The engine of each car is a rather complex device, on the operation of which the comfort of your movement depends. Therefore, it is very important to service the motor in a timely manner and qualitatively identify emerging malfunctions, and do preventive maintenance. You need to know that it is advisable to regularly, according to the regulations, change the oil and the fuel filter, this is already the key to the success of the engine's durability. If you do this at the wrong time, then there is an increased wear of the engine, which will lead to its failure much faster. This arises because the oil is no longer able to fully demonstrate its washing ability and fully lubricate the rubbing parts, which means that at a certain moment dry friction appears, and this leads to scuffing and destruction of those parts that have the highest load. Also, the used oil must undergo the required filtration, which cannot be provided by an unreplaced filter. So small metal particles, inclusions, will "stick" to the parts, which will also lead to dry friction faster. Any oil that has worked out its service life tends to deposit resinous substances that can easily enough clog the channels for the passage of oil in the engine. For this reason, the lubricant will not be able to fully flow to the friction pairs, which means that this fact will cause accelerated wear of parts and even to the likely wedge of the motor. Similar consequences can be for an engine in which oil is filled in by its type and class does not correspond to a specific engine.

Routine repairs, engine adjustments must be carried out in a timely manner and professionally. If these works are not performed correctly, accelerated wear of the motor cannot be avoided. You can give a vivid example with a "knocking" camshaft. In this situation, due to the problem that has arisen, there will be a significant clogging of the oil with metal particles, knock products. Another example is the incorrect operation of the cooling system, which can lead to early overheating of the motor. By running this problem, you can get a deformation of the cylinder head due to overheating, which, as a rule, leads to the formation of microcracks in it.

Experienced car enthusiasts know that driving style affects engine durability. So a more aggressive, high-speed, sporty style will lead to significant revolutions of the rotating parts, and therefore their quick failure due to wear. These modes will reduce the motor durability by up to 30%. In cold weather, starting the engine can be seriously difficult. This fact is caused by a change in the viscosity of the engine so that it becomes very, very difficult to crank the crankshaft. A warm garage box or special devices designed for remote switching on and warming up of the engine and oil sump will come to your aid. Comparing engine wear when starting cold below 20 degrees can be compared to a car's mileage of more than 500 km.

It is not recommended to operate the car in the winter season if you only need it for driving over a short distance. The reason for this is the appearance of deposits in the lubricant and the appearance of condensation, which leads to the "defeat" of the engine piston group by corrosion.

If you feel that the motor is not working stably and, most likely, repairs are required, how can you determine its volume, will you need capital?

It is important here to make a preliminary diagnosis in several directions. Detection of low pressure of the engine lubrication system, a pronounced knock in the crank-connecting rod system, will indicate increased wear of the liners and the crankshaft journal, a possible failure of the sliding bearings. In this case, the runout of the crankshaft journals and the amount of wear of the cylinder group are measured, after which appropriate repair measures are already taken.

You are guaranteed not to avoid a major overhaul if, after operating the engine, the engine jammed, the connecting rod broke, the piston group and rings were destroyed. Often, with such symptoms, cylinders and crankshaft are severely damaged.

In this article, we will look at the three most common causes of damage to engine components and describe the situations that lead to damage. The most common causes of damage are abrasive engine wear from dirt, water hammer and increased oil consumption.

Engine abrasion

Abrasive wear is the result of the scratching or cutting action of hard particles from mating parts, as well as the result of airborne or lubricated dust entering the surface of parts. Most often, abrasive wear of the engine manifests itself in the form of increased oil consumption.

Examination of damaged parts reveals a different nature of damage:

• a wide matte contact patch is formed on the piston skirt both on the side of the greatest lateral load and on the opposite side;
• the wear of the machining profile on the piston skirt is noted;
• thin grooves are formed on the piston skirt, piston rings, wall or cylinder liner in the direction of travel;
• piston rings and their grooves are worn in height;
• there is an increased thermal clearance on the piston rings, the edges of the rings become extremely sharp;
• the working edges of the oil scraper ring wear out;
• the piston pin has wavy grooves;
• abrasive wear leaves its marks on other parts, for example, on the valve stem.
• In case of damage caused by abrasive wear, several types of defects can be distinguished:
• If only one cylinder is damaged and the first piston ring is worn much more than the third, then the contaminants enter the combustion chamber through the intake system of the cylinder, that is, from above. The reason for this is either depressurization or mud deposits that were not removed before the start of repair work.
• If several cylinders are damaged or all cylinders and the first piston ring is worn much more than the third, then contamination enters the combustion chamber through the common intake system of all cylinders. The reasons for this situation are explained by depressurization and / or a destroyed or missing air filter.
• If the third piston ring is worn significantly more than the first, then it should be assumed that the engine oil is dirty. Oil contamination occurs either because the crankcase has not been cleaned and / or because of a dirty oil mist separator.

