First production car was released by Ford at the beginning of the 20th century. It proudly bore the prefix “T” and represented yet another milestone in human development. Before that, cars were the preserve of a handful of enthusiasts who staged drives and occasionally went on afternoon promenades.

Henry Ford started a real revolution. He put the cars on the assembly line, and soon his cars filled all the roads of America. Moreover, factories were also opened in the Soviet Union.

Henry Ford's main paradigm was extremely simple: “A car can be any color as long as it is black.” This approach made it possible for every person to have own car. Cost optimization and increased production scale have made the price truly affordable.

A lot of time has passed since then. Cars have continually evolved. Most of the changes and additions were made to the engine. The cooling system played a special role in this process. It has been improved year after year, making it possible to extend the life of the motor and avoid overheating.

History of the engine cooling system

It is worth recognizing that the engine cooling system has always been in cars, although its design has changed dramatically over the years. If you look solely at today, most cars are of the liquid type. Its main advantages include compactness and high performance. But this was not always the case.

The first engine cooling systems were extremely unreliable. Perhaps, if you strain your memory, you will remember films in which events take place at the end of the 19th and beginning of the 20th centuries. Back then, a car on the side of the road with a smoking engine was a common sight.

Attention! Initially, the main reason for engine overheating was the use of water as a coolant.

As a motorist, you should know that modern cars Antifreeze is used as a resource for the cooling system. There was even an analogue of it in the Soviet Union, only it was called antifreeze.

In principle, these are the same substance. It is based on alcohol, but due to additional additives, the effectiveness of antifreeze is radically higher. For example, antifreeze in the engine cooling system covers protective film absolutely everything that has an extremely negative effect on heat transfer. Because of this, the life of the motor is reduced.

Antifreeze works completely differently. It only covers with a protective film problem areas. Also among the differences you can remember the additional additives that are in antifreeze, different boiling temperatures, and so on. In any case, the most revealing comparison will be with water.

Water boils at a temperature of 100 degrees. The boiling point of antifreeze is about 110-115 degrees. Naturally, thanks to this, cases of engine boiling have practically disappeared.

It is worth recognizing that the designers conducted many experiments aimed at modernizing the engine cooling system. Suffice it to recall exclusively air cooling. Such systems were used quite actively in the 50-70s of the last century. But due to low efficiency and cumbersomeness, they quickly fell out of use.

As successful examples cars with air-cooled engine cooling systems, we can recall:

• Fiat 500,
• Citroën 2CV,
• Volkswagen Beetle.

The Soviet Union also had cars powered by air system engine cooling. Perhaps every motorist born in the USSR remembers the legendary “Cossacks”, whose engine was installed at the rear.

How does a liquid engine cooling system work?

Scheme fluid system cooling is not anything overly complicated. Moreover, all designs, regardless of which companies were involved in their production, are similar to each other.

Device

Before moving on to consider the principle of operation of the engine cooling system, it is necessary to study the basic design elements. This will allow you to accurately imagine how everything happens inside the device. Here are the main details of the unit:

• Cooling jacket. These are small cavities filled with antifreeze. They are located in those places where cooling is most needed.
• The radiator dissipates heat into the atmosphere. Typically its cells are made from a combination of alloys to achieve the greatest efficiency. The design must not only effectively reduce the temperature of the liquid, but also be durable. After all, even a small pebble can cause a hole. The system itself consists of a combination of tubes and ribs.
• The fan is mounted at the back of the radiator so as not to interfere with the oncoming air flow. It works using an electromagnetic or hydraulic clutch.
• The temperature sensor records the current state of antifreeze in the engine cooling system and, if necessary, circulates it in a large circle. This device is installed between the pipe and the cooling jacket. In fact, this structural element is a valve, which can be either bimetallic or electronic.
• The pump is a centrifugal pump. Its main task is to ensure continuous circulation of the substance in the system. The device operates using a belt or gear. Some motor models may have two pumps at once.
• Radiator heating system. It is slightly smaller in size than a similar device for the entire cooling system. In addition, it is located inside the cabin. Its main task is to transfer heat to the car.

Of course, these are not all the elements of the engine cooling system; there are also pipes, pipes and many small parts. But for a general understanding of the operation of the entire system, such a list is quite sufficient.

Principle of operation

IN engine cooling system there is an inner and outer circle. According to the first, the coolant circulates until the antifreeze temperature reaches a certain point. Usually it is 80 or 90 degrees. Each manufacturer sets its own restrictions.

