The main faults of the diesel engine. Malfunctions in diesel engines and how to eliminate them

Engine malfunctions most often occur due to violations of thermal and load modes of operation, tightness of internal cavities, as well as the use of low-quality fuels and oils.

Cylinder piston group. Under the most difficult conditions, a cylinder-piston group operates in the engine. As the cylinder-piston group wears out, as well as when the rings coke or break, the tightness of the working volume of the cylinder becomes insufficient. This leads to a decrease in the pressure and temperature of the compressed air, resulting in difficult starting (fuel does not spontaneously ignite) and interruptions in engine operation. When the air-fuel mixture is burned, gases under high pressure break into the crankcase, from where they exit into the atmosphere through the breather. With wear of parts, loss of elasticity of the rings, the amount of oil that penetrates into the over-piston space and burns there under the influence of high temperature increases.

External signs of a malfunction of the cylinder-piston group are smoke from the breather, excessive oil consumption, difficult diesel start-up, power reduction, white smoke during start-up, blue smoke during operation.

Crank mechanism. One of the main factors affecting the operation of the crankshaft and connecting rod connections is the clearance in the bearings. With an increase in the gap, the conditions of liquid friction are violated, dynamic loads increase, gradually acquiring a shock character. The oil pressure in the engine line decreases, as it is facilitated by its flow through the increased clearances of the crankshaft bearings. This impairs the lubrication of cylinder liners, pistons and rings.

External signs of an increase in gaps are a decrease in oil pressure (with a working lubrication system), as well as knocks that are heard in certain modes with a stethoscope.

Gas distribution mechanism. IN during operation of the engine, the tightness of the working volume of the cylinder is violated due to leaks in the valves due to burning of their chamfers and working chamfers of the sockets in the cylinder head, due to leaks in the junction of the head and block and burnout of the gasket, due to violation of the thermal gap between the valve and its drive.

As the gears of the gas distribution mechanism, bearings and camshaft cams wear out, as well as the deviation of the thermal gaps between the valve and the rocker arm from the nominal values, the valve timing is violated.

These faults predetermine the appearance of metallic knocks in the area of ​​the valve mechanism and multi-cause external qualitative signs, such as difficult start-up, interruptions in operation, and power reduction.

Also, engine malfunctions include malfunctions of the systems included in it (lubrication systems, power systems, cooling systems, start-up systems).

The main malfunctions of the diesel engine power system and their causes.

The power system accounts for 25 ... 50% of all malfunctions observed on tractor diesel engines. The working process and the wear rate of engine parts are greatly influenced by the condition of the air purification system sucked into the cylinders. With an increase in operating time, the performance of the air cleaner deteriorates - the transmission coefficient of abrasive particles of various sizes and resistance. The reasons for this change are the accumulation of dust in the filter elements, as well as a decrease in the level and deterioration of the properties of the oil in the sump. An increase in resistance causes an increase in vacuum in the intake manifold, which increases the risk of uncleaned air being sucked in through leaks in the air path, reduces the degree of filling of the cylinders with air and, consequently, the power and efficiency of the engine.

For the timely detection of malfunctions in the air purification and supply system, the tightness of the system, the resistance of the air cleaner and the intake tract (by vacuum in it) are monitored using diagnostic tools or standard instruments.

ABOUT unsatisfactory operation of the fuel equipment testify to the difficult start of the diesel engine and unstable operation, increased opacity of exhaust gases, reduced power and efficiency.

Difficult start-up and unstable operation of a diesel engine occur due to water entering the cylinders, the presence of air in the fuel, coking or sticking of the needle in the sprayer housing, excessive wear of the fuel pump precision pairs, uneven fuel supply to the cylinders, significant wear of the regulator mechanisms. It is also possible that the springs of the plungers, delivery valves and injectors break, the fuel pump rack or the regulator clutch jams, and the booster pump malfunctions.

The reason for the increased opacity of exhaust gases is incomplete combustion of fuel due to poor operation of the injectors, too early or, conversely, late injection of fuel into the cylinders, excessive fuel supply, lack of air (with severe clogging of the air cleaner).

As the injector parts wear out and the spring elasticity decreases, the fuel injection start pressure decreases, and this results in an increase in the volume of injected fuel and the injection start angle, a change in power and efficiency. With a significant decrease in injection pressure, fuel can leak from the atomizer after the needle is seated in the seat, which quickly leads to its coking, deterioration in the quality of atomization, and freezing of the needle. Coking of the flow sections of the atomizers determines the change in throughput and the uneven operation of the diesel engine.

The performance of the power supply system is also impaired when malfunctions of the simplest auxiliary devices- tank, fuel lines and their connections, filters, fuel priming pump.

The main malfunctions of the power supply system of a gasoline engine and their causes.

The main malfunctions of the power supply system of carburetor engines can be attributed. Violation of the fuel supply due to clogging of fuel filters, nozzles, overheating of the fuel pump, freezing of water. However, most of the faults in the power system are in the carburetor.

Violation of the correct operation of the carburetor is primarily due to a change in its technical condition and the appearance of various misalignments, accompanied by depletion or enrichment of the combustible mixture, leakage or lack of fuel, as well as various defects in the ignition system and the control of fuel supply and ignition processes.

The main malfunctions of carburetors include:

A) Difficulty starting the engine associated with a violation of the fuel supply, the preparation of a lean or rich mixture, as well as various.

B) Difficulty starting the engine associated with a violation of the fuel supply, the preparation of a lean or rich mixture, as well as various violations in the operation of the starting system and ignition.

C) depletion of the combustible mixture. External signs of a lean mixture are accompanied by pops in the carburetor or self-ignition of the combustible mixture after the ignition is turned off.

