A sad story: from an engine (new, moderately used or overhauled) they expected many years and many hundreds of thousands of kilometers of reliable and honest work, but it immediately began to smoke, lost power, began to act up at startup, there is oil and eventually got up.
Now the vast majority uses cars that were created in countries that are decades ahead of us in the mass motorization of the population. And these cars are built on principles close to those that exist in aviation - DIAGNOSTICS ACCORDING TO REGULATIONS.
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 soot is a gradual process. There are many reasons and we all analyzed them. For some types of engines this is more relevant, for others less so. The problem is most acute for engines with direct fuel injection.
It is often said that engines have become less reliable. And I would put it differently. Engines have become more demanding both on our fuel and in our conditions, carbon deposits must be cleaned every 10 thousand, then there will be no problems.
In addition, fuel equipment sensor errors, air filter clogging, and much more greatly affect the accumulation of soot.
Overheat. This phenomenon rarely occurs suddenly. It usually "sneaks" very gradually in the form of small smudges of antifreeze, which can be both noticeable and manifest as a puddle under the car, or antifreeze getting into the combustion chamber, which can most often be seen only with an endoscope through the spark plug 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 long and intensive operation. Often the piston group, and with it the entire engine, die suddenly. In such cases, it is extremely important to understand what exactly caused this wear in order to eliminate the cause during the repair. Otherwise, the repair turns into an endless and hopeless elimination of consequences.
Let's look at a few typical examples:
Intensive wear as a result of the fuel washing off the lubricant from the cylinder walls.
Errors in the operation of the fuel equipment, a “pouring” nozzle, misfiring or inaccuracies in setting the injection advance angle lead to the formation of an excess 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 upper zone 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, intensive wear of the piston rings is observed, with the formation of a characteristic sharp edge. The cylinder liner in the upper zone of operation of the rings acquires critical wear (about 0.2 mm) literally in 500 - 800 km of run. The piston skirt is not seriously affected at the initial stage. Later, characteristic dark spots with vertical scoring appear on the piston skirt, indicating friction zones in conditions of insufficient lubrication. When examined under a microscope on the piston skirt, it is possible to detect embedded particles of wear products of the piston rings. The engine oil of a “dead” engine for the reasons described above usually has significant fuel impurities. So, along with the black smoke of the over-enriched exhaust, not only soot and unburned diesel fuel fly out into the pipe, but also a significant part of the engine resource.
Quick and sad consequences are caused by abrasive getting 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 and 1/2 revolution. For example, V slave is 12 liters, revolutions are 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 air consumed is enough for the accumulated abrasive to literally eat the engine from the inside. Inaccurate installation of the air filter, loose clamps, cracks in the connecting corrugations, the possibility of air being sucked into the engine past the filter - all this leads to a quick death of the motor from the "road" abrasive.
Risk of technical abrasive entering the motor during maintenance or repair.
A tractor in a dusty field and a luxurious boat in neutral waters can be equally subject to such misfortunes. How many times have you seen how the desire of a diligent owner of a passenger car to “polish” the intake manifold with a sandpaper, or competently and carefully grind the carburetor body parts on the plate, leads to an almost instantaneous (200 - 500 km) death of the engine. It is impossible to remove the technical abrasive by “rinsing with gasoline”. In the modern practice of engine repair, the very desire to grind something (for example, valves) is puzzling, but nevertheless, in such an insidious way, abrasive particles sometimes manage to get into the engine.
Then the following picture is formed: solid particles entering 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 it 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 receive significant deviations from the original geometric shape and dimensions. The rapidly increasing gap causes intense breaking of the annular groove.
When an abrasive enters the engine, intense wear of the working surfaces of the rings is accompanied by the formation of numerous vertical scratches. On the edges of the rings there is a micro breakage or microburrs. The zone of maximum cylinder wear is usually lower than in the case of wear due to excess fuel described above and is approximately at the middle of the operating height of the cylinder. The working area of the piston skirt is damaged in the form of numerous vertical scratches, giving 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 motor 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 about 200,000 double strokes, even a small amount of hard inclusions on the piston skirt becomes obvious, which clearly indicates the abrasive nature of intensive wear. The often notorious bath of gasoline, in which yesterday<сполоснули>lapped valve, and today the mechanic of another shift washed something before assembling the motor and is the true reason<необъяснимых>wear.
