• radiator
• expansion tank
• coolant pump
• fan
• thermostat
• supply lines

Engine cooling system allows the engine to warm up quickly and protects it from overheating, maintaining the optimum temperature. The radiator is connected by a tube to the expansion tank. The radiator neck is closed by a plug equipped with a safety valve that discharges excess heated fluid from the radiator into the expansion tank, as well as an inlet valve that allows the fluid to return to the radiator if the engine temperature drops.

At the stopper in the “closed” position, the protrusions should be adjacent to the tank. The fluid level is checked on the expansion tank. If the liquid level drops below the “LOW” mark, it is necessary to add it so much that the level rises to the “FULL” mark.

The coolant pump, mounted on the front of the engine housing, is driven by the timing belt.

Rice. Components of the cooling system in the car (radiator, expansion tank, fan): 1 - radiator, 2 - radiator cap, 3,4,5 - fasteners, 6 - fan casing, 7 - fan impeller, 8 - fan motor, 9 - expansion tank, 10 - a tube connecting the radiator to the expansion tank

Rice. Components of the cooling system (liquid supply lines): 1 - thermostat cover, 2 - cover gasket, 3 - thermostat, 4 - radiator inlet hose, 5 - radiator outlet hose, 6 - engine inlet hose, 7 - engine intake pipe, 8 - gasket, 9 - inlet hose of the radiator of the heating device, 10 - outlet inlet hose of the radiator of the heating device.

The main elements of a liquid cooling system and their purpose

In liquid cooling systems for piston engines, it circulates in a closed circuit, and heat is dissipated into the environment using an air-blown radiator.

The main parts of the liquid cooling system:

• Cooling jacket(1) is a cavity enveloping the parts of the engine that require cooling. The liquid circulating through the cooling jacket takes heat from them and transfers it to the radiator.
• Coolant pump, or pump(5) - ensures the circulation of liquid through the cooling circuit. Some engines, such as mini-tractors, may use a thermosyphon cooling system - that is, a system with natural circulation of the coolant, in which this pump is absent. It can be driven either through a belt drive from the motor shaft or from a separate electric motor.
• Thermostat(2) - designed to maintain the operating temperature of the engine. The thermostat redirects the coolant in a small circle - bypassing the radiator if the temperature has not reached the operating temperature.
• Radiator cooling system (3) usually has a lamellar structure, which is blown from the outside by a stream of air. Usually, aluminum is used to make a radiator, but other materials that conduct heat well can also be used. For example, copper is often used to make oil coolers.
• Fan(4) is necessary to supply additional air to blow the radiator, including during stops and when driving at low speed. In older cars, the fan was driven from the engine shaft by a belt drive, but in modern cars, with the exception of large trucks, it is powered by an electric motor.
• Expansion tank contains a supply of coolant. The expansion tank is vented to the atmosphere through a valve that maintains excess coolant pressure during operation, which allows the engine to operate at a higher temperature, preventing the coolant from boiling. In older car models, there were often no expansion tanks and the coolant supply was in the upper tank of the radiator. With the spread of antifreeze based on ethylene glycol, the use of an expansion tank has become mandatory, because. when heated, a special liquid tends to expand.

The temperature of gases in the cylinders of a running engine reaches 1800-2000 degrees. Only part of the heat released in this case is converted into useful work. The rest is discharged into the environment by the cooling system, lubrication system and external surfaces of the engine.

An excessive increase in engine temperature leads to burnout of the lubricant, a violation of the normal gaps between its parts, which results in a sharp increase in their wear. There is a danger of seizing and jamming. Overheating of the engine causes a decrease in the filling ratio of the cylinders, and in gasoline engines it also causes detonation combustion of the working mixture.

A large decrease in the temperature of a running engine is also undesirable. In a supercooled engine, power is reduced due to heat loss; the viscosity of the lubricant increases, which increases friction; part of the combustible mixture condenses, washing away the lubricant from the cylinder walls, thereby increasing the wear of parts. As a result of the formation of sulfur and sulfur compounds, the cylinder walls are subject to corrosion.

The cooling system is designed to maintain the most favorable thermal conditions. Cooling systems are divided into air and liquid. Air is now extremely rare on cars. Liquid cooling systems can be open or closed. Open systems are systems that communicate with the environment through a vapor tube. Closed systems are separated from the environment, and therefore the pressure of the coolant in them is higher. As you know, the higher the pressure, the higher the boiling point of the liquid. Therefore, closed systems allow the coolant to be heated to higher temperatures (up to 110-120 degrees).

According to the method of circulation of the liquid, the cooling system can be:

• forced, in which circulation is provided by a pump located on the engine;
• thermosyphon, in which the circulation of the liquid occurs due to the difference in the density of the liquid heated by the engine parts and cooled in the radiator. During engine operation, the liquid in the cooling jacket heats up and rises to its upper part, from where it enters the upper radiator tank through the pipe. In the radiator, the liquid gives off heat to the air, its density increases, it goes down and returns to the cooling system through the lower tank.
• combined, in which the most heated parts (cylinder heads) are forcibly cooled, and cylinder blocks - according to the thermosiphon principle.

Cooling system device

The most widely used in automotive internal combustion engines are closed liquid systems with forced circulation of the coolant (coolant). Such systems include: a cooling jacket for the block and cylinder heads, a radiator, a coolant pump, a fan, a thermostat, pipes, hoses, and an expansion tank. The heater core is also included in the cooling system.

The coolant in the cooling jacket, heated by the heat generated in the engine cylinder, enters the radiator, cools in it and returns to the cooling jacket. Forced circulation of liquid in the system is provided by a pump, and its enhanced cooling is due to intensive air blowing of the radiator. The degree of cooling is controlled by a thermostat and by automatically switching the fan on or off. Liquid is poured into the cooling system through the radiator neck or expansion tank. The capacity of the cooling system of a passenger car, depending on the engine size, is from 6 to 12 liters. The coolant is drained through the plugs, usually located in the cylinder block and the lower radiator tank.

