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.
"4x4" 02.2000
G.Tsvelev, "Motorservis"
In order for a car with a diesel engine to fully show its best qualities, and not to discourage its owner forever from an interest in a diesel engine, one must have a good idea of the features of its operation.
and repair, know the causes of the most common
malfunctions and how to eliminate them. For the owner of a diesel jeep, what knowledge will certainly not be superfluous, because the possibility of any qualified diesel repair becomes zero at a distance of more than 50 km from big cities, and you have to rely on your own strength. It can be said with a high degree of probability that the largest number of malfunctions of diesel engines with a volume of 2.5 liters and above (and the vast majority of them are installed on jeeps) is associated with violation of operating rules and unskilled repairs. Improper operation should also include the use of low-quality diesel fuel, which is poured into all Russian gas stations without exception, and the owner is powerless to do anything here.
Basic rules for the operation of diesel engines and the consequences of their violation
1. Timely change the oil and use oil of the appropriate quality and viscosity.
In all diesel engines, without exception, it is recommended to change the oil and filter at least every 7,500 km, even if the instructions provide for long service intervals. This recommendation is due to the high sulfur content in Russian diesel fuel, which leads to its rapid oxidation and aging.
Oil for modern engines should be used with a quality class of at least CD according to API or B2 according to ACEA.
The viscosity index recommended for a particular motor is usually indicated in the instructions. The most versatile are all-weather oils with viscosity indices 5W40 and 10W40, synthetic and semi-synthetic.
All modern oils are approved for use in both gasoline and diesel engines (for example, SH / CE), and it is absolutely not necessary to buy oil with the word "diesel" in the name. Synthetic or semi-synthetic oils have more stable characteristics throughout their entire service life and thus reduce engine wear. However, the frequently occurring opinion is unfounded.
about the need to use only synthetic oils in modern turbodiesels, mineral oils can also be used without restrictions if their quality class meets the requirements of the instructions.
As for the question of which manufacturer's oil to choose, the difference here is insignificant, unless, of course, you run into a fake.
You just need to choose the type of oil once and do not practice frequent changing it to another: when different oils interact,
poorly soluble deposits, because in
The motor always has a small non-bleeding residue. Rapid blackening of engine oil (sometimes after 1000
km after replacement) should not cause concern, this is a common occurrence and is caused by the work of detergents and dispersants.
2. Timely replace the timing belt.
The timing belt and injection pump should be changed at least every 60 thousand km. According to the instructions on the part of Japanese motors, the replacement interval is 100 thousand km, but it should be remembered that this is the limit value - for such a long time the belt can only last in absolute cleanliness, without hitting
giving oil to it.
Consequences of a broken timing belt.
-
distributor failure.
- deformation of valves
always meet pistons, break rocker arms and camshafts, often completely incapacitating the block head.
The cost of repairs in this case can be several thousand dollars.
When replacing the timing belt, the tension roller must also be changed,
since its destruction leads to the same consequences.
A break in the injection pump belt does not lead to any serious consequences, however, if this happened on the road, it is good
it’s also not enough - set the injection without special equipment
it is very difficult.
3. Keep the fuel system clean.
To do this, periodically drain the sediment from the fuel filter by unscrewing the drain plug located at the bottom of the filter. The fuel filter itself must be changed every 8-10 thousand km. It is undesirable to do this less frequently, since a clogged filter creates increased hydraulic resistance and disrupts the normal operation of the fuel equipment. It is recommended to flush the fuel tank twice a year, in spring and autumn, completely removing it from the vehicle.
Everyone can verify the relevance of such a procedure on their own by seeing how much dirt and water will pour out of the tank.
Failure to follow these simple rules often leads to the need for a serious repair of the fuel pump and injectors, and in an unfortunate set of circumstances, to damage to the engine itself.
4. Do not attempt to start the engine from a tow.
In many cases, such an attempt leads to serious damage to a perfectly serviceable motor. So, for example,
if there is summer diesel fuel in the tank, and it is 10 ° C outside, an attempt to start is pointless: at -5 ° C, paraffins already crystallize and the fuel loses its fluidity. Fuel equipment parts are known to be lubricated with fuel, and its absence leads to dry friction and damage to them.
