General arrangement and operation of the liquid cooling system

The cooling system is designed to forcibly remove excess heat from engine parts and transfer it to the surrounding air. This creates a certain temperature regime at which the engine does not overheat and does not overcool. Heat in engines is removed in two ways: liquid (liquid cooling system) or air (air cooling system). These systems absorb 25-35% of the heat released during fuel combustion. The temperature of the coolant in the cylinder head should be 80-95 °C. This temperature regime is the most beneficial, ensures the normal operation of the engine and should not change depending on the ambient temperature and engine load. The temperature during the engine operating cycle varies from 80-120 °C (minimum) at the end of the intake to 2000-2200 °C (maximum) at the end of the combustion of the mixture.

If the engine is not cooled, then the high-temperature gases heat up the engine parts and they expand. The oil on the cylinders and pistons burns out, their friction and wear increase, and from excessive expansion of parts, the pistons in the engine cylinders jam, and the engine may fail. To avoid negative phenomena caused by overheating of the engine, it must be cooled.

However, excessive cooling of the engine adversely affects its operation. When the engine is overcooled, fuel vapors (gasoline) condense on the walls of the cylinders, washing away the lubricant, diluting the oil in the crankcase. Under these conditions, intense wear occurs piston rings, cylinder pistons and reduced efficiency and engine power. The normal operation of the cooling system contributes to obtaining highest power, reducing fuel consumption and increasing the life of the engine without repair.

Most engines have liquid cooling systems (open or closed). In an open cooling system, the interior is in direct communication with the surrounding atmosphere. Closed cooling systems have become widespread, in which the internal space only periodically communicates with the environment using special valves. In these cooling systems, the boiling point of the coolant rises and the boiling point decreases.

Rice. 1. Scheme of the liquid cooling system: 1 - radiator; 2 - upper tank; 3 - radiator cap; 4 - control tube; 5 - upper radiator pipe; 6 and 19 - rubber hoses; 7 - bypass channel; 8 to 18 - outlet and inlet pipes, respectively; 9 - thermostat; 10 - hole; 11 - block head; 12 - water distribution pipe; 13 - liquid temperature indicator sensor; 14 - cylinder block; 15 and 21 - drain taps; 16 - water jacket; 17 - impeller of a water centrifugal pump; 20 - lower radiator pipe: 22 - lower radiator tank; 23 - fan drive belt; 24 - fan

The engines of GAZ-24 Volga, GAZ-bZA, ZIL-130, MA3-5335 and KamAZ-5320 vehicles have a closed liquid cooling system with forced circulation of liquid created by a water centrifugal pump. The liquid cooling system of an automobile engine (Fig. 1) consists of a water jacket, a radiator, a fan, a thermostat, an impeller pump, outlet and inlet pipes, a fan drive belt, a fluid temperature indicator sensor, drain taps and other parts. There is a double-walled space (water jacket) around the engine cylinders and the block head where the coolant circulates.

During engine operation, the coolant heats up and is supplied to the radiator by a water pump, where it is cooled, and then again enters the cylinder block jacket. For reliable operation engine, it is necessary that the coolant constantly circulates in a vicious circle: engine - radiator-engine. The liquid can circulate in a small circle, bypassing the radiator ( cold engine, thermostat closed), or in a large circle, entering the radiator (warmed engine, thermostat open). The direction of movement of the coolant is shown in fig. 42 arrows.

The engine water jacket consists of a cylinder block jacket and a block head jacket, interconnected by holes in the gasket between the head and the block. The impeller of the water centrifugal pump and the fan are driven by a V-belt. When the pump impeller rotates, the coolant is forced into the water distribution tube located in the head of the block. Through the holes in the tube, the liquid is directed to the exhaust valves, due to which the most heated parts of the head and cylinders are cooled. The heated coolant flows into the upper outlet pipe. If the thermostat is closed, then the liquid again flows through the bypass channel to the centrifugal pump. When the thermostat is open, the coolant flows into the upper radiator tank, cools, flowing through the tubes, and enters the lower radiator tank. The liquid cooled in the radiator is supplied to the pump through the lower inlet pipe.