Elimination of defects and prevention consists in checking the intake system for leaks, checking and replacing the air filter; before installation, the engine crankcase and intake pipes should be cleaned of contamination. Cleanliness must be observed during repair work.

Water hammer

Water hammer is a powerful source of energy. And this energy can have a devastating effect on many engine components: the piston collapses or deforms, the connecting rod bends or breaks, the piston ring bridge of the damaged piston shows signs of static fracture, the piston pin breaks.

This defect is caused by liquid (water or fuel) that has entered the combustion chamber. Since neither water nor fuel is compressed, a water hammer causes a sharp force on the piston, gudgeon pin, connecting rod, cylinder head, crankcase, bearings and crankshaft.

Too much liquid may end up in the combustion chamber for the following reasons: Water enters the combustion chamber through the intake system (for example, when driving over a surface flooded with water); water ends up in the combustion chamber due to defective gaskets. Too much fuel is entering the combustion chamber as a result of a faulty injection nozzle.

Increased oil consumption

Low oil consumption is normal. It fluctuates depending on the type of engine and its mode of operation. If the oil consumption rates prescribed by the manufacturer are exceeded, then we can talk about such a concept as increased oil consumption. Possible reasons for increased consumption:

• Due to the depressurization of the turbocharger. The turbocharger oil circuit is clogged or coked. The pressure in the oil circuit that increases for this reason forces the oil out of the turbocharger into the intake duct and into the exhaust system.
• Oil enters the combustion chamber with the fuel, for example due to wear on the high pressure fuel pump, which is usually lubricated through the engine oil circuit.
• A leaky intake system allows dirt particles to enter the combustion chamber, leading to increased wear.
• If the piston protrusion is incorrectly adjusted, the piston can hit the cylinder head. This results in vibrations that affect the fuel injectors. In this case, the nozzle stops closing completely, so too much fuel gets into the combustion chamber, and an overdose of fuel occurs.
• The oil has worn out. Exceeded oil change intervals result in blockages and / or destruction of the filter paper, as a result of which crude oil begins to circulate in the oil circuit.
• Bent or twisted connecting rods result in disruption of piston movement, resulting in a failure to properly seal the combustion chamber. In the most critical cases, the pumping action of the piston rings may occur. In this case, oil is actively fed into the combustion chamber.
• If the piston rings are broken, skewed, or improperly installed, these circumstances can lead to insufficient sealing between the combustion chamber and the crankcase. Due to this leakage of the seal, oil can enter the combustion chamber.
• Cylinder head bolts are not tightened properly. This can lead to deformations, and therefore to a violation of the tightness of the oil circuit.
• Worn pistons, piston rings and cylinder contact surfaces increase the amount of breakthrough gases. And this leads to overpressure in the engine crankcase. If the pressure is too high, oil mist can be squeezed out through the crankcase ventilation into the combustion chambers.
• If the oil level is too high, the crankshaft is immersed in an oil bath, leading to the formation of oil mist. And if the oil is too old or of poor quality, then the formation of oil foam is also possible. Then the oil mist and foam, together with the breakthrough gases, enter the intake duct through the engine ventilation, and therefore into the combustion chambers.
• In the event of malfunctions in the combustion process, fuel overflow is possible. Due to the dilution of oil with fuel, the wear of the pistons, piston rings and the working surface of the cylinders increases manifold.
• If the cylinder is skewed, for example due to old and / or incorrectly tightened cylinder head bolts, the piston rings lose their ability to seal properly between the combustion chamber and the crankcase. Thus, oil mist can enter the combustion chamber. With particularly strong deformations, it is even possible that the pumping action of the piston rings appears, that is, a situation where oil is simply pumped into the combustion chamber.
• Poor cylinder finish with poor honing on its running surface interferes with oil retention. This leads to a significant increase in the wear of mating parts such as pistons, piston rings and cylinder working surfaces, and, consequently, to insufficient sealing of the engine crankcase. When using clogged or worn honing heads, a graphite layer forms on the cylinder running surface. That is, a so-called insulating jacket appears. It significantly reduces the scraper potential, which leads to increased wear, especially during cold starts.