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 of usually around 54:60 HRC in a short time received abnormally large wear, turning in<алюминиевых>piston bosses, therefore particles were present in the friction zone that were much harder than the material of the piston pin itself. In practice, it happened, unfortunately, to analyze cases with malicious application of powders or pastes to motors.
In this situation. An absolute boon 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 trouble for the driver operating the car and the mechanic repairing it. Overheating of the engine, negligence in repairs - and please - increased oil consumption, blue smoke, knocking.
When "opening" such a motor, scuffs on 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?
It's not the engine's fault, of course. It is simply necessary to foresee what these or those interventions in its 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 the enormous forces of gas pressure and inertia acting on them contributes to the appearance and development of defects, ultimately leading to engine failure.
In many cases simple replacement damaged parts - no best technology engine repair. 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 a few moves ahead, calculating possible consequences their 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 seemingly simple detail, but it is extremely responsible and complex at the same time. Its design embodies the experience of many generations of developers.
And to some extent, the piston forms the appearance of the entire engine. In one of the previous publications, we even expressed such an idea, paraphrasing a well-known aphorism: “Show me a piston, and I will tell you what kind of engine you have.”
So, with the help of a piston in the engine, several problems are solved. The first and main thing 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 is then converted by the crankshaft into engine torque.
It is impossible to solve the problem of converting gas pressure into torque without reliable sealing of the moving piston in the cylinder. Otherwise, a breakthrough of gases into the engine crankcase and oil from the crankcase into the combustion chamber are inevitable.
To do this, a sealing belt with grooves is organized on the piston, in which compression and oil scraper rings special profile. In addition, special holes are made in the piston to discharge oil.
But this is not enough. During operation, the bottom of the piston (fire zone), 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 - heat is transferred through them from the bottom to the cylinder wall and then to the coolant. However, in some of the most loaded designs, additional oil cooling of the pistons is done, supplying oil from below to the bottom using special nozzles. Sometimes internal cooling is also used - the nozzle supplies oil to the internal annular cavity of the piston.
For reliable sealing of cavities from the penetration of gases and oils, the piston must be held in the cylinder so that its vertical axis coincides with the axis of the cylinder. All sorts of distortions and "shifts" that cause "hanging" of the piston in the cylinder, adversely affect the sealing and heat transfer properties of the rings, increase the noise of the engine.
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 task of designing a skirt is complicated by the fact that the temperature coefficients of expansion of the materials of the cylinder and piston are different. Not only are they made of different metals, their heating temperatures vary many times over.
To prevent the heated piston from jamming, modern engines take measures to compensate for its thermal expansion.
First, in the cross section, the piston skirt is shaped like an ellipse, the major axis of which is perpendicular to the axis of the pin, and in the longitudinal section, it is a cone, tapering towards the bottom of the piston. This shape allows the skirt of the heated piston to conform to the cylinder wall, preventing jamming.
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 light aluminum alloys for the manufacture of pistons is not a whim of designers. At high speeds, typical for modern engines, it is very important to ensure a low mass of moving parts. Under 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 a reverse cone at the bottom of the skirt, designed to reduce noise due to the “relaying” of the piston in dead spots. A special microprofile on the working surface helps to improve the lubrication of the skirt - microgrooves with a pitch of 0.2-0.5 mm, and a special anti-friction coating helps to reduce friction. The profile of the sealing and fire belts is also defined - here is the highest temperature, and the gap between the piston and the cylinder in this place should not be large (there is an increased likelihood of gas breakthrough, the risk of overheating and breakage of the rings) or small (there is a high risk of jamming). Often, the resistance of the fire belt is increased by anodizing.