The water jacket of the ZIL-130 car engine is connected to the radiator with flexible hoses. The upper tank of the radiator is connected to the inlet pipe jacket, and the lower tank is connected to the inlet pipe of the water pump. The left and right rows of cylinders are connected to the pump by two pipelines. A thermostat is installed in the pipe through which the heated coolant is supplied to the upper tank of the radiator. The compressor water jacket is permanently connected to the engine cooling system by flexible hoses. The radiator 18 of the heater is connected to the engine cooling system with hoses] the heater is turned on by a crane.

When starting, warming up and running the engine, while the temperature of the water in the cooling system is below 73 ° C, the liquid circulates through the water jackets of the block, block heads and compressor, but does not enter the radiator, since the thermostat is closed. Coolant is supplied to the water pump (regardless of the position of the thermostat valve) through the bypass hose from the inlet pipe jacket, from the compressor and from the heater radiator (if it is turned on).

Rice. 2. The cooling system of the car engine ZIL - 303 1 - radiator; 2 - blinds; 3 - fan; 4 - water pump; 5 and 27 - respectively, the upper and lower radiator tanks; 6 - radiator cap; 7 - outlet hose; 8 - compressor; 9 - inlet hose; 10 - bypass hose; 11 - thermostat; 12 - branch pipe; 13 - flange for installing a carburetor; 14 - inlet pipeline; 15 - heater valve; 16 and 17 - inlet and outlet tubes, respectively; 18 - heater radiator; 19 - liquid temperature indicator sensor; 20 - dosing insert; 21 - water jacket of the block head; 22 - water jacket of the cylinder block; 23 - drain valve of the cylinder block jacket; 24 - drain cock drive handle; 25 - drain valve of the radiator pipe; 26 = inlet

The water pump pumps fluid into the system, and its main flow passes through the water jacket of the cylinder block from its front to the rear. Washing the cylinder liners from all sides and passing through the holes in the mating surfaces of the cylinder block and block heads, as well as in the gasket located between them, the coolant enters the head jackets. At the same time, a significant amount of coolant is supplied to the most heated places - exhaust valve pipes and spark plug sockets. In the heads of the block, the coolant moves in the longitudinal direction from the rear end to the front due to the presence of holes of the appropriate diameter drilled in the mating surfaces of the cylinder block and heads, and metering inserts installed in the rear channels of the inlet pipeline. The hole in the insert limits the amount of fluid entering the intake manifold jacket. Warm liquid passing through the intake manifold jacket heats up combustible mixture coming from the carburetor (through the internal channels of the pipeline), and improves mixture formation.

Before starting work, it is necessary to check the liquid level in the radiator, since if it is insufficient, the circulation of the liquid is disturbed and the engine overheats. The refrigeration system must be filled with clean, soft water that does not contain lime salts. When using hard water, a large amount of scale is deposited in the radiator and water jacket, leading to overheating of the engine and a decrease in its power. Frequent water changes in the cooling system cause increased scale formation. Water can be softened in the following ways: boiling, adding chemicals to water, and magnetically treating it. It has been established that, passing through a weak magnetic force field, water acquires new properties: it loses its ability to form scale and dissolves the previously formed scale that was in the engine cooling system.

Water is poured into the cooling system through the radiator neck, which is closed with a stopper (Fig. 43). To drain water from the cooling system, taps located at the lowest points of the cooling system are used.

The diesel cooling system of the KAMAZ-5320 vehicle is designed for the continuous use of TOCOL-A-40 or TOCOL-A-65 liquids (freezing at low temperatures). The use of water in the cooling system is allowed only in special cases and for a short time. The cooling system includes water jackets of the block and cylinder heads, a water pump, a radiator, a fan with a fluid coupling, blinds, two thermostats, an expansion tank, connecting pipes, hoses, a pump drive V-belt, drain taps or plugs, coolant temperature sensors and other parts. .