Any building or structure is designed and erected in such a way that during a given service life, subject to certain rules of technological and technical operation, the necessary, in accordance with the designation, the performance characteristics provided for by the project are maintained (# M12293 0 854901275 4120950664 77 333169391 2302717373 589252483 1264343928 350062449 4 see table 1 # S).

During operation, each structure is exposed to two groups of impacts (# M12293 1 854901275 4120950664 81 435422279 884731037 2822 350062471 4 3900756975 table 5 # S):

1) external, mainly natural - such as solar radiation, temperature fluctuations, precipitation, etc.;

2) internal, technological or functional caused by processes occurring in buildings.

All these impacts are taken into account in projects by selecting materials and structures, protecting them with special coatings, limiting technological hazards and other measures. However, it is not always possible to fully take into account all the impacts in projects and during construction, especially when introducing new technological processes, during the construction of buildings and structures in areas that are poorly studied in terms of construction, and when defects or defects are allowed in projects and during construction. In addition, during the operation of buildings and structures, unforeseen situations often arise in the operation of technological equipment, in the maintenance of individual structures and structures in general.

Table 5

Factors affecting buildings and structures

# G0 External influences (natural and artificial	Impact result	Internal influences (technological and functional)
Radiation	Mechanical physico-chemical (+) destruction	* Loads (permanent, temporary, short-term)
Temperature		* + Shock, vibration, abrasion, spillage
* Air flow		* + Temperature fluctuations
Precipitation (including acids)		Humidity
Gases, chem. substances
* Lightning discharges
Electromagnetic waves (including radio)
Sound vibrations (noise)		* + Biological pests
* + Biological pests
Ground pressure
* Wandering currents
* Frosty heaving
Ground moisture
Seismic waves
Vibrations

In the totality of factors affecting buildings and structures, in each specific case, one of them becomes decisive, leading in the development of wear; therefore, the mechanism and the intensity of wear become specific, different from other cases.

For the rational technical operation of buildings and structures, it is important to be able to assess the aggressiveness of the environment, to identify the main causes of damage in order to expediently and timely use the forces and means at the disposal of the operational service to prevent and eliminate them.

In our country, for more than ten years, the operation of buildings and structures has been guided by preventive maintenance systems(PPR) of buildings for residential, public, industrial purposes, which indicate the service life of individual structural elements, engineering equipment and structures in general, i.e. the frequency of their repair has been established. The introduction of these systems is essential for streamlining inspections and repairs of buildings and structures. However, the terms of repairs envisaged in them are not differentiated in relation to various options for structures in terms of structural solutions, their service life, climatic and other conditions, as a result of which they are averaged.

A sad story: an engine (new, moderately used or overhauled) was expected for many years and many hundreds of thousands of kilometers of reliable and honest operation, but it suddenly started to smoke, lost power, became capricious at startup, there was oil and eventually got up.

Now the overwhelming majority uses cars that were created in countries that were dozens of years ahead of us in the general motorization of the population. And these cars are built on principles close to those that exist in aviation - REGULATORY DIAGNOSTICS.
Those who have been abroad know that there most often people come to the service with a question, see if everything is in order. This is especially the case in Germany.

Engine. What is the most common cause of premature engine wear?

2. Engine overheating.

The accumulation of carbon deposits is a gradual process. There are many reasons and we have all analyzed them. For some types of engines this is more relevant, for others less. The problem is most acute for engines with direct fuel injection.
It is often said that engines have become less reliable. And I would formulate it differently. Engines have become more demanding, and on our fuel and in our conditions, cleaning from soot must be done every 10 thousand, then there will be no problems.
In addition, errors in the sensors of the fuel equipment, clogging of the air filter and much more strongly affect the accumulation of carbon deposits.
Overheat. This phenomenon rarely occurs suddenly. It usually "creeps up" very gradually in the form of small drips of antifreeze, which can be either noticeable and appear as a puddle under the car, or the ingress of antifreeze into the combustion chamber, which can most often be seen only with an endoscope through the candle hole.