Radiator transfers heat from the coolant to the air. It consists of a core, upper and lower tanks and fasteners. For the manufacture of radiators, copper, aluminum and alloys based on them are used. Depending on the design of the core, radiators are tubular, plate and honeycomb. The most widely used tubular radiators. The core of such radiators consists of vertical tubes of oval or round section, passing through a series of thin horizontal plates and soldered to the upper and lower radiator tanks. The presence of plates improves heat transfer and increases the rigidity of the radiator. Tubes of oval (flat) section are preferable to round ones, since their cooling surface is larger; in addition, in the event of freezing of the coolant in the radiator, the flat tubes do not break, but only change the shape of the cross section.

In plate radiators, the core is designed so that the coolant circulates in the 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 reservoirs. The air cooling the radiator is sucked by the fan through the passages between the soldered plates. To increase the cooling surface, the plates are usually made wavy. Lamellar radiators have a larger cooling surface than tubular ones, but due to a number of disadvantages (rapid contamination, a large number of soldered seams, the need for more thorough maintenance) they are used less often.

In the core of the honeycomb radiator, air passes through horizontal, circular tubes, which are washed from the outside by the 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 honeycomb radiators is a larger cooling surface than in other types of radiators.

A filler neck closed with a stopper and a branch pipe for connecting a flexible hose that supplies coolant to the radiator are soldered into the upper tank. On the side, the filler neck has an opening for a steam outlet tube. The branch pipe of the discharge flexible hose is soldered into the lower tank. The hoses are attached to the branch pipes with clamps. Such a connection allows a relative displacement of the engine and radiator. The neck is hermetically sealed by a plug that isolates the cooling system from the environment. It consists of a body, a steam (outlet) valve, an air (inlet) valve and a locking spring. In the case of boiling liquid in the cooling system, the vapor pressure in the radiator increases. If a certain value is exceeded, the steam valve opens and steam exits through the steam outlet pipe. After the engine stops, the liquid cools, the vapor condenses and a vacuum is created in the cooling system. This creates a risk of squeezing the radiator tubes. To prevent this phenomenon, an air valve is used, which, when opened, lets air into the radiator.

To compensate for changes in coolant volume due to temperature changes in the system, a expansion tank. Some radiators do not have a filler neck, and the system is filled with coolant through the expansion tank. In this case, the steam and air valves are located in its plug. The marks applied on the expansion tank allow you to control the level of coolant in the cooling system. Level check is carried out on a cold engine.

coolant pump provides its forced circulation in the cooling system. The centrifugal type pump is installed in front of the cylinder block and consists of a housing, a shaft with an impeller and an oil seal. The casing and the impeller of the pumps are cast from magnesium and aluminum alloys, the impeller, in addition, from plastics. The pump is driven by a belt from the engine crankshaft pulley. Under the action of the centrifugal force that occurs during the rotation of the impeller, the coolant from the lower radiator tank enters the center of the pump housing and is thrown to its outer walls. From the hole in the wall of the pump housing, the coolant enters the hole in the cooling jacket of the cylinder block. The gasket prevents the coolant from flowing out between the pump housing and the block, and an oil seal at the shaft exit.

To enhance the flow of air passing through the core of the radiator, a fan. It is mounted either on the same shaft with the coolant pump, or separately. It consists of an impeller with blades screwed to the hub. To improve the airflow of the engine and radiator, a guide casing can be installed on the latter. The fan drive can be carried out in several ways. The simplest is mechanical, when the fan is rigidly fixed on the same axis as the coolant pump. In this case, the fan is constantly on, which leads to excessive power consumption of the engine. In addition, the fan operates even in non-optimal modes, for example, immediately after starting the engine. Therefore, in modern engines, such a connection is not used, and the fan is connected to the drive through a coupling. The design of the clutch can be different - electromagnetic, friction, hydraulic, viscous (viscous coupling), but all of them provide automatic switching on of the fan when a certain coolant temperature is reached. This inclusion provides a temperature sensor. Moreover, the use of a fluid coupling and a viscous coupling makes it possible not only to automatically turn the fan on and off, but also to smoothly change its rotational speed depending on the temperature.

The fan can be driven not from the engine crankshaft, but by a separate electric motor. This connection is used most often, as it allows quite simply automatic control of the on and off moments using a thermistor sensor (its electrical resistance changes depending on heating). If the operation of the cooling system is controlled by the engine controller, then it becomes possible to change the speed. In addition, the fan "reacts" to the driving modes. For example, it turns on at idle when driving in traffic jams to prevent overheating and turns off when driving at high speed in the countryside, when the radiator's natural air flow is enough to cool it.

During the engine start-up period, in order to reduce wear, it is necessary to warm it up to operating temperature faster and maintain this temperature during further operation. To accelerate the warm-up of the engine and maintain its optimum temperature, it is used thermostat. The thermostat is installed in the cylinder head cooling jacket on the path of fluid circulation from the jacket to the upper radiator tank. In cooling systems, thermostats with liquid and solid fillers are used.

The liquid filled thermostat consists of a body, a corrugated brass cylinder, a stem and a double valve. A liquid is poured inside a corrugated brass cylinder, the boiling point of which is 70-75 degrees. When the engine is not warmed up, the thermostat valve is closed and circulation occurs in a small circle: coolant pump - cooling jacket - thermostat - pump.

When the coolant is heated to 70-75 degrees in the corrugated cylinder of the thermostat, the liquid begins to evaporate, the pressure rises, the cylinder, expanding, moves the stem and, raising the valve, opens the way for the liquid through the radiator. At a liquid temperature in the cooling system of 90 degrees, the thermostat valve opens completely, at the same time, with a beveled edge, it closes the liquid outlet to a small circle, and circulation occurs in a large circle: pump - cooling jacket - thermostat - upper radiator tank - core - lower radiator tank - pump.