All that we have said is far from a complete list of requirements for a piston. The reliability of its operation also depends on the parts associated with it: piston rings (dimensions, shape, material, elasticity, coating), piston pin (clearance in the piston bore, method of fixation), cylinder surface condition (deviations from cylindricity, 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 defects, breakdowns and engine failure. In order to repair the engine in the future with high quality, it is necessary not only to know how the piston is arranged and works, but also to be able to determine, by the nature of the damage to the parts, why, for example, a scuff has occurred or ...
Why did the piston burn out?
An analysis of various piston damages shows that all causes of defects and breakdowns are divided into four groups: cooling failure, lack of lubrication, excessively high thermal and force effects 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 scuffing on the guide belt leads to a violation of the sealing and heat transfer properties of the piston rings.
Ultimately, this can cause burnout of the fire belt.
We also note that with almost all malfunctions of the piston group, increased oil consumption occurs. With severe damage, thick, bluish exhaust smoke, a drop in power and difficult starting due to low compression are observed. In some cases, the sound of a damaged piston is heard, especially on a cold engine.
Sometimes the nature of the piston group defect can be determined even without disassembling the engine according to the above outward signs. But more often than not, such an “indiscriminate” diagnosis is inaccurate, since different causes often give almost the same result. That's why possible reasons defects require detailed analysis.
Violation of piston cooling is perhaps the most common cause of defects. This usually happens when the engine cooling system malfunctions (chain: “radiator-fan-fan switch-on sensor-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 liquid, its temperature, and with it the temperature of the piston, begin to rise. The piston expands faster than the cylinder, moreover, unevenly, and eventually the clearance in certain places of the skirt (usually near the pin hole) becomes equal to zero. Seizure begins - the seizure and mutual transfer of materials of the piston and cylinder mirror, and with further engine operation, the piston jams.
After cooling, the shape of the piston rarely returns to normal: the skirt is deformed, i.e. compressed along the major axis of the ellipse. Further work of such a piston is accompanied by a knock and increased consumption oils.
In some cases, the piston burr extends into the sealing belt, rolling the rings into the piston grooves. Then the cylinder, as a rule, turns 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 conditions, especially at low temperatures. Under such conditions, the fuel entering the cylinder washes away the oil from the cylinder walls, and scoring occurs, which are usually located in the middle part of the skirt, on its loaded side.
Double-sided scuffing of the skirt 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.
The lack of lubrication of the piston pin is the reason for its jamming in the holes of the piston bosses. This phenomenon is typical only for designs with a pin pressed into the upper head of the connecting rod. This is facilitated by a small gap in the connection between the pin and the piston, so the "sticking" of the fingers is more often observed in relatively new engines.
Excessively high thermal force effect on the piston from hot gases in the combustion chamber is a common cause of defects and breakdowns. So, detonation leads to the destruction of the jumpers between the rings, and glow ignition - to burnouts.
In diesel engines, an excessively large fuel injection advance angle causes a very rapid increase in pressure in the cylinders (“rigidity” of work), which can also cause breakage of the jumpers. The same result is possible when using various fluids that make it easier to start a diesel engine.
The bottom and the fire belt can be damaged if too high temperature in the combustion chamber of a diesel engine caused by a malfunction of the injector nozzles. A similar picture also occurs when the piston cooling is disturbed - for example, when the nozzles supplying oil to the piston, which has an annular internal cooling cavity, coke. Seizure that occurs on the top of the piston can also spread to the skirt, trapping the piston rings.
Mechanical problems, perhaps, give the largest variety of piston group defects and their causes. For example, abrasive wear of parts is possible both “from above”, due to dust entering through a torn air filter, and "from below", with the circulation of abrasive particles in the oil. In the first case, the cylinders in their upper part and the compression piston rings are the most worn, and in the second case, the oil scraper rings and the piston skirt. By the way, abrasive particles in the oil can appear not so much from untimely engine maintenance, but as a result of the rapid wear of any parts (for example, camshafts, pushers, etc.).
Rarely, piston erosion occurs at the “floating” pin hole when the retaining ring pops out. The most likely causes of this phenomenon are the non-parallelism of the lower and upper heads of the connecting rod, which leads to significant axial loads on the pin and the “knocking out” of the retaining ring from the groove, as well as the use of old (lost elasticity) retaining rings when repairing the engine. The cylinder in such cases turns out to be damaged by a finger so much that it can no longer be repaired by traditional methods (boring and honing).