As soon as the threshold temperature limit is overcome, the liquid begins to circulate in the second circle. In this case, it passes through special bimetallic cells in which it is cooled. Simply put, antifreeze enters the radiator, where it quickly cools with the help of a counter flow of air.

This engine cooling system is quite effective, as it allows the car to operate even at maximum speeds. In addition, counter air flow plays a big role in cooling.

Attention! The engine cooling system is responsible for the operation of the stove.

To better explain the working principle modern systems engine cooling let's delve a little deeper into design features scheme. As you know, the main element of an engine is the cylinders. The pistons in them constantly move during the trip.

If we take as an example Gas engine, then during compression the spark plug starts a spark. It ignites the mixture, causing a small explosion. Naturally, the temperature at this time reaches several thousand degrees.

To prevent overheating, there is a liquid jacket around the cylinders. It takes some of the heat and subsequently releases it. Antifreeze constantly circulates in the engine cooling system.

How the use of different coolants affects the cooling system

As mentioned above, previously ordinary water was used in cooling systems. But such a decision could not be called extremely successful. In addition to the fact that the engines were constantly boiling, there was another side effect, namely scale. In large quantities it paralyzed the operation of the device.

The reason for scale formation lies in the chemical structure of water. The fact is that water in practice cannot be 100% pure. The only way to achieve complete exclusion of all foreign elements is distillation.

Antifreeze, circulating inside the engine cooling system, does not create scale. Unfortunately, the process of constant exploitation does not pass without a trace for them. Under the influence of high temperatures, substances can be decomposed. The result this process is the formation of decomposition products in the form of a coating of corrosion and organic matter.

Quite often, foreign substances get into the coolant circulating inside the system. As a result, the efficiency of the entire system deteriorates significantly.

Attention! The biggest damage is done by the sealant. Particles of this substance, when sealing holes, get inside, mixing with the coolant.

The result of all these processes is that various deposits form inside the engine cooling system. They impair thermal conductivity. IN worst case Blockages form in the pipes. This, in turn, leads to overheating.

Frequent system malfunctions

Of course, liquid cooling systems have many advantages in comparison with their closest analogues. But even they sometimes fail. Most often, a leak forms in the structure, which leads to fluid leakage and deterioration of engine performance.

A leak in the engine cooling system can occur for the following reasons:

1. Due to severe frosts the liquid inside froze and the structure was damaged.
2. Common cause The formation of a leak is a leak in the connection between the hoses and the pipes.
3. High coking can also cause leakage.
4. Loss of elasticity due to high temperatures.
5. Mechanical damage.

It is the latter reason, according to statistics, that most often causes leaks in engine cooling systems. Most of the impacts occur in the radiator area. The stove also suffers quite often.

Also, the thermostat in the engine cooling system often fails. This occurs due to constant contact with coolant. As a result, a corrosive layer is formed.

Results

The design of an engine cooling system may not seem particularly complicated. But it took years of experimentation and thousands of unsuccessful attempts. But now every car can operate at its maximum possible thanks to high-quality heat removal from the engine.

While driving, many engine mechanisms are in constant motion. Their friction is so strong that the temperature begins to rise very quickly. But the main culprit high temperature a combustible mixture, as a result of combustion the temperature rises to 2000-2500 °C. In this case, the engine can quickly fail, because for its normal operation, the most optimal temperature is 80-90 ° C. In order to maintain engine performance, it must be cooled. For this purpose, the engine has a cooling system.

The most in a simple way engine cooling is a counter flow of air. This system is practically not used for cars, but it is widely used for cooling motorcycle engines. Sometimes the oncoming air also cools the engine of the car. Among the brands known to us, this system was used on.

The operating principle of the air cooling system is based on the fact that air is supplied to the engine using a fan. And the cooling is automatically controlled by a thermostat, with which you can maintain the desired temperature without allowing either cooling or overheating. For most car engines A liquid cooling system is used. The operating principle of this system is much simpler than air cooling. It is based on the fact that the heat emanating from the cylinders is absorbed by the cooling medium. As a temperature regulator, i.e. cooling medium used special liquid. Heated by the cylinder walls, it enters the radiator, cools there and again passes to the cylinder walls, absorbing heat. Thus, the coolant constantly circulates; this system is driven by a pump. Antifreeze is used for cooling - a mixture of ethylene glycol and alcohol. Ordinary water can also be used as a cooling medium, but in cold weather its use is unacceptable, since if it freezes it will damage the engine. Antifreeze does not freeze to minus 40 ° C.