The thermostat with a solid filler consists of a housing inside which is placed a copper cylinder filled with a mass consisting of copper powder mixed with ceresin. The top of the bottle is closed with a lid. Between the cylinder and the cover there is a diaphragm, on top of which a rod is installed that acts on the valve. In a cold engine, the mass in the cylinder is in a solid state, and the thermostat valve is closed by a spring. When the engine warms up, the mass in the cylinder begins to melt, its volume increases and it presses on the diaphragm and stem, opening the valve.

Coolant temperature control is carried out according to the temperature gauge and using the engine overheating warning light on the instrument panel. The signal lamp and pointer are controlled by sensors screwed into the upper radiator tank and into the cylinder head cooling jacket.

Water (in obsolete engine designs) or antifreeze can be used as a coolant. The quality of the coolant used for the engine cooling system is no less important for the durability and reliability of its operation than the quality of fuel and lubricants.

antifreeze- coolants for the car cooling system that do not freeze at negative temperatures. Even if the ambient temperature is below the minimum operating temperature of the antifreeze, it will not turn into ice, but into a loose mass. With a further decrease in temperature, this mass will harden without increasing in volume and without damaging the engine. The basis of antifreeze is an aqueous solution of ethylene glycol or propylene glycol. Propylene glycol base is used less often. Its main difference is harmlessness to humans and the environment, but also a higher price with the same consumer qualities. Ethylene glycol is aggressive to engine materials, so additives are added to it. There can be up to a dozen of them in total - anti-corrosion, anti-foaming, stabilizing. It is the set of additives that determines the quality and scope of antifreeze. According to the type of additives, all antifreezes are divided into three large groups: inorganic, organic and hybrid.

Inorganic (or silicate) - the most "ancient" liquids, in which silicates, phosphates, borates, nitrites, amines, nitrates and their combinations are used as corrosion inhibitors. This group of antifreezes also includes Tosol, which is widespread in our country (although many mistakenly consider it a special type of coolant). Their main disadvantage is a short service life due to the rapid destruction of additives. The components of the additives that have become unusable form deposits in the cooling system, worsening heat transfer. It is also possible the formation of silicate gels (clots) in the coolant.

Most modern organic (or carboxylate) antifreezes use additives based on salts of carboxylic acids. Such antifreezes, firstly, form a much thinner protective film on the surfaces of the cooling system, and secondly, inhibitors act only in places where corrosion occurs. Consequently, additives are consumed much more slowly, thereby significantly increasing the life of antifreeze.

An intermediate position between organic and inorganic antifreezes is occupied by hybrid ones. Their additive package mainly includes salts of carboxylic acids, but also a small proportion of silicates or phosphates.

Antifreezes are available either as concentrates or as ready-to-use liquids. The concentrate must be diluted with distilled water before use. The proportion is determined by the required minimum freezing point of the antifreeze. The basis of antifreeze is colorless, so manufacturers paint them in different colors using dyes. This is done to make it easier to control the level of antifreeze and to warn of the toxicity of fluids. Color matching is not always evidence of antifreeze compatibility.

In modern engines, the engine cooling system can be used to cool the exhaust gases in the exhaust gas recirculation (EGR) system, cool the oil in an automatic transmission, and cool the turbocharger. Some direct injection turbocharged engines have a dual circuit cooling system. One circuit is designed to cool the cylinder head, the other - the cylinder block. In the cylinder head cooling circuit, the temperature is maintained 15-20 degrees lower. This allows you to improve the filling of the combustion chambers and the mixture formation process, as well as reduce the risk of detonation. The circulation of liquid in each of the circuits is regulated by a separate thermostat.

The main malfunctions of the cooling system

External signs of malfunctions of the cooling system is overheating or hypothermia of the engine. Overheating of the engine is possible as a result of the following reasons: insufficient amount of coolant, weak tension or breakage of the coolant pump belt, failure to turn on the clutch or fan motor, sticking of the thermostat in the closed position, large scale deposits, severe contamination of the outer surface of the radiator, malfunction of the outlet (steam) plug valve radiator or expansion tank, coolant pump malfunction.

A thermostat stuck closed stops fluid from flowing through the radiator. In this case, the engine overheats, and the radiator remains cold. Insufficient amount of coolant is possible in case of its leakage or boiling away. If the coolant level has dropped as a result of boiling, add distilled water, if the liquid has leaked out, add antifreeze. It is possible to open the cap of the radiator or expansion tank only when the coolant has cooled down sufficiently (10-15 minutes after the engine has stopped). Otherwise, pressurized coolant may splash out and cause burns. Liquid leakage occurs through leaks in the pipe connections, cracks in the radiator, expansion tank and cooling jacket, if the coolant pump seal, radiator cap is damaged, or the cylinder head gasket is damaged. When operating a car, it is necessary to monitor not only the level, but also the condition of antifreeze. If its color becomes reddish-brown, then the parts of the system are already corroding. Such antifreeze must be replaced immediately.

Engine hypothermia can occur due to the thermostat sticking in the open position, as well as in the absence of insulating covers in winter. If the closed cooling system is not hermetic, then increased pressure is not created in it and the engine does not warm up to operating temperature. And since the engine does not warm up, the ECU constantly enriches the mixture. Thus, a leaky cooling system increases fuel consumption. The systematic operation of the engine on an enriched mixture leads to oil dilution, increased carbon formation, and rapid failure of the catalytic converter.

The internal combustion engine (ICE) of each vehicle experiences significant loads during operation. To ensure its 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. The air type in modern automotive industry is used only in sports cars, as an addition to the liquid type, 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 Zaporozhets engines often overheated on hot summer days.