Sometimes foreign objects can get into the cylinder. This most often occurs with careless work during engine maintenance or repair. A nut or bolt, caught between the piston and the head of the block, is capable of many things, including simply “failing” the piston bottom.
The story about defects and breakdowns of pistons can be continued for a very long time.
Electronics.
Here everything is most often manifested even more clearly. Most of the failures at the beginning manifest themselves in the form of mistakes that 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. For a long time, you can ignore the light "pokes" of the box, which are easily eliminated by flashing or, in extreme cases, the prevention of the board. But quickly enough it will lead to the need to rebuild the box.
Timing errors are often a sign of chain wear, gears, and then end with a bulkhead of the motor for hundreds of thousands of rubles. Work such as replacing the timing belt should generally be carried out "in automatic mode» to run 80 thousand. Everyone knows what happens when it breaks.
Having the opportunity to compare how much those who have not turned off the old algorithm of approach to car maintenance in their minds and those who “come for diagnostics” spend on car maintenance, I can say that the costs of the former in total during the time they own 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 causes of defects. However, many drivers and mechanics forget about them, as they say, with all the ensuing consequences.
Although this is obvious, during operation it is still necessary:
- maintain the power supply, lubrication and cooling systems of the engine in good condition, service them in time,
2. do not overload a cold engine,
3. avoid the use of poor 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 locks of the rings. The epidemic of "small gap disease", which once struck many mechanics, is still not over. Moreover, practice has shown that attempts to "tighter" install the piston in the cylinder in the hope of reducing engine noise and increasing its resource almost always end up the opposite: piston scuffing, knocking, oil consumption and re-repair. 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 the same:
quality spare parts
correct processing of worn parts,
thorough washing and careful assembly with mandatory control at all stages.
Initially, smart people put a two-row chain and twin gears. The load on each tooth and link of the chain was small and there were no problems with chains in nature.
Now, under the slogan of reducing weight and metal consumption, as well as ecology, engines have become the way we see them.
After 120 thousand run, it is necessary to change without exception without waiting for the marks to leave and break or jump.
Departure of the mark from the norm even by a millimeter is the reason for replacement.
Andrey Goncharov, expert of the Car Repair section
All parts lose their original characteristics during operation. The reason for this is WEAR - the process of changing spare parts, as a result of which the mechanism loses its original properties.
Visual signs of wear: change in the size and structure of the surfaces of parts.
Types of wear parts
Changing the characteristics of used spare parts is a process that is the result of their interaction and use. Some of the changes occur even during normal operation of the mechanisms. Such changes are called NATURAL and are laid down when the node starts.
2 types of unnatural wear of parts:
- NORMAL
It is the result of improper operation, installation violations. It leads to gradual failures of equipment and deterioration of the technical condition of the facility.
- EMERGENCY
As the numerical values of normal wear increase, objects and mechanisms become completely unusable.
Factors that affect wear rates:
- Movement design
- Precision and cleanliness of processing
- The strength of the material of a particular part and those in contact with it
- Lubrication quality
- Operating conditions of the unit (regularity, nature of the load, temperature, pressure)
- Maintenance regularity
Reasons for wearing parts
All reasons can be grouped into 3 groups:
- Physical/Mechanical
It is a consequence of high loads and the effect of the friction force of one part on another. Contact parts wear out and cracks, scratches, roughness appear on their surfaces.
- Thermal / molecular mechanical
Jointly working parts experience overheating due to high speeds and specific pressures. Due to a sharp increase in temperature, seizing and subsequent destruction of the molecular bonds of particles inside the metal occurs. Parts warp and melt.
- Chemical / corrosive
It is observed on the surface of metal parts as a result of exposure to water, air, chemicals. There are processes of corrosion and corrosion of the metal. To avoid this, it is recommended to use .
It should be understood that the cause of wear and tear of parts is not one single factor, but several interrelated ones.