In this case, it is necessary to establish and eliminate, first of all, the possible causes of a violation of the fuel supply to the float chamber.

Typical defects in the depletion of the combustible mixture during engine start-up are associated with incomplete closing of the air damper, clogging of the GTZ and ACX, low fuel level in the float chamber, jamming of the fuel supply valve, jamming of the SROG recirculation valve in the open position, as well as various leaks in the connection of the carburetor with the inlet pipe and inlet pipe with head block - cylinder.

D) rich combustible mixture. The operation of the engine on a re-enriched mixture is accompanied by pops in the muffler. The defect is associated with incomplete opening of the air damper, clogging of the air jets, violation of the optimal position of the mixture quality screw, and an increased fuel level in the float chamber.

D) Unsatisfactory starting and warming up of a cold engine may be associated with loose closing of the air damper and a malfunction of its actuator. For proper adjustment of the carburetor drive, it is necessary to press the throttle pedal and pull out the choke rod handle. The air damper drive lever should be fixed on the rod in the closed position of the air damper.

E) Difficulty starting a hot engine. The operation of the engine in these modes is accompanied by pops in the muffler. The main reason for the difficult start of the engine in a hot state is associated with increased evaporation of fuel in the float chamber.

G) The engine is unstable or stalls in the modes XX mainly due to improper operation of the XX system as well as the ignition system.

Incorrect operation in this mode is accompanied by pops in the carburetor when starting the car from a place or at the beginning of the movement and indicates an over-depletion of the combustible mixture. If these defects are observed at a higher speed KB, then in this case the

H) Failures during acceleration of the car, low dynamics of acceleration can be caused by insufficient supply of the accelerator pump.

The main malfunctions of gasoline engines include the following:

The engine does not start - the fuel pump fuse is blown, the fuel pump malfunctions or the pressure it develops is low, the filters and fuel lines are clogged, the nozzles are clogged, the camshaft (crankshaft) position sensors are malfunctioning or open.

Low developed power, high fuel consumption - malfunction of the mass air flow sensor, oxygen sensor, clogging of the catalyst in the engine exhaust tract, clogging of nozzles.

The instability of the crankshaft speed at idle can most often be caused by a malfunction of the coolant temperature sensor.

Given the sufficient complexity of the power systems of gasoline engines, the list of the number of faults can be significantly expanded.

The main malfunctions of the cooling system of internal combustion engines, their causes

The normal thermal regime of a diesel engine depends primarily on the tightness of the cooling jacket.

Violation of the tightness of the cooling jacket may be due to a number of reasons. When the sleeves sag, the joint between the head and the block is loose, the head or block is cracked, the sleeve sealing ring is inoperative, water enters the cylinders or crankcase. This is detected by a change in the color of the exhaust gases, as well as by the formation of an oil-in-water emulsion on the surface of the oil in the diesel crankcase, which can be observed at the end of the dipstick to control the oil level, as well as by oil stains on the surface of the water in the radiator.

With the cooling system charged deteriorating heat extraction from the heated walls of the block, liners and cylinder head, it characterizes malfunctions of the water pump drive and its components (loosening the drive belt tension, cutting the pump impeller pin), as well as the formation of scale on the walls, which reduces their thermal conductivity.

If the circulation of the coolant is normal (it is observed with the steam-air valve or radiator cap removed), the diesel overheating is largely due to the operation of the radiator. Causes overheating there may be an untimely connection of the radiator with a thermostat, clogging of the radiator, scale formation in the tubes, which sharply reduces their thermal conductivity; weakening the tension of the fan drive belts. The slow warming up of the diesel engine after starting depends mainly on the malfunction of the thermostat, which prematurely connects the radiator.

During operation in the radiator, it is sometimes observed foaming coolant. As a rule, this is due to the presence of oil in the coolant and is necessarily accompanied by an increase in its temperature and overheating of the diesel engine. The appearance of oil in the coolant indicates that the connection between the cooling system and the diesel lubrication systems has occurred. The connection point is usually a channel in the cylinder head for supplying oil to the valve train, and a possible cause is the porosity of the casting or a crack in the cylinder head, a gasket failure between the head and the cylinder block. Since the oil pressure in the lubrication system is several times greater than in the cooling system, on a warm diesel engine, oil seeps through pores or cracks into the cooling system.

20. The main malfunctions of the transmission of cars and their causes.

The main causes of malfunctions of transmission mechanisms are their misalignment, leakage of crankcases, violation of lubrication regimes (frequency of replacement, grades of oils used), as well as wear and increase in joint gaps, which predetermine a significant increase in shock loads in kinematic pairs and transmission bearings.

normal operation friction clutches in many cases depends on the serviceability of the control mechanisms. First of all, this applies to the main clutch of tractors. Silent shifting is only possible when the clutch is disengaged. Since the introduction of gears into engagement is difficult, the engagement is accompanied by a characteristic grinding or contact of the ends of the gears, their wear and chipping of the teeth. With such operation, the working length of the teeth quickly decreases, and this leads to an increase in the specific loads on the teeth, their accelerated wear and chipping. If large fragments get into the engagement or into the space between the gear wheel and the housing, the teeth or the housing may break with emergency consequences.

Clutch performance may also be impaired as a result of gradual reduce pedal free play. This leads to increased heating and wear of the release bearing, incomplete engagement of the clutch and slipping of the discs.

Difficulty shifting gears can be determined brake malfunction, since if it fails, even with a normal, complete disengagement of the clutch, the input shaft of the gearbox will not stop quickly. Therefore, it is necessary to detect misalignment or unacceptable wear of the brake pads in a timely manner. Grinding of teeth when shifting gears is a signal for immediate troubleshooting of clutch and brakes.