"Opening" of several engines with similar symptoms at first glance always gives a more or less similar picture - severe wear of the cylinder-piston group. However, catastrophic wear is not always a direct consequence of prolonged and intensive operation. Often the piston group, and with it the entire motor, die suddenly. In such cases, it is extremely important to understand what exactly caused this wear in order to eliminate the cause during repair. Otherwise, the repair turns into an endless and hopeless elimination of the consequences.

Let's consider a few typical examples:

Intense wear as a result of the fuel washing off the lubricant from the cylinder walls.

Errors in the operation of the fuel equipment, "pouring" injector, misfiring or inaccuracies in setting the injection advance angle lead to the formation of an excessive amount of unburned fuel in the over-piston space. Getting on the cylinder walls, fuel particles mix with the oil film, significantly reducing its lubricating properties. As a result, in the most stressed area of ​​the cylinder, the piston rings operate under conditions of insufficient lubrication.

Significant excess fuel

It is able to completely wash off the oil film, and the operating conditions of the rings in this case are close to the dry friction mode. In such cases, there is intense wear of the piston rings, with the formation of a characteristic sharp edge. The cylinder liner in the upper operating zone of the rings acquires critical wear (about 0.2 mm) literally after 500 - 800 km of run. The piston skirt is not seriously affected at the initial stage. Later, characteristic dark spots with vertical marks appear on the piston skirt, indicating friction zones in conditions of insufficient lubrication. When examined under a microscope, it is possible to detect embedded particles of wear products of the piston rings on the piston skirt. The engine oil "deceased" for the reasons described above usually has significant impurities of fuel. So, together with the black smoke of the re-enriched exhaust, not only soot and unburnt diesel fuel, but also a significant part of the engine's resource, flies into the pipe.

Quick and sad consequences are caused by the ingress of abrasive into the engine.

It is not difficult to calculate that for every minute of operation, a naturally aspirated diesel engine pumps through itself an amount of air equal to the product of the working volume by 1/2 revolutions. For example, V slave - 12 liters, revolutions 2000 rpm, i.e. 12 m2 per minute or 720 m3 per hour. A very low concentration of solid particles in such a volume of consumed air is enough for the accumulated abrasive to literally eat up the engine from the inside. Inaccurate installation of the air filter, loose clamps, cracks in the connecting corrugations, the possibility of air sucking into the engine past the filter - all lead to the rapid death of the motor from the "road" abrasive.

Danger of technical abrasive entering the motor during maintenance or repair work.

A tractor in a dusty field and a luxury boat in neutral waters can be equally susceptible to such misfortunes. How many times it was necessary to observe how the desire of the diligent owner of the car to "polish" the intake manifold with sandpaper, or to correctly and accurately grind the carburetor body parts on the plate, leads to almost instantaneous (200 - 500 km) death of the engine. It is impossible to remove technical abrasive by “rinsing with gasoline”. In modern practice of motor repair, the very desire to grind something (for example, valves) causes bewilderment, but nevertheless, in such an insidious way, particles of abrasive sometimes manage to get into the engine.

Further, the following picture is formed: solid particles falling into the friction zone cause intense wear. Piston rings wear intensively not only in radial thickness, but also in height. In this case, the first compression ring receives the maximum wear, since it is this ring that is exposed to solid particles in the first place. Intensive wear of the first ring in height appears as a result of the accumulation of solid particles in the gap between the ring and the annular groove of the piston. The end surfaces of the ring quickly acquire significant deviations from the original geometric shape and dimensions. The rapidly increasing clearance causes intense breakage of the annular groove.
When an abrasive enters the engine, intensive wear of the working surfaces of the rings is accompanied by the formation of numerous vertical notches. Micro breakage or micro burrs appear on the edges of the rings. The zone of maximum cylinder wear is usually lower than in the above-described case of excess fuel wear and falls at about the middle of the cylinder working height. The working area of ​​the piston skirt is damaged in the form of numerous vertical marks, which give the piston skirt a matte gray color. When examined under a microscope, embedded solid particles are found on the piston skirt - the killers of the engine and the culprits of this type of wear.