Now let's talk about how the cooling system works. This device includes a cylinder cooling jacket, radiator, pump, thermostat, fan and fan belt, louvers, connecting pipes and hoses with clamps, as well as a water temperature indicator. All of the above parts are very important and if one of them breaks down, the entire cooling system may fail.

If the engine is the heart of the car, then the water pump can be called the heart of the cooling system. Its main function- ensure fluid circulation. The fan creates a flow of air that cools the liquid. The higher the speed of the machine, the stronger the fan works.

You already know what a cooling jacket is: it is formed by double cylinder walls, and coolant enters the space between them. The radiator consists of an upper and lower tank, between which there are tubes. The top tank contains hot liquid that needs to be cooled. A large amount of water cools down very slowly at once. But when the car is on the way, you don’t have time to wait, so the designers invented a device so that the water in it is cooled in small portions.

For example, if the tea in a cup is very hot, you can put it in a teaspoon and blow it. The operation of the radiator is based on the same principle. From the upper tank, hot liquid flows in thin streams, which are well blown, into the lower tank. There the liquid is collected already cooled.

The radiator neck is firmly closed with a plug. But the liquid can be so hot that it can even boil. For these cases, there are valves on the plug. Whenever overpressure Steam is released through one valve (exhaust). Through another valve (inlet) air enters the radiator when the pressure in the mechanism is below atmospheric. If the engine has not yet cooled down after a long period of operation, then opening the radiator cap is very dangerous, because You can get burned by hot steam or water.

The thermostat regulates the operation of the cooling system. When the liquid heats up, the alcohol in the corrugated cylinder of the thermostat will begin to evaporate, the pressure inside the cylinder with alcohol will increase, and the cylinder, stretching in height, will open the thermostat valve. This happens at a temperature not lower than 80 °C. As soon as the temperature rises to 90 °C, the valve will open completely and water will be able to circulate freely in the system. The valve will close only when the temperature drops, this happens when the motorist slows down the car or stops.

On the road, even if it is very good and smooth, the car will still shake a little. Therefore, the position of the engine in relation to the radiator is constantly changing, and it cannot be placed on a solid support. Only rubber support is allowed. For the same reason, they do not make a rigid connection between the engine and the radiator. But the rubberized hoses and pipes are just right. They are light and flexible, so they are not afraid of ravines and bumps.

Blinds necessary to regulate the amount of air that passes through the radiator. They consist of a series of vertically mounted plates that can be rotated using a handle located inside the car. When the handle is in starting position, the blinds are open and the air, without being delayed, freely passes to the radiator. If you pull the handle towards you, the blinds will close and air access to the radiator will stop. By extending the handle only halfway, air, although not much, will flow to the radiator. Blinds are used by drivers infrequently and mainly in the cold season to protect the radiator from hypothermia. When starting the engine in winter time The blinds need to be closed so that it warms up faster and prevents the water in the radiator from freezing.

Of course, the operation of the cooling system must be monitored. To do this on dashboard There is an electric water temperature indicator. It is connected by a wire to a sensor placed in the cooling jacket. On the road, the driver needs to monitor the readings of this device. The engine should not overheat, because... This leads to rapid wear mechanism. Most often, overheating occurs due to insufficient coolant or a malfunction of the cooling system. Hypothermia most often occurs in winter due to faulty blinds or lack of insulating cover.

Overheating and cooling significantly reduce engine power, so it is necessary to regularly check the coolant level in the radiator to see if it is leaking.

The cooling system needs regular inspection, during which it is necessary to lubricate the fan bearings and tighten its belt and hose clamps, if necessary. If you use water for cooling, then cold weather, especially at temperatures below 0 °C, it is necessary to ensure that the water in the radiator does not freeze, otherwise the radiator itself and the cylinder will be damaged. To protect the engine from frost, an insulating cover is placed on the radiator lining. 

If you want to visually familiarize yourself with the engine cooling system, be sure to watch this video.

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Engine design and operation

Purpose and principle of operation of the cooling system

The cooling system serves to forcibly remove heat from the engine cylinders and transfer it to the surrounding air. The need for a cooling system is caused by the fact that engine parts in contact with hot gases become very hot during operation. If not refrigerated internal parts engine, then due to overheating, the lubricant layer between the parts may burn out and moving parts may seize due to their excessive expansion.

The cooling system can be air or liquid.

