The engine cooling system serves to maintain the normal thermal operating conditions of engines by intensively removing heat from hot engine parts and transferring this heat to the environment.

The rejected heat consists of the part of the heat released in the engine cylinders that is not converted into work and is not carried away from the engine. exhaust gases, and from the heat of friction that occurs during the movement of engine parts.

Most of the heat is removed to the environment by the cooling system, a smaller part by the lubrication system and directly from the outer surfaces of the engine.

Forced heat removal is necessary because at high gas temperatures in the engine cylinders (during the combustion process 1800–2400 °C, the average gas temperature during the operating cycle at full load is 600–1000 °C), natural heat transfer to the environment is insufficient.

Failure to properly dissipate heat causes deterioration in lubrication of rubbing surfaces, oil burnout and overheating of engine parts. The latter leads to a sharp drop in the strength of the material of parts and even their burning (for example, exhaust valves). When the engine overheats greatly, the normal clearances between its parts are disrupted, which usually leads to increased wear, jamming and even breakdown. Engine overheating is also harmful because it causes a decrease in the filling factor, and in gasoline engines, in addition, it causes detonation combustion and self-ignition of the working mixture.

Excessive engine cooling is also undesirable, since it entails condensation of fuel particles on the cylinder walls, deterioration of the mixture formation and flammability of the working mixture, a decrease in its combustion rate and, as a consequence, a decrease in engine power and efficiency.

Classification of cooling systems

In automobile and tractor engines, depending on the working fluid, systems are used liquid And air cooling. Liquid cooling has become the most widespread.

With liquid cooling, the liquid circulating in the engine cooling system absorbs heat from the cylinder walls and combustion chambers and then transfers this heat to the environment using a radiator.

Based on the principle of heat removal to the environment, cooling systems can be closed And open (flow-through).

Liquid cooling systems for automobile and tractor engines have a closed cooling system, i.e., a constant amount of liquid circulates in the system. In a flow-through cooling system, the heated liquid, after passing through it, is discharged into environment, and the new one is taken to be fed into the engine. The use of such systems is limited to marine and stationary engines.

Air cooling systems are open-loop. The cooling air, after passing through the cooling system, is discharged into the environment.

The classification of cooling systems is shown in Fig. 3.1.

According to the method of circulating liquid, cooling systems can be:

forced in which circulation is provided by a special pump located on the engine (or in the power plant), or by the pressure under which the liquid is supplied to the power plant from the external environment;

thermosiphon, in which fluid circulation occurs due to the difference in gravitational forces resulting from different densities of the fluid heated near the surfaces of engine parts and cooled in the cooler;

combined, in which the most heated parts (cylinder heads, pistons) are cooled forcibly, and the cylinder blocks are cooled according to the thermosiphon principle .

Rice. 3.1. Classification of cooling systems

Systems liquid cooling can be open or closed.

Open systems– systems communicating with the environment using a steam pipe.

Most automobile and tractor engines currently use closed systems cooling, i.e. systems isolated from the environment by a steam-air valve installed in the radiator cap.

The pressure and, accordingly, the permissible temperature of the coolant (100–105 °C) in these systems is higher than in open systems (90–95 °C), as a result of which the difference between the temperatures of the fluid and the air sucked through the radiator and the heat transfer from the radiator increase. This allows you to reduce the size of the radiator and the power required to drive the fan and water pump. In closed systems, there is almost no evaporation of water through the steam outlet pipe and no boiling when the engine operates in high mountain conditions.

Liquid cooling system

In Fig. 3.2 shows the diagram fluid system cooling with forced circulation of coolant.

Cylinder block cooling jacket 2 and block heads 3, The radiator and pipes are filled with coolant through the filler neck. The liquid washes the walls of the cylinders and combustion chambers of a running engine and, when heated, cools them. Centrifugal pump 1 pumps liquid into the cylinder block jacket, from which the heated liquid enters the block head jacket and is then forced through the upper pipe into the radiator. The cooled liquid in the radiator returns to the pump through the lower pipe.

Rice. 3.2. Liquid cooling system diagram

The fluid circulation is changed depending on the thermal state of the engine using a thermostat 4. When the coolant temperature is below 70–75 °C, the main thermostat valve is closed. In this case, the liquid does not enter the radiator 5 , and circulates along a small circuit through the pipe 6, what contributes quick warm-up engine to optimum thermal regime. When the temperature-sensitive element of the thermostat heats up to 70–75 °C, the main thermostat valve begins to open and let water into the radiator, where it is cooled. The thermostat opens completely at 83–90 °C. From this moment on, water circulates through the radiator, i.e. large, circuit. The temperature of the engine is also regulated using rotary blinds by changing the air flow created by the fan 7 and passing through the radiator.

IN last years The most effective and rational way to automatically regulate the temperature of the engine is to change the performance of the fan itself.

Fluid system elements

Thermostat designed to provide automatic control of coolant temperature during engine operation.