The number of such inclusions on the piston skirt is usually not large - only a few points per 1 cm2, however, if we take into account that a small part of the total abrasive that has entered the piston skirt has penetrated into the material of the piston skirt, and also take into account that, on average, per 100 km of run, the piston makes about 200 thousand double strokes, then even a small amount of solid inclusions on the piston skirt becomes obvious, clearly indicating the abrasive nature of intensive wear. Often the notorious gasoline bath in which yesterday<сполоснули>a lapped valve, and today the mechanic of the other shift washed something before assembling the motor and is the true reason<необъяснимых>wear and tear.

The last, and perhaps the most obvious indicator of the presence of abrasive wear is

The nature of the damage to the piston pin.

Judge for yourself: if a finger with a surface hardness is usually about 54:60 HRC in a short time has received abnormally large wear, turning in<алюминиевых>the piston bosses, therefore, particles were present in the friction zone that were significantly harder than the piston pin material itself. In practice, it happened, unfortunately, to deal with cases with the malicious application of powders or pastes to motors.

In this situation. an unconditional benefit would be the creation of a serious specialized scientific and expert laboratory. But until such an organization has been created, transport workers and repairmen have to deal with many controversial situations on their own.

By themselves, defects in the mechanical part of the engine, as you know, do not appear. Practice shows: there are always reasons for damage and failure of certain parts. It is not easy to understand them, especially when the components of the piston group are damaged.

The piston group is a traditional source of troubles that lie in wait for the driver who operates the car and the mechanic who repairs it. Engine overheating, negligence in repairs - and please - increased oil consumption, gray smoke, knocking.

When "opening" such a motor, seizures on the pistons, rings and cylinders are inevitably found. The conclusion is disappointing - expensive repairs are required. And the question arises: what was the fault of the engine, that it was brought to such a state?

The engine is certainly not to blame. You just need to foresee what these or those interventions in his work lead to. After all, the piston group of a modern engine is "thin matter" in every sense. The combination of the minimum dimensions of parts with micron tolerances and enormous forces of gas pressure and inertia acting on them contributes to the appearance and development of defects that ultimately lead to engine failure.

In many cases, simply replacing damaged parts is not the best engine repair technique. The reason for the appearance of the defect remained, and if so, then its repetition is inevitable.

To prevent this from happening, you need to think several moves ahead, calculating the possible consequences of your actions. But this is not enough - it is necessary to find out why the defect occurred. And here, without knowledge of the design, operating conditions of parts and processes occurring in the engine, as they say, there is nothing to do. Therefore, before analyzing the causes of specific defects and breakdowns, it would be nice to know ...

How does a piston work?

The piston of a modern engine is a simple detail at first glance, but extremely important and complex at the same time. Its design embodies the experience of many generations of developers.

And to some extent, the piston shapes the entire engine. In one of the previous publications, we even expressed such an idea, paraphrasing a well-known aphorism: "Show me the piston, and I will tell you what kind of engine you have."

So, using the piston in the engine, several problems are solved. The first and foremost is to perceive the pressure of the gases in the cylinder and transfer the resulting pressure force through the piston pin to the connecting rod. This force will then be converted by the crankshaft into engine torque.

It is impossible to solve the problem of converting the gas pressure into a rotational moment without a reliable seal of the moving piston in the cylinder. Otherwise, gases will inevitably burst into the engine crankcase and oil will enter the combustion chamber from the crankcase.

For this, a sealing belt with grooves is organized on the piston, in which compression and oil scraper rings of a special profile are installed. In addition, special holes are made in the piston for oil discharge.

But this is not enough. During operation, the piston crown (fire belt), in direct contact with hot gases, heats up, and this heat must be removed. In most engines, the cooling problem is solved using the same piston rings - through them, heat is transferred from the bottom to the cylinder wall and then to the coolant. However, in some of the most loaded structures, additional oil cooling of the pistons is done by supplying oil from the bottom to the bottom using special nozzles. Sometimes internal cooling is also used - the nozzle supplies oil to the inner annular cavity of the piston.

For reliable sealing of the cavities against the penetration of gases and oil, the piston must be held in the cylinder so that its vertical axis coincides with the axis of the cylinder. Various kinds of distortions and "shifting", causing the "dangling" of the piston in the cylinder, negatively affect the sealing and heat transfer properties of the rings, increase the noise of the engine.