The plant allows the engine to operate at a coolant temperature not exceeding 105 °C. The temperature regime of the engine is maintained by two thermostats, a hydraulic clutch for turning on the fan and blinds. If the engine is not warmed up, then the coolant supplied by the pump enters the left row of cylinders and through the discharge pipe into the right row. It washes the outer surfaces of the cylinder liners of both rows, then through the holes in the upper plane of the cylinder block, the head gasket enters the cylinder heads, cooling the most heated places - exhaust channels and injector sockets. The heated liquid passes from the cylinder heads to the right and left pipes located in the "collapse" of the engine, then it is fed through the connecting pipe to the water distribution box (or thermostat box). The thermostat valves are closed, and the coolant is again supplied to the water pump through the bypass pipe 6.

Rice. 3. The cooling system of the diesel car KamAE-5320: 1 - pulley crankshaft; 2 - lower tank; 3 - blinds; 4 - radiator; 5 - fluid coupling of the fan drive; 6 - bypass pipe; 7 - discharge pipe; c - upper tank; 9 - upper branch pipe; 10 - thermostat; 11 - water distribution box; 12 - connecting pipe; 13 - inlet tube; 14 - right water pipe; 15 - outlet tube; 16 - intake manifold; 17 - sensor for the control lamp of liquid overheating; 18 - expansion tank; 19 - neck with a sealing plug; 20 - plug with valves; 21 - outlet pipe from the compressor; 22 - outlet tube of the left water pipe; 23 - compressor; 24 - left water pipe; 25 - head cover; 26 - cylinder head; 27 - water pump; 28 - drain cock or plug; 29 - water pump pulley; 30 - fan; 31 - lower branch pipe

Thermostats are installed in a separate box, mounted on the front end of the right row of cylinders. The expansion tank is located on the engine with right side and is connected to the upper tank of the radiator, water distribution box, compressor and water jacket of the cylinder block. The expansion tank compensates for the change in the volume of liquid when it is heated, and allows you to control its level in the cooling system. Steam from the upper sections of the radiator and the system is discharged into the tank and condenses in it. The air collected in the tank improves the performance of the cooling system. TOCOJ1-A-40 or TOSOL-A-65 is poured into the cooling system through a neck having a sealed plug on the thread. Steam and air valves are installed in the plug.

In the diesel cooling system, a fan drive fluid coupling is used, which transmits torque from the engine crankshaft to the fan. Using a fluid coupling, they maintain the most favorable temperature conditions in the cooling system and dampen the resulting fluctuations during a sharp change in the crankshaft speed. The fan drive fluid coupling has automatic control.

The fluid coupling is driven from the crankshaft of the engine through a splined drive shaft. Fan located coaxially with crankshaft, mounted on a hub mounted on the driven shaft. The leading part of the fluid coupling consists of: the drive shaft assembly with the casing; a drive wheel bolted to a casing and a pulley shaft; pump and generator drive pulley bolted to the shaft. The leading part of the fluid coupling rotates on ball bearings. The driven part of the fluid coupling consists of: the driven wheel assembly, bolted to the driven shaft. The driven part of the fan drive fluid coupling rotates on ball bearings. The sealing of the hydraulic coupling is carried out by two sealing rings and self-clamping glands.

Rice. 4. Fan drive fluid coupling: 1 - front cover; 2 - body; 3 - casing; 4, 7, 13 and 20 - ball bearings; 5 - oil supply pipe; 6 - drive shaft; 8 - sealing rings; 9 - driven wheel; 10 - drive wheel; 11 - pulley; 12 - pulley shaft; 14 - thrust sleeve; 15 - fan hub; 16 - driven shaft; 17 and 21 t - self-clamping glands; 18 - gasket; 19 and 22 - bolts

To control the hydraulic clutch of the fan drive, there is a spool-type switch mounted on the discharge pipe at the front of the engine. Depending on the temperature of the liquid in the cooling system, the fluid coupling switch connects or disconnects the drive shaft from the driven one, changing the amount of oil entering the fluid coupling from the lubrication system. The oil for the operation of the hydraulic coupling is supplied by a pump into its cavity, then it is fed through the tube into the channels of the drive shaft and through the holes in the driven wheel into the interblade space. When the drive wheel rotates, the oil from its blades passes to the blades of the driven wheel, and it begins to rotate, transferring torque to the shaft and fan. Hydraulic coupling with the help of a crane Turns on or off, and in connection with this, the fan turns on or off. The valve is located in the hydraulic clutch switch housing.