With an air cooling system (Fig. 1, a), heat from the engine cylinders is transferred directly to the air blowing them. To do this, in order to increase the heat transfer surface, cooling fins are made on the cylinders and head, manufactured by casting. The cylinders are surrounded by a metal casing. Air is sucked through the resulting air jacket using a fan to cool the engine. The fan is driven by a belt drive from the crankshaft pulley.

The air cooling system was used only on low-power engines. The advantage of such a system is the simplicity of the device, some reduction in engine weight and ease of maintenance. For’more powerful engines The use of an air cooling system encounters a number of difficulties due to the need to remove a large amount of heat and ensure uniform cooling of all hot spots of the engine.

To the system liquid cooling With forced circulation The fluids include water jackets of the head and block, respectively, a radiator, lower and upper connecting pipes with hoses, a water pump with a water distribution pipe, a fan and a thermostat.

The water jackets of the head and block, pipes and radiator are filled with water. When the engine is running, the water pump driven by it creates a circular circulation of water through the water jacket, pipes and radiator. Through the water distribution pipe, water is primarily directed to the most heated areas of the block. Passing through the water jacket of the block and head, water washes the walls of the cylinders and combustion chambers and cools the engine. The heated water flows through the upper pipe into the radiator, where, branching through the tubes into thin streams, it is cooled by air,

which is sucked between the tubes by the rotating fan blades. The cooled water again enters the engine water jacket.

In some engines with overhead valves, water from the pump is forced only into the jacket of the head, seats and exhaust valve pipes, and then through the outlet pipe it is discharged to the radiator. In this case, the cylinders are cooled by water circulating in its jacket due to the presence of a temperature difference between the water in the water jacket of the block and the head. More heated water from the water jacket of the block is displaced more cold water, coming from the water jacket of the head, which ensures natural convection circulation of water (thermosiphon). With this cooling, the operating conditions of the engine cylinders improve.

A thermostat installed in the upper water pipe regulates the circulation of water through the radiator, maintaining its optimal temperature.

In V-shaped carburetor engines a common water pump, connected by a lower pipe to the radiator and installed on the same shaft with the fan, pumps water through two pipes and water distribution channels into the water jackets of both sections of the block. Heated water is removed from the heads through channels, usually cast into top cover block, and through a common thermostat and the upper pipe flows back to the radiator. On diesel engines, the layout of the cooling system elements is somewhat modified.

Reliable and trouble-free internal combustion engine operation(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 the coolant temperature sensor is triggered, it 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 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

1. If the temperature gauge needle is not in the middle, but tends to the red zone while driving;
2. It’s cold in the cabin, the heating stove does not provide sufficient temperature;
3. 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

Flushing the cooling system

1. Antifreeze, antifreeze or water is drained. Before doing this, you need to start the engine for a couple of minutes.
2. Fill the system with water and cleaner.
3. Turn on the engine for 5-30 minutes (depending on the brand of cleaner) and turn on the interior heating.
4. After the time specified in the instructions has passed, the engine must be turned off.
5. Drain the used cleaner.
6. Rinse with water or a special compound.
7. 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:

1. Airing the engine cooling system: remove the air lock.
2. Insufficient pump performance: replace the pump. Select a pump with maximum height impellers.
3. The thermostat is faulty: it can be fixed by replacing it with a new device.
4. Low performance of the coolant radiator: flush the old one or replace the standard one with a model with higher heat-dissipating properties.
5. 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.

Most serious car malfunctions are related to engine overheating. The temperature of the gases in the cylinder reaches 2000 degrees. When fuel burns in the cylinder, a large amount of heat is generated, which must be removed and thereby prevent overheating of engine parts.

Principles of designing cooling systems

A decrease in the efficiency of the cooling system leads to an increase in the temperature of the pistons and a decrease in the gaps between the piston and the cylinder. Thermal clearances decrease to zero. The piston touches the cylinder walls, scoring occurs and the overheated oil loses lubricating properties and the oil film breaks. This mode of operation can lead to engine seizure. Overheating is accompanied by uneven expansion of the cylinder head, mounting bolts, engine block, etc. Subsequent destruction of the engine is inevitable: cracks in the cylinder head, deformation of the interface between the head and the cylinder block itself, cracks in the valve seats, etc. — it’s unpleasant to even list all this, so it’s better not to let it come to that!