To quickly warm up the engine when starting it, install a thermostat in the outlet pipe of the cylinder head jacket. It maintains the desired temperature of the coolant by changing the intensity of its circulation through the radiator.

In Fig. 3.3 shows a bellows-type thermostat. It consists of a body 2, corrugated cylinder (bellows), valve 1 and the rod connecting the bellows to the valve . The bellows is made of thin brass and filled with a highly volatile liquid (for example, ether or a mixture of ethyl alcohol and water). Windows located in the thermostat housing 3 depending on the coolant temperature, the valves can either remain open or be closed .

When the temperature of the coolant washing the bellows is below 70 °C, the valve 1 closed and the windows 3 open. As a result, the coolant does not enter the radiator, but circulates inside the engine jacket. When the coolant temperature rises above 70 °C, the bellows, under the vapor pressure of the liquid evaporating in it, lengthens and begins to open the valve 1 and gradually cover the windows with valves 3. At coolant temperatures above 80–85 °C, the valve 1 opens completely, but the windows close completely, as a result of which all the coolant circulates through the radiator. Currently this type thermostats are used very rarely.

Rice. 3.3. Bellows type thermostat

Nowadays, engines are equipped with thermostats in which the damper 1 opens when the solid filler – ceresin – expands (Fig. 3.4). This substance expands when the temperature rises and opens the damper 1 , ensuring the flow of coolant into the radiator.

Rice. 3.4. Solid thermostat

Radiator is a heat dissipation device designed to transfer heat from the coolant to the surrounding air.

Radiators for automobile and tractor engines consist of upper and lower reservoirs connected to each other by a large number of thin tubes.

To enhance heat transfer from the coolant to the air, the fluid flow in the radiator is directed through a series of narrow tubes or channels blown by air. Radiators are made from materials that conduct and release heat well (brass and aluminum).

Depending on the design of the cooling grille, radiators are divided into tubular, plate and honeycomb.

Currently the most widespread tubular radiators. The cooling grille of such radiators (Fig. 3.5a) consists of vertical tubes of oval or round cross-section, passing through a series of thin horizontal plates and soldered to the upper and lower radiator reservoirs. The presence of plates improves heat transfer and increases the rigidity of the radiator. Tubes of oval (flat) cross-section are preferable, since with the same cross-section of the jet, their cooling surface is larger than the cooling surface of round tubes; in addition, when the water in the radiator freezes, the flat tubes do not burst, but only change the cross-sectional shape.

Rice. 3.5. Radiators

IN plate radiators the cooling grill (Fig. 3.5b) is designed so that the coolant circulates in space , formed by each pair of plates soldered together at the edges. The upper and lower ends of the plates are also soldered into the holes of the upper and lower radiator tanks. The air cooling the radiator is sucked by a fan through the passages between the soldered plates. To increase the cooling surface, the plates are usually wavy. Plate radiators have a larger cooling surface than tubular ones, but due to a number of disadvantages (quick contamination, a large number of soldered seams, the need for more careful maintenance) they are used relatively rarely.

Cellular radiator refers to radiators with air tubes (Fig. 3.5c). In the honeycomb radiator grille, air passes through horizontal, circular tubes, washed from the outside with water or coolant. To make it possible to solder the ends of the tubes, their edges are flared so that in cross-section they have the shape of a regular hexagon.

The advantage of cellular radiators is that they have a larger cooling surface than other types of radiators. Due to a number of disadvantages, most of which are the same as those of plate radiators, honeycomb radiators are now extremely rare.

In a traffic jam filler neck radiator installed steam valve 2 and air valve 1 , which serve to maintain pressure within specified limits (Fig. 3.6).

Rice. 3.6. Radiator plug

Water pump ensures circulation of coolant in the system. As a rule, small-sized single-stage low-pressure centrifugal pumps with a capacity of up to 13 m 3 /h, creating a pressure of 0.05–0.2 MPa, are installed in cooling systems. Such pumps are structurally simple, reliable and provide high performance (Fig. 3.7).

The pump body and impeller are cast from magnesium and aluminum alloys, and the impeller is also made from plastic. In water pumps for automobile engines, semi-closed impellers are usually used, that is, impellers with a single disk.

Centrifugal water pump impellers are often mounted on the same shaft as the fan. In this case, the pump is installed in the upper front part of the engine, and it is driven from the crankshaft using a V-belt drive.

Rice. 3.7. Water pump

A belt drive can also be used when installing a centrifugal pump separately from the fan. In some truck and tractor engines, the water pump is driven from the crankshaft by a gear drive. The shaft of a centrifugal water pump is usually mounted on rolling bearings and is equipped with simple or self-adjusting seals to seal the working surface.

Fan in liquid cooling systems they are installed to create an artificial air flow passing through the radiator. Fans of automobile and tractor engines are divided into two types: a) with blades stamped from sheet steel attached to the hub; b) with blades that are cast integrally with the hub.

The number of fan blades varies between four and six. Increasing the number of blades above six is impractical, since the fan performance increases extremely insignificantly. Fan blades can be made flat or convex.