Normal performance gear train persists for a long period if engagement is provided for the entire width of the teeth of the wheels, noiseless engagement of the switched pairs of gears, their correct relative position, normal clearances in the bearings of the shafts or gear blocks.

Signs wear of gear teeth, shaft splines and gear wheels are noise and vibration as a result of an increase in shock loads in the transmission when the tractor traction force fluctuates.

The main malfunctions of the electrical equipment of tractors and cars. Their reasons.

The most vulnerable elements in the electrical equipment of the tractor include wiring. Breakage of wires and lugs, damage to the insulation, leading to a short circuit in the circuit - all this is a consequence of mechanical and thermal effects, unacceptable tension and twisting of the wires, their friction against the metal parts of the tractor. There are frequent cases of failure in the operation of batteries, starters, generators and voltage regulators. Malfunctions and failures in the operation of electrical equipment occur mainly due to untimely and poor-quality maintenance.

The indicators of the technical condition of electrical equipment include the level and density of the electrolyte, the degree of charge and the state of the contact terminals of the batteries, the values ​​​​of current and voltage during generator operation, the current of the protection relay, the current consumed by the starter at the time of closing the contacts of the electromagnetic relay.

TO battery failures include sulfation and short circuiting of the plates; accelerated self-discharge of batteries (more than 3% per day) caused by foreign impurities in the electrolyte; cracks and holes in the monoblock. Signs of sulfation of the plates are a decrease in battery capacity, rapid boiling of the electrolyte during charging and accelerated discharge when using the starter. The short circuit of the plates is characterized by a decrease in the density of the electrolyte and a sharp drop in voltage to zero when tested with a load plug, as well as a slight increase in the density of the electrolyte when the battery is being charged.

The performance of the battery depends to a large extent on the health of the charging circuit. Charging circuit failure manifests itself in the absence or small value of the charging current. The reasons may be a slippage of the generator drive belt, a malfunction of the generator itself (winding breakage, short circuit) or a voltage regulator. In this case, the battery will not be charged. Systematic undercharging of the battery also occurs with a large transient resistance in the connection of the battery terminals with the tips due to the oxidation of the contact surfaces and insufficient tightening of the tips. Battery overcharging may occur due to a faulty voltage regulator.

Poor starter performance with a working battery, it is observed due to the burning of the collector and brushes, misalignment of the switching on relay, short circuit in the starter windings, lack of contact between the starter and the ground. A break in the power circuit is the cause of the loss of performance of any current consumer.

The main malfunctions of plows and their causes

The most common malfunctions of agricultural machines are deformations, blunting and improper installation of working bodies, misalignment of components, loosening of fasteners, wear and tear of parts, failures in the operation of hydraulic systems. Working with faulty machines leads to a deterioration in the quality of technological operations.

Let's present the main faults and their causes in the form of a table

External signs of malfunction	Causes of the malfunction
Unsteady plow,	The blades of the plowshares are blunt, rounded
especially on dense	share socks
The presence of a comb, leave	Front or rear body plow deeper
front or	the rest, since no horizontal
back body	plow position
Wall failure	Misalignment of the plow, wear and curvature of the field
	boards, improper knife setting
rear recess	Large gap between nut and stop
plow bodies	central brace
uneven height	Fracture or bending of moldboards, bending of the plow frame
ridges after the passage
buildings
Clogging space	Overhang is incorrectly set
between buildings and pre-
plows
Hard to hit	Rear axle lock not working
rear plow body	small angle of entry of the groove for the latch roller
PLP-6-35 in the furrow
after turning

The main malfunctions of seeders and their causes.

Machine failures occur due to various reasons. During the operation of machines, it is important to know the signs of basic malfunctions and learn how to determine their causes. To identify the causes of malfunctions, it is advisable to use algorithms for their search, which reduces labor costs and machine downtime. For clarity, we will show in the form of a table the malfunctions of seeders and their causes.

Malfunction
established norm seeding is not maintained	Seeder shaft shifts spontaneously, regulator lever is loose
Uneven distribution division of seeds in rows and seed damage	Deflection of the shaft of the sowing units, unequal working length of the coils or the gap between the valve plane is not maintained and coupling rib, unsatisfactory cleaned seeds
Unsatisfactory seeding depth	Coulter discs do not rotate, coulters Soil stuck, seeder out of adjustment to a given seeding depth
Sowing errors	The length of the marker or bout marker is not calculated accurately, the coulter leaders are bent, they are incorrectly placed on the coulter coulters on the beam, coulters clogged, seeds do not enter the furrow when working metering units and supplying seeds to the seed tubes, individual metering units are clogged with foreign objects or seeds, kinks in the seed tubes, metering coils do not rotate due to drive failure
Do not rise or do not deepen	Faulty hydraulic system tractor
Seeding stopped fertilizer	Formed a set of fertilizers, clogged seeding holes or fertilizer ducts

Tasks, place and types of machine diagnostics.

Technical diagnostics has a great influence on the intensity of the use of equipment, which is taken into account by the availability factor. Prevention of failures, their prompt elimination sharply reduce machine downtime for technical reasons, increase their productivity and the quality of agricultural operations, which has a positive effect on the timing of work, contributes to additional profits for agricultural producers (Fig. 3.1). Therefore, diagnostics is practically used in one volume or another for all types of maintenance and repair equipment. In addition to traditional work (periodic maintenance, TR and KR, storage of cars), diagnostics have recently been used in the pre-assembly of cars in the pre-sales service, in the certification of service work, technical inspection (especially cars), valuation when purchasing and selling used cars and aggregates (Table 3.1). Due to the increase in the complexity of machines, the use of diagnostics has become necessary for the technological regulation (setting) of agricultural machines and for the introduction of automation as a control operation to confirm the possibility of high-quality functioning of the object.