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 structure. Ensuring the normal operating temperature of the power unit is achieved by circulating the coolant through the channels of the system. Thus, each internal combustion engine unit is cooled equally regardless of the 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 liquids. Thus, the cooled antifreeze displaces hot liquid from the power unit, sending it to the radiator channels.
• Forced- the circulation of the coolant is due to the pump.
• Combined- heat is removed from most of the engine by force, and some sections are cooled by a thermosyphon 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 in the cylinder block.
• Cooling radiator - a device for cooling the liquid itself. Consists of curved tube channels and metal fins for better heat dissipation. Cooling occurs both due to the oncoming air flow and the internal fan.
• Fan. Element of the cooling system, designed to enhance the flow of air. On modern cars, it turns on only when the temperature sensor is triggered, when the radiator is unable to fully cool the liquid with an oncoming air flow. In older models of cars, 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 channels of the system. It is driven by a belt or gear drive from the crankshaft. As a rule, powerful engines with direct fuel injection are equipped with an additional pump.
• Thermostat. The most important part of the cooling system that controls the circulation in a large cooling circle. The main task is to ensure normal temperature conditions during the operation of the vehicle. Usually installed at the junction of the inlet pipe and the cooling jacket.
• Expansion tank - a container necessary to collect excess coolant that occurs during its heating.
• Heating radiator or stove. In its design, it is similar to a cooling radiator in a smaller size. However, it is used exclusively for heating the car interior in winter and does not play a direct role in cooling the internal combustion engine.

Circles of circulation

The cooling system in the car has two circles of circulation: large and small. It is the small one that is considered the main one, since when the unit is started, coolant immediately begins to circulate through it. In the work of the small circle, only the channels of the cylinder block, the pump, as well as the interior heating radiator are involved. The circulation takes place in a small circle until the internal combustion engine reaches normal operating temperature, after which the thermostat trips and opens a large circle. Thanks to such a system, engine warm-up is significantly reduced, and in winter, the system not only cools the unit, but maintains its normal temperature regime.

A fan, a cooling radiator, inlet and outlet channels, a thermostat, an expansion tank, as well as those elements that take part in the functioning of a small circle are involved in the work of a large circle. The outer circle, also known as the big circle, starts working when the temperature of the coolant reaches 80-90 ° C, and ensures its cooling.

How the system works

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

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

Possible problems and their solution

Despite the simplicity of the design, the cooling system of the power unit is capable of failing during the operation of the vehicle. In this regard, the engine will operate at elevated temperatures, due to which the resource of its parts will be significantly reduced. The reasons for the incorrect operation of the cooling can be completely different.

Thermostat wear

Most often, problems in the system are associated precisely with the valve that switches circulation circles, it is also a thermostat. If the part is stuck in one position or the valve closes the channels of the circulation circles loosely, it may take much longer for the engine to warm up, or vice versa, the unit will begin to overheat without sufficient cooling.

The principle of operation of the thermostat

As a rule, the breakdown of the thermostat is associated with a violation of its integrity. The basis of the valve is thermal wax, which, when heated, expands and compresses the membrane, which opens a large circle of circulation. 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. Also, the cause of wear can be an untimely replacement of the coolant or its poor quality. Corrosion of the thermostat spring causes the part to stick in the open or less commonly closed position. In both cases, the engine will not be able to operate in the normal temperature range - the fluid will either be constantly cooled, even when it is not necessary, or vice versa, 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 to make a non-removable method. To do this, immediately after starting the engine, touch the radiator inlet pipe. If it became warm almost immediately after starting the internal combustion engine, this indicates that the thermostat is stuck in the open position. Conversely, when the nozzle remains cold, even if the temperature reading is at its peak, this indicates the inability of the thermostat to open.

You can more accurately make sure 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 with water and heated. When the water temperature reaches 90 ° C, a serviceable valve must definitely work - the thermostat stem will move. If this does not happen, it is safe to assume that the part is defective.

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

Hydraulic pump problems

One of the reasons for the overheating of the power unit of the machine 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 it will not do it fully. Checking this is quite simple, you just need to bring the engine in and observe the behavior of the drive belt. If it works with overshoots, the tension should be increased or the belt should be replaced with a new one. Most often this solves the problem.

There are situations when the problem lies in the pump itself: wear of the impeller, bearing, sometimes even a crack in the shaft is possible. Among other things, the joints between the pipes and the pump may not be tight, and the pressure created by the pump will cause the coolant to leak. Diagnosing a leak is quite simple, you need to put sheets of white paper on the floor under the engine for several hours. If even small spots of blue or greenish color are visible on it, this indicates wear on the pump gaskets.

You can check the operation of the pump itself by pinching 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, it will feel like the liquid quickly ran along the line. It is also worth remembering that the increased noise of the internal combustion engine and the backlash of the pump pulley indicate bearing wear. Usually its wear is associated with the seepage of fluid through the stuffing box, which washes away the grease from the bearing.

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

Pump replacement:

1. First of all, it is necessary to disconnect the mass of the car from the battery, and the piston of the first cylinder must be at top dead center. Remove the belt tension roller and remove the camshaft pulley.
2. Next, drain the coolant from the bottom plug in the radiator.
3. Having unscrewed the fixing bolts of the pump, it must be disconnected from the cylinder block.
4. Assessing the visually 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.
5. A new mechanism must be installed with a new gasket, since the old one can even have minor damage, which will subsequently lead to a coolant leak. The pump is installed in such a way that the number indicated on the body faces up.
6. Further assembly is carried out in the reverse order of disassembly. It is better to fill in a new coolant, but you can also use the one that was, if its resource has not yet been exhausted.

Heatsink 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 heavily clogged with dust and insects is unable to fully cool both the oncoming air flow and the fan. Often cleaning it solves the problem with cooling.

The device is 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 possible - radiator cracks, which can occur both in an accident and as a result of corrosion. The radiator in most cases can be restored. Brass and copper are repaired by soldering, and aluminum with special sealants.

