’s diesel engine. Good luck and easy travels!
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Today, many motorists have cars that use diesel fuel as fuel. Many owners of such cars will be interested to know about what types of diesel engine malfunctions there are and how to fix them. It seems to us that this article will be especially interesting to car owners who, after using gasoline modifications of their cars for a long time, switched to diesel cars. This is due to the large difference in maintenance and operation of such models. To enjoy owning such a car, you need to know as much as possible about it.
Diesel engine malfunctions and their elimination, knowledge of these features, the ability to find and fix problems that arise will be useful for all drivers. Imagine this situation. A trip outside of urban areas in a jeep, and most of these vehicles have diesel power units, was interrupted due to its breakdown. “Civilization” is dozens of kilometers away, there is no one to expect help from, and no one knows what to do. Let's try to talk in simple words about possible breakdowns of such machines.
A little about the features of such cars
The design principle of diesel engines is not very different from gasoline power units. Both designs are characterized by the presence of a cylinder block, pistons, valves and other parts. The only difference is in the reinforcement of the structure of some of them. This must be done because the compression pressure of the combustible mixture of a diesel engine is about 20 units, versus 10-12 for carburetor models.
Diesel engines operate a little differently than gasoline units. The combustible mixture is supplied to the compression zone separately. The first air enters the cylinders and its compression begins. At the end of this process, its temperature reaches approximately 700°C, so when diesel fuel is injected under high pressure, it ignites.
At this time, there is a sharp increase in pressure in the ignition zone, which is accompanied by noise and some vibration. Such features of these power units allow the use of inexpensive diesel fuel; operation occurs with a very lean mixture. This predetermines higher efficiency and better “ecology” compared to gasoline engines. However, there is a caveat here; this is only possible with a fully operational power unit.
About symptoms of malfunction
Breakdowns of any engines, especially diesel engines, most often occur due to wear of parts, violations of maintenance and operating rules, overheating of the power unit, use of poor quality fuel and other problems. However, the most common malfunctions of diesel power units are:
- The diesel engine cannot be started;
- Interruptions during operation and reduction in power;
- High exhaust smoke;
- Sudden stop;
- Knocks during operation;
Why won't the engine start?
This is possible if there is no fuel in the system. The reason for this may be clogged diesel fuel coarse and fine filters. Their clogging can occur due to low-quality fuel or when using summer varieties in the cold season. In this case, washing the filters and replacing them with the appropriate type of diesel fuel helps.
Air getting into the power system will also prevent it from starting. It is necessary to carefully inspect all pipelines for signs and eliminate them. An incorrectly installed injection pump after repair will not allow the engine to start.
Insufficient power and interruptions
This can happen when diesel injector nozzles become coked. It will help to wash the injectors and sprayers in a bath of diesel fuel and clean them with a needle with a diameter of 0.25 mm. Failures can come from the high-pressure pump due to a violation of its adjustments. This can also be expected due to the jamming of the plunger of this pump. It is best to fix such problems in workshops. It cannot be ruled out that the filters in the power supply system become clogged and air gets in there.
Heavy exhaust smoke
The appearance of black smoke from the exhaust pipe indicates an overload of the power unit. Changing to a lower gear will clear the exhaust. This phenomenon may also be caused by a lack of air due to a dirty air filter. Flushing a car's air cleaner cleans up the exhaust.
White smoke may appear when the engine is not warmed up or after water gets into the diesel fuel. Blue smoke can serve as a signal to the driver that the oil level in the pan is too high. Bringing it to normal eliminates the appearance of smoke. Signs of piston wear are also determined by the appearance of blue smoke. You should also check the reliability of the connections in the pipelines and do not forget to drain the sediment from the fuel tank.
Unexpected engine stop. The culprit for this problem may be a lack of fuel in the power system. If it is present in the tanks, you should check the cleanliness of the fuel filters. Washing the filters or installing new filter elements will relieve the driver of such a malfunction.
Check the cleanliness of the hole in the gas tank cap; it serves to connect its cavity to the atmosphere. If there is no air in the tank, the fuel pump is unable to provide the engine with the required amount of fuel.
About possible overheating
First of all, check the coolant level in the radiator and if it is insufficient, add the required amount of antifreeze. Problems may arise. If it gets stuck in the closed position, the coolant, moving in a small circle, will quickly overheat. In this case, only replacing it will correct the situation. Clogged cooling system, especially the radiator, and weak fan belt tension also lead to overheating of the power unit.
Knocking noises during operation. This can happen due to increased clearance in the valve timing mechanism; in this case, valve adjustment is necessary. Ignition too early leads to knocking noise in the fuel pump. It is necessary to correctly set the timing of the supply of high pressure fuel into the combustion chamber of the cylinder. A faulty injector can also be a source of knocking noise in diesel engines.
