Oil deposits in the engine. Resin deposits in a car engine

Changing the properties of the oil in a running engine

The main changes in properties in a running engine occur for the following reasons:

1. high temperature and oxidizing effects;
2. mechanochemical transformations of oil components;
3. permanent accumulation:

• conversion products of oil and its components;
• fuel combustion products;
• water;
• wear products
• contaminants in the form of dust, sand and dirt.

Oxidation

In a running engine, hot oil constantly circulates and comes into contact with air, products of complete and incomplete combustion of fuel. Air oxygen accelerates oil oxidation. This process is faster in oils prone to foaming. The metal surfaces of the parts act as catalysts for the oil oxidation process. The oil heats up in contact with heated parts (primarily cylinders, pistons and valves), which greatly speeds up the process of oil oxidation. The result can be solid oxidation products (deposits).

The nature of the oil change in a running engine is influenced not only by the chemical transformations of the oil molecules, but also by the products of complete and incomplete combustion of the fuel, both in the cylinder itself and breaking through into the crankcase.

Effect of Temperature on Oxidation engine oil.

There are two types of engine temperature conditions:

• operation of a fully warmed-up engine (main mode).
• operation of an unheated engine ( frequent stops vehicle).

In the first case, there is high temperature mode of changing the properties of the oil in the engine, in the second - low temperature. There are many intermediate working conditions. When determining the level of oil quality, motor tests are carried out both in high and low temperatures.

Oxidation products and changes in engine oil characteristics.

acids(acides). The most significant products of oil oxidation are acids. They cause corrosion of metals, and alkaline additives are consumed to neutralize the resulting acids, as a result of which the dispersant and detergent properties and reduced oil life. An increase in the total acid number, TAN (total acid number) is the main indicator of the formation of acids.

Carbon deposits in the engine(carbon deposits). A variety of carbon deposits form on the hot surfaces of engine parts, the composition and structure of which depend on the temperature of the metal and oil surfaces. There are three types of deposits:

• soot,

• sludge.

It must be emphasized that the formation and accumulation of deposits on the surface of engine parts is the result of not only insufficient oxidative and thermal stability of the oil, but also its insufficient detergency. Therefore, engine wear and reduced oil life is a complex indicator of oil quality.

Nagar(varnish, carbon deposits) are products of thermal destruction and polymerization (cracking and polymerization) of oil and fuel residues. It is formed on strongly heated surfaces (450° - 950°C). Nagar has a characteristic black color, although it can sometimes be white, brown or other colors. The thickness of the deposit layer periodically changes - when there are a lot of deposits, heat removal worsens, the temperature of the upper layer of deposits rises and they burn out. Less deposits form in a warm engine running under load. According to the structure, deposits are monolithic, dense or loose.

Nagar has a negative effect on the operation and condition of the engine. Deposits in the piston grooves around the rings prevent their movement and pressing against the cylinder walls (jamming, sticking, ring sticking). increases the breakthrough of gases into the crankcase and oil consumption Pressing the rings with deposits to the cylinder walls leads to excessive wear of the cylinders (excessive wear).

Cylinder wall polishing(bore polishing) - deposits on the top of the pistons (piston top land) polish the inner walls of the cylinders. Polishing prevents the oil film from retaining and retaining on the walls and significantly accelerates the wear rate.

varnish(lacquer). A thin layer of brown to black, hard or sticky carbonaceous substance that forms on moderately heated surfaces due to the polymerization of a thin layer of oil in the presence of oxygen. The skirt and the inner surface of the piston, connecting rods and piston pins, valve stems and lower parts of cylinders. The varnish significantly impairs heat removal (especially of the piston), reduces the strength and persistence of the oil film on the cylinder walls.

Deposits in the combustion chamber(combustion chamber deposits) are formed from particles of carbon (coke), as a result of incomplete combustion of fuel and metal salts included in the composition of additives as a result of thermal decomposition of oil residues entering the chamber. These deposits heat up and cause pre-ignition. working mixture(until sparks appear). This kind of ignition is called preignition or preignition. This creates additional stresses in the engine (detonation), which leads to accelerated wear bearings and crankshaft. In addition, individual parts of the engine overheat, power decreases, and fuel consumption increases.

Clogged spark plugs(spark plug fouling). Deposits accumulated around the spark plug electrode close the spark gap, the spark becomes weak, and the ignition becomes irregular. As a result, engine power is reduced and fuel consumption is increased.

Tars, sludge, resinous deposits(sludge) (resins, sludge, sludge deposits) in the engine, sludge is formed as a result of:

• oxidation and other transformations of oil and its components;

• accumulation in the oil of fuel or decomposition products and incomplete combustion;

• water.

Resinous substances are formed in oil as a result of its oxidative transformations (crosslinking of oxidized molecules) and polymerization of oxidation products and incomplete combustion of fuel. The formation of resins increases when the engine is not warm enough. Products of incomplete combustion of fuel break into the crankcase during prolonged idling or in stop-start mode. At high temperatures and intensive engine operation, the fuel burns more completely. To reduce tar formation and engine oils, dispersant additives are introduced that prevent coagulation and precipitation of resins. Resins, carbon particles, water vapor, heavy fuel fractions, acids and other compounds condense, coagulate into larger particles and form sludge in the oil, the so-called. black sludge.

Sludge(sludge) is a suspension and emulsion in oil of insoluble solids and resinous substances from brown to black. Composition of crankcase sludge:

• oil 50-70%

• water 5-15%

• products of oil oxidation and incomplete combustion of fuel, solid particles - the rest.

Depending on the temperature of the engine and oil, the processes of sludge formation are somewhat different. Distinguish between low temperature and high temperature

Low temperature sludge(low temperature sludge). It is formed when breakthrough gases containing fuel and water residues interact with oil in the crankcase. In a cold engine, water and fuel evaporate more slowly, which contributes to the formation of an emulsion, which subsequently turns into sludge. The formation of sludge in the crankcase (sludge in the sump) is the cause of:

• increase in viscosity (thickening) of the oil (viscosity increase);

• clogging of channels of the lubrication system (blocking of oil ways);

• oil supply disturbance (oil starvation).

The formation of sludge in the rocker box is the cause of insufficient ventilation of this box (foul air venting). The resulting sludge is soft, friable, but when heated (during a long trip) becomes hard and brittle.

high temperature sludge(high temperature sludge). It is formed as a result of the combination of oxidized oil molecules under the influence of high temperature. An increase in the molecular weight of the oil leads to an increase in viscosity.

In a diesel engine, sludge formation and an increase in oil viscosity are caused by the accumulation of soot. Soot formation is facilitated by engine overload and an increase in the fat content of the working mixture.

additive consumption. Consumption, the operation of additives is the determining process of reducing the oil resource. The most important engine oil additives - detergents, dispersants and neutralizers - are used to neutralize acidic compounds, are retained in filters (along with oxidation products) and decompose at high temperatures. The consumption of additives can be indirectly judged by a decrease in the total base number TBN. The acidity of the oil increases due to the formation of acid oxidation products of the oil itself and sulfur-containing products of fuel combustion. They react with additives, the alkalinity of the oil gradually decreases, which leads to a deterioration in the detergent and dispersant properties of the oil.

