In which engines wear mechanisms faster. The main causes of engine wear

In this article, we will look at the three most common causes of engine component damage and describe the situations that lead to breakdowns. The most common causes of damage are abrasion of the engine due to dirt, water hammer and increased oil consumption.

Abrasive engine wear

Abrasive wear is the result of hard particles scratching or cutting the mating parts, as well as the result of dust entering the surface of the parts, introduced by air or introduced with lubricant. 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 from the side of the greatest lateral load and from the opposite side;
• wear of the processing profile on the piston skirt is noted;
• thin grooves form on the piston skirt, piston rings, cylinder wall or liner in the direction of travel;
• piston rings and their grooves have wear in height;
• an increased thermal clearance is noted 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 grooves of a wavy profile;
• 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 significantly more than the third, then contaminants enter the combustion chamber through the cylinder intake system, that is, from above. The reason for this is either depressurization or mud deposits that were not removed before the repair work began.
• If several or all cylinders are damaged and the first piston ring is worn significantly more than the third, then contaminants enter the combustion chamber through the common intake system of all cylinders. The reasons for this situation are due to 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 engine 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 suction pipes should be cleaned of dirt. Maintain cleanliness 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: a piston collapses or deforms, a connecting rod bends or breaks, a piston ring bridge of a damaged piston shows signs of static fracture, a piston pin breaks.

The cause of this defect is liquid (water or fuel) that has entered the combustion chamber. Since neither water nor fuel is subject to compression, water hammer causes a sudden force on the piston, piston pin, connecting rod, cylinder head, crankcase, bearings and crankshaft.

Too much liquid can end up in the combustion chamber for the following reasons: water enters the combustion chamber through the intake system (for example, when driving on a surface flooded with water); water enters the combustion chamber due to defective gaskets. Too much fuel enters the combustion chamber due to a faulty injection nozzle.

Increased oil consumption

A little oil consumption is normal. It varies 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 thing as increased oil consumption. Possible reasons for the increased consumption:

• Due to depressurization of the turbocharger. The oil circulation line in the turbocharger system is clogged or coked. Due to the pressure in the oil circuit that rises for this reason, oil is forced 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 of 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, which leads to increased wear.
• If the piston protrusion is incorrectly adjusted, the piston may hit the cylinder head. As a result, oscillations occur that affect the fuel injectors. At the same time, the nozzle ceases to close completely, so too much fuel enters the combustion chamber, and an overdose of fuel occurs.
• The oil has worn out. Exceeded oil change intervals result in clogging and/or destruction of the filter paper, resulting in unclean oil circulating in the oil circuit.
• Bent or twisted connecting rods lead to a violation of the movement of the piston, which entails a violation of the necessary sealing of the combustion chamber. In the most critical cases, the pumping action of the piston rings may occur. In this case, oil is actively supplied to the combustion chamber.
• If piston rings are broken, misaligned, or incorrectly installed, these circumstances can lead to insufficient sealing between the combustion chamber and the crankcase. As a result of this seal failure, oil can enter the combustion chamber.
• Cylinder head bolts not properly tightened. This can lead to deformations, and hence to a violation of the tightness of the oil circuit.
• Due to worn pistons, piston rings and cylinder contact surfaces, the volume of blow-by gases increases. And this leads to excess pressure in the crankcase. If the pressure is too high, oil mist can be forced out through the crankcase ventilation into the combustion chambers.
• Too high an oil level causes the crankshaft to sink into an oil bath, which leads 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 oil mist and foam, together with breakthrough gases, enter the suction channel through the engine ventilation, and hence into the combustion chambers.
• In case of malfunctions in the combustion process, fuel overflow is possible. Due to the dilution of the oil with fuel, the wear of pistons, piston rings and the working surface of the cylinders increases many times over.
• If the cylinder is misaligned, for example due to old and/or incorrectly tightened cylinder head bolts, the piston rings lose their sealing capacity between the combustion chamber and the crankcase. Thus, oil mist can enter the combustion chamber. With particularly strong deformations, it is even possible for the piston rings to act as a pump, that is, a situation where oil is simply pumped into the combustion chamber.
• Poorly machined cylinder with poor honing of its running surface interferes with the oil retention process. This leads to a significant increase in wear of such mating parts 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 working surface of the cylinder. That is, there is a so-called insulating jacket. It significantly reduces the oil scraping potential, which leads to increased wear, especially during cold starts.