Reliable and trouble-free operation of the internal combustion engine (engine internal combustion) cannot be carried out without a cooling system. It is convenient to present its basic principles of operation in the form of a diagram of the engine cooling system. The main purpose of the system is to remove excess heat from the engine and. Additional feature– heating the car with the interior heater stove. The device and operating principle shown in the diagram are different types cars are approximately the same.

Diagram, elements of the cooling system and their operation

The main elements that make up the engine cooling system circuit are found and are similar in different types of engines: injection, diesel and carburetor.

General diagram of a liquid engine cooling system

Liquid cooling of the motor makes it possible to equally absorb heat from all components and parts of the engine, regardless of the degree of thermal load. A water-cooled engine produces less noise than a water-cooled engine. air cooled, has higher speed warming up at start-up.

The engine cooling system contains the following parts and elements:

cooling jacket (water jacket);
radiator;
fan;
liquid pump (pump);
expansion tank;
connecting pipes and drain taps;
interior heater.

A cooling jacket (“water jacket”) is considered to be cavities communicating between double walls in those places where excess heat is most needed to be removed.
Radiator. Designed to dissipate heat into the surrounding atmosphere. It structurally consists of many curved tubes with additional ribs to increase heat transfer.
Fan turning on electromagnetic, less often hydraulic coupling, when triggered temperature sensor coolant increases the air flow flowing into the car. Fans with a “classic” (always on) belt drive are rarely found these days, mainly on older cars.
The centrifugal liquid pump (pump) in the cooling system ensures constant circulation of coolant. The pump drive is most often implemented using a belt or gears. Engines with turbocharging and direct injection fuel pumps are usually equipped with an additional pump.
The thermostat - the main unit that regulates the flow of coolant, is usually installed between the radiator inlet pipe and the “water jacket”, and is structurally designed in the form of a bimetallic or electronic valve. The purpose of the thermostat is to maintain the specified operating temperature range of the coolant in all engine operating modes.
The heater radiator is very similar to the smaller radiator of the cooling system and is located in the car interior. Fundamental difference consists in the fact that the heater radiator transfers heat to the passenger compartment, and the cooling system radiator transfers heat to the environment.

Principle of operation

The principle of operation of liquid engine cooling is as follows: the cylinders are surrounded by a “water jacket” of coolant, which removes excess heat and transfers it to the radiator, from where it is transferred to the atmosphere. The liquid continuously circulates to ensure optimal engine temperature.

Operating principle of the engine cooling system

Coolants - antifreeze, antifreeze and water - during operation form sediment and scale, disrupting the normal operation of the entire system.

Water is not chemically pure in principle (with the exception of distilled water) - it contains impurities, salts and all kinds of aggressive compounds. At elevated temperature they precipitate and form scale.

Unlike water, antifreezes do not create scale, but during operation they decompose, and the decomposition products negatively affect the operation of mechanisms: internal surfaces metal elements Corrosive plaque and layers of organic substances appear.

In addition, various foreign contaminants may enter the cooling system: oil, detergents or dust. Can also be used for emergency repair of damage in radiators.

All these contaminants settle on the internal surfaces of components and assemblies. They are characterized by poor thermal conductivity and clog thin tubes and radiator honeycombs, disrupting effective work cooling system, which leads to engine overheating.

Video about how engine cooling works, operating principles and malfunctions

Something else useful for you:

Flushing

Flushing the engine cooling system is a process that many drivers often neglect, which sooner or later can cause fatal consequences.

Signs that it's time to flush

If the temperature gauge needle is not in the middle, but tends to the red zone while driving;
It’s cold in the cabin, the heating stove does not provide sufficient temperature;
Radiator fan turns on too often

It is impossible to flush the cooling system with plain water, since contaminants are concentrated in the system and cannot be removed even by water heated to high temperatures.

Scale is removed with the help of acid, and fats and organic compounds are removed exclusively with alkali, but both compounds cannot be poured into the radiator at the same time, since they are mutually neutralized according to the laws of chemistry. Manufacturers of cleaning products, in an attempt to solve this problem, have created whole line funds, which can be divided into:

alkaline;
acidic;
neutral;
two-component.

The first two are too aggressive and pure form They are almost never used, as they are dangerous for the cooling system and require neutralization after use. Less common are two-component types of cleaners containing both solutions - alkaline and acidic, which are poured alternately.

The greatest demand is neutral cleaners, which do not contain strong alkalis and acids. These drugs have varying degrees of effectiveness and can be used both for prevention and for capital flushing engine cooling system from heavy contamination.

Flushing the cooling system

Antifreeze, antifreeze or water is drained. Before doing this, you need to start the engine for a couple of minutes.
Fill the system with water and cleaner.
Turn on the engine for 5-30 minutes (depending on the brand of cleaner) and turn on the interior heating.
After the time specified in the instructions has passed, the engine must be turned off.
Drain the used cleaner.
Rinse with water or a special compound.
Fill with fresh coolant.