The effect of increasing power and forcing the engine. The antioxidant and detergent properties of the oil are especially important when boosting engines. Gasoline engines are boosted by increasing the compression ratio and crankshaft speed, and diesel engines by increasing effective pressure (mainly with turbocharging) and crankshaft speed. With an increase in the crankshaft speed by 100 rpm or with an increase in effective pressure by 0.03 MPa, the piston temperature increases by 3°C. When forcing engines, their mass is usually reduced, which leads to an increase in mechanical and thermal loads on parts.

Motor oils "Automobile lubricants and special liquids" NPIKTs, Saint Petersburg. Baltenas, Safonov, Ushakov, Shergalis.

EFFECT OF TEMPERATURE ON DEPOSITS IN THE ENGINE

Study of deposits in automobile engines.

One of the reserves for improving performance operational reliability ICE is to reduce the deposits of deposits, varnishes and sediments on the surfaces of their parts in contact with engine oil. Their formation is based on the aging processes of oils (oxidation of hydrocarbons that make up the oil base). Defining influence on engine oil oxidation, deposit formation and efficiency ICE operation generally renders the thermal regime of heat-loaded parts.

Key words: temperature, piston, cylinder, motor oil, deposits, soot, varnish, performance, reliability.

Deposits on the surfaces of internal combustion engine parts are divided into three main types - deposits, varnishes and sediments (sludge).

Nagar - solid carbonaceous substances deposited during engine operation on the surfaces of the combustion chamber (CC). At the same time, carbon deposits mainly depend on temperature conditions, even with the same composition of the mixture and the same design of engine parts. Nagar has a very significant effect on the course of the combustion process. air-fuel mixture in the engine and on the durability of its operation. Almost all types of abnormal combustion (knock combustion, glow ignition, and others) are accompanied by one or another effect of soot on the surfaces of the parts that form the combustion chamber.

Lacquer is a product of a change (oxidation) of thin oil films that spread and cover parts. piston-cylinder group(CPG) of the engine under the influence of high temperatures. The greatest harm to internal combustion engines is caused by varnish formation in the area of ​​the piston rings, causing the processes of their coking (occurrence with loss of mobility). Lacquers, deposited on the surfaces of the piston in contact with oil, disrupt proper heat transfer through the piston, impair heat removal from it.

The quality of engine oil has a decisive influence on the amount of precipitation (sludge) formed in the internal combustion engine, temperature regime details, design features engine and operating conditions. Deposits of this type are most typical for winter operation conditions, they are intensified with frequent starts and stops of the engine.

thermal state of the internal combustion engine has a decisive influence on the processes of formation of various types of deposits, the strength characteristics of the materials of parts, the output effective indicators of engines, the wear processes of the surfaces of parts. In this regard, it is necessary to know the threshold temperatures of the CPG parts, at least at characteristic points, the excess of which leads to the previously indicated negative consequences.

It is advisable to analyze the temperature state of the parts of the ICE CPG according to the temperature values ​​at characteristic points, the location of which is shown in Fig. 1 . The temperature values ​​at these points should be taken into account during the production, testing and development of engines to optimize the design of parts, when choosing engine oils, when comparing thermal states various engines, while solving a number of other technical problems design and operation of internal combustion engines.

Rice. Fig. 1. Characteristic points of the cylinder and piston of the internal combustion engine during the analysis of their temperature state for diesel (a) and gasoline (b) engines

These values ​​have critical levels:

1. The maximum temperature value at point 1 (in diesel engines - at the edge of the CS, in gasoline engines - in the center of the piston bottom) should not exceed 350C (for a short time, 380C) for all aluminum alloys commercially used in automotive engine building, otherwise the edges of the CS in the diesel engines and, often, burnout of pistons in gasoline engines. In addition, the high temperatures of the firing surface of the piston bottom cause the formation of deposits of high hardness on this surface. In the practice of engine building, this critical temperature value can be increased by adding silicon, beryllium, zirconium, titanium and other elements to the piston alloy.

The prevention of exceeding critical temperatures at this point, as well as in the volumes of internal combustion engine parts, is also ensured by optimizing their shapes and proper organization of cooling. Exceeding the temperatures of CPG engine parts of acceptable values ​​is usually the main limiting factor for forcing them in terms of power. For temperature levels, a certain margin should be kept, taking into account possible extreme operating conditions.

2. The critical temperature value at point 2 of the piston - above the upper compression ring (VKK) - 250 ... 260C (short-term, up to 290C). When this value is exceeded, all mass engine oils coke (intense varnish formation occurs), which leads to “occlusion” of piston rings, that is, the loss of their mobility, and as a result, to a significant decrease in compression, an increase in engine oil consumption, etc.

3. The maximum temperature limit at point 3 of the piston (the point is located symmetrically along the cross section of the piston head on its inner side) is 220C. At higher temperatures, intense varnish formation occurs on the inner surface of the piston. Lacquer deposits, in turn, are a powerful thermal barrier that prevents heat removal through the oil. This automatically leads to an increase in temperatures in the entire volume of the piston, and hence on the surface of the cylinder mirror.

4. Maximum permissible value temperatures at point 4 (located on the surface of the cylinder, opposite the place where the VCC stops at TDC) - 200C. When it is exceeded, the engine oil liquefies, which leads to a loss of stability in the formation of an oil film on the cylinder mirror and “dry” friction of the rings on the mirror. This causes an intensification of molecular mechanical wear of CPG parts. On the other hand, it is known that the reduced temperature of the cylinder walls (below the dew point of the exhaust gases) contributes to the acceleration of their corrosion-mechanical wear. The mixture formation also deteriorates and the rate of combustion of the air-fuel mixture decreases, which reduces the efficiency and economy of the engine, causing an increase in the toxicity of exhaust gases. It should also be noted that at significantly lower temperatures of the piston and cylinder, condensed water vapor penetrating into the crankcase oil causes intense coagulation of impurities and hydrolysis of additives with the formation of precipitation - "sludge". These sediments pollute oil channels, oil sump nets, oil filters, significantly disrupt the normal operation of the lubrication system.

The intensity of the processes of formation of carbon deposits, varnishes and deposits on the surfaces of internal combustion engine parts is significantly affected by the aging of motor oils during their operation. The aging of oils consists in the accumulation of impurities (including water), changes in their physical and chemical properties, and oxidation of hydrocarbons.

The change in the fractional composition of pure filled oil as the engine is running is mainly caused by reasons that change the composition of its oil base and percentage additives for individual components (paraffin, aromatic, naphthenic).