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

It is impossible to solder an aluminum radiator, however, special sealants are offered for their repair, or you can use the usual “cold welding”. Before starting to repair cracks, it is important to clean the defective areas well. The adhesive mass is well kneaded to a homogeneous state and applied to the problem area. It is worth remembering that you can operate the car only the next day after the repair - epoxy glue dries for a long time.

As for the cooling fan, its failure may be due to a broken electrical wiring or a violation 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 engine itself or the sensor responsible for its timely switching on may have broken. In this case, it is better to contact a car service, where they will determine the reason why the fan does not turn on. In case of problems with the sensor, the airflow may either continuously or not turn on at all.

In cars where the fan starts to rotate when torque is transmitted from the engine, the breakdown is most often associated with a broken drive belt. Its replacement is quite simple: it is necessary to loosen the pulley tension and install a new belt.

Learn more about the device and repair of the 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 cause of system contamination is the use of ordinary water as a coolant. Running water from a tap contains a large amount of salts, creates scale and rust on the walls of highways. The use of distilled water is less harmful, but it is not able to provide full cooling during the hot period. In addition, in winter, at sub-zero temperatures, the water will freeze and expanding can violate the integrity of individual parts and connections.

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

Washing process

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

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

After draining, the plugs are re-twisted and water with citric acid or, better, a special cleaning liquid is poured into the expansion tank.

Next, the engine starts and runs in idle mode for 15 minutes. In this case, it should be ensured that a large circle of circulation opens. Also, when washing, do not forget that the salon stove should work 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 a clean liquid without visible impurities flows out when draining.

Filling with new coolant can be carried out immediately after flushing. Pour antifreeze or antifreeze into the expansion barrel carefully and slowly to avoid air locks in the system.

When the tank is almost completely filled, it must be closed and the internal combustion engine run for several minutes so that the liquid spreads evenly throughout the system. Further, after turning off the unit, antifreeze or antifreeze is added to a level between the maximum and minimum marks on the barrel.

In conclusion, it should be said that there is no fundamental difference in the use of antifreeze or antifreeze. However, in many countries of the world, automakers have long ceased to use antifreeze, since its effectiveness is somewhat lower. Modern antifreeze is manufactured using the latest technology and to a greater extent protects the engine from overheating, and the cooling system lines from contamination.

The operation of an internal combustion engine (ICE) leads to excessive heating of all its parts, and without their cooling, the operation of the main unit of the vehicle is impossible. This role is performed by the engine cooling system, which is also responsible for heating the interior of the car. In turbocharged engines, it reduces the temperature of the air forced into the cylinders, and in automatic transmissions, this system cools the fluid that is used to operate it. Some models of machines are equipped with an oil cooler, which takes part in the thermoregulation of the oil used to lubricate the engine.

The cooling system of the internal combustion engine is air and liquid

Both of these systems are not perfect and have both advantages and disadvantages.

Advantages of the air cooling system:

• light weight of the engine;
• simplicity of the device and its maintenance;
• low demand for temperature changes.

Disadvantages of an air cooling system:

• great noise from the engine;
• overheating of individual parts of the motor;
• the inability to build cylinders in blocks;
• difficulty in using the generated heat to heat the car interior.

In modern conditions, automakers prefer to equip their cars mainly with engines with liquid cooling systems. Air structures cooling motor components are very rare.

Advantages of liquid cooling system:

• not so noisy engine compared to the air system;
• high start speed when starting the motor;
• uniform cooling of all parts of the power mechanism;
• less prone to detonation.

Disadvantages of a liquid cooling system:

• expensive maintenance and repair;
• possible leakage of liquid;
• frequent hypothermia of the motor;
• freezing of the system during periods of frost.

The structure of the liquid cooling system of the engine

The main components of the ICE liquid cooling system include the following parts:

• engine water jacket
• fan;
• radiator;
• pump (centrifugal pump);
• thermostat;
• expansion tank;
• heater heat exchanger;
• constituent controls.

The water jacket of the engine is a plane between the walls of the unit in those places that require cooling.

The radiator of the cooling system is a mechanism that is designed to return the heat created by the operation of the engine. The assembly is a construction of many curved aluminum pipes, which also have additional ribs that contribute to greater heat dissipation.

The fan is used to speed up the circulation of air around the heatsink. The fan turns on at boundary heating of a cooling liquid.

A centrifugal pump (in other words, a pump) ensures the continuous movement of fluid during engine operation. The drive for the pump can be different: belt, for example, or gear. On cars with turbocharged engines, additional pumps are often installed that promote fluid circulation and are started from the control unit.

The thermostat is a device in the form of a bimetallic (or electronic) valve located between the radiator inlet and the "cooling jacket". This device provides the desired temperature of the liquid used to cool the internal combustion engine. When the engine is cold, the thermostat is closed, so the forced circulation of the cooling fluid passes inside the engine without affecting the radiator. When the liquid is heated to the limit temperature, the valve opens. At this point, the system begins to function in full force.

The expansion tank is used to fill the coolant. This unit also compensates for the change in the amount of liquid in the system during temperature changes.

Heater radiator - a mechanism designed to heat the air in the vehicle interior. Its working fluid is collected directly near the entrance to the "shirt" of the motor.

The main element of the coordination of the internal combustion engine cooling system is a sensor (temperature), an electronic control unit, as well as actuators.

Feature of the engine cooling system

The cooling system is controlled by the powertrain control system. The pump starts the circulation of fluid in the "cooling jacket" of the engine. Given the degree of heating, the liquid moves either in a small or in a large circle.

In order for the engine to warm up faster after starting, the liquid circulates in a small circle. After it is heated, the thermostat opens, allowing the liquid to circulate through the radiator, at the exit from which the liquid is affected by an air stream (oncoming or from a running fan), which cools it.

Turbocharged engines can use a dual-circuit cooling system. A feature of its work is that one circuit controls the cooling of the injected air, and the second - the cooling of the engine.