Flushing the cooling system is simple and accessible: even inexperienced car owners can perform it. This operation significantly extends the engine life and maintains it performance characteristics at a high level.

Malfunctions

There are a number of the most common malfunctions in the engine cooling system:

Airing the engine cooling system: remove the air lock.
Insufficient pump performance: replace the pump. Select a pump with maximum height impellers.
The thermostat is faulty: it can be fixed by replacing it with a new device.
Low performance of the coolant radiator: flush the old one or replace the standard one with a model with higher heat-dissipating properties.
Insufficient performance of the main fan: Install a new fan with higher performance.

Video - identifying cooling system faults in a car service center

Regular care timely replacement coolant guarantees long-term operation the car as a whole.

The cooling system of an internal combustion engine is designed to remove excess heat from engine parts and components. In fact, this system is bad for your pocket. Approximately a third of the heat obtained from the combustion of precious fuels has to be dissipated into the environment. But that's the way it works modern internal combustion engine. The ideal would be an engine that can operate without dissipating heat into the environment, and convert all of it into useful work. But the materials used in modern engine construction will not withstand such temperatures. Therefore, at least two main, basic engine parts - the cylinder block and the cylinder head - have to be additionally cooled. At the dawn of the automotive industry, two cooling systems appeared and competed for a long time: liquid and air. But the air cooling system gradually lost its ground and is now used mainly on very small engines of motor vehicles and generator sets low power. Therefore, let’s take a closer look at the liquid cooling system.

Cooling system design

Modern cooling system car engine includes engine cooling jacket, coolant pump, thermostat, connecting hoses and radiator with fan. The heater heat exchanger is connected to the cooling system. Some engines also use coolant for heating. throttle assembly. Also, in engines with a supercharging system, coolant is supplied to liquid-air intercoolers or to the turbocharger itself to reduce its temperature.

The cooling system works quite simply. After starting a cold engine, the coolant begins to circulate in a small circle using a pump. It passes through the cooling jacket of the engine block and cylinder head and returns to the pump through the bypass (bypass) pipes. In parallel (on the vast majority of modern cars), the liquid constantly circulates through the heater heat exchanger. As soon as the temperature reaches the set value, usually about 80–90 ˚С, the thermostat begins to open. Its main valve directs the flow to the radiator, where the liquid is cooled by a counter flow of air. If the air flow is not enough, then the cooling system fan comes into operation, in most cases having an electric drive. The movement of fluid in all other components of the cooling system continues. Often the exception is the bypass channel, but it does not close on all cars.

In recent years, cooling system designs have become very similar to one another. But two fundamental differences remain. The first is the location of the thermostat before and after the radiator (along the direction of fluid movement). The second difference is the use of circulation expansion tank under pressure, or a tank without pressure, which is a simple reserve volume.

Using the example of three cooling system schemes, we will show the difference between these options.

Components

Cylinder head and block jacket They are channels cast in an aluminum or cast iron product. The channels are sealed, and the joint between the block and the cylinder head is sealed with a gasket.

Coolant pump bladed, centrifugal type. Driven into rotation either timing belt, or the auxiliary drive belt.

Thermostat is an automatic valve that is activated when a certain temperature is reached. It opens and some of the hot liquid is dumped into the radiator, where it cools. Recently they began to use electronic control this simple device. The coolant began to be heated with a special heating element to open the thermostat earlier if necessary.

Fluid replacement and flushing

If you have not had to replace any component in the cooling system before, then the instructions recommend changing antifreeze at least every 5–10 years. If you have never had to add water to the system from a canister, or even worse, from a roadside ditch, then when replacing the fluid, the system does not need to be flushed.

But if the car has seen a lot in its lifetime, then when replacing the fluid it is useful to do so. Having opened the system in several places, you can thoroughly rinse it with a stream of water from a hose. Or just drain old fluid and fill it with clean water, boiled water. Start the engine and warm up to operating temperature. After waiting until the system cools down, so as not to get burned, drain the water. Then purge the system with air and add fresh antifreeze.

Flushing the cooling system is usually started in two cases: when the engine overheats (this manifests itself primarily in the summer) and when the stove stops heating in winter. In the first case, the reason lies in the radiator tubes overgrown with dirt on the outside and clogged on the inside. In the second case, the problem is that the heater radiator tubes are clogged with deposits. Therefore, during a scheduled fluid change and when replacing cooling system components, do not miss the opportunity to thoroughly rinse all components.

Tell us what cooling system malfunctions you have encountered. And I wish you a hot heater in winter and good cooling in summer.

Internal combustion engine (ICE) of each vehicle experiences significant loads during operation. To ensure it correct operation and the safety of individual mechanisms and their parts, an important point is sufficient cooling of the motor.

There are two main types of internal combustion engine cooling systems: air and liquid. Air type in modern automotive industry it is used only in sports cars, as an addition to liquid, since the benefit of air flow alone to ensure the normal operating temperature of the unit is negligible.

The first vehicles of the automaker ZAZ were equipped exclusively with air cooling. Despite various engineering ideas, the Zaporozhtsev engine in hot weather summer days often overheated.