The guide belt - the piston skirt - is designed to hold the piston in this position. The requirements for the skirt are very contradictory, namely: it is necessary to provide a minimum, but guaranteed, clearance between the piston and the cylinder, both in a cold and in a fully warmed-up engine.

The problem of designing a skirt is complicated by the fact that the temperature coefficients of expansion of the cylinder and piston materials are different. Not only are they made of different metals, their heating temperatures vary many times over.

To prevent the heated piston from jamming, measures are taken in modern engines to compensate for its thermal expansion.

Firstly, in cross-section, the piston skirt is given the shape of an ellipse, the major axis of which is perpendicular to the axis of the pin, and in the longitudinal - a cone tapering to the piston crown. This shape allows the skirt of the heated piston to match the cylinder wall, preventing seizure.

Secondly, in some cases, steel plates are poured into the piston skirt. When heated, they expand more slowly and limit the expansion of the entire skirt.

The use of lightweight aluminum alloys for the manufacture of pistons is not a whim of the designers. At the high speeds found in modern engines, it is very important to maintain a low mass of moving parts. In such conditions, a heavy piston will require a powerful connecting rod, a "mighty" crankshaft and an overly heavy block with thick walls. Therefore, there is no alternative to aluminum yet, and you have to go to all sorts of tricks with the shape of the piston.

There may be other "tricks" in the piston design. One of them is an inverse taper in the lower part of the skirt, designed to reduce noise due to the "shifting" of the piston in dead spots. A special micro-profile on the working surface - micro-grooves with a pitch of 0.2-0.5 mm - helps to improve the lubrication of the skirt, and a special anti-friction coating helps to reduce friction. The profile of the sealing and firing belts is also certain - here is the highest temperature, and the gap between the piston and the cylinder in this place should not be large (the probability of gas breakthrough increases, the danger of overheating and breakage of the rings), nor small (there is a great danger of jamming). Often, the resistance of the fire belt is increased by anodizing.

All that we have told is not a complete list of requirements for the piston. The reliability of its operation also depends on the parts associated with it: piston rings (size, shape, material, elasticity, coating), piston pin (clearance in the piston bore, fixing method), state of the cylinder surface (deviations from cylindricality, microprofile). But it is already becoming clear that any, even not too significant, deviation in the operating conditions of the piston group quickly leads to the appearance of defects, breakdowns and engine failure. In order to qualitatively repair the engine in the future, it is necessary not only to know how the piston works and works, but also to be able to determine, by the nature of damage to parts, why, for example, there was a scuffing or ...

Why did the piston burn out?

Analysis of various piston damages shows that all causes of defects and breakdowns are divided into four groups: impaired cooling, lack of lubrication, excessively high thermal-force effect from gases in the combustion chamber and mechanical problems.

At the same time, many causes of piston defects are interrelated, as are the functions performed by its various elements. For example, defects in the sealing belt cause overheating of the piston, damage to the fire and guide belts, and seizure on the guide belt leads to a violation of the sealing and heat transfer properties of the piston rings.

Ultimately, this can provoke burnout of the fire belt.

We also note that almost all piston group malfunctions result in increased oil consumption. Serious damage will result in thick, bluish exhaust smoke, drop in power and difficult starting due to low compression. In some cases, the knock of a damaged piston is heard, especially on an unheated engine.

Sometimes the nature of the piston group defect can be determined without disassembling the engine according to the above external signs. But more often than not, such a "CIP" diagnosis is inaccurate, since different reasons often give practically the same result. Therefore, the possible causes of defects require detailed analysis.

Disruption of piston cooling is perhaps the most common cause of defects. This usually occurs when the engine cooling system malfunctions (chain: "radiator-fan-sensor for turning on the fan-water pump") or due to damage to the cylinder head gasket. In any case, as soon as the cylinder wall ceases to be washed from the outside by the liquid, its temperature, and with it the temperature of the piston, begins to rise. The piston expands faster than the cylinder, moreover, unevenly, and ultimately the clearance in some places of the skirt (as a rule, near the hole for the pin) becomes equal to zero. Seizure begins - the seizure and mutual transfer of the materials of the piston and the cylinder mirror, and with further engine operation, the piston becomes jammed.