The only correct solution in this case is to look for a warm garage and warm up the fuel system.
This broken plunger is the result of an attempted tow launch at -20°
Often when starting from a tow, damage to the timing drive occurs, especially on those engines where it is driven by a toothed belt.
A serviceable diesel engine should start freely without additional means of heating up to -20°C. If this is not
occurs, it is easier to find and fix the problem than
bring the engine to overhaul.
5. Warm up the engine and avoid prolonged driving
dy at high speeds.
Warming up the diesel engine is necessary, although the opposite opinion can often be found, including in some instructions. A cold diesel engine really allows you to move immediately without jerks and dips, but the thermal clearances in unheated parts are increased, and the lubricating properties of cold and thick oil, on the contrary, are not high enough, which leads to a significant increase in wear of parts in this mode. Therefore, a small warm-up for 3-5 minutes before the start of movement is absolutely necessary for a diesel engine. Long-term operation at high speeds, more than 3,500 - 4,000 rpm, when the loads on the crank mechanism and the cylinder-piston group are especially high, leads to a sharp increase in their wear and a decrease in engine life. The range of 1600 - 3200 rpm should be considered optimal for long-term use.
6. Do not force deep puddles at high speed.
Good off-road driving performance of a diesel jeep often provokes its driver to famously cut through semi-halfs and fords, raising splashes and waves like a boat. If you knew how many motors got into overhaul due to water hammer!
A bent connecting rod is a victim of water hammer.
As you know, diesel has no intake throttling and its suction properties are high, and the volume of the combustion chamber is very small. Even a small amount of water that has entered the manifold and then into the over-piston space causes a phenomenon called water hammer - since the liquid is incompressible and there is nowhere for it to go on the compression stroke, the connecting rod is damaged (bent).
The air filter does a great job of letting water through.
Therefore, it is recommended to force deep puddles, which
called "step".
7. Use only high-quality spare parts and do not re-
mount the engine in unfamiliar places.
Attempts to save on spare parts or the cost of repairing a diesel engine most often end up not at all with the result that we would like to get. Because of the big
thermal and dynamic loads quality requirements
spare parts and components are very high, and the market
spare parts is flooded with second-rate goods, and often outright marriage.
So, for example, a glow plug bought for $5, which
2-3 times cheaper than its normal price, works at its best
case for two weeks, and sprayers for $ 10 have to be rejected right at the stand. There were cases of drawing a new chain for a week of work, and this is on the Mercedes "e 300D, where the factory chains freely "care" for 200 thousand km.
The same recommendation applies to repairs: you can find a service or a master who has the price of the same work.
2-3 times lower than in a specialized technical center, but
very often such repairs lead to loss of time, money and
even engine damage.
Piston burnout due to a defective injector nozzle.
Diesel repair requires a good knowledge of the features
the design of the motor being repaired and the strict implementation of the repair instructions.
The main malfunctions of diesel engines and how to eliminate them
1. Difficulty starting the engine.
Most often, it is difficult to start a cold engine in winter. If the fuel and oil are appropriate for the season, and the starter provides sufficient starting speed and at the same time the warm engine starts and runs without comment, then the cause of poor starting is either low compression or a faulty preheating system. The lower compression limit for most engines is 20-26 bar. If the compression is at the lower limit specified for a particular motor, or its spread across the cylinders exceeds 3-5 bar. the motor needs to be repaired. In 90% of cases, repair by replacing the rings is ineffective and requires boring the block with the installation of repair pistons.
The wear of the piston group can definitely be judged
and without measuring compression when from the open cover
oil filler or disconnected crankcase ventilation hose, crankcase gases escape intensively. By the way, this is the simplest check that you can independently carry out when buying a car. If this phenomenon is detected, then the purchase should be abandoned or the price should be immediately reduced by the cost of the overhaul.