The fan can operate in three modes:
- automatic - the temperature of the coolant in the engine is maintained at 80-95 ° C; the hydraulic clutch switch valve is set to position B (mark on the body); when the coolant temperature drops below 80 ° C, the fan automatically turns off;
- the fan is off - the valve of the hydraulic coupling switch is set to position 0; the fan can rotate at a low frequency;
- the fan is always on - in this mode, short-term operation is allowed in case of possible faults hydraulic clutch or its switch.

The temperature of the liquid in the cooling system is controlled by a remote thermometer, the receiver of which is located in the driver's cab on the instrument panel, and the sensor is in the water distribution box (diesel car KAMAZ-5320), in the water channel of the inlet pipeline (engines of GAZ-53A and ZIL-130 cars), in head of the block (engine of the car GAZ-24 "Volga"). If the temperature of the water in the cooling system exceeds a certain value, then a signal lamp lights up on the instrument panel, for example, red (GAZ-63A car) at a water temperature of 105-108 ° C.

Schematic diagram of forced cooling systems of modern engines is the same.

The ZIL-130 engine has a closed cooling system with forced fluid circulation. The system consists of a cooling jacket for the block and cylinder head, a radiator, connecting pipes, a water centrifugal pump, a fan, a thermostat, drain cocks for the cylinder block jacket and a radiator drain cock. The figure shows the cabin heater and windshield heater included in the cooling system (a. . The fluid is supplied to the heater through the pipeline, and the outlet is through the pipeline when the valve is open

When the engine is running, the water pump creates fluid circulation through the cooling jacket, pipes and radiator. Passing through the shirt of the block and head, the coolant washes the cylinder walls, combustion chambers and other parts. The heated liquid enters the upper part of the radiator through a pipe and then through a large number of tubes from the upper part of the radiator to the lower one, while giving off heat to the air flow. The cooled liquid from the lower tank (reservoir) of the radiator again enters the engine jacket. The system is calculated so that when passing through the radiator, the temperature of the liquid drops by 6-10 °C. The thermostat, installed in the upper water pipe, automatically changes the intensity of fluid circulation through the radiator, maintaining its most favorable temperature. The air supply to the radiator can be controlled by means of blinds - curtains in front of the radiator, which are opened manually or automatically depending on the thermal regime of the engine.

A compressor is installed on the engines of ZIL, MAZ, KamAZ trucks brake system, the cylinders of which are liquid-cooled, connected in parallel to the engine cooling system.

Monitoring the operation of the cooling system consists in checking the liquid level and observing the readings of a thermometer, consisting of a sensor and a receiver installed on the instrument panel.

Engine SMD -14 caterpillar tractor DT-75M has a closed cooling system with forced circulation of coolant. The cooling system includes: a centrifugal-type water pump with a fan, cooling jackets of the block and block heads driven by a V-belt; outlet pipe; radiator, consisting of upper and lower cast tanks, between which the core is soldered; liquid temperature indicator sensor; connecting pipes and hoses. To remove air from the system, a hole in the water pump housing is closed with a plug. The engine cooling system includes a starting engine cooling jacket. Fill the system with liquid through the radiator neck, and drain through the taps. The intensity of liquid cooling in the radiator is manually regulated by lifting the curtains located in front of the radiator to a greater or lesser height.

Rice. 5. Engine cooling system ZIL -130

The circulation of the coolant in the system is carried out by a water pump, which sucks the liquid from the lower radiator tank through the pipe and delivers it to the water distribution channel of the crankcase. Through the side holes in the water distribution channel, the liquid is supplied simultaneously to all cylinders. From the crankcase cooling jacket, the liquid enters the water jacket of the block head and then through three holes in the upper wall of the head into the drain pipe and then into the upper radiator tank. Part of the fluid from the crankcase through the connecting pipe enters the cylinder jacket of the starting engine, and from there through the head of its cylinder into the outlet pipe.