The main tasks of technical diagnostics are:

Control of the technical condition to establish the values ​​of the parameters to the requirements of the technical documentation;

Search for the place and causes of failure (malfunction);

Forecasting the technical condition.

For each diagnosed machine, normative indicators of serviceability (operability) during operation, maintenance, TR and KR are established.

Technical diagnostics, depending on its type, is performed in various places. Diagnosis for simple types of maintenance is carried out directly at the temporary parking lot. With complex TO-3 for tractors, TO-2 for combines, diagnostics are usually carried out in a repair shop. Application diagnostics are carried out either directly in the field, involving a mobile repair and diagnostic workshop, or in a central workshop. Pre-repair, pre-repair and post-repair diagnostics are usually performed at the repair site.

Types of diagnosis depend on the content of the work, from the pre-sale maintenance of the machine to its disposal.

Pre-sales diagnostics units and machines are carried out after their transportation and reassembly before direct sale in order to assess the quality of reassembly and the readiness of the machine for operation

Maintenance diagnostics perform in order to identify values ​​of machine parameters that exceed the allowable.

Application diagnostics carried out upon receipt of the application of the machine operator about a malfunction that appeared during operation in the form of unusual knocks, grinding of parts, overheating of the component, a decrease in power, machine productivity, an increase in fuel consumption, etc.

Resource diagnostics components and assemblies are carried out before repair in order to determine its type. At the same time, resource parameters are controlled, the limiting values ​​of which determine the carrying out of the RC of the unit.

Pre-repair and pre-repair diagnostics units and machines are performed before repair or in the process of repairing an object (current or capital). The main content of such diagnostics is to check the state of resource components and assembly units in the unit.

Post-repair diagnostics are carried out in order to control the quality of repairs in terms of functioning parameters and parameters characterizing the ability to perform specified functions until the next repair. The objects of diagnostics are units and complete machines.

Diagnosis during disposal machines are carried out in the process of decommissioning the machine in order to select components that can be used in the repair of other similar machines. Practice shows that after the decommissioning of the machine, 50% or more of its components can be used after their maintenance and repair or restoration.

Methods and means of facilitating the start of engines when storing machines in open areas.

To start engines in winter and protect them from starting wear, the following are used: stationary devices and structures located on the territory of the enterprise and providing constant heating or periodic heat supply (warming up) to the engine from an external heat source; individual heaters for preheating of cooling and lubrication systems, working in combination with the use of winter oils and low-freezing liquids for the engine cooling system.

Warming up with hot water consists in the fact that hot water is poured through the engine cooling system, having a temperature of 85 - 90 ° C and supplied from the distribution hoses (with the engine drain valves open). Centralized heating is more rational, in which hot water is supplied directly from the boiler through pipes using pumps through a flexible hose to the engine cooling system. Water is drained through a drain cock through the outlet hoses to the boiler. In this way, hot water circulation is established in a closed circuit of the engine. In this case, the water pressure should be at least 30 - 35 kPa, and the temperature should not exceed 90 ° C.

Heating and heating with steam. Steam is the most intense heat carrier and can be used for engine heating according to two schemes: without condensate return and with condensate return. In the first case, steam is introduced into the engine cooling system through the radiator neck, drain cock or directly into the cooling jacket.

Electrical devices to facilitate starting the engine at low temperatures.

Devices to facilitate starting, affecting individual engine systems, the temperature state of its parts and operating materials, reduce the moments of resistance to rotation of the crankshaft, improve the conditions for the formation and ignition of fuel-air mixtures. The effectiveness of various methods and devices to facilitate starting depends on the type of engine, its design features and operating conditions. This type of funds include: glow plugs and air heating; air heating plugs in the intake manifold; electric air heaters. To facilitate starting engines, devices for supplying starting fluid with a low boiling point can also be used.

Electric heaters are used to heat the liquid in the engine cooling system, crankcase oil, fuel in the fuel system and battery electrolyte. According to the method of converting electrical energy into thermal energy, they are divided into heaters, induction, semiconductor, electrode, resistance, infrared, emitters, etc. Resistance heaters are the most widely used, but more and more attention is paid to them. semiconductor heaters.

The engine can be equipped with an individual pre-start heater. Heating crankcase oil, cylinder block and crankshaft bearings before starting allows you to reduce the viscosity of engine oil, facilitate its pumpability through the lubrication system and, thereby, reduce the moment of resistance to rotation and wear of engine parts during start-up. Individual starting preheaters differ in the type of coolant that ensures the transfer of heat to the engine, the fuel consumed and the degree of automation of the work process. As an example of heaters of this type, the PZhD-30 diesel heater is installed on cars of the KamAZ-740 and ZIL-133 families.

Many motorists, in order to save money, tend to purchase a car with a diesel engine, completely ignoring 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 such as:

• original manufacturing defect;
• untimely maintenance and violation of the rules of operation;
• systematic use of low quality fuel, technical deterioration of the fuel supply system and other parts during operation;
• and unskilled 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 exit from working condition, as a rule, is provoked by work under constant loads close to critical, and distances exceeding the working resource.

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 the vehicle maintenance regulations.

For example, in cars used on the territory of our country, due to the high percentage of sulfur in diesel fuel, the oil is subject to mandatory complete replacement after a car run of 7500 km, regardless of the technical instructions of the car manufacturer. The flushing of the system is not carried out in this case, in order to avoid the occurrence of oxides.

Diesel fuel system malfunctions

1. Flushing of 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 him try to remove the tank and see for himself how much dirt 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 waxes and the engine goes out of working condition. In this case, there is only one way out, to place the car in heat 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, 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 “sin”) and drive a car at maximum speeds, this is unacceptable for a diesel engine. Before starting the movement, the engine must be warmed up, at least 3-7 minutes.