General picture of the cooling system

Regardless of what type of engine is installed in the car and what brand of car, the cooling system has a generally similar design. Ensuring normal operating temperature power unit is achieved by circulating coolant through the channels of the system. Thus, each internal combustion engine unit is cooled in equally regardless of temperature load.

The hydraulic cooling system can also be of several varieties:

Thermosiphon- circulation is carried out due to the difference in density of hot and cold liquid. Thus, cooled antifreeze displaces hot liquid from the power unit, sending it into the radiator channels.
Forced- coolant circulation occurs thanks to the pump.
Combined- heat is removed from most of the engine by forced means, and individual areas are cooled by a thermosiphon method.

The forced system is perhaps the most effective and is used in most modern passenger cars.

Essential elements

The engine cooling system contains the following elements:

Cooling jacket or “water jacket”. It is a system of channels passing through the cylinder block.
A cooling radiator is a device for cooling the liquid itself. Consists of channels of curved pipes and metal fins for better heat transfer. Cooling occurs both due to the counter flow of air and an internal fan.
Fan. An element of the cooling system designed to enhance air flow. On modern cars it turns on only when the temperature sensor is triggered, when the radiator is unable to fully cool the liquid with the oncoming air flow. In older car models, the fan runs constantly. Rotation is transmitted to it from the crankshaft through a belt drive.
Pump or pump. Provides circulation of coolant through the system channels. It is driven by a belt or gear drive from the crankshaft. Usually, powerful engines with direct fuel injection are equipped with an additional pump.
Thermostat. The most important detail cooling systems that control circulation through a large cooling circle. The main task is to ensure normal temperature conditions during vehicle operation. Usually installed at the junction of the inlet pipe and the cooling jacket.
The expansion tank is a container necessary to collect excess coolant that occurs during its heating.
Heating radiator or stove. Its design is similar to a cooling radiator in a smaller size. However, it is used exclusively for heating the car interior in winter period and direct role in engine cooling does not play.

Circles of circulation

The cooling system in a car has two circulation circles: large and small. The small one is considered the main one, since when the unit is started, coolant immediately begins to circulate through it. In the operation of the small circle, only the channels of the cylinder block, the pump, and the interior heating radiator are involved. Circulation takes place in a small circle until the internal combustion engine reaches normal operating temperature, after which the thermostat activates and opens the large circle. Thanks to this system, engine warm-up is significantly reduced, and winter time the system does not so much cool the unit as maintain its normal temperature regime.

The operation of a large circle involves a fan, a cooling radiator, intake and exhaust channels, thermostat, expansion barrel, as well as those elements that take part in the functioning of the small circle. The outer circle, also known as the large circle, begins to work when the temperature of the coolant reaches 80-90 o C, and ensures its cooling.

How the system works

In general, the operation of the system is quite simple. A powered hydraulic pump circulates coolant through the cylinder block jacket. The circulation speed depends on the number of revolutions of the internal combustion engine crankshaft.

Antifreeze passing through the channels in the cylinder block removes excess heat from the unit and enters back into the receiving compartment of the pump, bypassing the thermostat. When the coolant temperature reaches 80-90 o C, the thermostat opens a large circulation circle, blocking the small one. Thus, the liquid after the cylinder block is directed to the cooling radiator, where its temperature is reduced due to the oncoming air flow and the fan. Next, the process is repeated.

Possible problems and troubleshooting

Despite the simplicity of the design, the cooling system of the power unit can fail during vehicle operation. In this regard, the engine will operate at elevated temperatures, which will significantly reduce the service life of its parts. Causes incorrect operation cooling can be completely different.

Thermostat wear

Most often, problems in the system are associated with the valve that switches the circulation circles, also known as the thermostat. If a part jams in one position or the valve does not close the channels of the circulation circles tightly, warming up the engine may take much longer or, conversely, the unit will begin to overheat severely without sufficient cooling.

Thermostat operating principle

As a rule, thermostat failure is associated with a violation of its integrity. The basis of the valve is thermal wax, which, when heated, expands and compresses the membrane, opening a large circulation circle. If the wax leaks out of the part for any reason, the valve will stop functioning and the antifreeze will not be able to fully cool. Wear may also be caused by untimely replacement coolant or its low quality. Corrosion of the thermostat spring causes the part to jam in the open or, less commonly, closed position. In both cases the engine will not be able to operate normally. temperature range- the liquid will either be constantly cooled, even when there is no need for it, or, on the contrary, it will be hot all the time.

Determining wear is quite simple and can be done in two ways. The easiest way to check is with a non-removable method. To do this, immediately after starting the engine, touch the radiator inlet pipe. If it becomes warm almost immediately after starting the engine, this indicates that the thermostat is stuck in the open position. Conversely, when the hose remains cold even if the temperature indicator is at its peak, this indicates an inability of the thermostat to open.