How to restore worn parts?
The main methods for restoring parts:
- Restoration by mechanical and locksmith processing
Suitable for parts with flat mating surfaces. The worn place is processed (grinded, grinded, etc.) and transferred to the next size. Machining is used separately and as the final stage of other methods.
- Renovation by welding and surfacing
By surfacing strong metals, the dimensions of damaged parts are restored.
- Restoration of a part by metallization
The size of the worn part is restored by applying the molten metal in a thin (from 0.03 mm) and thick (over 10 mm) layer.
- Galvanic hardfacing (chromium plating)
The application of chromium in a thin layer (up to 1 mm) provides resistance to mechanical abrasion. The method is similar to metallization, but less versatile. Remanufactured parts do not tolerate dynamic loads well.
- Hardening and bonding with plastic
Plastics allow you to get fixedly connected units, as well as stop the wear of parts. Unlike previous methods, metal and non-metal parts are subject to plastic restoration. The cost of repairing plastics is significantly lower. With the help of modern casting materials, it is possible to restore a part of complex and non-standard geometry.
The fact that the engine is the heart of the car is clear to everyone, and the desire of every motorist to extend its life is natural. Engine failures occur, both due to the fact that something is clogged or misaligned in the engine, and due to wear. The latter has much more severe consequences. But wear, as a rule, does not occur suddenly, and by individual manifestations it can be established that the engine, as it were, has crossed the line that separates natural wear that accompanies any normal operation from intensive, in which there is a rapid and irreversible destruction of the engine.
The main reasons for premature wear are:
1. "Dry friction" in contact pairs of mating parts
This, in turn, comes from the fact that the oil film, which must always separate the entire set of friction points that touch each other, moving parts, is squeezed out and an avalanche-like destruction of the metal immediately begins at these points. In addition, a sharp increase in temperature in the “dry friction” zone leads to heating of the metal and a change in its properties, which in turn will cause further, even more dramatic destruction, even if the root cause is eliminated. Simply put, the engine turns out to be irrevocably “locked up”. By the way, in this situation, many have a strong desire to quickly sell the car for a reasonable price.
What are the main reasons leading to "dry friction"? There are only two of them. This is either too high a specific pressure in the friction points from excessive clearances or sudden dynamic loads leading to penetration of the oil film, or “oil starvation” due to problems in the lubrication system.
2. Engine overheating
Every year, with the onset of warm days, many motorists meet on the road with raised hoods, from under which steam pours. At the same time, not everyone understands how dangerous even short-term overheating is for the engine. Let's dwell on this in more detail. Most vulnerable spot in terms of overheating, it is a cylinder-piston group. Maintaining the desired temperature conditions is provided by the coolant, which must continuously remove heat from the heating zone to the radiator. The heat released in the combustion chamber, when the heat removal is stopped, is capable of raising the temperature in the combustion chamber several times in a few seconds. At the same time, piston rings, due to their smaller mass and geometry, expand faster than the cylinder walls and turn into a kind of cutting tool that leaves deep scratches on the cylinder walls.
The rings themselves lose their elasticity from overheating, as a result of which the engine loses power, starts to consume oil even without overhaul it is not possible to get rid of this trouble. According to our observations, even a single overheating of the engine never remains without consequences. And even short-term overheating, if it does not cause the consequences described above, then valve stem seals most likely after that it will have to be changed. It is for this reason that when buying a car it is more expedient to ask not about what mileage it has, but about whether the engine has overheated. This is especially true for cars whose engines are significantly boosted and have more intense temperature conditions.
A characteristic mistake of many of our motorists is the desire to reach home, despite the fact that the temperature arrow is moving towards the red zone. But do not forget that the temperature sensor is most often located in the radiator area. Now imagine that for one of the many reasons the movement of the coolant slowed down or stopped altogether. In this case, a vapor lock immediately forms in the channels washing the cylinders and the temperature reaches critical values \u200b\u200bin a few seconds, while the arrow is just starting to move to the right. The situation is even worse for cars that have only an indication in the form of a light bulb.