After cooling, the shape of the piston rarely returns to normal: the skirt turns out to be deformed, i.e. compressed along the major axis of the ellipse. Further operation of such a piston is accompanied by a knock and increased oil consumption.

In some cases, piston seizure extends to the sealing belt, rolling the rings into the piston grooves. Then the cylinder, as a rule, is turned off from work (compression is too low), and it is generally difficult to talk about oil consumption, since it will simply fly out of the exhaust pipe.

Insufficient piston lubrication is most often characteristic of starting modes, especially at low temperatures. In such conditions, the fuel entering the cylinder washes the oil from the cylinder walls, and seizure occurs, which are usually located in the middle of the skirt, on its loaded side.

Double-sided skirt seizure usually occurs during prolonged operation in the oil starvation mode associated with malfunctions of the engine lubrication system, when the amount of oil falling on the cylinder walls decreases sharply.

Lack of lubrication of the piston pin is the reason for its jamming in the holes of the piston pin bore. This phenomenon is typical only for designs with a finger pressed into the upper connecting rod head. This is facilitated by the small clearance in the connection of the pin to the piston, therefore, “sticking” of the fingers is more often observed in relatively new engines.

An excessively high thermal-force effect on the piston from the hot gases in the combustion chamber is a common cause of defects and breakdowns. So, detonation leads to the destruction of the bridges between the rings, and glow ignition leads to burnouts.

In diesel engines, an excessively large fuel injection advance angle causes a very rapid increase in pressure in the cylinders ("hardness" of work), which can also cause breakage of the jumpers. The same result is possible with the use of various fluids that facilitate diesel engine starting.

The bottom and firing belt can be damaged if the temperature in the diesel combustion chamber is too high, caused by a malfunction of the injector nozzles. A similar picture arises when the cooling of the piston is disturbed - for example, when the nozzles supplying oil to the piston with an annular cavity of internal cooling become coked. The seizure on the top of the piston can spread to the skirt, engaging the piston rings.

Mechanical problems, perhaps, give the greatest variety of piston group defects and their causes. For example, abrasive wear of parts is possible both “from above”, due to the ingress of dust through a torn air filter, and “from below”, when abrasive particles circulate in the oil. In the first case, the most worn out are the cylinders in their upper part and the compression piston rings, and in the second, the oil scraper rings and the piston skirt. By the way, abrasive particles in the oil may appear not so much from untimely engine maintenance, but as a result of rapid wear of any parts (for example, a camshaft, pushers, etc.).

Rarely, but erosion of the piston at the hole of the "floating" pin occurs when the circlip pops out. The most probable reasons for this phenomenon are the non-parallelism of the lower and upper connecting rod heads, leading to significant axial loads on the pin and "knocking out" the retaining ring from the groove, as well as the use of old (lost elasticity) retaining rings when repairing the engine. In such cases, the cylinder is damaged by the finger so much that it can no longer be repaired by traditional methods (boring and honing).

Sometimes foreign objects can enter the cylinder. This most often occurs during careless work during engine maintenance or repair. A nut or a bolt, caught between the piston and the block head, is capable of a lot, including simply "failing" the piston crown.

The story about piston defects and breakages can be continued for a very long time.

Electronics.
Here everything is most often manifested even more clearly. Most of the refusals at the beginning are manifested in the form of errors, which are erased and the person leaves reassured. But practice has shown that any, the most insignificant deviation from the norm is a sign of a certain trend. You can ignore the light "poking" of the box for a long time, which can be easily removed by flashing or, in extreme cases, by prophylaxis of the board. But quickly enough this will lead to the need to bulkhead the box.

Timing errors are often a sign of chain wear, gears, and then end up with a bulkhead of the motor for hundreds of thousands of rubles. Such work as replacing the timing belt in general should be carried out "in automatic mode" up to a run of 80 thousand. Everyone knows what happens at a cliff.

Having the opportunity to compare how much those who have not turned off in their minds the old algorithm of approach to car maintenance and those who “come for diagnostics” spend on the maintenance of cars, I can say that the expenses of the first in the amount of the time of owning a car are about 30 50% is usually more than the latter.