Vehicle engine cooling system

Purpose and arrangement of the cooling system. The distribution of the costs of heat obtained as a result of fuel combustion for useful work and losses is called the heat balance of the engine. The heat balance can be represented as a diagram, which shows that 25...35% of the total amount of heat is used for the useful operation of the engine and, therefore, the effective efficiency of the engine is 25...35%.

The engine cooling system maintains a certain, most favorable thermal mode of its operation. During hypothermia, friction losses increase, engine power decreases, gasoline vapors condense on cold parts and flow down in the form of drops along the cylinder mirror, washing away the lubricant. The wear of parts increases, and the oil needs to be changed more often.

Overheating impairs the quantitative filling of the cylinder with a combustible mixture, causes dilution and burnout of the oil, as a result of which the pistons in the cylinders can jam and the bearing shells melt.

Automotive engines can be liquid or air cooled. On the engines of domestic cars (excluding ZAZ -968, which has air cooling), a closed liquid cooling system is used with forced circulation of the liquid, carried out by a water pump. A closed system is called because it does not directly communicate with the atmosphere. As a result, the pressure in the system increases, the boiling point of the coolant rises to 108 ... 119 ° C and its consumption for evaporation decreases. The coolant temperature of a normally operating engine should be 85 ... 95 ° C.

The liquid cooling system includes: a cooling jacket for the block and cylinder heads, a radiator, a water pump, a fan, a thermostat, blinds, pipes, hoses, drain cocks, a heater radiator, a temperature gauge and a control lamp.

Rice. 1. Thermal balance of the internal combustion engine.

Rice. 2. Radiators:
a - device; b - tubular core; c - lamellar core; 1 - upper tank with a pipe; 2 - steam pipe; 3 - filler neck with a stopper; 4 - core; 5 - lower tank; 6 - branch pipe with a drain cock; 7 - tubes; 8 - transverse plates.

The liquid in the engine cooling jacket is heated by the removal of heat from the cylinders, enters the radiator through a thermostat, cools in it and returns to the engine jacket under the action of a centrifugal pump. Cooling of the liquid is facilitated by intensive blowing of the radiator and engine with air flow from the fan.

To reduce the formation of scale in the cooling system when filling it with water, it is necessary to use soft water containing no more than 0.14 mg of calcium oxide (CaO) per 1 liter. Hard water poured into the cooling system must be boiled.

The capacity of the engine cooling system is: for a GAZ -53A car - 23.0 liters, ZIL -130 - 29.0 liters, GAZ -24 - 11.6 liters.

The radiator consists of upper and lower tanks and a core. It is mounted on a car on rubber cushions with springs.

The most common tubular and plate radiators. In the former, the core is formed by several rows of brass tubes passed through horizontal plates, which increase the cooling surface and give the radiator rigidity. In the second, the core consists of one row of flat brass tubes, each of which is made of corrugated plates soldered together at the edges.

The top tank has a filler neck and a steam pipe. The radiator neck is hermetically sealed with a plug that has two valves: a steam valve to reduce pressure when the liquid boils, which opens at an excess pressure of more than 40 kPa (0.4 kgf / cm2), and an air valve that allows air to pass into the system when the pressure decreases due to cooling of the liquid and this prevents the radiator tubes from flattening by atmospheric pressure.

The centrifugal water pump creates a forced circulation of the coolant; it is bolted through the gasket to the top of the cylinder block. The main parts of the pump: housing, shaft with plastic impeller, mounted on two ball bearings. The self-sealing stuffing box, consisting of a rubber collar, a metal cage, a spring and a washer made of a wear-resistant graphite-lead mixture, prevents fluid from escaping at the point where the shaft exits the pump casing.

The fan amplifies the flow of air through the core of the radiator. The fan hub is mounted on the water pump shaft. Together they are driven from the crankshaft pulley by one or two trapezoidal belts.

The fan is enclosed in a casing mounted on the radiator frame, which helps to increase the speed of the air flow passing through the radiator.

In the cooling system of 3M3-53 and GAZ-24 engines, to maintain the most favorable thermal conditions, the fan is driven by an electromagnetic friction clutch, which turns on and off automatically depending on the temperature of the coolant. The clutch consists of an electromagnet mounted together with a pulley on the water pump hub, and a fan hub connected by a leaf spring to an armature that rotates freely on two ball bearings.

Rice. 3. Scheme of operation of the steam and air valves of the radiator cap:
a - steam path; b - air path; 1 - steam pipe; 2 - steam valve; 3 - air valve.

Rice. 4. Water pump:
1 - shaft with impeller; 2 - self-sealing stuffing box; 3 - body; 4- washer; 5-spring; 6 - rubber cuff.

Rice. 5. Electromagnetic drive clutch
1 - water pump pulley; 2 - electromagnet; 3 - fan hub; 4 - cover; 5 - water pump shaft hub; 6 - body; 7 - self-clamping gland;

The electromagnet coil is connected to a thermal relay, the measuring transducer (sensor) of which is installed in the upper radiator tank. When the coolant temperature reaches 90 ... 95 ° C, the relay contacts close and the electromagnet coil receives current from the vehicle's battery, the armature is attracted to the electromagnet and the fan hub begins to rotate. When the coolant temperature drops to 80 ... 85 ° C, the relay contacts open and the fan turns off.

Blinds are hinged steel plates mounted in front of the radiator. The position of the blinds is adjusted by the driver from the cab of the car with a handle, changing the air flow going through the core of the radiator.

The thermostat is used to quickly warm up a cold engine and automatically control the temperature of the coolant when the car is moving.

The thermostat of engines 3M3-53 and GAZ-24 consists of a body, a corrugated cylinder filled with a volatile liquid, and a stem with a valve. On the ZIL-130 engine, a more reliably operating thermostat with a solid filler is used. Such a thermostat consists of a copper cylinder, closed with a lid, between which a rubber membrane is hermetically fixed. The balloon is filled with an active mass consisting of ceresin (mountain wax) mixed with copper powder. The volume of the active mass increases when heated.