5. Try to refuel only at proven and well-established gas stations. Indeed, almost half of all diesel engine fuel system malfunctions are due to poor quality.

1. Due to the wear of the piston group of the engine, there is a decrease in compression and therefore problems arise when starting the engine in the winter, even despite the serviceability of the glow plugs and seasoned fuel.

2. Another problem of engine wear is crankcase pressure and high fuel consumption. An overhaul of the motor will only help here.

3. Increased fuel consumption and black indicates wear on the injector nozzles. It happens that the atomizer bites and a kind of knock appears, and white smoke on the exhaust. It is impossible to drive for a long time on faulty injector nozzles, burnout of the prechambers and pistons of a diesel engine may occur.

4. If there is a problem starting a hot engine, then this indicates wear on the injection pump plunger pairs.

Interesting video - valve malfunctions:

I wish you all good luck! And fewer problems.

Diesel engines are widely used in engineering vehicles, trucks and shuttle vehicles. Less commonly, this type of engine is found in passenger cars, however, due to the general increase in their popularity, diesel engines have become increasingly installed on them.

The design of the combustion chamber in 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 twisted. This improves the self-ignition that occurs in the main chamber. Such diesel engines are most often found in passenger cars, as their noise level is much lower compared to other engines and the rev range is wider.

In the second case, the combustion chamber is located directly in the piston, and the fuel enters the space above the piston. Low-speed motors with large volumes most often have this design. Such motors initially made a lot of noise and vibrated, but consumed a small amount of fuel. Gradually, high-pressure diesel engine fuel pumps appeared with optimization of the combustion process. Stable engine operation was achieved at a range of up to 4500 rpm. Noise and vibrations 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 vehicle interior warm up more slowly due to lower engine operating temperatures. The issue is resolved by installing additional heaters on the motors. This option has become widespread on modern engines.

It would seem that this is all, but no. Many motorists buy passenger 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 ones. Gasoline engines are rather demanding on the desired octane number.

Diesel engines are in vain considered unpretentious, since their demands on the quality of fuel and consumables are quite high. It's no secret that domestic diesel fuel is far behind imported European fuel in terms of quality. Using good old diesel fuel can adversely affect engine performance. However, leading Russian oil companies are trying to solve this problem.

Diesel fuel "Euro 4" fully complies with the standards and allows the engine to keep working for a long time. Some also try to use auto chemicals (anti-gel products), which can improve the quality of the fuel, but it is recommended to use them only if the warranty period has already expired.

Thus, when purchasing cars with diesel engines that are not officially supplied to Russia, you run the risk of quickly rendering an 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 frequently than the gasoline competitor (average every 7.5 km).

A good advantage of a diesel engine, compared to a gasoline engine, is more economical fuel consumption with high vehicle mileage. An older gasoline engine consumes gasoline no longer as economically as a brand 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 justifies itself 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 uncommon. Read more about how a 4-stroke diesel engine works.

The operating cycle of such an engine consists of four cycles:

1. intake (injection). On 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.
2. Compression. The piston, moving up from 180 to 360 degrees, reaches the top dead center. At the same time, the air is compressed by 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.
3. Workflow, extension. The crankshaft rotates from 360 to 540 degrees, again reaching bottom dead center. As is known from physics, highly compressed air is heated to very high temperatures, due to which the fuel coming from the intake valve ignites spontaneously. At this stage, an important difference between a diesel engine and a gasoline engine is revealed. Diesel fuel begins to be supplied even before the crankshaft reaches top dead center (ignition advance). The products of combustion push the piston down. During the working process in a diesel engine, the pressure of the gases is constant, and due to this they are able to develop more torque. The proportion of air-fuel mixture in a diesel engine differs from that of a gasoline engine by a large amount of air.
4. 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.

Diesel internal combustion engine power supply system

Purpose

The power supply system in a diesel engine is a whole complex of special devices. Its main task is not only the flow of fuel into the injection nozzles, but also the provision of high pressure during supply. The power system performs other important functions:

• dosing of a precisely defined amount of fuel, taking into account the load on the engine in different operating modes;
• ensuring efficient fuel injection in a fixed period of time with the required intensity;
• spraying and uniform distribution of fuel throughout the entire space of the combustion chamber in the cylinders;
• pre-filtering of diesel fuel before supplying it to the pumps of the power system.

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 desired pressure. Injectors supply finely atomized diesel fuel into the combustion chamber

As an example, a diagram of a 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 supply system consists of basic and additional elements. The main elements are: a fuel tank, coarse and fine filters for diesel fuel, a fuel priming pump, high pressure fuel pump, injection nozzles (through which fuel is injected), a low pressure pipeline, a high pressure line and an air filter.

Additional items may vary. Among them are electric pumps, exhaust, soot filters and mufflers. The power supply system of a diesel engine is divided into two groups depending on the installed fuel equipment: diesel equipment for fuel supply and air supply.

In fuel supply equipment, as a rule, high-pressure fuel 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 has a fuel priming pump. It provides fuel supply from the fuel tank and passes fuel through fine and coarse filters. The pressure created by this pump allows fuel to be supplied through the low pressure pipeline to the injection pump.

The injection pump of a diesel engine supplies fuel to the injection nozzles under high pressure. The flow depends on the order of operation of the diesel engine cylinders.

Diesel injectors are located in the cylinder head. Their main task is to accurately atomize the fuel in the combustion chamber. A drainage system is also provided, which removes excess fuel and air supplied through separate pipelines. Nozzles come in open and closed types, but the closed type is used more often. The nozzle of such a nozzle is a hole closed by a shut-off needle. The key element of the nozzle is the atomizer. He receives one or more nozzle holes, which form a torch at the time of fuel injection.