You can more accurately verify that the reason for the incorrect operation of the cooling system lies precisely in the malfunction of the thermostat by dismantling it. The removed valve is placed in a container of water and heated. When the water temperature reaches 90 o C, a working valve must work - the thermostat rod will move. If this does not happen, you can confidently consider the part to be faulty.

A failed thermostat cannot be repaired, but requires mandatory replacement. Its cost for most cars rarely exceeds 1000 rubles. It is quite possible to replace the valve yourself, without visiting a car service center.

Hydraulic pump problems

One of the reasons for overheating of the car’s power unit may be a malfunction of the cooling system pump. Most often the problem is that the hydraulic pump drive belt has broken or its tension is too weak. In this case, the pump will stop pumping antifreeze, or will not do it fully. Checking this is quite simple, you just need to bring the engine in and observe the behavior drive belt. If it works with slippage, the tension should be increased or the belt should be completely replaced with a new one. Most often this solves the problem.

Situations arise when the problem lies in the pump itself: wear of the impeller, bearing, and sometimes even a crack in the shaft. Among other things, the joints connecting the pipes to the pump may not be sealed, and pump generated pressure will cause coolant to leak. Diagnosing a leak is quite simple; you need to place sheets of white paper on the floor under the engine for several hours. Even if it shows small spots blue or greenish color, this indicates wear of the pump gaskets.

You can check the functionality of the pump itself by holding the upper radiator hose with your fingers for a few seconds while the unit is running. A working pump will create strong pressure and after releasing the hose, you will feel as if the liquid is quickly running along the line. It is also worth remembering that increased noise internal combustion engine operation and play in the pump pulley indicate bearing wear. Usually its wear is associated with fluid seeping through the seal, which washes the lubricant from the bearing.

The coolant pump, unlike the thermostat, can be partially replaced, but often car owners prefer to completely change the mechanism.

Pump replacement:

First of all, it is necessary to disconnect the vehicle mass from the battery, and the piston of the first cylinder must be in the upper dead center. Dismantle the belt tension roller and remove the camshaft pulley.
Next, you should drain the coolant from the bottom plug in the radiator.
After unscrewing the pump's mounting bolts, it must be disconnected from the cylinder block.
By visually assessing the removed mechanism, it is important to determine its wear. If the impeller, oil seal and drive gear are damaged, it is better to replace the pump completely.
The new mechanism must be installed with a new gasket, since the old one may have even minor damage, which will subsequently lead to a coolant leak. The pump is installed so that the number indicated on the body faces up.
Further assembly is carried out in the reverse order of disassembly. It is better to fill in new coolant, but you can also use the existing one if its resource has not yet been exhausted.

Radiator and fan problems

Insufficient engine cooling may be due to problems with the radiator and fan. First of all, it is worth remembering that a radiator that is too clogged with dust and insects is unable to be fully cooled either by the oncoming air flow or by the fan. Often cleaning it solves the cooling problem.

The design of a “classic” engine cooling radiator. In many modern engines, the coolant is not poured through the radiator neck, but into the expansion tank

And yet, more serious situations are also possible - radiator cracks, which can occur both during an accident and as a result of corrosion. In most cases, the radiator can be restored. Brass and copper are repaired using soldering, and aluminum with special sealants.

Before soldering, the damaged areas are thoroughly cleaned with emery cloth until a metallic shine appears. Afterwards, the crack is treated with soldering flux and a uniform layer of solder is applied using a powerful soldering iron (see video).

It is not possible to solder an aluminum radiator, however, special sealants are offered for repairing them, or you can use regular “cold welding”. Before starting to seal cracks, it is important to thoroughly clean the defective areas. The adhesive mass is well kneaded until smooth and applied to the problem area. It is worth remembering that the car can only be used the next day after repair - epoxy glue takes quite a long time to dry.

As for the cooling fan, its failure may be due to a break in the electrical wiring or a disruption of the drive from the crankshaft if the rotation is transmitted from the power unit.

In the first case, it is worth visually assessing the condition of the wires going to the fan motor; if a break is detected, you need to reconnect the damaged contacts. If the condition of the wires is normal, but the fan still does not work, the motor itself or the sensor responsible for its timely activation may have broken down. In this case, it is better to contact a car service center, where they will determine the reason why the fan does not turn on. If there are problems with the sensor, the airflow may either continuously or not turn on at all.

In cars where the fan begins to rotate when transmitting torque from the engine, the breakdown is most often associated with a broken drive belt. Replacing it is quite simple: you need to loosen the pulley tension and install a new belt.

Learn more about the design and repair of a cooling fan.

Flushing the cooling system and replacing the fluid

The hydraulic cooling system requires timely flushing of the lines, otherwise corrosion, salt deposits, and other contaminants may form on the walls of the channels.

Causes of clogging

The main reason for system contamination is the use of ordinary water as a coolant. Running water from the tap contains a large amount of salts, which creates scale and rust on the walls of the lines. The use of distilled water is less harmful, but it is not able to provide complete cooling during the hot period. In addition, in winter, at sub-zero temperatures, water will freeze and, expanding, can damage the integrity of individual parts and connections.