The engine and oil cooling system is designed to prevent such developments, but in order for the system to cope with its tasks, it is necessary to use high-quality coolant (coolant). Low-freezing coolants are called antifreeze- from English word"antifreeze". Previously, coolants were prepared based on aqueous solutions of monohydric alcohols, glycols, glycerin and inorganic salts. Currently, preference is given to monoethylene glycol, a colorless syrupy liquid with a density of approximately 1.112 g/cm2 and a boiling point of 198 g. The task of coolant is not only to cool the engine, but also not to boil over the entire operating temperature range of the engine and its components, to have high heat capacity and thermal conductivity, not to foam, not to have a harmful effect on pipes and seals, and to have lubricating and anti-corrosion properties.

In the 70s, antifreeze was produced based on aqueous solution monoethylene glycol with a crystallization temperature of 40 degrees. It did not require dilution with water when added to the cooling system. This drug was named Antifreeze- by the name of the laboratory “Technology of Organic Synthesis”. Because the name is not patented, then TOSOL is a ready-to-use product, and “antifreeze” is a concentrated solution (although TOSOL is also antifreeze).

Ready-made antifreezes are colored for safety and catchy colors are chosen: blue, green, red. During operation, antifreeze loses beneficial features- anti-corrosion properties decrease, the tendency to foam increases. The service life of domestic coolants is from 2 to 5 years, imported 5-7 years.

The figure below shows a diagram of the car's cooling system. There is nothing special or complicated in the cooling system and yet...

Rice. 1 - engine, 2 - radiator, 3 - heater, 4 - thermostat, 5 - expansion tank, 6 - radiator cap, 7 - upper pipe, 8 - lower pipe, 9 - radiator fan, 10 - fan switch sensor, 11 - sensor temperature, 12 - pump.

When the engine starts, the water pump begins to rotate. The pump drive may have its own pulley driven by an accessory belt or driven by the rotation of a timing belt. The cooling system contains an impeller, which rotates and drives the coolant. For quick warm-up engine system is “shorted”, i.e. The thermostat is closed and does not allow fluid to enter the radiator. As the coolant temperature rises, the thermostat opens, transferring the system to a different state where the coolant travels along a long path - through the radiator of the cooling system ( shortcut closed by thermostat). Thermostats have various characteristics discoveries. Typically the opening temperature is marked on the edge. It’s probably not worth explaining the design of the radiator. A fan switch sensor is installed at the bottom of the radiator. If the coolant temperature reaches a certain value, the sensor will close, and because If it is electrically connected to the break in the power supply circuit of the electric fan, then when it is shorted, the cooling system fan should turn on. As the coolant cools, the fan turns off and the thermostat closes the long path to a short one. It's simple, but not very...

This scheme is the basis, but life does not stand still and various manufacturers improve cooling systems. On some cars you will not find a sensor for turning on the cooling fan, because... The fan is turned on by the engine ECU depending on the readings of the coolant temperature sensor. It is worth paying attention to the situation in which when the ignition is jammed, the cooling system fan immediately turns on. Either the temperature sensor is faulty, or its circuits are damaged, or the engine ECU itself is faulty - it “does not see” the engine temperature and, just in case, immediately turns on the fan.

On some vehicles, special electric valves are installed on the way to the heater, allowing or blocking the path of coolant (BMW, MERCEDES). Such valves sometimes “help” the cooling system fail.

Troubleshooting the cooling system

Specialists from the AB-Engineering company under the leadership of A.E. Khrulev. has developed a table of the causes and consequences of engine overheating. Myself engine overheating- this is the temperature regime of its operation, characterized by boiling of the coolant. But not only overheating is a malfunction. Engine operation at a constantly low temperature is also considered a malfunction, because in this case, the engine operates at an unusual temperature regime. Failure of a thermostat, electric fan or viscous coupling, thermal switches, etc. will lead to abnormal operation of the cooling system. If the driver detects signs of violation in time thermal regime engine operation and will not allow irreversible processes, then repair of the cooling system will not be expensive and time-consuming. Therefore, we strongly recommend that you (and your clients) pay attention to temperature conditions engine.

A. The first thing you need to do is check the connection diagram of the cooling system pipes if the car is not new or has been repaired after being repaired at another service center.

To some, such a proposal may seem funny, but life has shown the opposite, examples:

• the car assembled after a major overhaul had a connection between the crankcase ventilation system pipe and the expansion tank of the cooling system;
• installed non-standard fan with blades directing the air flow in the wrong direction;
• the electric fan blades rotate freely on the shaft of the switched off engine;
• The electric fan connectors are loose or torn, etc.