The capacity of the cooling system of autotractor engines is determined by the type of engine and is in the range of 7.5-50 liters.

TO Category: - Cars and Tractors

At present, all progressive mankind uses one or another automobile transport(cars, buses, trucks).

The Russian Encyclopedic Dictionary interprets the word car (from auto - mobile, easily moving), a trackless transport vehicle, mainly on wheels, driven by its own engine ( internal combustion, electric or steam).

There are cars: passenger (cars and buses), trucks, special (fire, ambulance and others) and racing.

The growth of the country's car park caused a significant expansion of the network of car maintenance and repair enterprises and required the involvement of a large number of qualified personnel.

To cope with the huge amount of work to maintain the growing car fleet in a technically sound condition, it is necessary to mechanize and automate the processes of car maintenance and repair, and to dramatically increase labor productivity.

Enterprises by maintenance and car repair are equipped with more advanced equipment, new technological processes, providing a reduction in labor intensity and an increase in the quality of work.

Purpose and types of cooling system

The temperature of the gases in the combustion chamber at the moment of ignition of the mixture exceeds 2000°C. Such a temperature, in the absence of artificial cooling, would lead to strong heating of engine parts and their destruction. Therefore air or liquid cooling of the engine is necessary. With air cooling, a radiator, water pump and pipelines are not required, there is no danger of “defrosting” the engine in winter when filling the cooling system with water. Therefore, despite the increased power consumption for driving the fan and difficult start-up at low temperatures, air cooling is used in passenger cars and a number of foreign cars.

Cooling system - liquid closed type with forced circulation of liquid, with an expansion tank. Such a system is filled with water or antifreeze that does not freeze at temperatures down to minus 40°C.

When the engine is excessively cooled, heat losses with the coolant increase, fuel does not completely evaporate and burns, which penetrates into the oil pan in liquid form and dilutes the oil. This leads to a decrease in power and efficiency of the engine and rapid wear details. When the engine overheats, the decomposition and coking of the oil accelerates, the deposition of soot occurs, as a result of which heat removal worsens. Due to the expansion of parts, temperature gaps decrease, friction and wear of parts increase, and cylinder filling deteriorates. Coolant temperature during engine operation should be 85-100°C.

IN automotive engines a forced (pump) liquid cooling system is used. Such a system includes cylinder cooling jackets, a radiator, a water pump, a fan, blinds, a thermostat, drain cocks, and coolant temperature gauges.

The liquid circulating in the cooling system takes heat from the walls of the cylinders and their heads and transfers it through the radiator to the environment. Sometimes it is envisaged to direct the flow of circulating fluid through a water distribution pipe or a longitudinal channel with holes in the first place to the most heated parts (bulging valves, spark plugs, combustion chamber walls).

IN modern engines The engine cooling system is used to heat the intake manifold, cool the compressor and heat the cab or passenger area of ​​the body. Modern automobile engines use closed liquid cooling systems that communicate with the atmosphere through valves in the radiator cap. In such a system, the boiling point of water rises, water boils less often and evaporates less.

The device, composition and operation of the cooling system

The device of the cooling system includes: a pipe for draining liquid from the heater radiator; branch pipe for draining hot liquid from the cylinder head to the heater radiator; thermostat bypass hose; outlet branch pipe of the cooling jacket; radiator inlet hose; expansion tank; cooling jacket; plug and tube of the radiator; fan and its casing; pulley; radiator outlet hose; fan belt; coolant pump; coolant supply hose to the pump; and thermostat.

The radiator is designed to cool hot water coming out of the engine cooling jacket. It is located in front of the engine. A tubular radiator consists of an upper and lower tank connected to each other by three or four rows of brass tubes. Transversely arranged horizontal plates give the radiator rigidity and increase the cooling surface. The radiators of the ZMZ-53 and ZIL-130 engines are tubular-tape with serpentine cooling plates (ribbons) located between the tubes. The cooling systems of these engines are closed, so the radiator caps have steam and air valves. The steam valve opens at an overpressure of 0.45-0.55 kg / cm² (ZMZ-24, 53). When the valve is opened, excess water or steam is discharged through the steam outlet pipe. The air valve protects the radiator from compression by air pressure and opens when the water cools, when the pressure in the system drops by 0.01-0.10 kg / cm².