You can check the preheating system with a conventional tester. To do this, connect a voltmeter to a common bus, which supplies voltage to the candles, and turn on the ignition. If the glow voltage of 12V (on parts of Japanese cars 6V or 24V) comes to the candles and is removed 20-30 seconds after the control lamp in the cab goes out, then the candle control relay is working properly. If the voltage does not come at all, then you need to check the fuse. Next, disconnect the common bus from the candles and check their resistance with an ohmmeter. In serviceable 12-volt candles, the cold resistance is usually 0.6-0.8 ohms. If it is equal to zero - there is a short circuit in the candle, if infinity - an open circuit.
This spark plug should be replaced.
Faulty injection pumps or injectors affect cold starts to a much lesser extent, however, together with reduced compression, insufficient injection advance and a poorly sprayed fuel injector can make starting impossible.
Sometimes a poor start of a serviceable engine after a long stop is caused by air leaks in the fuel system. During the parking time, the fuel "leaves" the injection pump. and without bleeding the system, the engine will not start.
Difficulty starting a hot engine with an easy cold start is always caused by a malfunction of the injection pump,
associated with the wear of the plunger pair (hydraulic head). When the fuel heats up, its viscosity decreases and hydraulic losses in the gaps increase.
The plunger in this case is not able to develop enough pressure to open the nozzles at starting speeds.
and no fuel enters the combustion chamber. In this case, you can not do without replacing the plunger.
2. Increased engine smoke.
Increased smoke, in addition to being unpleasant in itself, is also a sign of a malfunction and therefore always requires a timely search for the cause and its elimination.
White-gray smoke with a pungent smell of unburned diesel fuel is caused by the fact that the fuel does not burn in the cylinder, but evaporates on the hot parts of the exhaust tract. This is usually caused by malfunctions of the fuel supply equipment, a late injection angle, or a failure in one of the cylinders. Operation of the engine in this case is unacceptable, as this can lead to further, more serious damage to the engine.
If, during a cold start, the engine emits a large amount of bluish smoke and is unstable, and as
warming up, this disappears, then this indicates a reduced compression in one of the cylinders or a malfunction of one or two glow plugs. Because of this, when starting, one of the cylinders does not work and the fuel in it evaporates without burning, and then, as the engine warms up, stable self-ignition begins, the cylinder starts up and the smoke disappears.
With this phenomenon, you can operate the machine for some time without fear of damage, but you should still remember that uneven operation of a cold engine significantly accelerates wear.
Black smoke during sudden gas supply and when driving under load is usually caused by injector malfunctions or early injection advance angle. An early injection angle usually causes a significant ignition delay followed by a sharp increase in cylinder pressure due to the autoignition of most of the fuel charge at once, which provokes harsh engine operation and the formation of a large amount of soot.
Sometimes black smoke is caused by malfunctions of the turbocharger, which does not develop sufficient boost pressure or passes a significant amount of oil into the intake tract due to wear on the labyrinth seals of the turbine shaft.
Operation of a car with increased smoke does not damage the engine or its parts, however, long-term driving with faulty injector nozzles or an early injection angle leads to burnout of the prechambers, burning of the pistons and destruction of the jumpers, which requires further serious repairs.
At the same time, a slight emission of black smoke when the gas pedal is pressed sharply for no more than 1 second is considered acceptable and does not require intervention in the fuel system.
3. Unstable operation of the engine, power drop
sti and traction.
If the engine is in good condition, starts easily and does not consume oil, then these phenomena are usually explained by malfunctions in the high-pressure fuel pump or other elements of the fuel system.
So unstable idling and traction dips, accompanied by the appearance of bluish smoke, are associated with a malfunction of the booster pump inside the high-pressure fuel pump. This usually requires repair of the fuel pump with complete disassembly, which cannot be done without the appropriate
stand. Sometimes a simpler reason leads to the same effect - air leakage. To exclude it, it is necessary to disconnect the suction hose from the fuel filter and “feed” the engine from a separate container with clean diesel fuel. If the motor has worked normally, you should look for a place for air leakage, if not, repair the high-pressure fuel pump.