The main question of this article is whether driving at low speeds leads to premature wear of the motor? And which modes are the most "wear-inducing" ...
The setting of expert tests, in general, is understandable. The engine is the same: VAZ "eight-valve". Stand, equipment, gasoline and several canisters of oil - each test cycle requires its replacement. The task is simple - you need to "drive" the same distance, at the same speed, but using different engine operating modes. On different tracks...
How to achieve this? You can drive at the same speed, maintaining engine speeds of 1500, 2500, and even 4000 rpm. The higher the speed, the lower the gear, it is important that the power delivered by the motor is the same. It is easy to do this at the stand - we measure the torque using a dynamometer, the speed is known - therefore, we know the power. “Speed” is multiplied by engine hours, which we also record - here is the mileage.
It is more difficult with wear - every time, after the engine has been running in a fixed mode for a given time, the engine will have to be disassembled and weighed the main parts that form friction units, these are bearing shells and piston rings. Plus, there is an additional intermediate control, which will be carried out by determining the content of wear products in oil samples. We found chrome - therefore, the first piston rings wear out; found iron - cylinders and necks of the shaft; tin appeared - it will determine the wear rate of the bearing shells (since it is part of the anti-friction layer); aluminum - a consequence of wear of the pistons and bearings of the camshaft.
The engine worked at the specified constant modes with approximately the same power of 50 hours each. Not much for a resource, but we get wear rates, and then by simple extrapolation we estimate the approximate resource of the motor. At the same time, the engine speed during the test cycles was changed from 1200 to 4000, that is, more than three times. And then the load on the motor was increased - and the cycle was run again. And then - more ... It turned out to be a voluminous table, where for each point of the regime its own wear rate was recorded, moreover, divided by nodes - bearings and rings.

This is how the average wear rate of the first piston rings of the engine changes when the operating mode changes.

"Black zones" of active wear showed up immediately. The most serious ones are when a large load is applied to low speeds, and with high oil temperatures. The wear rate in this mode is maximum - both for bearings and piston rings with cylinders. Engineers call this area zone of towing modes.
With an increase in speed, the wear zone immediately began to decrease and somewhere at 1800 rpm it disappeared. All friction units "surfaced" on oil films, direct contact between the surfaces of the parts disappeared - and with it, the wear rate turned to almost zero. But you need to understand that zero wear rate on the graphs does not mean that it does not exist, just wear in these modes is less than the measurement error. In practice, of course, this is not entirely true. Microparticles of dust, wear products, soot that have slipped through the oil filter will give some wear here too.

And so - connecting rod bearing shells

With an increase in the frequency of rotation of the crankshaft, the wear zone again begins to appear and grow. In our case - already somewhere from 3800 rpm under heavy load, and further - it progresses. Moreover, here the wear of bearings and piston rings with cylinders behaves differently. The fastest speeds begin to feel the crankshaft bearings. Why? The fact is that with an increase in revolutions, the loads on the bearings sharply increase - the pressure of inertial forces depends on the revolutions squared. But the rings again get their wear from high speeds - somewhere from 4500 rpm, and there it is mainly due to an increase in oil temperature.
Where is the most favorable area for the operation of the motor? For the VAZ G8s we tested (it doesn’t matter, carburetor or injection, eight- or sixteen-valve), the optimal speed zone at which the engine is able to take any load without any damage to itself is approximately 2000 ... 3000 rpm. Here we take into account that the initial state of the engine can be different, and engine oils too ... The principle is simple - the more the engine is worn out, the higher the lower and the lower the upper limits of the wear-free operation zones. The higher the viscosity of the oil, the lower the engine speed can be safely loaded. But there are no exact figures - it is very individual.
And how does this compare with motors of a different dimension? There is one clue here ... In principle, the friction units of the motor do not feel the revolutions, but the linear speeds of movement of the surfaces of the parts. There is such a parameter of the motor - average piston speed, is the product of the piston stroke and the crankshaft speed, divided by thirty. The range that we have obtained approximately corresponds to the average piston speeds of 5…7 m/s. This means that for "long-stroke" engines, whose piston stroke is larger than the diameter, the zone of optimal modes will shift to the region of lower revolutions. Hence - and their "elasticity". For "short-stroke" the zone of optimal modes will shift to the region of higher speeds.
By the way, it is this range of changes in the average piston speeds that is usually laid down to determine the main areas of operation of engines with large resources. Marine diesel engines, diesel generators, etc.
So - take your dimension, follow the basic steps, and approximately get your safe rpm range. But that's about it...
In general, the conclusion is clear. Both low-speed modes with heavy loads and extreme speeds are harmful to the motor. Alexander Shabanov

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 repairs, including 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.

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;
• a significant part of the damage is the result of improper care of the vehicle, its storage 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 the road surface. 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, in an accident, the front part of the car body most often suffers, damage to the rear area is less common, and damage to the side areas 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 a shift in individual parts, excessive vibrations, excessive load on the chassis, and a violation of the vehicle's 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, propeller shaft housing, spars, seat attachment points, 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, editing 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 up 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 polished 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.