If an expansion tank is installed in the cooling system, then the steam and air valves are located in the plug of this tank (ZIL-131).

To drain the liquid from the cooling system, open the drain cocks of the cylinder blocks and the drain cock of the radiator pipe or expansion tank.

For ZIL engines, drain valves of cylinder blocks and a radiator pipe have remote control. The crane handles are brought into the engine compartment above the engine.

Louvre shutters are designed to change the amount of air passing through the radiator. The driver controls them with a cable and a handle brought into the cab.

The water pump is used to create water circulation in the cooling system. It consists of a housing, a shaft, an impeller and a self-sealing stuffing box. The pump is usually located in the front of the cylinder block and is driven by a V-belt from the engine crankshaft. The pulley drives the water pump impeller and fan hub simultaneously.

cooling system car repair

The self-sealing stuffing box consists of a rubber seal, a graphitized textolite washer, a clip and a spring that presses the washer against the end of the inlet pipe.

The fan is designed to increase the flow of air passing through the radiator. The fan usually has 4-6 blades. To reduce noise, the blades are arranged in an X-shape, in pairs at an angle of 70 and 110°. The blade is made of sheet steel or plastic.

The blades have bent ends (ZMZ-53, ZIL-130), which improves ventilation engine compartment and improves fan performance. Sometimes the fan is placed in a casing, which helps to increase the speed of air sucked through the radiator.

To reduce the power required to drive the fan and improve the operation of the cooling system, fans with an electromagnetic clutch (GAZ-24 Volga) are used. This clutch automatically turns off the fan when the temperature of the water in the upper tank of the radiator is below 78-85°C.

The thermostat automatically maintains a stable thermal regime of the engine. As a rule, they are installed at the outlet of the coolant from the cooling jackets of the cylinder heads or the engine intake pipe. Thermostats can be liquid and solid filled.

The liquid thermostat has a corrugated cylinder filled with an easily evaporating liquid. The lower end of the cylinder is fixed in the thermostat housing, and a valve is soldered to the stem from the upper end.

When the coolant temperature is below 78°C, the thermostat valve is closed, and all the liquid through the bypass hose is sent back to the water pump, bypassing the radiator. As a result, overheating of the engine and intake manifold is accelerated.

When the temperature exceeds 78°C, the pressure in the balloon increases, it lengthens and lifts the valve. Hot liquid through a branch pipe and a hose goes to the top tank of a radiator. The valve fully opens at a temperature of 91°C (ZMZ-53). The thermostat with a solid filler (ZIL-130) has a cylinder filled with ceresin and closed with a rubber diaphragm. At a temperature of 70-83°C, ceresin melts, expanding, moving up the diaphragm, buffer and rod. This opens the valve and coolant begins to circulate through the radiator.

As the temperature drops, ceresin hardens and shrinks in volume. Under the action of the return spring, the valve closes and the diaphragm moves down.

In the engines of VAZ-2101 Zhiguli cars, the thermostat is made as a two-valve and is installed in front of the water pump. With a cold engine, most of the coolant will circulate in a circle: water pump→cylinder block→cylinder head→thermostat→water pump. In parallel, the liquid circulates through the jackets of the inlet pipeline and the mixing chamber of the carburetor, and when the valve of the passenger room heater is open, through its radiator.

When the engine is not fully warmed up (fluid temperature is below 90°C), both thermostat valves are partially open. Part of the fluid goes to the radiator.

When the engine is fully warmed up, the main flow of fluid from the cylinder head is directed to the radiator of the cooling system.

To control the temperature of the coolant, signal lamps and pointers on the instrument panel are used. Instrumentation sensors are located in the cylinder heads, the upper radiator tank and the intake manifold cooling jacket.