A rod located in the guide part of the cover rests on the membrane. The stem is pivotally connected to the valve.

When the engine is cold, the thermostat valve is closed and the coolant is directed through the channel to the pump inlet, and through it into the cooling jacket, that is, it circulates in a small circle without entering the radiator. For the ZIL-130 engine, with the thermostat valve closed, the coolant pumped into the jacket by the pump is bypassed through the air compressor cooling system.

Rice. 6. The scheme of the thermostat:
a - circulation of the coolant in a small circle; b - circulation of the coolant in a large circle; 1 - body; 2 - stem with valve; 3 - corrugated cylinder.

When the coolant is heated to 70 ... 80 ° C, the thermostat valve opens under the action of the vapors of the liquid filling its cylinder, or due to the expansion of the solid filler, and the coolant circulates through the radiator, i.e. in a large circle.

The temperature of the coolant is controlled by a temperature gauge, the measuring transducer of which is screwed into the cooling jacket of the cylinder block. At a temperature in the cooling system above 95 ° C for 3M3-53 and GAZ-24 engines or 115 ° C for ZIL-130 engines, a signal lamp lights up on the shield, which is turned on by a measuring transducer installed in the upper radiator tank.

The liquid from the cooling system of the GAZ-24 engine is drained through two taps: under the radiator and on the right in the cylinder block.

The 3M3-53 and ZIL-130 engines have three drain cocks: one under the radiator and two on the bottom of the water jacket of both sections of the block.

Application of antifreeze. It is advisable to fill the cooling system of a car operating at low temperatures with a low-freezing liquid (antifreeze), consisting of a mixture of ethylene glycol and water. Antifreeze fluid is produced in grades 40 and 65. Antifreeze grade 40 consists of 53% ethylene glycol and 47% water. It is designed for areas with moderately low temperatures. Grade 65 antifreeze consists of 66% ethylene glycol and 34% water, it is used in conditions of lower temperatures. Given the rather high expansion coefficient of antifreeze, only 93 ... 95% of the capacity fills the cooling system. During operation, it is necessary to monitor the level of antifreeze in the system and add water, as it evaporates faster than ethylene glycol.

For the cooling system of VAZ car engines, the Tosol liquid is used, which contains, in addition to ethylene glycol, additives that reduce metal corrosion.

Ethylene glycol fluids are poisonous. When they enter the body, poisoning occurs, sometimes with a fatal outcome. Special measures to protect the respiratory tract and skin are not required, but after filling the cooling system, hands should be thoroughly washed with hot water and soap.

When the warm season sets in, the antifreeze must be drained, rinsed and filled with water. The drained antifreeze is filtered, poured into a hermetically sealed container and stored in it until the next winter. Liquid "Tosol" is used throughout the year, as it does not cause corrosion.

The starting heater, installed on 3M3-53, ZIL-130 engines, serves to warm them up before starting at low air temperatures. The main parts of the heater: boiler with combustion chamber and flame tube, fuel tank, fuel supply regulator with solenoid valve and control panel. The cavity of the boiler around the flame tube is filled with coolant (water or antifreeze) and is permanently connected by branch pipes and hoses to the engine cooling jacket.

When the heater is turned on, gasoline enters the combustion chamber from the tank, and air is supplied with the help of a fan driven by an electric motor. The resulting combustible mixture is initially ignited by an electric glow plug, which, after the combustion becomes stable, is turned off. As it heats up, the density of the liquid in the boiler decreases, and it enters the engine cooling jacket, heating the cylinders and the inlet pipeline, and the gases leaving the flame tube are directed under the lower part of the crankcase and heat up the oil in it.

The main malfunctions of the cooling system include fluid leakage and the formation of scale in the system.

On the vehicles under study, a closed-type liquid cooling system is used, i.e. it is not directly connected to the atmosphere, as a result of which the pressure in the system increases and the boiling point of the coolant rises, as well as the liquid consumption for evaporation decreases. The circulation of liquid in the system is forced, using a liquid pump. The cooling system communicates with the atmosphere through valves located in the radiator filler cap (for 3M3-53-11 and EIL-130 vehicles) or the expansion tank plug (for ZIL-645 vehicles), which open at a certain vacuum or excess pressure in system. The engine cooling system maintains the engine temperature within 80…95 °С.

The cooling system includes: cooling jackets for the block, cylinder heads and intake piping, radiator, pipes, hoses, water pump, fan, thermostat, shutters, drain cocks.

The radiator consists of the lower and upper tanks, the core, the branch pipes, the neck with the stopper and the steam pipe.

The core of the radiator is tubular, consisting of several rows of flat tubes soldered into the upper and lower tanks.

To increase the cooling surface, brass plates are placed between the tubes (for 3M3-53-11 and EIL-130 car engines) or copper tape (for the ZIL-645 car engine). On the ZIL-645 engine, the radiator is filled with liquid from expansion tank 13, which is designed to remove air from the radiator when filling the cooling system and compensate for changes in the volume of coolant in the system when it expands from heating.

The water pump is centrifugal, mounted on the front wall of the cylinder block. The impeller of the pump is on the same shaft as the fan. To prevent liquid from entering the bearing housing at the rear end of the shaft in the impeller hub, a self-clamping gland is placed, consisting of a rubber cuff with a spring, a clip and a textolite washer, which is tightly pressed against the end of the pump housing. There is a hole in the bearing housing through which, when the stuffing box parts are worn, the liquid flows out. To lubricate the bearings in their housing there is an oiler and a control hole for the release of excess lubricant.