In Japanese SUVs, a common place for air leakage is the manual pump membrane on the filter housing. Sometimes in these motors, the cause of unstable operation is a clogged or jammed metal return line, called the "return". It should also be remembered that the washers under the “return” are disposable and their repeated use, in addition to leakage, can lead to a violation of the drain from the nozzles to the “return”.
4. Increased engine noise.
For many diesel drivers who have previously driven only gasoline cars, the sound of their well-functioning engine sounds excessive or threatening to them.
The owner should be aware that noises that stand out from the general uniform knock of a running engine, in tone or not coinciding with the frequency of the engine, or appearing and disappearing in a certain rpm range, should cause concern. You should immediately alert the appearance of extraneous sounds, accompanied by a loss of engine power and the appearance of white smoke. These are ominous symptoms. In any case, if there are any concerns, it is better to play it safe and, after stopping the operation of the engine, proceed to determine the cause of the knock.
Early detection of faults
avoids major repairs.
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.
In the human body, nature provides for the determination of diseases by the nervous system, which reacts to any “malfunctions” of health. So engine diagnostics is designed to detect violations in the operation of such a valuable node for a car. Therefore, I would like to have some way to quickly and reliably first check for an engine malfunction.
Symptoms of a diesel engine failure
Engine starting difficult
Deterioration of the discharge elements of the high pressure pump. Incorrect fuel advance angle in the engine. Nozzle wear causing poor fuel atomization. Injection pressure too low.
Lack of fuel in front of the high pressure pump due to air entering the fuel supply system. Malfunctions of the booster fuel pump. Too low a dose of fuel at start-up, caused by improper operation of the regulator. Fuel thickening in winter. Faulty glow plugs.
Engine power reduction
Worn high pressure fuel pump or regulator precision parts. Incorrect adjustment of the pump or all-mode regulator. Incorrect injection timing. Worn or damaged nozzles. Excessive injection pressure reduction. Insufficient amount of fuel supplied by the injection system due to a clogged fuel filter, insufficient performance of the fuel priming pump, or air in the fuel system.
Increased fuel consumption
Incorrect injection timing. Deterioration of the discharge elements of the high pressure pump. Incorrect adjustment of the high pressure pump. Worn or damaged nozzles. Too much injection pressure drop. The air filter is dirty. Fuel leak. Insufficient compression.
Black smoke exhaust
Poor mixture formation in the combustion chamber due to carbon deposits or loose valve closures. Late fuel injection. Poor atomization of fuel by injectors. Incorrect valve clearances. Insufficient compression.
Gray or white smoky exhaust
Incorrect injection timing. Insufficient compression. Blown head gasket. Engine overcooling.
Rigid engine operation
Too early fuel injection. There is a big difference between the doses of fuel injected into different engine cylinders. Incorrect operation of some injectors. Insufficient compression.
Engine overheating
Incorrect injection timing. Poor atomization of fuel by injectors (jet instead of "torch").
Full engine power does not develop
Short travel at the accelerator pedal, the accelerator pedal rod is incorrectly adjusted. The air filter is dirty. Air in the power system. Damaged fuel lines. Faulty mounting sprayers (nozzles). Sprayers are defective. The fuel injection advance angle has been knocked down. High pressure fuel pump defective.
Increased fuel consumption
Unsealed power system. Clogged fuel drain line (from pump to fuel tank). High idle speed or injection advance has been lost. The engine is not working well. Faulty atomizers, faulty nozzles. High pressure fuel pump defective.
Increased engine noise
Contamination in the power system, as a result of which the sprayers do not work. The sealing washers under the nozzles are missing or poorly installed, the nozzle is too tightly (too loosely) wrapped in the cylinder head. Air in the power system.
Uneven engine idling
Idle speed set incorrectly. The accelerator pedal is difficult to move. Loose fuel supply line between high pressure fuel pump and fuel filter. High pressure pump base plate damaged. Malfunctions in the fuel supply. Faulty atomizers, faulty nozzles. Incorrect injection timing.