These include:

processes of thermal decomposition of oil in areas of overheating (for example, in valve bushings, areas of the upper piston rings, on the surfaces of the upper chords of the cylinder mirror). Such processes lead to the oxidation of the lightest fractions of the oil base or even their partial boiling off;

adding to the hydrocarbons the base of unevaporated fuel, which enters the crankcase oil sump through the piston seal zone during the initial periods of starts (or with a sharp increase in the fuel supply to the cylinders to accelerate the vehicle);

water entering the oil pan or oil sump of the engine, which is formed during the combustion of fuel in the COP of cylinders.

If the crankcase ventilation system operates efficiently enough, and the crankcase walls are heated to 90-95°C, water does not condense on them and is removed to the atmosphere by the crankcase ventilation system. If the temperature of the crankcase walls is significantly lowered, then the water that has entered the oil will take part in its oxidation processes. The amount of condensed water in this case can be quite significant. Even if we assume that only 2% of gases can break through all the compression rings of the cylinder, then 2 kg of water will be pumped through the crankcase of an engine with a working volume of 2-2.5 liters for every 1000 km of run. Suppose that 95% of the water is removed by the crankcase ventilation system, then after a run of 5000 km, about 0.5 liters of H2O will fall on 4.0 liters of engine oil. This water, when the engine is running, is converted by an antioxidant additive contained in engine oil into impurities - coke and ash.

For the reasons stated earlier, it is necessary to keep the temperature of the crankcase walls sufficiently high during engine operation, and, if necessary, to use dry sump lubrication systems with a separate oil tank.

It should be noted that measures that slow down the processes of changing the composition of the oil base significantly slow down the formation of carbon deposits, varnish and deposits, and also reduce the wear intensity of the main parts of automobile engines.

Fractional and chemical composition oils can vary in a fairly wide
limits under the influence of various factors:

the nature of the raw material, depending on the field, the properties of the oil well;

features of the technology for the manufacture of motor oils;

features of transportation and duration of storage of oils.

For a preliminary assessment of the properties of petroleum products, various laboratory methods are used: determination of the distillation curve, flash points, turbidity and solidification, assessment of oxidizability in media with different aggressiveness, etc.

The aging of automotive engine oil is based on the processes of oxidation, decomposition and polymerization of hydrocarbons, which are accompanied by the processes of oil contamination with various impurities (soot, dust, metal particles, water, fuel, etc.). Aging processes significantly change the physical and chemical properties of the oil, lead to the appearance of various oxidation and wear products in it, and worsen its performance. There are the following types of oil oxidation in engines: in a thick layer - in the oil pan or in the oil tank; in a thin layer - on surfaces hot metal parts; in a foggy (drip) state - in the crankcase, valve box, etc. In this case, the oxidation of oil in a thick layer gives precipitation in the form of sludge, and in a thin layer - in the form of varnish.

The oxidation of hydrocarbons is subject to the theory of peroxides by A.N. Bach and K.O. Engler, supplemented by P.N. Chernozhukov and S.E. Crane. Oxidation of hydrocarbons, in particular in motor engine oils, can go in two main directions, shown in Fig. 2, the results of oxidation for which are different. In this case, the result of oxidation in the first direction is acidic products (acids, hydroxy acids, estolides and asphaltogenic acids), which form precipitation at low temperatures; the result of oxidation in the second direction are neutral products (carbenes, carboids, asphaltenes and resins), from which either varnishes or deposits are formed in various proportions at elevated temperatures.

Rice. 2. Pathways for the oxidation of hydrocarbons in a petroleum product (for example, in engine oil for internal combustion engines)

In the processes of oil aging, the role of water that enters the oil during the condensation of its vapors from crankcase gases or in other ways is very significant. As a result, emulsions are formed, which subsequently enhance the oxidative polymerization of oil molecules. The interaction of hydroxy acids and other products of oil oxidation with oil-in-water emulsions causes increased formation of deposits (sludge) in the engine.

In turn, the resulting sludge particles, if they are not neutralized by the additive, serve as catalysis centers and accelerate the decomposition of the oil that has not yet been oxidized. If this does not produce timely replacement engine oil, the oxidation process will occur as a chain reaction with increasing speed, with all the ensuing consequences.

The decisive influence on the formation of deposits, varnishes and deposits on the surfaces of internal combustion engine parts in contact with engine oil is their thermal state. In turn, the design features of engines, their operating conditions, operating modes, etc. determine the thermal state of the engines and thus affect the formation of deposits.

No less important influence on the formation of deposits in the internal combustion engine is exerted by the characteristics of the engine oil used. For each specific engine, it is important that the oil recommended by the manufacturer corresponds to the temperature of the surfaces of the parts in contact with it.

In this paper, the analysis of the relationship between the temperatures of the piston surfaces ZMZ engines-402.10 and ZMZ-5234.10 and the processes of formation of carbon deposits and varnishes on them, as well as an assessment of sedimentation on the surfaces of the crankcase and valve cover of engines when using engine oil M 63 / 12G1 recommended by the manufacturer.

To study the dependence of the quantitative characteristics of deposits in engines on their thermal state and operating conditions, various methods can be used, for example, L-4 (England), 344-T (USA), PZV (USSR), etc. . In particular, according to the 344-T method, which is normative document United States, the condition of a "clean" unworn engine is rated 0 points; the state of an extremely worn and polluted engine - 10 points. A similar method for assessing varnish formation on piston surfaces is the domestic ELV method (authors - K.K. Papok, A.P. Zarubin, A.V. Vipper), the color scale of which has points from 0 (no varnish deposits) to 6 (maximum deposits varnish). To recalculate the points of the ELV scale into points of the 344-T method, the readings of the first one must be increased by one and a half times. The specified method is similar to the domestic method of negative assessment of deposits of the All-Russian Research Institute of Oil and Gas (10 point scale).

For experimental studies, 10 ZMZ-402.10 and ZMZ-5234.10 engines were used. Experiments to study the processes of deposit formation were carried out jointly with the laboratories for testing cars and trucks UKER GAZ on engine stands. During the tests, among other things, the flow rates of air and fuel, the pressure and temperature of the exhaust gases, the temperature of the oil and the coolant were monitored. At the same time, the following modes were maintained on the stands: the crankshaft speed corresponding to the maximum power (100% of the load), and, alternately, for 3.5 hours - 70% of the load, 50% of the load, 40% of the load, 25% of the load and no load (with closed throttle valves), i.e. experiments were carried out on the load characteristics of engines. At the same time, the temperature of the coolant was kept in the range of 90...92C, the temperature of the oil in the main oil line was 90...95C. After that, the engines were disassembled and the necessary measurements were made.

Preliminary studies were carried out to change the physico-chemical parameters of motor oils during testing of ZMZ-402.10 engines as part of GAZ-3110 vehicles at the UKER GAZ test site. At the same time, the following conditions are met: average technical speed 30 ... 32 km / h, ambient temperature 18 ... 26C, mileage up to 5000 km. As a result of the tests, it was obtained that with an increase in vehicle mileage (engine operation time), the amount of mechanical impurities and water in engine oils, its coke number and ash content increased, and other changes occurred, which is presented in Table. 1

Carbon formation on the surfaces of the piston bottoms of the ZMZ-5234.10 engines was characterized by the data presented in fig. 3 (for engines ZMZ-402.10 the results are similar). From the analysis of the figure, it follows that with an increase in the temperature of the piston bottoms from 100 to 300С, the thickness (existence zone) of carbon deposits decreased from 0.45 ... 0.50 to 0.10 ... engines. The hardness of the soot increased from 0.5 to 4.0...4.5 points due to the sintering of soot at high temperatures.