There is also an inseparable type power supply system, in which the injection pump and the injection nozzle in their totality represent a pump-injector device. The service life of such motors is short, and the generated noise often exceeds the specified norms.

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 practically unchanged, and the air supply system undergoes significant changes.

Supercharging occurs with the help of 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 the compressors according to the degree of boost (low, medium, high).

Diagnostics of the diesel engine power supply 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, fuel pump, clogging of the radiator, air filter, cooling channels, oil channels, damage to the flywheel, valves, etc. d.

Malfunctions can occur in a variety of ways. Their timely detection will allow the engine to last longer. The main signs by which it can be understood that there is a malfunction are as follows: the engine does not start, does not develop the declared power, smokes heavily, and tapping occurs during operation.

Troubleshooting the diesel engine power system

If the engine does not start, the first step is to check the presence of 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 leakage of the system. To eliminate excess air, it is necessary to bleed the system and eliminate its leakage.

Pipelines, tank intake and fuel filters may be clogged. The water in them can freeze. It is necessary to warm them thoroughly and clean them with a rag soaked in hot water. If the injection pump does not work, then it is necessary first of all to 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, malfunction of the high and low pressure pumps. The malfunction is eliminated by cleaning the filters, pumping and removing excess air, adjusting the injection advance clutch at the nozzle, replacing or repairing the high and low pressure pumps, if warming up does not help.

Uneven engine operation occurs due to loss of efficiency by the injectors, a malfunction of the high-pressure fuel pump or the regulator. Faulty nozzles 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 disengagement of the rail retainer. To eliminate it, it is necessary to adjust the angle of the start of the fuel supply or replace the injection pump rail.

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 sludge is drained until clean fuel begins to flow. Then the plugs are tightly wrapped, and the fuel system is pumped by a hand pump. After that, the engine starts. After 3-4 minutes, all air congestion will be eliminated. The sludge from the fuel tanks is drained using special taps in the same way.

To wash the coarse and fine diesel fuel filter, the fuel is drained, the caps are removed and washed with clean diesel fuel. Then the old filter elements are replaced. After assembly, make sure that there is no air leakage with the engine running. Otherwise, the bolts for fastening the cups to the housings are tightened manually.

The air filter is removed from the vehicle and the filter element is removed. The body and the inertial damper are washed in diesel fuel or hot water, and the parts are blown with compressed air, the air intake mesh is cleaned. Damaged parts are replaced.

The exhaust duct is checked for leaks. The filter element is cleaned by blowing with dry compressed air or flushing. The filter element must be replaced if it has through damage.

The average life of the filter element is about 30,000 km. It should be flushed no more than three times, and purge no more than six times.

Lubrication of the fuel injection advance clutch is carried out through one of the holes before oil spills from the other hole. It is filled with 0.3 liters of engine oil.

To check the fuel injection advance angle, it is necessary to turn the crankshaft to the position when the mark on the leading half-coupling is at the top, and the latch enters 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, it is necessary to unscrew the 3 bolts of the driven half-coupling and by turning the crankshaft and the advance clutch, the marks are aligned.

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. The nozzle should inject misty diesel fuel and the injection jet should be cone shaped. If these parameters are not met, then diesel injectors need to be repaired. Checking and adjustment of the injection pump is also carried out by specialists in fuel equipment.

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 problems and, as a result, increase the life of your car's diesel engine. Good luck and easy roads!

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Malfunctions can occur in any power unit. Especially when it comes to a used car. Moreover, along with minor breakdowns, serious problems may appear that finally disable the machine. Their timely identification can save the motorist from significant financial losses caused by unforeseen major repairs.

For this, diesel diagnostics are intended, usually performed simultaneously with the periodic maintenance of the vehicle. Timely measures taken to eliminate minor malfunctions eliminate many future troubles.

Self-diagnosis of a diesel engine. Is it possible to do without a car service

Detecting various problems in the engine at an early stage and correcting them in a timely manner is the basis of proper car care. However, not every owner of a used vehicle is able to pay for diagnostics in a specialized workshop.

In addition, the geographically nearest car service can be located hundreds of kilometers from the garage. Therefore, the question of whether self-diagnosis of a diesel engine is possible, and what is required for this, is of particular relevance. Let's try to figure it out!

The need for diagnostics

The effectiveness and efficiency of the repair of diesel units is determined by many factors. One of the main conditions is the correct diagnosis.

A very high level of reliability of functional units and mechanisms that equip diesel vehicles is considered their main advantage. Due to this quality, most motorists prefer such cars, refusing gasoline power units.

Timely replacement of worn parts of a diesel engine minimizes the likelihood of their unforeseen failure during operation. It has been verified by experts that there are practically no spontaneous breakdowns in a properly functioning unit.

Any malfunction indicates insufficient attention of the owner, who did not notice the defect in time.

As for minor parts that are not particularly important for the normal operation of a diesel engine, they can suddenly lose their performance. At the same time, the usual functions of the internal combustion engine practically do not change.

In such cases, diagnostics and repair of diesel engines can be carried out in field conditions. Malfunctions of secondary elements of the power unit are identified and eliminated right on the road, right at the time of their discovery.

Specialists have established several obvious reasons that indicate malfunctions of diesel components that require the intervention of a mechanic:

1. increased smoke emission accompanying the operation of the engine;
2. difficulties with starting the power plant;
3. manifestation of increased noise effects during operation;
4. unstable operation of the motor, accompanied by a decrease in power.

The detection of these symptoms indicates the need for diagnostic measures. They will help you determine the cause of the problem and take corrective action.