A separate cause of many overheating is the influence of the air conditioner. First, in the path of the air flow that cools the engine radiator, additional radiator, this stream is very heating. Secondly, when the air conditioner is on, the engine receives a fairly high additional load. And thirdly, all this is sharply aggravated when the engine is running at idling, when the coolant circulation rate is minimal, and the share of power taken by the air conditioner from the engine in this mode approaches 50%. In this case, the cooling of the radiators is provided only by an electric fan, which also creates an additional load. Not surprisingly, very often when checking prestigious cars, we find traces of increased engine wear at low mileage. The reason for this is most likely that when the noble owner of the car cooled off in an air-conditioned office in hot weather, his chauffeur spent hours doing the same in his car.
How, in practical terms, to avoid such phenomena and thereby extend the life of the engine? If you bought new car, then everything is simple - follow the instructions. If the car is supported, then the smallest details are fundamentally important, indicating how the car was operated before you and what is the degree of wear and tear today. According to our statistics, after during the "pre-sale" examinations, at least 60% of potential buyers from the purchase this car refuse precisely according to the results of the engine check.
Many hope in such situations to help special additives. Here one must be extremely careful and use them as potent drugs only as prescribed by specialists. A long-term study of this issue allows us to conclude that the use of some additives for preventive purposes can end very badly, and on the other hand, the targeted use of some additives for a “well-explored purpose” gives a positive result.
In conclusion, I would like to give owners of used cars a few recommendations that could prevent premature exit its out of order:
1. Do not calm down until you have established for sure the true causes of such manifestations as the consumption of antifreeze and oil, as well as extraneous sounds from the engine, and even more so any signs of low oil pressure.
2. Under no circumstances allow even a short-term operation of the engine when the arrow of the temperature gauge approaches the red zone. The temperature indication system has an inertia of about 3-5 minutes, during which the cost of damage to your car can exceed the cost of a tow truck or a towing vehicle by several times.
3. The greatest loads, and, accordingly, wear and tear fall on the connecting rod-piston group of the engine during sharp accelerations, therefore, only owners of relatively fresh and sufficiently powerful cars can indulge in the pleasure of starting with a slip.
The engine of each car is a fairly complex device, the operation of which depends on the comfort of your movement. Therefore, it is very important to carry out maintenance of 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 fuel filter, this is already the key to the success of the engine's durability. If this is not done on time, then there is increased wear on the engine, which will lead to its failure much faster. This occurs because the oil is no longer able to fully show its washing abilities and fully lubricate the rubbing parts, which means that dry friction appears at a certain moment, and this leads to scuffing and destruction of those parts that have the highest load. Also, used oil must undergo the required filtration, which an unreplaced filter cannot provide. 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 tarry substances that can easily clog the oil passages in the engine. For this reason, the lubricant will not be able to fully reach the friction pairs, which means that this fact will cause accelerated wear of parts and even to a probable motor wedge. Similar consequences can be for a motor in which oil is filled in by type and class that does not correspond to a particular engine.
Current repairs, engine adjustment, must be carried out in a timely and qualified manner. 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 improper operation of the cooling system, which can lead to early overheating of the motor. By running this problem, you can get deformation of the cylinder head due to its overheating, which, as a rule, leads to the formation of microcracks in it.
Experienced motorists know that driving style affects the durability of the motor. So a more aggressive, high-speed, sporty style will lead to significant revolutions of rotating parts, and hence their early failure due to wear. These modes will reduce the durability of the motor up to 30%. In the cold season, starting the engine can be seriously complicated. This fact is caused by a change in the viscosity of the motor so that it becomes very, very difficult to crank the crankshaft. A warm garage box or special devices designed to remotely turn on and warm up the engine and oil sump will come to your aid. Compare the wear of the engine when starting at a cold temperature below 20 degrees can be compared with a car mileage of more than 500 km.
It is not recommended to operate the car in the winter season if you need it only for short distances. The reason for this is the appearance of deposits in the lubricant and the appearance of condensate, which leads to corrosion of the piston group of the engine.