Rice. 3. Dependences of carbon formation on the surfaces of the piston bottoms of ZMZ-5234.10 engines on their temperatures:
a - soot thickness; b - soot hardness;
the symbols show the averaged experimental values

Evaluation of varnish deposits on the side surfaces of the pistons and their internal (non-working) surfaces was also carried out on a ten-point scale, according to the 344-T method used in all leading research institutions in the country.

Data on varnish formation on the surfaces of engine pistons are presented in fig. 4 (the results for the studied brands of engines are the same). The test modes are indicated earlier and correspond to the modes in the studies of carbon formation on parts.

From the analysis of the figure, it follows that the varnish formation on the surfaces of engine pistons unambiguously increases with an increase in the temperatures of their surfaces. The intensity of varnish formation is affected not only by an increase in the temperature of the surfaces of parts, but also by the duration of its action, i.e. the duration of the engines. In this case, however, the processes of varnish formation on the working (rubbing) surfaces of the pistons slow down significantly compared to the internal (non-working) surfaces, due to the erasing of the varnish layer as a result of friction.

Rice. 4. Dependences of varnish deposits on the surfaces of pistons of ZMZ-5234.10 engines on their temperatures:
a - internal surfaces; b - side surfaces; the symbols show the averaged experimental values

Nagar and varnish formation on the surfaces of parts is significantly intensified when oils of groups "B" and "C" are used, which is confirmed by a number of studies carried out by the authors on similar and other types of automobile engines.

A systematic increase in varnish deposits on the internal (non-working) surfaces of the pistons causes a decrease in heat removal to the crankcase oil with an increase in engine operating time. This causes, for example, a gradual increase in the level of the thermal state of the engines as the operating time approaches the oil change at the next TO-2 of the car.

The formation of sediments (sludge) from motor oils occurs to the greatest extent on the surfaces of the crankcase and valve cover. The results of studies of sedimentation in ZMZ-5234.10 engines are shown in fig. 5 (for engines ZMZ-402.10 the results are similar). Deposit formation on the surfaces of the previously mentioned parts was evaluated depending on their temperatures, for the measurement of which thermocouples were mounted (welded by capacitor welding): on the surfaces of the crankcase, 5 pieces for each engine, on the surfaces of valve covers, 3 pieces.

As follows from Fig. 5, with an increase in the temperatures of the surfaces of engine parts, sedimentation on them decreases due to a decrease in the water content in the crankcase oil, which does not contradict the results of previous experiments by other researchers. In all engines, sedimentation on the surfaces of crankcase parts turned out to be greater than on the surfaces of valve covers.

On motor oils of forcing groups "B" and "C", sedimentation on ICE parts in contact with engine oil occurs more intensively than on oils of forcing groups "G", which is confirmed by a number of studies.

In this work, deposits on the cylinder mirrors during operation of engines with the most modern oils were not studied, however, we can confidently assume that for the engines under study they will be no more than when they are operated with lower quality oils.

The results obtained on the relationship of temperature changes in the main parts of the ZMZ-402.10 and ZMZ-5234.10 engines (pistons, cylinders, valve covers and oil pans) and the amount of deposits made it possible to reveal the regularities in the processes of formation of carbon deposits, varnishes and deposits on the surfaces of these parts. To do this, the results were approximated by functional dependencies by the least squares method and are presented in Figs. 3-5. The obtained regularities of the processes of formation of deposits on the surfaces of parts of automobile carburetor engines should be taken into account and used by designers and engineering and technical workers involved in fine-tuning and operation of internal combustion engines.

The car engine works with the greatest efficiency only under certain conditions. The optimal temperature regime of heat-loaded parts is one of such conditions and provides high technical characteristics of the engine with a simultaneous decrease in wear and deposits and, consequently, an increase in its reliability.

The optimal thermal state of the internal combustion engine is characterized by the optimal temperatures of the surfaces of their heat-loaded parts. Analyzing the studies of the processes of formation of deposits on the parts of the studied ZMZ carburetor engines and similar studies on gasoline engines, it is possible to determine with a sufficient degree of accuracy the intervals of optimal and dangerous temperatures for the surfaces of parts of this class of engines. The information obtained is presented in Table. 2.

At temperatures of engine parts in a dangerous low-temperature zone, the thickness of soot on the surfaces of the parts forming the combustion chamber increases, which leads to the detonation combustion of air-fuel mixtures, and also at low temperatures of the surfaces of engine parts, the amount of precipitation from engine oils increases on them. All this disrupts the normal operation of the engines. In turn, deposits lead to a redistribution of heat flows passing through the pistons and an increase in piston temperatures at critical points - in the center of the fire surface of the piston bottom and in the VKK groove. The temperature field of the ZMZ-5234.10 engine piston, taking into account the deposits of deposits and varnishes on its surfaces, is shown in Fig. 7.

The problem of heat conduction by the finite element method was solved with the first-class GU obtained by thermometering the piston in the rated power mode during bench tests of the engine. Thermoelectric experiments were carried out with the same piston, for which preliminary studies of the temperature state were carried out without taking into account deposits. The experiments were carried out under identical conditions. Previously, the engine worked on the stand for more than 80 hours, after which the stabilization of deposits and varnishes begins. As a result, the temperature in the center of the piston bottom increased by 24°C, in the zone of the VPC groove - by 26°C in comparison with the piston model without deposits. The temperature value of the piston surface above the VCC 238°C is included in the hazardous high-temperature zone (Table 2). Close to the dangerous high temperature zone and the temperature value at the center of the piston crown.

At the design and development stage of engines, the effect of carbon deposits on the heat-receiving surfaces of pistons and varnishes on their surfaces in contact with engine oil is taken into account extremely rarely. This circumstance, together with the operation of engines as part of a vehicle under increased thermal loads, increases the likelihood of failures - piston burnout, piston ring coking, etc.

N.A. Kuzmin, V.V. Zelentsov, I.O. Donato

Nizhny Novgorod State Technical University. R.E. Alekseeva, Moscow-Nizhny Novgorod Motorway Administration

One of the biggest is the accumulation of carbon deposits in them, which impairs their performance and even leads to serious malfunctions. Most often, carbon deposits form in modern engines with direct gasoline injection. Here's why it happens and how to prevent it.

Where is the soot from?

The formation of carbon deposits is caused by many factors and is common to all types of engines. internal combustion- gasoline and diesel, naturally aspirated and turbocharged, with indirect and direct fuel injection.