Device Features

coolant pump central type, is driven from the crankshaft pulley by a V-belt. The fan has a four-bladed impeller, which is bolted to the pulley hub and is driven by the pump drive belt. The thermostat with a solid sensitive filler has a main valve and a bypass valve. Beginning of opening of the main valve at a coolant temperature of 77-86°C, the stroke of the main valve is at least 6 mm. Radiator - vertical, tubular-plate, with two rows of tubes and tinned steel plates. The filler cap has an inlet and an outlet valve.

A warning.

Checking the level and density of liquid in the cooling system

The correct filling of the cooling system is checked by the liquid level in expansion tank, which on a cold engine (at 15-20 ° C) should be 3-4 mm higher than the “MIN” mark on the expansion tank.

A warning. It is recommended to check the coolant level on a cold engine, because when heated, its volume increases and in a warm engine, the fluid level can rise significantly.

If necessary, check the density of the coolant with a hydrometer, which should be 1.078-1.085 g / cm³. At low density and at high density (more than 1.085-1.095 g / cm³), the temperature of the beginning of liquid crystallization rises, which can lead to its freezing in the cold season. If the fluid level in the tank is below normal, then top up with distilled water. If the density is normal, add fluid of the same density and grade as is in the system. If below normal, bring it up to it using TO-SOL-A liquid.

Filling the cooling system with liquid

Refueling is carried out when changing the coolant or after repairing the engine. Carry out the filling operations in the following order:

1. Remove the plugs from the radiator and from the expansion tank and open the heater valve;

2. Fill the coolant into the radiator, and then into the expansion tank, after placing the radiator cap. Close the expansion tank with a stopper;

3. Start the engine and let it run for Idling 1-2 min to remove air pockets. After the engine has cooled down, check the coolant level. Jew. If the level is below normal, and there are no signs of leakage in the cooling system, add fluid.

Pump Drive Belt Tension Adjustment

Belt tension is checked by deflection between the pulleys of the pump generator or between the pump and the crankshaft. Under normal belt tension, deflection "BUT" under a force of 10 kgf (98N) should be within 10-15 mm, and the deflection " IN" within 12-17 mm. To increase belt tension, loosen the alternator fastening nuts, move it away from the engine and tighten the nuts.

coolant pump

To disassemble the pump: - Disconnect the pump housing from the cover; - fix the cover in a vice, using gaskets, and remove the impeller of the roller with a puller A.40026; - remove the hub of the fan pulley from the roller using a puller А.40005/1/5; - unscrew the locking screw and remove the bearing with the pump shaft; - remove the gland from the housing cover.

Check the axial clearance in the bearing (should not exceed 0.13 mm at a load of 49N (5 kgf)), especially if significant pump noise was noted. Replace bearing if necessary. It is recommended to replace the pump seal and the gasket between the pump and the cylinder block during repairs. Inspect pump body and cover for deformation or cracks

Assembling the pump: - install the stuffing box with a mandrel, avoiding distortion, into the housing cover; - press the bearing with the roller into the cover so that the seat of the locking screw coincides with the hole in the cover of the pump casing; - tighten the bearing lock screw and caulk the contours of the socket so that the screw does not loosen; - press the pulley hub onto the roller using tool A.60430, keeping the size 84.4 + 0.1 mm. If the hub is made of cermet, then after removing it, press only a new one; - press the impeller onto the roller using tool A.60430, which provides a technological gap between the impeller blades and the pump housing of 0.9-1.3 mm; - assemble the pump housing with a cover, install a gasket between them.

Thermostat

At the thermostat, the temperature of the start of opening and the stroke of the main valve should be checked. To do this, install the thermostat on the stand BS-106-000, lowering it into a tank with water or coolant. Jew. Place the bracket of the indicator leg into the main valve from below. The initial temperature of the liquid in the tank should be 73-75°C. The temperature of the liquid gradually increases by about 1°C / m with gradual coloring so that it is the same throughout the volume of the liquid. The temperature at which the main valve stroke is 0.1 mm is taken as the temperature at which the valve opens. The thermostat must be replaced if the temperature at which the main valve opens is not within 81+5/4°C or if the valve stroke is less than 6 mm. The simplest check The thermostat can be operated by touch directly on the car. After starting a cold engine with a working thermostat, the lower radiator tank should heat up when the needle of the fluid temperature gauge is approximately 3-4 mm from the red zone of the scale, which corresponds to 80-85 ° C.