If you feel that the motor is not working stably and, most likely, repairs are required, how to determine its volume, will capital be required?
Here it is important to pre-diagnose in several directions. Detection low pressure engine lubrication system, a pronounced knock in the crank system, will indicate increased wear of the liners and crankshaft journal, possible failure of the plain bearings. In this case, the beating 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 the operation of the motor, the engine jammed, the connecting rod broke, the piston group and rings were destroyed. Often, with such symptoms, the cylinders and crankshaft receive great damage.
The body of the car is exposed to a variety of influences to a greater extent than any other part of it, and therefore wears out faster. Damage to the body or its wear is one of the common reasons for contacting a car service. scale body repair, which includes slipway, reinforcement and painting work, can only be performed by specialists in a service station, where there is all the necessary equipment, and minor damage can be repaired on their own.
The body of the car is exposed to a variety of influences to a greater extent than any other part of it, and therefore wears out faster. Damage to the body or its wear is one of the common reasons for contacting a car service. Large-scale body repair, which includes slipway, reinforcement and painting work, can only be performed by specialists in a service station, where there is all the necessary equipment, and minor damage can be repaired on your own.
Causes of body damage
Body damage and wear can be caused by a variety of causes:
- technological and structural damage is associated with a violation of the body metal processing technology, painting work, poor build quality, insufficiently rigid fastening of parts, design flaws;
- operational damage and natural wear are associated with stress, static and dynamic loads to which body elements are subjected during operation. In particular, these are damages associated with metal fatigue, high-frequency vibrations of working units;
- emergency damage occurs during accidents, road accidents, collisions;
- Much of the damage is the result of improper maintenance. vehicle, storing it in adverse conditions, the same reasons lead to accelerated wear.
The main factors leading to damage:
- Corrosion is the oxidation and destruction of metal. It can be caused by both atmospheric precipitation, humid air and condensate, as well as chemically aggressive substances - electrolyte solutions, anti-icing reagents, emissions contained in the atmosphere. Contact of metal parts with parts made of other materials can also lead to corrosion. Hard-to-reach areas, gaps, bends of edges, which are difficult to thoroughly dry, ventilate and clean, are especially susceptible to it;
- abrasive wear - the impact on the body of solid particles contained in polluted air or falling on it from pavement. Abrasive wear accelerates the corrosion process;
- contact friction of doors, wings and other metal parts in contact with each other;
- vibration, leading to the appearance of cracks, the destruction of welded joints.
Driving on roads with poor coverage, bumps and potholes, accompanied by shocks, shocks, vibrations, is one of the main causes of body damage. If you store the car outdoors or in a damp and cold garage, do not wash for a long time or do not wipe dry after washing, do not treat with protective compounds, drive in an aggressive manner, carelessly, the likelihood of damage and accelerated wear increases.
According to statistics, the front end is most often affected in an accident. car body, damage to the posterior region is less common, and damage to the lateral regions is the least recorded. The scale of emergency damage is directly proportional to the speed of the colliding objects. In a collision, kinetic energy is released until it is completely extinguished, a chain reaction will develop, causing damage and destruction of body parts.
Types of wear and damage
The body is subject to a variety of damage resulting from one of the above factors or a combination of them:
- deformation of body parts - dents, folds, distortions. Serious deformations of the body lead to the shift of individual parts, excessive vibrations, excessive load on undercarriage, violation of vehicle stability;
- the most serious deformations are distortions, leading to a change in the geometry of the body. As a result, the shape and dimensions of door and window openings, the cabin frame, and the trunk lid change. Doors and windows jam or, conversely, they sag;
- spars displacement - another manifestation of geometry violations;
- cracks may appear at the junctions of the car pillars with the body due to shock, vibration, and improper balancing of the wheels. Cracks also form on the mudguard, strut, casing cardan shaft, spars, in places where seats, shock absorbers, struts, spring brackets and fuel tank;
- welded joints in other places are often destroyed, especially points and seams subject to the highest loads - joints of a spacer with a spar, a mudguard with an arch;
- body fasteners - bolts, nuts, nut holders - can break off. If these damages are not immediately repaired, they will lead to larger problems;
- loose fit of individual body parts leads to knocks and creaks during static load and movement;
- due to mechanical damage and exposure to aggressive substances, the paintwork and anticorrosion coating is destroyed.