Rice. 7. Engine cooling system: 1 - blinds; 2 - the upper tank of the radiator; 3 - air outlet hose from the radiator; 4 - compressor; 5 - radiator inlet hose; 6 - outlet hose of the right side of the cylinder block; 7- box of thermostats; 8 - bypass cavity; 9 - thermostat; 10 - outlet pipe of the left side of the cylinder block; 11 - hose for removing air and liquid from the compressor cooling system; 12 - fluid drain hose into the lower radiator tank; 13 - expansion tank; 14 - plug of the expansion tank; 15 - control valve of the expansion tank; 16 - pipe for venting air and fluid from the right cylinder head; 17 - air outlet tube; 18 - cylinder head; 19 - cylinder block; 20 - drain valve; 21 - radiator outlet hose; 22 - crankshaft pulley; 23 - drive belts; 24 - liquid pump; 25 - tension roller; 26 - lower radiator tank; 27 - fan; 28 - pulley of the liquid pump and fan; 29 - automatic fan shutdown clutch

Fan - six-bladed, axial type. The fan and water pump are driven by a belt from the crankshaft pulley.

Rice. 8. Water pumps of the EIL-130Ca) engine and the ZIL-645(b) engine: 1, 2. 3 and 4 - respectively a spring, a rubber seal, a textolite thrust washer and a clip of a self-clamping stuffing box; 5 - bearing housing; 6 - water pump shaft; 7 - pump impeller; 8 - self-clamping gland; 9 - pump housing; 10 - pulley; 11 - pulley hub; 12 - ball bearings; 13 - spacer sleeve; 15 - retaining ring; 16 - sealant; 17 - bolt; 18 - liquid ejector; 19- bearing housing

Rice. Fig. 9. Fluid coupling of the ZIL-645 engine fan: a - longitudinal section; b - diagram of the locked position of the clutch; c - diagram of the unlocked position of the clutch; 1- clutch cover; 2 - clutch housing; 3 - ball bearing; 4 - flange; 5 - drive disk; 6 - seal; 7 - camera cover; 8 - plate valve; 9 - bimetallic thermostat; A - backup camera

On the ZIL-645 engine, the fan is driven by two V-belts through a hydraulic coupling with automatic control, carried out using a bimetallic thermostat.

The hydraulic coupling is designed to ensure the operation of the fan in automatic mode and consists of a housing, a cover, a bimetallic spiral thermostat connected through an axis to a plate valve of the reserve chamber cover. The coupling is filled with PMS-10000 working fluid in the amount of 30…35 g. The water pump shaft is rigidly connected to the coupling flange. The fan is attached to the clutch body with studs, under which plates are installed to block the clutch in case of breakage.

Switching on and off of the clutch is carried out by a bimetallic thermostat depending on the temperature of the air blowing the clutch body. At low air temperatures, the bimetallic regulator sets the valve to a position that closes the passage of the working fluid into the cavity between the driving and driven parts of the coupling. In this case, the working fluid is in the reserve chamber, and due to the gaps between the driving and driven parts of the coupling, they can rotate relative to each other. When the air temperature rises, the bimetallic thermostat turns the valve, thereby opening the holes connecting the reserve and working cavities. Under the action of centrifugal forces, the working fluid fills the gaps between the driving and driven parts of the coupling. In this case, due to the high viscosity of the liquid, the clutch is switched on.

Rice. 10. Thermostats for engines 3M3-53-1 lfa), ZIL-130(b) and ZIL-645(c). 1 - supply pipe; 2 - branch pipe of a small circle of circulation; 3 - gasket; 4 - outlet pipe; 5 - thermostat valve; 6 - stock; 7 - body; 8 - corrugated balloon; 9- rubber buffer; 10-stock; 11 - damper; 12 - return spring; 13 - solid filler (ceresin); 14 - balloon; 15-rubber diaphragm; 16 - clip; 17 - bushing; 18 - racks; 19-adjusting screw; 20 - radiator valve; 21 - valve seat; 22 - bypass valve; 23 - thrust washer; 24 - compensation spring

It is not recommended to disassemble the coupling under operating conditions.

The thermostat is installed at the outlet of the coolant from the cooling jacket of the engine inlet pipeline (the ZIL-645 engine has 2 thermostats installed in the thermostat box fixed on the cover of the timing gears). A liquid thermostat is installed in the ZMZ-BZ-11 engine, consisting of a corrugated brass cylinder with an easily evaporating liquid, a housing and a valve. When the temperature in the cooling system exceeds 70 ° C, the liquid in the cylinder evaporates, under the influence of the increasing pressure of its vapors, the cylinder stretches and opens the thermostat valve.

In the cooling system of ZIL-130 and -645 engines, a thermostat with a solid filler is used, consisting of a mixture of ceresin with copper powder. The filler is placed in a copper cylinder, closed with a rubber diaphragm resting against a rubber buffer. A rod is installed on top of the buffer, connected to a lever, which is held in the closed position by means of a spring. When the coolant is heated to 70 ° C, the filler in the cylinder begins to melt and, expanding, raises the diaphragm up. The pressure of the diaphragm through the buffer and the rod is transmitted to the lever, which opens the thermostat shutter. The ZIL-645 engine has, in addition to the main radiator valve, a bypass valve, which is open when the engine warms up and closes when the liquid is heated to a temperature of 78 ... 95 ° C. This opens the main valve and fluid begins to circulate through the radiator.

When the engine is running, the liquid from the lower tank of the radiator through the outlet hose is pumped by a water pump into the cooling jacket of the cylinder block and block heads. When a cold engine warms up, the pipe connecting the engine cooling jacket is closed by a thermostat valve and the liquid circulates in a small circle, bypassing the radiator and coming from the cooling jacket back to the water pump. When the liquid warms up, the thermostat valve opens, and it begins to circulate in a large circle through the radiator, which provides the necessary heat removal.

The blinds consist of shutters located in front of the radiator, and a control handle brought out into the driver's cab.

TO Category: - Car maintenance