Fluctuations in the frequency of revolutions of the crankshaft
Deterioration of the speed controller. Misalignment or wear of the injection system. Excessive resistance to the movement of elements in the control system. Air entering the fuel system. Excess gas pressure in the crankcase.
Sudden engine stop
Displacement of the discharge advance angle (disconnection of the pump with the drive). Clogged fuel filter and lack of fuel supplied to the pump. Lack of fuel supply caused by damage to the high pressure fuel pump or priming pump. Injection line damage. Wear and distortion of the separator piston, rotor or pistons of the high pressure pump.
Glow plugs often fail
The injectors in the corresponding cylinders are faulty.
Can't turn off engine
Shut-off solenoid valve defective.
The level of engine oil in the crankcase rises
Leakage through the seal of the chain or gear drive of the high pressure pump.
Weak engine braking
Clogged fuel drain lines. Fast idle speed set incorrectly.
Why do you need to diagnose diesel engines?
Modern diesel vehicles are characterized by a fairly high level of reliability of all their components and assemblies. If the driver replaces failed and worn-out diesel elements in a timely manner, the risk of their unexpected failure during operation is reduced to zero.
Experts in the field of auto repair say that spontaneous failures in the normal functioning of diesel engines are almost never observed. If any of their important component breaks, this means that its defect was not noticed by the owner of the car for a very long time.
But the minor parts of a diesel engine can fail suddenly, but at the same time they do not pose a serious threat to the performance of the internal combustion engine. Diagnostics and repair of diesel engines with such minor breakdowns can be performed even on the road.
Most often, adjustment, repair or replacement of diesel components is required when the driver notes:
A large release of smoke by the unit (by the color of the smoke, experienced craftsmen can even establish the presence of certain defects);
Launch problems;
High noise level;
Loss of traction power and generally unstable engine operation.
If these symptoms appear, diagnostic measures should be carried out immediately to find out their cause and perform the required repairs.
Methods for diagnosing diesel engines
Can be distinguished three main methods for diagnosing diesel engines:
- Visual and acoustic inspection.
Measurement of various parameters.
Computer (electronic) diagnostics.
The first method allows you to detect gross faults. Of course, it alone is not enough, but even a visual and acoustic inspection carried out by an experienced craftsman makes it possible to assess the condition of engine parts, for example, by air filters, by the sound of exhaust gases, etc.
The second method is aimed at a more accurate determination of faults using a variety of measurements that characterize the activity of the motor. For example, diagnosing diesel engines involves measuring relative compression and leaks in cylinders. According to these indicators, it is already possible to identify a number of problems of internal combustion engines.
The third method helps to detect breakdowns in the electronic engine control system. The software used makes it possible to identify faults very accurately by monitoring sensors and electronics.
Means for diagnosing diesel engines
The best way to find out the factors that lead to diesel breakdowns in our technological age is computer diagnostics of its electronic systems. It allows you to evaluate the general technical condition of the motor, check all control units, individual components and parts using a powerful computer scanner.
Such a scanner performs a multi-stage inspection of the unit, checking in turn the operation of the fuel system, and then the control system. An important part of the examination is precisely the diagnosis of the fuel equipment of diesel engines, in which malfunctions are quite common.
During the diagnostic procedure, it is necessary o the following steps are performed:
- analysis of the functioning of injectors (their electrical part);
Taking readings from all available temperature sensors;
Establishment of compression indicators in the engine block (in cylinders);
Measurement of the values of vacuum transducers.
Computer diagnostic equipment for diesel engines collects together information about the identified problems, displays data about them on the display and gives detailed instructions for eliminating defects. Not a single hidden flaw goes unnoticed by the scanner, which means that any breakdown will be eliminated during the repair work, which will ensure the safety of driving a vehicle with a diesel engine.