Even cosmetic damage to the body is fraught with danger: if the scratch has affected the anti-corrosion coating, corrosion will quickly begin to spread. Corrosion can be superficial, covering a large area, and local, extending deep into. The latter is more dangerous because it leads to corrosion brittleness of the metal.
Changes in the geometry of the body, distortions, cracks in parts and destruction of welded joints can lead to a deterioration in vehicle controllability and provoke accidents. Therefore, body damage of any nature (corrosion, mechanical) and scale must be repaired as soon as possible.
Ways to eliminate damage to the body
In the presence of mechanical damage, if possible, the original shape of the damaged part is restored, if it cannot be restored, then it is replaced with a new one.
The simplest category of repair is the elimination of external damage to the skin that did not affect the interior frame, subframe. If, due to body deformations, the distances between the attachment points of the main units have changed, it is necessary to restore the geometry. This is not always possible, sometimes the damage is so extensive that it is more cost-effective and safer to replace the entire body. Repair will be cheaper if you order a suitable body from disassembly in good condition.
The main methods and techniques of body repair:
- preliminary rough alignment - drift;
- final alignment - straightening;
- elimination of bubbles formed during straightening by heating the metal with a torch or spot welding machine, followed by cooling;
- soldering - sealing dents with tin solder, removing excess with a file and polishing. It is used if the dent is small, and it is difficult to dismantle the part for punching and straightening;
- filling small dents, followed by filing and polishing the putty. Usually putty is applied in several layers;
- extracting hollow parts using a special tool - a nail puller. Cylindrical rods resembling nails are welded to the cleaned dent, then they are pulled with a nail puller, using it as a lever;
- crack welding;
- straightening distortions with the help of power equipment;
- Painting works.
To eliminate surface deformations, it is necessary to remove a layer of paint and mastic, completely freeing up the place of tightening. Deep dents are leveled gradually, from the edges to the center. If parts of different stiffness are in the damage zone, they start with more rigid ones. If a wrinkle has formed, start by smoothing it out. An anvil of the desired profile is placed under the surface to be straightened. Removable elements are best straightened on a workbench.
To straighten the distortions, power equipment is needed - a jack, a hydraulic square with extension cords, inserts and chains. The chains must be attached at right angles to the damaged area so that the dressing is carried out in the opposite direction of the deformation. Stretching begins with a minimum stroke, then the force gradually increases.
After straightening, residual stress may remain, which, when the car is moving, is transferred to the bushings and shock absorbers and often leads to their separation. To avoid this, the editing of the body with significant deformations should be carried out with the mechanical units removed. If, due to deformation, access to them is limited, it is necessary to perform preliminary editing without removing these units. Stretching is recommended to be accompanied by percussion of folds. After straightening is completed, the entire straightened section is tapped with a straightening hammer through a wooden gasket to relieve internal stress.
A frameless body, in which the base does not detach from the frame, can only be repaired at a service center using special equipment with a rigid base. Painting is also best done in a special spray booth; it cannot be done outdoors, since dust and midges will immediately stick to fresh paint. If paint and varnish work is carried out in the garage, you must first clean it there.
Before painting, it is better to disassemble the body into separate parts for better painting of hard-to-reach areas. Damaged areas are carefully cleaned from corrosion, primed with acid soil. The entire surface to be painted is sanded with a machine or manually using sandpaper, degreased, processed from a spray gun with an acrylic primer. After the primer dries, the surface is polished again. Usually three layers of paint are applied, its viscosity decreases with each layer.
In addition to the inevitable damage to the car body during operation and its natural wear and tear, accidental and improper maintenance damage and accelerated wear are possible. Any damage to the body must be repaired as soon as possible, as they can provoke a chain of new faults. The work of straightening dents can be done in the garage with your own hands, and in case of serious violations of body geometry, it is better to contact a service that has the necessary power equipment.