Deposits in the engine result from imperfect combustion of the air-fuel mixture. For example, in gasoline direct injection engines, one of the causes of carbon deposits is the way the fuel is delivered - gasoline in this case does not wash the valves, but goes directly into the combustion chamber. This causes deposits to build up on the valves and therefore restricts the flow of oxygen into the combustion chamber over time, which in turn leads to improper combustion of the fuel mixture.

If you look at the problem more broadly, it is not difficult to find and other indirect causes the appearance of soot in car engines. They are related to what last years most car enthusiasts have changed the way they use the car. Everything today more people operate the car like a bicycle, public transport or for a short walk/ride to the store.

Most often, large ones accumulate in the engines of vehicles operated in urban mode, over short distances. It doesn't matter what brand or model it is. The way the car is used is important: low speed, low operating temperatures, use of the car without warming up the engine - this is the main formula that guarantees the rapid appearance of soot in the engine, - explains Vladimir Drozdovsky, an expert from Profmotorservis.

Plus add to that the fact that many modern gasoline engines today are often turbocharged, meaning that turbo car in city mode, it is most often used at low engine speeds. In the upper speed range, turbo engines are rarely used today in urban conditions. But even naturally aspirated modern engines with direct direct injection of gasoline also do not encourage owners to drive. high revs. The point is that today atmospheric engines well generate high torque at low speeds. Accordingly, the car owner no longer needs to drive at high speeds often. This essential difference turbineless modern motors from 20 year old engines.

Unfortunately, lower RPMs take longer to warm up (plus keep in mind that many engines today are aluminum, which quickly lose their heating temperature, unlike the old cast iron ones), and low RPMs do not naturally remove carbon deposits from the engine. As a result, in power unit on various details deposits begin to accumulate.

In the past, up to 2000 rpm, it was impossible to drive even at a constant speed. Today, during acceleration, you do not need to exceed them. Hence the large accumulation of deposits in the engine.

Another reason for the formation of soot is it's the wrong oil change and late service engine. For example, the main enemy of any internal combustion engine is the increase in engine oil change intervals. After all, it is known that the longer the oil in the engine does not change, the more by-products. Unfortunately, today many manufacturers have deliberately increased their service intervals for oil change. For example, many automakers have extended oil change intervals from 10,000 km to 15,000 km (in Russia).

In their opinion, modern engine design, electronics and quality synthetic oils allow the engine to use engine oil for 15 thousand km without harm. Some manufacturers have gone even further, extending the service interval to 20,000 km. And look at the recommendations of manufacturers in Europe and you will be surprised. There, in comparison with Russia, the service intervals for changing the oil have been increased even more - up to 25 thousand km and even 30 thousand km!

But we have already told you why you should not listen to the dealer and the factory, strictly following the recommendations for changing the oil. In most cases, you need to understand that the recommendations of the manufacturers relate to the general light operating conditions of the car. If you use the car mainly in the city, then you can immediately safely reduce the recommended maximum mileage car before changing the oil by 20-30 percent. If you use the car for short distances on an underheated engine, do not hesitate to divide the manufacturer's recommendations by two.

But oil is half the trouble. Today, in difficult economic conditions, when the incomes of the population leave much to be desired, and the cost of fuel is already approaching the cost of 1 liter of milk, many drivers are trying to save on maintenance their cars, visiting not only unauthorized informal technical services, but also not very professional craftsmen working in the so-called garage car services. Yes, this allows car owners to save a lot on maintenance and save time. But there is one problem. In such cheap garage car services, many car mechanics no way to connect vehicle to the computer to update the vehicle software and to diagnose possible problems.

Do you know that the most common cause excessive carbon deposits in the engine is the engine control unit software not updated? Indeed, because of this, the engine of the car may not work properly, resulting in improper combustion of the fuel mixture. And manufacturers often update software for their cars.

Another one of the immediate causes of carbon buildup is engine mistiming, which is the responsibility of the timing belt/timing chain. Unfortunately, in gasoline engines, the belt and even the chain tend to stretch. This is a problem with many modern engines ( good example are popular TSI/TFSI engines in the world). If the tension of the chain or belt weakens, the timing system is out of sync, which in turn leads to improper combustion of the fuel mixture.

From this we conclude: everything that has an indirect or direct effect on the course of the combustion process is the cause of the accumulation of carbon deposits in the engine. This also applies to poor quality fuel or the operation of the ignition system (coils, etc.).

How to prevent the accumulation of carbon deposits in the engine?

The above leads to a simple general conclusion: you need to take care of your car's engine. How? Everything is very simple. You need to visit the technical center regularly. And not only when it's time to change the oil in the engine. It is advisable to call in the service more often, conducting computer diagnostics. You must consider your car's engine as a complete machine, without dividing it into regions, serving each in turn. Thus, an engine check should not be limited to changing the oil and filter, but should include a complete engine diagnostics, including software updates.

In addition, the more often you connect the machine to the computer, the more likely it is that problems will be detected in time. After all, a mechanic cannot always understand in a timely manner that, for example, some kind of ignition coil has started to work incorrectly. But by connecting diagnostic equipment, he can find out about it before the car starts to show signs of malfunction.

The engine of a modern car is reliable and durable enough that, with proper operation and timely maintenance, it can "walk" 300-400 thousand km and even more. But no matter how hard designers and manufacturers try, the processes of aging and wear in the engine are inevitable. As well as the formation of various deposits.

The service life of a modern car is quite long and is at least 10-15 years. Of course, during this time, breakdowns and failures of individual parts and assemblies are very likely; abrupt, abrupt changes in the state of the engine. But still this happens relatively rarely, since it is probabilistic in nature. But the processes of changing the dimensions, physical and chemical properties of parts and components occur slowly, but continuously.

As long as such changes do not go beyond the tolerances laid down by the designers, consumer qualities engines remain stable. But here one or more parameters turned out to be acceptable limits.

In the operation of the engine immediately there are violations. No, there is no talk of failures or breakdowns yet. But there is a violation of the operation of a separate component, which has not yet led to the loss of its and, accordingly, the engine performance.

Unlike failures and breakdowns related to probabilistic phenomena, the described processes occur even in varying degrees, but with absolutely all engines. Moreover, it is often much more difficult to determine where and in what place deviations occurred than to establish the fact and cause of an obvious breakdown.

Wear or... deposits?

Let's start with the most inevitable - wear and tear. You have to put up with him, because you can’t stop him completely. Although it is possible to slow down - the achievements of recent years in the materials and technology of engine production, in the development of engine oils and filters, combined with strict adherence to the rules for operating and maintaining the engine, provide numerous examples of delaying the deadline overhaul far beyond 300 thousand kilometers.

It turns out that for the time being, you can not even remember about wear and tear. Therefore, at least during 100-200 thousand kilometers, other factors come to the fore, reducing the actual life of the engine. And first of all, this is the formation of various kinds of deposits.

We have already written about the danger of deposits in the lubrication system and engine crankcase associated with low quality, inconsistency of the oil grade or its untimely replacement (see "ABS-auto" 3/2000). At the same time, deposits accumulating in fuel system and the intake manifold, combustion chamber, exhaust system, are not always given importance, considering them to be something of secondary importance. However, practice shows that their influence on the engine is very significant, and in some cases dangerous. This is exactly what will be discussed.