Modern methods of diagnostic examination

Of course, car service workshops have specialized equipment that greatly simplifies the troubleshooting activities in power units. To date, there are three ways in which diesel engine diagnostics are carried out:

• the specialist performs a visual inspection of the motor, supplemented by an acoustic inspection of the installation;
• deviations of existing parameters from optimal values ​​are studied. To do this, they are measured;
• diagnostics on a specialized computer stand.

The purpose of the first method is to identify obvious faults. An experienced mechanic is able to notice any deviations in diesel engines. The condition of engine parts is evaluated by many factors, such as the appearance of filters or the sound of an exhaust.

The accuracy of the second method is determined by the quality of measurements. The activity of the internal combustion engine is characterized by certain parameters, the deviation from which indicates a malfunction. For example, by measuring the compression and the size of the leaks in the cylinders, you can detect problems in the motor.

The third method is considered the most accurate. It provides for the identification of faults in the computer control system. Monitoring sensors and other electronics allows the software to determine the cause of the breakdown.

Acoustic examination of a diesel engine

Studying the sounds of a running engine can give an idea of ​​the wear of some components and spare parts. Certain mechanical noises indicate the condition of the power unit. More about diesel mechanism malfunctions detected by acoustic diagnostics:

1. when a motor operating at low speeds is loaded, a muffled knock is heard in the piston group. This is the first symptom of piston wear. To eliminate the malfunction, worn liners are bored out, and pistons that have become unusable are replaced with new parts;
2. exceeding the allowable gaps in the valves is manifested by a characteristic clattering knock. Due to the frequency, this sound cannot be confused with other noises in the power unit. It is heard less often than other knocks. This is because the frequency of rotation of the camshaft, the cams of which drive the valve, is half the speed of the crankshaft. A separate article is devoted to adjusting valve clearances in power units of passenger cars;
3. if at idle the engine is sharply pressed on the gas pedal, sometimes you can hear a dull metallic knock. Its frequency is determined by the number of revolutions of the crankshaft. This phenomenon indicates the need to replace the main bearings. It also helps to eliminate the malfunction by grinding the crankshaft;
4. worn connecting rod bearings show themselves more distinctly. Determination of a faulty element is carried out by turning off the injectors one by one. The breakdown is eliminated in a manner similar to the previous one.

As you can see, by the sounds of running diesel engines, even an ignorant motorist is able to establish the cause of the unit's malfunction, by eliminating which it is possible to perform subsequent engine recovery.

Compression measurement

The second method of diagnosing a diesel engine involves the study of deviations in the values ​​of some performance indicators of engines using diesel fuel as fuel. To do this, measure the necessary parameters and compare them with the regulatory data set out in the technical documentation.

Unfortunately, the size of this article does not allow a detailed description of all the necessary manipulations required to perform a compression test. We only note that a special device is used for this. A special tool called a compression meter is able to provide fairly accurate readings of the desired value.

Comparing them with the normative data, the following malfunctions can be detected in the diesel unit:

1. excessive wear of the parts of the piston group, which threatens to overhaul the power plant;
2. problems in the valve system are usually solved by adjusting the thermal gaps. If the actions performed did not cause an increase in compression to the optimum level, measures are taken to grind the valves. Most often, this helps to restore the normal operation of the system. Otherwise, the valve seats must be repaired.

You can determine which of the listed faults caused a drop in the compression level by pouring a small amount of engine oil into each of the cylinders. After that, the measurements are repeated. An increase in indicators indicates a malfunction in the piston group.

Consistently low compression levels are determined by valve train malfunctions.

Computer diagnostics

An examination of the condition of the electronic systems of a diesel engine is carried out on special equipment. At home, holding such events is impossible, since a special computer scanner is required. A fairly complex high-tech device performs multi-stage engine diagnostics, in turn examining the functionality of the fuel and control systems of the unit.

Such a study consists of several phases, almost equivalent in importance:

• checking the performance of the electrical components of the injectors;
• evaluation of the readings of all temperature sensors that equip the motor;
• measurement of compression values ​​in the cylinder block;
• setting indicators of vacuum converters.

A smart scanner combines the received data on detected malfunctions and displays the latest information on the monitor. A thorough analysis of the causes of the detected defects allows the computer to determine the best ways to eliminate them.

Conclusion

From the foregoing, we can conclude that every motorist is able to independently diagnose a diesel unit. To do this, you just need to thoroughly study the performance characteristics of your iron horse. By carefully observing the operation of the machine, an experienced driver intuitively recognizes the slightest deviations from the norm.

A modern diesel engine, even if not equipped with an electronic fuel management system and a common rail modification, is more powerful, reliable and economical than a gasoline engine of the same size. The condition of the diesel fuel system directly determines these indicators. In the event of a malfunction, one or more of these characteristics are significantly reduced. Reduce time and money spent on repairs by quickly and accurately diagnosing the cause of performance degradation. It is possible to determine which node caused the malfunction of the diesel engine fuel equipment by analyzing its symptoms.

Common symptoms of a diesel fuel system failure

The nature of the operation of the diesel engine immediately before the occurrence of a breakdown indicates how well the flow and combustion of fuel in the cylinders took place. These indications are used in the preliminary diagnosis of the reasons for the decrease in vehicle performance.

Diesel engine does not start well

To start the unit, a long rotation of the starter is required, the start does not occur immediately and at first it works intermittently either.

Faults:

• lack of "diesel" at start-up - the regulator is faulty, or the booster pump;
• lack of fuel in front of the injection pump - air enters the system;
• lack of injection pressure due to wear of high-pressure fuel pump parts;
• advance angle failure;
• poor dispersion of fuel - the nozzle does not provide a sufficiently wide "torch".