Application high-quality antifreeze or antifreeze is more appropriate. Special cooling substances have a significant resource and do not freeze even at very high temperatures. low temperatures. However, the additives contained in the composition begin to precipitate over time, clogging the system.

Washing process

First of all, before flushing, all coolant is drained through the drain plug on the radiator, located at the very bottom, and on the cylinder block to remove any residue.

It is important to remember that draining the fluid should only be done on a cold engine!

After draining, the plugs are tightened again and water is poured into the expansion tank. citric acid or better yet, a special cleaning fluid.

Next, the engine starts and idles for 15 minutes. In this case, care should be taken to open a large circulation circle. Also, when washing, do not forget that cabin stove should operate in maximum heating mode. When the unit has cooled down, the liquid can be drained by opening the radiator and cylinder block plugs. It is recommended to repeat this process until clean liquid without visible contaminants flows out when draining.

Filling with new coolant can be done immediately after flushing is completed. Pour antifreeze or antifreeze into the expansion barrel carefully and slowly to avoid the formation air jams in system.

When the tank is almost completely filled, you need to close it and start the internal combustion engine for a few minutes so that the liquid spreads evenly throughout the system. Next, after turning off the unit, antifreeze or antifreeze is added to the level between the maximum and minimum marks on the barrel.

In conclusion, it is worth saying that fundamental difference There is no use of antifreeze or antifreeze. However, in many countries around the world, car manufacturers have long stopped using antifreeze, since its effectiveness is somewhat lower. Modern antifreeze is made using latest technologies and to a greater extent protects the engine from overheating and the cooling system lines from contamination.

» Car engine cooling system, principle of operation, malfunctions

The automotive engine cooling system needs to be checked periodically. Many significant car malfunctions are caused by engine overheating. Combustion temperature value air-fuel mixture reaches several thousand degrees. Accordingly, a large amount of heat is generated, which must be removed so as not to overheat the motor, which can lead to serious problems.

Engine overheating problems

Ineffective operation of the cooling system can lead to exceeding the operating temperature of the pistons, reducing thermal gap between the piston and the cylinder walls down to zero. This causes the piston body to touch the cylinder walls, causing scratches and scoring. Also when overheating engine oil loses its lubricating properties, the oil film is disrupted. The engine may seize due to this.

Overheating of the cooling system and engine is accompanied by different expansion of the cylinder head, block and mounting bolts due to different materials, which leads to curvature of the mounting surface of the head, pulling out of the bolts, and cracking of the valve seats. It is clear that after similar changes Repairing an engine is difficult and sometimes impossible.

Engine coolants

A properly functioning cooling system should prevent overheating, but for the system to function properly, it requires the use of high-quality coolant. Antifreeze at low temperatures technical fluids are called antifreeze (from the English antifreeze). Today, antifreezes are produced, as a rule, based on monoethylene glycol, which is a thick liquid with a boiling point of about 200 °C.

The purpose of the coolant is not only to cool the engine, but also to transfer heat to heat the cabin and heat the fuel in winter. The vehicle coolant must meet the following requirements:

do not freeze throughout the entire range of engine operating temperatures;
have high values of heat capacity and thermal conductivity;
do not form foam;
do not corrode the plastic and rubber of the pipes;
do not damage the seals;
lubricate and protect cooling system and engine parts from corrosion;
do not deposit scale and other deposits of various kinds on the internal walls of the working surface of the cooling system

It is customary to distinguish between the concepts of “antifreeze” and “antifreeze”. It is believed that antifreeze is a finished product, and antifreeze is a concentrate. Although, of course, the composition is the same, just with a different name.

Automotive antifreezes are painted in noticeable, bright colors:

green,
orange, or shades of red
cyan (blue),
turquoise

This is done for the sake of safety, because antifreeze is very poisonous. As the liquid is used, it loses the necessary properties - the lubricating and anti-corrosion parameters are gradually lost, and the tendency to form foam increases.

Important: The service life of antifreeze is between 2–7 years.

After starting the car, together with the engine, the cooling system pump (also called a pump, water pump) begins to rotate, unless of course electronic connection pumps. The pump is driven into rotation by the timing belt or by means of a belt attachments- it depends on the design of the engine of a particular model. The water pump impeller rotates to pump coolant through the system. To quickly reach operating temperature, a small circuit is provided in the car’s cooling system, that is, liquid circulates only inside the engine, the thermostat is closed, and antifreeze is not supplied to the radiator.

As soon as the engine warms up to a certain temperature, the thermostat opens, passing antifreeze or antifreeze through the large cooling system circuit. The fluid passes through the radiator where it cools. The radiator is cooled by outside air, freely passing through the radiator grille, or forcedly blown by a fan. After cooling in the radiator, the antifreeze is supplied to the engine cooling system, picks up some of its heat and is again sent in a large circle.