Advantages of computer diagnostics
The scanner has earned the respect of motorists because the engine does not need to be disassembled for diagnostics. Computer equipment is connected to the unit and after a while gives out data about errors in the functioning of the system and all existing malfunctions. Ease of diagnosis and its 100% accuracy suits owners of diesel vehicles.
Automotive experts advise conducting a computer inspection of the car twice a year - before the summer and winter operating seasons. Since drivers always prepare their vehicle for seasonal use, this operation can be combined with engine diagnostics on a computer. The result of the procedure will be the reliability of its operation and the safety of driving.
A power supply system (in other words, fuel) is provided. There is an opinion that diesel cars are more picky about fuel quality. It really is. Yes, and the repair of such a system is many times more expensive. Today we will consider what the diesel engine fuel system is, its device and the main malfunctions.
Device
Conventionally, this system can be divided into two circuits: high and low pressure. The latter prepares the fuel and sends it to the "next level", to the second circuit. The high pressure system performs the function of the final injection of fuel into the combustion chamber of the engine.
The low pressure circuit chain includes a number of structural components. These are a filter, a separator, a fuel drive, a heater, and also a pump. Fuel passes through each of the above parts. The pump creates pressure in the system, the heater in cold weather heats the "diesel fuel" to the desired temperature (since in winter it turns into paraffin slurry), and through the filter the fuel enters the second, no less important circuit in the system. It consists of the following parts:
- It connects with the filter.
- Nozzles. Recently, injectors with direct fuel injection have gained great popularity. It is believed that they are designed for a more accurate dosage of fuel. The machine does not lose power, while the consumption drops.
- Fuel lines - lines through which the mixture enters the cylinders.
Below we will consider the main malfunctions of the diesel engine fuel system.
Difficult start
This happens especially often in cold weather. It is believed that it is almost impossible to start a diesel engine without preheating in winter. In order to somehow alleviate this situation, manufacturers have provided arctic fuel, which includes antifreeze additives. But a difficult start does not always indicate frozen fuel. If the car does not start well even “hot”, most likely the high-pressure pump, namely its injection elements, has failed. It is also worth checking the advance angle of the fuel supply to the engine. It is possible that the nozzles are worn out, due to which the mixture is poorly sprayed in the cylinder. In general, there are a lot of reasons for the difficult start of a diesel engine. Therefore, every detail is checked. Faulty may be incorrect operation of the pressure regulator, lack of fuel in front of the injection pump. Such malfunctions of the diesel engine fuel system (Volkswagen T4 is no exception) are accompanied by depressurization of the fuel lines, due to which air enters the pump, which is no longer able to generate the required pressure.
Power drop
Occurs due to wear or damage to the nozzles. Also, such malfunctions of the diesel engine fuel system occur due to insufficient fuel that enters the pump. Since a filter is installed in front of it, it is likely that it is simply clogged.
Big expense
These malfunctions of the power supply systems of diesel engines occur due to an incorrectly set injection advance angle. Also, increased fuel consumption is a consequence of improper operation of the fuel pump. Mixture injection pressure level too high. In addition, consumption increases due to low compression in the cylinders.
Black smoke from the exhaust
And if on KamAZ trucks this is considered to be a “factory disease”, which the owners simply do not pay attention to, then on foreign cars the smoke from the chimney is a reason to think seriously. These signs of a diesel engine malfunction indicate poor cylinder carburetion, which may be due to late fuel injection. You should also check the injectors and valve clearances. The “blackness” itself is formed due to soot and loose closure of the intake / exhaust valves of the engine.
White and gray smoke
The head gasket may have been blown in the engine. If this smoke disappears over time, the motor is simply overcooled. This is normal for northern latitudes.
hard work
A diesel engine is inherently noisier than a gasoline engine. However, if the vibrations have increased, most likely, early fuel injection has occurred. Determining the malfunction of a diesel engine is carried out by diagnosing injectors. The compression level in the cylinders is also checked. Its minimum level should be 23 kilograms per cubic centimeter. The range of indicators between the cylinders does not exceed 5-10 percent. The average diesel engine produces about 27-30 "kilograms". To determine, a special tool is used - a compression gauge.