Let's take a look at the points and components in the engine design that are most prone to deposit accumulation over the life of the engine. Some of them have little or no effect on the operation of the engine. Others, on the contrary, cause noticeable deviations in work even with relatively small deposits. Such critical components in terms of impact on the engine include the housing throttle valve, intake valve plates and, of course, nozzles.

Where do deposits come from?

The processes of deposit formation and their chemical composition are very different in different systems and devices. For example, the formation of deposits in the atomizing part of the injectors occurs mainly during the first 10-20 minutes after stopping a hot engine, when the injectors are under residual fuel pressure. The essence of the process is as follows: the fuel film, which inevitably remains in the zone of the atomizer seat, begins to evaporate under the influence of high temperature. Light fractions of gasoline evaporate, and heavier ones form a layer of solid deposits. Their main component is carbon.

Deposits on the intake valve plates have a more complex composition. So, low-quality fuel is the reason resinous deposits. Oil penetrating through worn valve stem seals and the gap between the valve stem and sleeve leads to coke deposits: it is formed as a result of high-temperature oxidation of the oil that enters the hot plate. By the way, the process of valve coking is most intensive at idle, driving with a low load and during engine braking, when the maximum vacuum is created in the intake manifold.

Engine oil also contributes to contamination of the throttle and regulator channels. idle move, since the products of oxidation and oil contamination are carried into the intake manifold through the crankcase ventilation system.

Another component of deposits is soot. The reason for its formation is the combustion of an excessively rich air-fuel mixture in cold start, warm-up and acceleration modes. Soot entering the exhaust system can gradually lead to clogging of the channels of the exhaust gas recirculation system.

For engines that have been operated in Russia for a long time, certain types of deposits prevail. This is due to the use of low quality fuel and oil. That is why the engine, which is able to work perfectly "there" for many years, "here" relatively quickly begins to "act up".

Immunity to... deposits?

It cannot be said that engine designers forgot about deposits and simply "washed their hands", shifting these problems to the consumer. On the contrary, in recent years a lot has been done to develop engines of a kind of "immunity" to deposits. In other words, many nodes and systems have latest models engines have become insensitive to deposits, i.e. the consequences of the accumulation of deposits are minimized.

For example, fuel dosing systems have long been adaptive; allow you to adapt (albeit within certain limits) to external conditions. And what are these external conditions? First of all - the accumulation of deposits in the spray part of the nozzles. The same approach is now used in most idle subsystems. Special design components have also appeared - deposit-resistant nozzles and Teflon-coated throttle valves.

The "immunity" to deposits provided by such difficult and very expensive measures is needed today more than ever. The fact is that the continuously tightening requirements for exhaust toxicity, efficiency and power density directly lead to the need for very “fine” tuning of the engine and all its systems. And it turns out that what more modern engine, the more painfully it reacts even to a small amount of deposits.

Why are deposits dangerous?

All deposits, without exception, have one thing in common - they negatively affect the operation of the engine. Poor starting performance, erratic idling, mixture misfiring, "spills" when accelerating, increased fuel consumption and exhaust emissions are far from complete list obvious symptoms caused by the appearance of "unfriendly" formations in the intake tract of the engine. But worst of all, these deposits can accelerate the wear of the engine many times over and even lead to failures and breakdowns of its parts and components.

Indeed, what could be the connection between the coking of nozzles and the wear of parts, for example, a crank mechanism or a cylinder-piston group? The most direct: in cold weather, the engine does not start the first time, and the lower the temperature, the more you have to make attempts to start. Well, each such attempt is the work of mating parts in the semi-dry or even dry friction mode, equivalent in terms of wear to 20-40, and sometimes 100 km real mileage.

How to clean parts from deposits?

We think that this example is quite enough to realize the seriousness of the problem. How can it be solved? The first thing that comes to mind is to simply remove the contaminated components and clean them chemically or mechanically. Indeed, this method gives best results but takes too much time. Especially when it comes to complex engines, including multi-cylinder ones. In addition, the disassembly and subsequent assembly of components and systems on modern vehicles often requires the replacement of a mass of gaskets and sealing elements that are not always at hand.

The CIP engine cleaning technology is more attractive. It is based on special chemical compounds - solvents, which act specifically on specific types of deposits. And in order to remove deposits at a given point, a certain cleaning technique is also required and special equipment. About what solvents, cleaning methods and equipment to use in a particular case, we will tell in our the following materials.

The main places of accumulation of deposits in engines:
1 - throttle body and idle speed controller;
2 - intake manifold;
3 - fuel rail;
4 - upper part of the nozzle;
5 - spray part of the nozzle;
6 - plate inlet valve;
7 - combustion chamber;
8 - piston bottom;
9 - oxygen sensor;
10 - catalyst;
11 - channels of the exhaust gas recirculation system.

Recall that on a serviceable car, the oil suddenly turned into a thick black slurry, after which the motors were sent for a “capital” or replacement - untimely and extremely expensive. without even asking our permission. Well, that's okay...

Summary previous article - a wave of sudden engine failures has swept through branded car services (and not only), associated with incomprehensible and unpredictable behavior of engine oil. Without any warning, the oil suddenly turned into a black oil, began to burn out very quickly. The result - overhaul or death of motors.

The epidemic hit cars regardless of their brands and manufacturers. Cases of the disease were registered in Moscow, and in St. Petersburg, and in Magnitogorsk, and in Murmansk - that is, almost throughout the country. And it was also noticed that the “sick” were mainly cars serviced at serious car services, in which barrel branded oil was poured. The situation was aggravated by the fact that these cases were irregular, met infrequently, but with enviable regularity. And, as any diagnostician knows, it is the “floating” defect that is the most difficult to catch.

The cause of this illness was incomprehensible, there were only hypotheses, but you can’t build a lawsuit in court on them (and most often it was the case that reached the court in proceedings). And then we promised to try to deal with the situation and acquaint our readers with the results.

Six months of work of our testing laboratory was not in vain. We managed to simulate a number of situations in the laboratory and, finally, get clear manifestations of this “deadly disease”. The symptoms that we will catch are a sharp increase in viscosity, a drop in alkaline and an increase in acid number, the deposition of thick tar-like deposits on the engine walls that prevent oil from pumping through the channels of the lubrication system.

IS THE OIL IN THE CANISTER SEPARATED? IS THERE RESIDUE? TO THE WASTE!

FALSE TRAIL

Let's start with the typical "excuses" of dealer service stations, on the basis of which they are trying to fight off warranty repair. The inquisitive mind of warranty specialists usually wanders in three directions - the use of low-quality fuel; antifreeze or water getting into the oil; lack of control over the oil level in the engine during operation.