Inspect the radiator for external clogging. Inspect the areas and paths of natural cooling of the engine. A negative example would be a heavy engine underbody guard that blocks the airflow that cools the engine from below. Sometimes a breakdown of the bumper, the lower part of which has air flow guides to the engine, leads to overheating (VW Passat B3).

B. After the inspection, it is necessary to check the coolant level in the system, the presence and serviceability of the radiator cap valves and expansion tank, and the integrity of the pipes and hoses. Check what kind of antifreeze or just water is poured into the system, because... Each liquid has its own boiling point.

If the first two points (A or B) reveal any malfunctions, they must be eliminated or taken into account when making a “sentence”. When adding coolant, you need to remember that not all cars are designed with a “just add water” mentality. For example on BMW car(M20, E34) when adding coolant, it is necessary to turn on the ignition and set the heater temperature controls to the “maximum heat” mode so that the heater valves turn on and open for the movement of coolant through the system, in addition, it is necessary to raise the radiator up, because The expansion tank, built into the radiator by the “miracle designers” of Germany, is located below the level of the cabin stove and it often becomes airy.

If there is a suspicion that the engine is airy (there is air in the system that prevents the movement of fluid), it is necessary to unscrew the special plugs of the cooling system to release the air. They are usually located at the top of the engine cooling system. Start the engine, turn on the interior heaters, turn on the fan. Observe the warming up of the engine, components and assemblies. If the system has an expansion tank, then check the fluid circulation, i.e. its movement through the system. When adding engine speed to 2,500 - 3,000, a powerful jet of coolant should flow into the tank. Air may escape from the plugs that are unscrewed (not completely!) for some time, and as soon as liquid flows out, the plugs must be tightened. As the engine warms up, warm air should come out of the cabin heater. If the engine warms up and the air from the heater is cold, then this is the first sign of airing in the cooling system. It is necessary to turn off the engine and take measures to find and eliminate this malfunction.

If the thermostat is working properly (the opening temperature can vary from 80 to 95 degrees), after warming up, the lower radiator hose should have approximately the same temperature as the upper one. If this is not the case, it means poor coolant flow through the radiator.

If the thermostat is working properly, the cooling system fan should turn on some time after it opens. If the system does not have an electric fan, then it is necessary to check the circuit switch sensor electromagnetic coupling or the operation of the viscous coupling. If the viscous coupling malfunctions, the cooling system fan on a warm engine can be stopped and held by hand (when stopping, be careful - stop with a soft object so as not to damage the fan impeller or hand). It is necessary to check the air pressure and its temperature - hot air must be directed towards the engine.

The pressure in the cooling system should increase slowly as the engine warms up and drop slowly after the engine is turned off. If the upper pipe leading to the radiator swells when the engine speed increases, it is necessary to check whether some of the exhaust gases are entering the cooling system. This is usually noticeable by the oil film in expansion tank or coolant bubbling. In this case, it usually comes out intensely from the muffler. White smoke from heated and evaporating coolant entering the engine cylinders. In this case, it is necessary to check the engine oil filler neck and sit on it white emulsion, then the coolant is not only in the engine cylinders, but also in the lubrication system (it is necessary to stop movement). Let's give a few examples from the practice of various services that “say” that engine diagnostics are inseparable from the diagnostics of all vehicle systems, including the cooling system.

MAZDA 626 car - the owner complains about uneven engine speed or increased speed idle move. Checking the control system (and self-diagnosis) did not reveal a malfunction. Noticed the increased voltage on temperature sensor coolant.

The control system adds the amount of fuel because reacts to high voltage on the sensor (engine cold). It turned out that there was not enough liquid in the cooling system, the sensor was “bare”. Simply add the coolant level to normal and the speed returns to normal.

FORD vehicles - coolant entered the oil in an unconventional way - through the oil cooling system located around the oil filter.

FORD vehicle - after the engine warmed up, one cylinder stopped working. Replacing the spark plug and other work led to a positive result (this had nothing to do with determining the malfunction, the engine simply cooled down during the work) - the cylinder began to work and the client left. The next day he is with us again. It turned out there was a crack in the block head in the area exhaust valve idle cylinder. As long as the engine is cold, everything is fine. When warmed up, the crack grew larger and began to leak coolant into the cylinder. The mixture became lean and interruptions began, and then the cylinder turned off completely.

There are many such examples that can be given; they are in the practice of every car repairman. The main conclusion everyone who is seriously involved in auto repair should make is to notice and analyze everything significant and insignificant, because these positions can suddenly change places.