In winter, a difficult start-up can be provoked by: failure of one or more glow plugs; the formation of a "paraffin plug" on the injectors when using an inappropriate (summer) type of fuel, the formation of "flakes" in the fuel line due to water (condensate) entering the tank.

Diesel engine does not develop the required power

When accelerating, the engine power is limited at a certain moment, the car does not develop maximum speed.

Faults:

• air ingress in case of damage to the fuel line;
• line clogging;
• malfunction of injectors, wear of their fasteners;
• failure of the high-pressure fuel pump, or its incorrect adjustment;
• incorrect setting of the injection advance angle.

The reason for the lack of fuel can also be a severe clogging of the air filter and an incorrect position of the accelerator pedal due to incorrect adjustment.

The motor is overheating

Temperature indicators are constantly above normal, while the car's cooling system is working.

Faults:

• the adjustment of the injection advance angle has gone astray;
• low fuel dispersion due to nozzle wear;
• detonation due to low-quality fuel.

The phenomenon sometimes occurs when the oil level in the engine crankcase is insufficient, or when it loses its properties from long-term operation.

Engine power has been noticeably reduced

Traction disappears with sharp acceleration, the acceleration time of the car increases. The effect is observed regardless of weather conditions and elevation changes.

Faults:

• insufficient amount of fuel in the system due to a breakdown of the booster pump;
• “poor” mixture - the fine filter is clogged;
• Significant weakening of the injection power - wear of the plunger pair, or incorrect adjustment of the injection pump;
• failure in the settings of the injection control regulator;
• Several injectors or their mountings are worn or damaged.

If problems occur in rainy weather or when driving in the mountains, their source is a lack of oxygen or a short circuit.

Engine runs hard or makes noise

The power unit reacts sharply to the accelerator, there is no smooth acceleration, with an increase in load, a characteristic fractional knock is heard in the area of ​​\u200b\u200bthe cylinders.

Faults:

• displacement of the injection phase towards early advancing;
• discrepancy in the amount of diesel entering different cylinders due to a violation of the adjustment of the nozzles;
• breakage or clogging of one of the sprayers;
• lack of proper sealing at the place of installation of the atomizer (there is no washer, the fastening is too tightened or loosened);
• air enters the fuel line;

In some cases, the reason is the lack of compression of the CPG.

Engine idling unevenly

It is noted mainly after maintenance (repair), or long-term operation without proper maintenance.

Faults:

• incorrect adjustment of the idle speed;
• airing in the section between the filter and the high pressure pump;
• damage to the base plate, in the high pressure fuel pump seal;
• failure of one or more nozzles, or failure of the nozzle or unit injector.

A separate cause of the problem is the limitation of the accelerator pedal travel (dirt, broken traction, etc.).

Significantly increased fuel consumption

It is noted regardless of the vehicle load.

Faults:

• clogging (loss of tightness) of the return channel of the fuel line (on the way to drain excess into the tank);
• idle speed is too high;
• injection advance adjustment failure;
• airing the main line.

Other reasons - clogged air filter; low compression in the cylinders; Timing gear needs to be repaired.

The computer gives an error

A vehicle equipped with an on-board computer displays a check engine message, or "engine error", if the pressure in the low pressure line or the fuel rail (common rail) does not correspond to the working indicator. Depending on the brand of the machine, the error code will be different.

Faults:

• the flow control sensor has failed;
• air entering the fuel line;
• the injection pump valve is not working properly.

For reliable diagnostics, you will need to connect a car dealer scanner to the on-board computer.

The motor suddenly spontaneously stops.

The car stalls while driving or immediately after starting.

Faults:

• damaged fuel line (faulty connection);
• booster pump broke;
• failure of the drive, piston-separator, pistons or high-pressure fuel pump rotor due to significant wear;
• Injection advance adjustment is broken.

Other reasons: the air filter is clogged, the tightness of the supercharger (turbine) is broken.

Unstable engine operation

The so-called "floating speed" is a spontaneous change by the motor of the readings of the crankshaft speed.

Faults:

• failure of the speed controller;
• the tightness of the fuel system is broken;
• lack of lubrication, or excess slip resistance of the parts of the adjustment system.
• significant production of high-pressure fuel pumps, or nozzles;
• unsatisfactory quality of diesel fuel.

The phenomenon sometimes occurs after a breakdown of the crankcase ventilation valve (CVKG) and the formation of their excess pressure.

Changing the color of smoke from the exhaust pipe of a car

from the exhaust pipe indicates hypothermia of the motor, severe wear of the CPG, or earlier than necessary advancing. Simultaneously with an increase in the level of engine oil, it may be a sign of a breakdown of the cylinder head gasket.

Dark (black) smoke is a sign of improper mixture formation (an excess of fuel and incomplete combustion). Causes: wear or clogging of injectors, “late” injection advance, wear of the CPG with loss of compression, incorrect valve adjustment.

Associated malfunctions of the fuel equipment

They appear either individually or in parallel with the main problems.

• On a car, you often have to change the glow plug - the nozzle corresponding to it is faulty.
• The engine oil level is getting higher - there is a leak in the injection pump drive seal.
• After the trip, it is not possible to turn off the diesel engine - the shut-off solenoid in the fuel line is faulty.
• The car has ceased to provide sufficient "engine braking" force - the return channel (reset) does not work, or the "idle" speed is incorrectly set.

The consequences of a violation are often common: the consumption of a "diesel" can increase both from the wear of the high-pressure fuel pump and from a lack of air when the air filter is clogged. It is possible to reliably establish that the breakdown relates specifically to the fuel system only by successive troubleshooting of the components and assemblies indicated by the problem.