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, it maintains the necessary, in accordance with the purpose, performance provided by the project 343928 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 little 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 as a whole.

Table 5

Factors affecting buildings and structures

#G0External influences (natural and artificial	Impact result	Internal influences (technological and functional)
Radiation	mechanical physical and chemical (+) destruction	* Loads (permanent, temporary, short-term)
Temperature		* + Shock, vibration, abrasion, spillage of liquids
* Air flow		* +Temperature fluctuations
Precipitation (including acids)		Humidity
Gases, chem. substances
* Lightning bolts
Electromagnetic waves (including radio)
Sound vibrations (noise)		* + Biological pests
* + Biological pests
Ground pressure
* Stray currents
* frost heave
ground moisture
seismic waves
vibrations

In the whole sum 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 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, identify the main causes of damage in order to expediently and timely use the forces and means available to 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) 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 is established. The introduction of these systems is important for streamlining inspections and repairs of buildings and structures. However, the terms of repairs provided for in them are not differentiated in relation to various options for structures in terms of design solutions, their service life, climatic and other conditions, as a result of which they are averaged.

The design life of any engine is determined by its manufacturer. Whether a specific unit will reach it, whether it will “die” earlier or significantly exceed this mileage, largely depends on the owner. Progress does not stand still: engines are improving more and more every year - now they are able to "move away" several hundred thousand kilometers without problems. But even the most reliable node can be “killed” ahead of time by improper operation.

Unfortunately, many people reduce motor care to use, believing that this is quite enough. Of course, the quality of lubrication is paramount in the life of an engine. It is pleasant to note that today the risk of running into a fake is much lower than a few years ago. This is a considerable merit of both the oil manufacturers themselves, who take active measures to protect their own products, and the sellers who do not want to sacrifice their own reputation for super profits from the "leftist".

In addition to the obvious reasons that can cause very intense engine wear, there are those that the car owner may not be aware of.

Intake manifold leak

So, experts put in the first place intake manifold leak(air ducts, air filter housings). On many modern foreign cars, the air intake is carried out in the area of ​​\u200b\u200bthe front fender. Even minor damage to this body part (for example, in an accident) can cause cracks or breaks in the air duct body, as a result of which all the abrasive, which is abundant in the wheel arch area, will go straight into the intake tract. Thus, without attaching importance to a trifling dent, it is easy to “get” into a serious engine repair.

Violation of the thermal regime

But the accelerated wear of the engine causes not only the ingress of abrasive through the power system. Owners of modern cars often note an inexplicable increase in engine operating temperature. In this case, the cooling system may be completely serviceable. The reasons in this case are often non-trivial - for example, a decrease in the capacity of the catalytic converter. The “clogged” cells of its ceramic liner provoke an increase in the temperature of the converter itself, which is transmitted along the chain to the exhaust manifold and further to the combustion chamber. Violation of the thermal regime can lead to the occurrence of piston rings and other troubles. Even worse consequences of a “clogged” converter are possible, for example, in V-shaped engines, the exhaust system of which is made according to a split scheme. The obstruction of one branch can lead to the development of very high pressure in the area from the combustion chamber to the jam, which, in turn, can cause partial destruction of the ceramic filler, chaotic movement of the formed fragments and, it is possible, their entry into the cylinders. The motor itself, of course, loses power, but continues to work further - one row of cylinders will forcibly rotate the other. To eliminate this phenomenon, today many cars use bypass cables between the exhaust manifolds to relieve possible excessive pressure.

Fuel equipment malfunction

A malfunctioning fuel equipment can also cause intense engine wear. It would seem that with the transition to injection systems, car owners have the right to forget about the power system altogether. Many do just that: even with the “Check Engine” on fire, they continue to operate. Someone promises himself to call on the service in the coming days, others write off everything as “glitches” of an imperfect electronic system. Meanwhile, such malfunctions can have a very significant impact on the condition of the engine. For example, with incomplete combustion of fuel, it washes away the oil film from the cylinder walls, and in the absence of lubrication, intensive wear occurs. In a gasoline engine, the washed-out oil, burning along with the fuel, leads to intense bluish smoke. The fuel equipment of a diesel engine, in the event of its own malfunction, can also cause accelerated wear of the cylinders and destruction of the pistons. The black smoke of an over-enriched exhaust is not only a blow to the environment, it is also a chance to ruin the engine. Premature engine wear is always a consequence. Do not ignore the prevention of causes, do not let circumstances ruin your engine: you will drive happily ever after.