Let's immediately remove the third option - it is obvious that even with a very small amount of oil in the sump, it should not change its properties in the way that we see in cases of advanced "disease". When using a “healthy” oil, the motor will react to a small amount of it by catching fire control lamps on the dashboard and sound alarm. First - with rolls and sharp accelerations and decelerations, when the receiving fungus is exposed. Any normal driver will respond to this immediately. And after topping up the oil, you will not feel any negative consequences in the future.

The most common alleged "reason" on the basis of which they try to void the warranty is the use of substandard fuel. Substandard in the understanding of service station mechanics is either a low octane number, or high content sulfur in the fuel, or the presence of a large amount of resins in it. Let's say right away that, apart from sulfur, everything else is current Technical Regulations, which regulates the quality of fuel, is not subject to control, therefore, it is not subject to jurisdiction. But, since there are such attempts at excuses, we will check.

FUEL - JUSTIFY!

Several bench engines, initially completely serviceable, were doomed to the slaughter. It’s a pity for them, but these are just pieces of iron, and living people suffer from the problem. Therefore - let these motors serve for the benefit of people.

Especially for the experiment, not without difficulty, they got 100 liters of fuel, more like a bodyagi. Instead of the declared 92nd octane number they measured only 89.5, the sulfur content went off scale over 800 ppm, the tar was more than 3.5 mg/dm3. The manufacturer is unknown, but in terms of quality it is something from some kind of "samovar" - an amateur mini-refinery that distills gas condensate into supposedly fuel. Worse than ever! You have to dislike your car very much to feed it with such good things.

We fed the engine all the bodyag we got. And, in order to completely aggravate the situation and provide the oil with the maximum possible contact with disgusting fuel, they broke off the side electrode on one of the candles. Now the fuel entering idle cylinder, V in large numbers fly into the engine crankcase.

The motor self-diagnostic system was indignant, the check-engin burned brightly and incessantly all the time of torture. The motor shook and vibrated, but... survived! His autopsy revealed no problems - everything was clean and no black deposits were observed anywhere. The oil pressure, of course, dropped a little - the dilution of the oil by the fuel affected. At the same time, as soon as the damaged candle was replaced with a normal one, literally half an hour later, the arrow of the oil pressure indicator returned to its previous position. It is understandable, gasoline is a volatile liquid, and at operating temperatures the oil into which it has entered will not live there for a long time.

Measurements of the physico-chemical parameters of the oil did not reveal anything unexpected! The viscosity of the oil dropped a little - after all, some fuel fractions of the so-called gasoline remained in it. Base number slightly decreased - from 7.8 to 7.4 mg KOH/g. The acid number increased by 0.3 mg KOH/g. The flash point dropped noticeably - from 224°C to 203°C. This clearly indicates that there was gasoline in the oil! But he couldn't kill him...

Moreover, in a real situation, its diagnostic system will be indignant at the poor-quality feeding of the motor in the first place. And this indignation is sure to leave an indelible mark on the computer logs. But in almost all cases when the warranty services refused to repair, motivating their decision to use low-quality fuel, the diagnostic system did not confirm anything of the kind.

Verdict: Gasoline not guilty!

SUSPECTED WATER

Water always gets into the oil in some quantities! It condenses from the moist air entering the cylinders and, together with crankcase gases, mixes with the oil. Coolant can only get into the oil if there is a leak in the cooling system - and only when the engine is stopped. During its operation, the oil pressure is higher than the pressure in the cooling system, and therefore the path for antifreeze to the oil is closed.

Well, let's try to simulate this situation. 3 liters were poured into the long-suffering engine fresh butter, and then thumped a whole liter of water there! And what? Never mind! Of course, an emulsion formed in the sump, the oil pressure dropped noticeably. But the motor worked, nothing critical was heard or seen. And then - gradually the oil pressure began to grow and soon returned to the initial level. What happened? The water simply evaporated, the oil returned to its original state. The autopsy of the motor showed no problems - everything was clean again. Changes in the physical and chemical parameters of the oil after the ingress and subsequent evaporation of water turned out to be within the measurement error! And this is the reason for the withdrawal from the guarantee - to refuse for insolvency!

After that, they dealt with a similar situation by replacing the water with antifreeze. The result is the same, the engine survived. But the viscosity of the oil has grown - it is understandable, the water has evaporated, and the ethylene glycol remains in the oil. The alkaline number decreased slightly, the acid number increased. Yes, of course, if you drive an engine with a broken cylinder head gasket for a very long time, constantly adding antifreeze to the tank and not trying to deal with the situation, then in the end, you can probably achieve the death of the oil, and with it the death of the engine! But this is just an extreme case of a disregard for the engine. Yes, and here there will already be a situation - not “ethylene glycol in oil”, but “oil in ethylene glycol”.

Conclusion - such a reason can only be considered when it was preceded by a long and constant loss of coolant in the engine. And with a complete lack of control of the condition of the oil at the same time. This is also not our case.

Verdict: It's not the coolant's fault!

GOT!!!

We checked two more versions. And, looking ahead, let's say - THEY WORKED!

The first one was suggested by oil specialists, with whom we constantly communicate. According to them, the picture that we are seeing, that is, sharp rise viscosity of the oil, may be due to the unexpected polymerization of some components of the additive package. The reason for this disgrace is the volumetric overheating of engine oil. And they remembered that at their seminars, some manufacturers of oils and cars, since recently, began to give a clear recommendation - if suddenly the oil was overheated, then you urgently need to run to the nearest service center and change it!

We tried to overheat the oil on a bench motor. It was not difficult for us to do this - we had to turn off the external engine airflow and select the appropriate operating mode. Unlike most cars, our sump oil temperature is constantly displayed on the control panel. Indeed, it rose by 20...25 degrees. This torture continued for many hours. Two oils worked fine, withstanding such a mockery. But the third behaved strangely - it began to noticeably thicken. And then, in the drain tank, where they left its remains for a couple of days, traces of oil separation were found. It drew the same “tar” that we observed on the walls of motors killed by oil. Both on the inner surface of the cylinder block and on the side surfaces of the pistons, there was much more contamination than usual.

So, we opened one option for the death of oil. But they didn’t experience much joy from this - after all, it’s not clear how you can track the real temperature of the oil in the sump in a living car? Indeed, in new cars, even the coolant temperature gauge was removed! It turns out that this information is not even redundant at all!

Let's go further... We remembered how it all started. It all started with a letter from our reader, who, having bought a canister of oil from a very well-known company for topping up, suddenly discovered in it ... an incomprehensible sediment! And from the answer technical specialist the Russian representative office of this company, which, in response to our request for an explanation of the situation, literally uttered the following: “I hereby inform you that in motor and transmission oils a small amount of sediment is allowed. It can be caused by the association of fine catalyst particles that are smaller than the pores of the factory filter element. These sediments... can be up to black in color. They are rare and, as a rule, only in those batches of oil that were made immediately after reloading the fresh catalyst in the apparatus. They do not affect the performance characteristics of commercial oil and, subsequently, in the process of operation, they again turn into a finely dispersed state.

At one time, our oilers were shocked by this answer! That is, one of the world's main oil producers honestly admits the possibility of a gross violation of oil production technology!