The rules are very simple and follow from the features of the piston group and the reasons for the appearance of defects. Nevertheless, many drivers and mechanics forget about them, as they say, with all the ensuing consequences.

Although this is obvious, it is still necessary during operation:

1. keep the power supply, lubrication and cooling systems of the engine in good working order, maintain them on time,

2.Do not overload a cold engine,

3.Avoid using low quality fuel, oil and inappropriate filters and spark plugs.

When repairing, it is necessary to add and strictly follow a few more rules. The main thing, in our opinion, is that one should not strive to ensure minimum piston clearances in the cylinders and in the ring locks. The "small gap disease" epidemic that once plagued many mechanics is still not over. Moreover, practice has shown that attempts to "more tightly" install the piston in the cylinder in the hope of reducing engine noise and increasing its resource almost always end in the opposite: piston scuffing, knocking, oil consumption and repeated repairs. The rule “better clearance is 0.03 mm more than 0.01 mm less” always works for any engine.

The rest of the rules are traditional:

quality spare parts,

correct handling of worn parts,

thorough washing and neat assembly with mandatory control at all stages.

Initially, smart people used a double-row chain and double gears. The load on each tooth and link in the chain was small and chain problems did not occur in nature.

Now, under the slogan of reducing weight and metal consumption, as well as ecology, the engines have become the way we see them.

After 120 thousand mileage, it is necessary to change the polls without waiting for the marks to leave and a cliff or jump.

Leaving the mark from the norm even by a millimeter is a reason for replacement.

Andrey Goncharov, expert of the heading "Car repair"

The main causes of accelerated engine wear

Untimely replacement of oil and oil filter leads to the operation of friction pairs in unfavorable conditions.

This is due to the deterioration of the performance properties of the engine oil (its viscosity changes, additives are produced, the tendency to form deposits on parts and in the channels of the lubrication system, etc.) and a large amount of wear products in the lubrication system (in an extremely dirty oil filter, a bypass valve and oil flows past the filter element).

Use of low-quality oil causes accelerated wear and rapid engine failure. An oil that does not have all the properties required for normal lubrication of friction pairs does not prevent the formation of scoring and destruction of the working surfaces of highly loaded parts (parts of the gas distribution mechanism, piston rings, piston skirts, crankshaft liners, turbocharger bearings, etc.).

The increased tendency of low-quality oils to form resinous deposits can lead to clogging of oil channels and leave friction pairs without lubrication, which will cause their accelerated wear, the formation of scoring and seizure. Similar effects are possible in the case of using oil that does not correspond to the given engine in terms of quality class (API classification, ACEA, etc.). For example, when a cheaper SF / CC is used instead of the recommended API SH / CD oil.

Unsatisfactory condition of the air or fuel filter(defects, mechanical damage), as well as various leaks in the intake system connections lead to the ingress of abrasive particles (dust) into the engine and intense wear, primarily of the cylinders and piston rings.

Failure to eliminate engine malfunctions or improper adjustments will accelerate wear on parts. For example, a "knocking" camshaft is a source of continuous contamination of the lubrication system with metal particles. Incorrect ignition timing, malfunction of the carburetor or engine management system, the use of spark plugs that do not match the engine cause detonation and glow ignition, threatening the destruction of pistons and surfaces of combustion chambers.

Overheating of the engine due to malfunctions in the cooling system can lead to deformation of the cylinder head (cylinder head) and the formation of cracks in it. With insufficient cooling, the oil film in friction pairs becomes weaker, which leads to intensive wear of the rubbing parts. Diesel engines have piston burnouts and other serious defects as a result of fuel equipment malfunctions.

Vehicle operating modes also affect the rate of engine wear. Engine operation mainly at maximum loads and crankshaft speeds can significantly reduce its resource (by 20-30% or more). Exceeding the permissible speed leads to destruction of parts.

About 70% of engine wear occurs during start-up. Cold start especially contributes to the reduction of the resource if the engine is filled with oil with an inappropriate viscosity-temperature characteristic. At a temperature of -30oC, it is equivalent (in terms of wear) to a mileage of several hundred kilometers. This is due, first of all, to the high viscosity of the oil at low temperatures - it takes more time for it to enter (pump) to the friction pairs.

Short trips on a cold engine in winter contribute to the formation of deposits in the lubrication system and corrosive wear of pistons, their rings and cylinders.