Gaps in acceleration
Symptoms - too short stroke of the gas pedal. In this case, the accelerator linkage should be adjusted. Also check the air filter. It is possible that the high pressure is faulty, because of which it cannot generate the desired pressure in the system.
Swimming "idle"
In this case, check the sealing washers under the nozzles. Look at the fastening of the fuel wire between the filter and the pump. Tighten more if necessary. Also, with similar symptoms of a malfunction in the diesel engine fuel system, look at the pump base plate for damage. The crankshaft may be worn. "Idle" swim because of the excess pressure of gases in the crankcase - check the ventilation.
Engine stalled
If it stalls on the move, check the offset of the injection advance angle. This is a violation of the connection between the drive and the pump. It is also a dirty filter, which causes a lack of fuel and low supply pressure. As for the pump itself, it is possible to misalign the separator pistons or the rotor. It is worth noting that the injection pump is the most expensive part in the power system of a diesel car. Due to the complex design, the element is difficult to repair, so the cost of restoration is comparable to the price of a new element purchased at a disassembly.
Prevention
To exclude malfunctions of the diesel engine fuel system (because a diesel failure is expensive and long), do not be lazy to carry out preventive maintenance. First of all, you need to flush the system at intervals of 1-2 times a year. This operation includes dismantling the fuel tank and removing the accumulated "sludge" in the fuel filter. Practice shows that a lot of sediment forms at the bottom during operation, which, when driving on an empty tank, instantly clogs up in filters and lines.
Fuel type
This is especially true for the use of the car in the so-called transitional season. The air temperature has already dropped, and gas stations are selling the rest of the summer fuel. It loses its fluidity already at -5 degrees. Then it turns into paraffin, which clogs in the pump and filters. Be sure to specify at gas stations what type of fuel will be poured - summer or winter. If it so happens that the temperature has dropped sharply, and there is summer diesel fuel in the tank, warm the car as much as possible with a preheater, or if it is a passenger car, connect a household heater to the garage. When starting a diesel engine, every degree matters.
Do not dilute fuel
Some craftsmen, if necessary, start a diesel engine in the winter, “bodyate” fuel with gasoline. This is absolutely impossible to do. In Russia, special arctic diesel additives have long been sold to prevent the formation of paraffin in the tank. In fact, the same additives are added to ordinary summer fuel at gas stations - this way it becomes suitable for operation in winter. There is nothing illegal in this. But diluting it with gasoline is just suicide (meaning for the fuel system).
Warming up in winter
Warm up or not? The fuel system of a diesel engine, which is significantly different from a gasoline engine, also needs this action. After starting the engine, let it idle for 3-5 minutes, after which drive the first 200 meters in a “sparing” mode for the car. A diesel engine, unlike a gasoline engine, is colder - it warms up much longer. Long idling is also not required, but you should not ignore the above recommendation.
gas station
Everyone scolds our gas stations for the poor quality of fuel, they say, there is no normal diesel fuel at Russian gas stations. This is fundamentally wrong. One simple rule: fill your car with expensive fuel at well-known gas stations. Everyone wants to save money by buying fuel 10-15 percent cheaper than the market value, literally lining up. However, after a couple of weeks, having got to repair the fuel station, they begin to blame not themselves, but gas stations. In fact, this is so, but no one forces them there by force. You always have a choice. Remember the main thing - a miser pays twice.
How to increase the resource of high pressure fuel pump?
As we said earlier, this is one of the most critical parts of the fuel system.
In order for the high pressure pump to last longer and malfunctions of the diesel engine fuel system bypass you, you need to:
- Do not leave the tank "half empty" overnight. This is how condensate forms on his machines, which then penetrates into the nozzles and the pump.
- Periodically drain the sludge through the drain plug.
- Do not drive on an empty tank and a constantly burning light bulb.
Conclusion
So, we found out the main malfunctions of the diesel engine. By following these simple rules, you will significantly extend the life of the system and reduce the risk of "getting repaired".