And we compared what is written and what we saw with our own eyes. After all, the premature death of oil is very similar to the picture that we could see due to sharp acceleration oil oxidation rate. It is this process that is accompanied by an increase in its viscosity and acid number, a drop in base number. And what can contribute to the uncontrolled acceleration of the chemical reaction, which, in fact, is the oxidation of oil? Precisely the presence of a catalyst!

Yes, of course, when storing such a “dirty” oil, the catalyst will be silent - after all, to activate its work, it requires special conditions, temperature and pressure. But they are just in the active zone of the friction units. So, check this out too!

The main problem that has arisen before us is where to get this catalyst? Our requests for help in this matter were answered only by Russian representation by MOTUL. It seems that only they, by the way, never exposed in cases of premature loss of oil, found it necessary to establish the truth! For this we sincerely thank them, and let them not consider our thanks as an advertisement for this company.

So, we have two options for the catalyst used in the production of hydrocracked base oil. We turned large granules of catalysts into a fine-grained powder of the desired fractional composition - such that it would fly through the pores of the oil filter. These powders were mixed with oil, and after half an hour they saw - here it is, a harmful sediment!

This oil was poured into the next engine, intended for slaughter, and a cycle of its long knurling began. At first everything went well, but after twenty hours of testing they began to notice that the oil pressure was dropping. And the oil on the dipstick became noticeably thicker - all the more, they initially used very good “synthetics” 5W-30, against its background, the increase in viscosity was especially noticeable! It's strange - the viscosity is clearly growing, and the pressure is dropping ... Maybe wear has appeared? But somehow this process progressed too quickly. The motor withstood only 40 hours of testing, after which the pressure completely disappeared. Then - everything, as usual, an autopsy, measurement, inspection.

The first thing that caught my eye was that from four liters of oil initially poured into the engine, only one and a half liters merged from it as a result of tests! And this is - in just 40 hours of very moderate modes, in terms of equivalent - less than 3000 kilometers! And the oil was terribly black. Measurements of engine parts did not reveal serious wear, although it was noticeable - the bearing shells and crankshaft journals were somehow very well polished. It is also clear - the catalyst powder worked as an abrasive. So why did the oil pressure drop so much? The presence of some solid agglomerates in the pallet immediately caught my eye, which sat firmly on the walls. These, apparently, were the very "harmless" according to the authors of the ill-fated letter "associations of fine particles." But they were clearly less than the volume of the initial sediment in the oil filled in the engine. We also did not notice particles in the filter. This means that the main part of the powder introduced by us into the oil has settled in the channels! This is the reason for the loss of pressure in the lubrication system.

And what did the analysis of the physico-chemical parameters of the oil that worked with this “harmless” powder show? The viscosity of the oil, which was originally 11.2 cSt at 100°C, has increased to 17.9 cSt! That is, the oil, which was originally in the SAE-30 class, jumped to the SAE-50 viscosity class in 40 hours! The acid number increased by more than 2.5 mg KOH/g. Recall that in the last resource examination for 180 engine hours, oils increased their acidity by only 0.75 ... 1.0 mg KOH / g! The base number decreased less, and the deposits on the walls of the crankcase were, although more than usual. Moreover, the oil at room temperature was so thick that it did not want to drain from the walls - we have not seen this before. By the way, the picture that we observed in our experiment was suspiciously reminiscent of the one that was given out by one of the oils during our previous “semi-synthetic” examination.

So, according to some oilers, "harmless" catalyst powder in a relatively short time ruined the oil and finished off the engine. And in this case, alas, even the “capital” will not help him - after all, removing the plugs that clog the oil channels, judging by the structure of deposits in the sump, will be extremely problematic. By the way, some conscious dealers major automakers faced with a similar problem, without talking, they changed either cylinder blocks or the entire engine assembly.

The results already clearly show that neither automakers nor car owners are to blame for the troubles that have happened. After all, the thermal instability of some types of oil, leading it to polymerization during volumetric overheating, and the possible presence of an aggressive catalyst deposit in it, which is allowed by some oil manufacturers, are the most serious "punctures" of these companies.

Summing up, while intermediate. Of course, someone would like to hear a loud appeal: they say, do not buy oil from firms A, B and C! And buy D-oil: it never gets sick! But we did not look for the guilty switchman, but investigated the problem. In addition, ten thousand cars can happily run on company A oil, but ten thousand will be the first to get into an unpleasant situation. On the other hand, we technically competently substantiated the inconsistency of the on-duty attacks on the burdock driver. Moreover, we were able to find some possible reasons mass cases of accelerated death of oil and the engine as a whole.

We sincerely want to believe that oil and gasoline manufacturers will carefully study our conclusions: all motorists are waiting for this. In the meantime, we recommend using our recommendations on "Methods of Self-Defense", following which you can save the engine in a critical situation.

DROP SAMPLE

On any porous paper (optimally - a piece of filter for a coffee maker or at least a piece of newspaper) with oil dipstick cold engine, put a drop of oil. If it quickly spreads over the paper, forming several concentric circles, then the oil is alive. But if it does not want to spread and remains a black drop at the point of fall - urgently replace it!

CAN'T CHECK OIL? FIND A PIECE OF NEWSPAPER!

P.S. It goes without saying that in the course of one of the next examinations of oils, we will separately analyze their resistance to the atrocities we have uncovered. One direction of search is already clear: a new wave of failures was noticed after one of the well-known refineries started working after modernization - after all, a similar catalyst is used in the production of high-octane gasoline!!! But doesn’t it come into the oil with this outwardly quite conditioned fuel? And from another region, information came about an allegedly accidental coincidence of the death of engines according to the scheme we described with the use of fuel containing an exorbitant dose of methanol, which is strictly prohibited in our country. This also needs to be dealt with.

HOT? TRAFFIC JAMS? CHECK THE OIL!

SELF DEFENSE METHODS

To protect yourself from possible trouble, we repeat our recommendations once again:

1. Use only oils purchased from trusted stores. For scheduled maintenance, it is better to come with your oil canister. After buying it, let it stand for a while, and, if possible, see if there is sediment in the canister. Usually the sediment can be seen on the transparent measuring strip on the canister.

2. Make it a rule, even if your engine is not noticed in increased oil appetite, at least once a week to get under the hood and monitor the level and condition of the oil on the dipstick. You should immediately be alerted by a sharp increase in oil consumption, or its sudden dilution, or, conversely, thickening.

3. Be especially attentive to the oil in the summer, when standing in traffic jams for a long time, or during long-distance high-speed hauls. It is then that volumetric overheating of the oil is possible.

4. Adopt the so-called. "drip test" of oil. Its essence and procedure are extremely simple. On any porous paper (optimally - a piece of a filter for a coffee maker, or at least a piece of newspaper) from the oil dipstick of a cold engine, drip a drop of oil. If it quickly spreads over the paper, forming several concentric circles, then the oil is alive. And, if it does not want to spread, remaining a black drop at the place of fall - urgently to the service station to replace it!