The radiator is equipped with a fan switch sensor, which, when a certain temperature is reached, turns on forced airflow or changes the fan speed. When the rotation speed changes, the amount of air passing through the radiator cells changes, and the cooling efficiency of the liquid is adjusted accordingly. As the liquid in the radiator cools, the fan turns off. If the antifreeze becomes colder than the response value, the large circuit is closed and circulation occurs again in a small circle.

Some cooling systems use several temperature sensors, the location of the sensors is:

on the radiator of the cooling system,
on the cylinder head,
directly on the thermostat housing.

This operating scheme is basic, but manufacturers are constantly improving cooling systems. Some cars do not have sensors for turning on the fan, which is triggered by a signal from the engine control unit depending on the readings of the temperature sensor. Thermostats can also be controlled by the “brains” of the motor, opening and switching circuits not automatically, but by a control signal. In some models, the pipes leading to the heater are equipped with solenoid valves regulating the supply of coolant to the heater radiator. If malfunctioning, these valves can cause cooling system problems.

One of the improvements in the cooling system is an electronically controlled pump, or rather a pump drive, which, depending on the engine temperature, turns the pump on or off, thereby facilitating more efficient thermal regulation and faster warming up of the vehicle’s cooling system.

Diagnosis of cooling system faults

Engine overheating- this is an operating mode that is caused by boiling of the coolant. However, overheating is not the only problem. Operating the motor at a constantly low temperature is also harmful, since the operating temperature must be maintained at a certain level. Cold engine consumes more fuel, does not operate at the best efficiency, is subject to increased loads because of increased viscosity lubrication systems.

Failure of the thermostat, fan, thermal relay and sensors interferes with the proper functioning of the cooling system. If signs of temperature violations are detected in time and fatal malfunctions do not occur, then repairs most likely will not be too long and expensive. Therefore, it is recommended that all specialists monitor temperature conditions motor operation.

Diagnosis of problems and malfunctions should begin with a cold engine. First you need to check the correct articulation of the pipes and pipes, the assembly of other elements of the cooling system, especially if the car was repaired shortly before the problem occurred. This may sound funny, but there are many examples where cooling does not work correctly due to assembly errors.

Some of these cases:

after reassembling the engine, the crankcase ventilation hose is connected to the coolant expansion tank;
a “non-original” cooling fan is installed, due to the incorrect position of the blades of which the air is directed in the wrong direction;
the fan impeller blades rotate freely on the shaft;
Sensor or fan connectors are oxidized, loose or damaged.

It would also be useful to conduct an external inspection of the radiator; perhaps it is dirty or the honeycombs are clogged. Sometimes too tight engine protection, blocking the path of air from below, can have a negative effect. A minor accident that only leads to a breakdown of the bumper can lead to overheating - special guides are formed in the bumper through which air passes to the engine ( VW Passat B5).

After visual inspection cooling system, you need to check the level of antifreeze, the serviceability of the valves of the radiator cap or tank, the tightness of hoses and pipes. It makes sense to decide what is poured into the system - antifreeze or just water.

If the first steps helped to identify any malfunctions in the engine cooling system, they must be eliminated or taken into account when making a “diagnosis”. When adding fluid, you must not forget that not every car can simply add antifreeze and that’s it. For example, in some BMWs, when adding coolant, you should turn on the ignition and set the heater adjustment to maximum in order for the heater solenoid valves to open.

If you suspect air has entered the cooling system, you need to unscrew special plugs designed to release air. They are usually located in the very high point systems. If your car has an expansion tank, you can check if the fluid is circulating. If, during systematic warming up of the engine, air flows into the passenger compartment from the heater air ducts cold air, this is the first sign of an air “bubble” in the system.

If the thermostat is known to be working, after warming up the radiator, its lower and upper hoses should have approximately the same temperature. A large temperature difference between these pipes indicates poor circulation of antifreeze through the radiator.

After a certain period of time after opening the thermostat, as the response temperature is reached, the radiator cooling fan should turn on. If the system does not contain an electric fan, you should check the circuit sensor electromagnetic coupling or the functioning of the viscous coupling. A sign of a malfunction of the viscous coupling can be considered the ability to stop and hold the fan by hand. Be sure to be careful! Try to stop it with a soft object to avoid the possibility of hand injury or damage to the impeller. The air flow should properly be directed towards the engine.

Cooling system pressure the vehicle temperature increases in proportion to the engine warming up and gradually decreases as it cools down. If the upper pipe leading to the radiator swells as the engine speed increases, then it makes sense to make sure that some of the gases from the engine do not enter the system. This happens if cylinder head gasket has broken between the cooling channel and the cylinder or if the cylinder head itself is damaged. One of the signs of this problem is an oil film in the expansion tank. Gases are also indicated by bubbles appearing in antifreeze while the engine is running.

There are many examples of how a malfunctioning cooling system led to serious problems for the owner, including engine replacement. The main conclusion should be made one thing - there are no trifles or unimportant malfunctions in the operation of the car. You need to notice all the changes, analyze them, make correct conclusions. If the car owner does not understand this, the car should be regularly serviced by good specialists.

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