Radiator

To remove the radiator from the car: - drain the liquid from it and the cylinder block by removing drain plugs in the lower radiator tank and on the cylinder block; at the same time, open the valve of the body heater, and remove the radiator cap from the filler neck; - Disconnect the hoses from the radiator; - Remove the fan cover; - unscrew the bolts securing the radiator to the body, remove the radiator from the engine compartment.

The tightness is tested in a bath of water. Having plugged the radiator pipes, bring air to it under a pressure of 0.1 MPa (1 kgf / cm²) and lower it into a bath of water for at least 30 s. In this case, air etching should not be observed. Slightly damage the brass radiator, solder with soft solder, and if significant, replace with a new one.

Cooling system repair

Main possible water pump parts defects: chips and cracks in the body, thread stripping in the holes, wear of seats for bearings and thrust bushing; bending and wear of the seat for the impeller on the shaft, under bushings, seals and fan pulleys; wear, cracks and corrosion of the surface of the impeller blades; wear of the inner surface of the bushings and the keyway. The housing of the cooling pump is made from ZIL-130 aluminum alloy AL4, the bearing housing is made of gray cast iron; for ZMZ-53 - from SCH 18-36, for YaMZ KamAZ - from SCH 15-32. The main defects in the housing of the bearings of the water pump of the ZIL-130 engine: wear of the end surface under the thrust washer; breaks of the end of the nest and wear of the hole for the rear bearing; and wear on the front bearing hole.

Cracks and breaks in the body are welded or sealed with synthetic materials. Chips on the flange and cracks on the body are repaired by welding. The part is preheated. We recommend welding with an oxy-acetylene neutral flame. Cracks can be sealed with epoxy. Worn surfaces for bearings with gaps of not more than 0.25 mm should be restored with Unigerm-7 and Unigerm-11 sealants. With a gap of more than 0.25 mm, thin (up to 0.07 mm thick) steel tapes are required to eliminate the defect.

The bent roller is corrected under a press, and the worn one is less than permissible restored by chrome plating and subsequent grinding to the nominal size. The worn keyway on the shaft is welded, and then a new groove is milled at an angle of 90-180° to the old one.

Impellers can be made by casting from aluminum alloy or nylon. In this case, the hub (sleeve) must be steel.

After reconditioning, the cooling pump housing must comply with the following technical requirements: end runout of the surface of the bearing housing under the thrust washer of the impeller relative to the axis of the holes for the bearings is not more than 0.050 mm; runout of the end surface of the collar of the bearing housing under the pump housing relative to the holes for the bearings is not more than 0.15 mm; the surface roughness of the bearing housing for the impeller thrust washer is not more than Ra=0.80 µm, the surface roughness of the bearing holes is not more than Ra=1.25 µm.

Rollers for cooling pumps are made at ZIL and ZMZ from steel 45, HRC 50-60; at YaMZ - from steel 35, HB 241-286; at KamAZ - from steel 45X, HRC 24-30. The main defects of the roller: wear of the surface under the bearings; wear of the neck under the impeller; groove wear; thread damage.

Worn surfaces are restored by surfacing in carbon dioxide, followed by chromium plating or iron plating, followed by grinding on a centerless grinding machine. On the sealing washer, risks and wear to a depth of not more than 0.5 mm are allowed. With more wear, the washer is replaced. When installing the roller, 100 g of Litol-24 grease should be placed in the inter-bearing cavity. The sealing washer and the end face of the support sleeve should be coated with a thin layer of sealant or grease, consisting by weight of 60% before installation. diesel oil and 40% graphite.

Worn or damaged threads in holes are repaired by threading repair size or welding with subsequent threading of nominal size.

After assembly, the gap between the water pump housing and the impeller blades should be 0.1 ... 1.5 mm and the roller should rotate easily.

Water pumps are run in and tested on special stands, for example, pumps for YaMZ-240B engines - at the OR-8899 stand, D-50 and D-240 engines - at KI-1803, and ZMZ-53 engines - at OR-9822. The run-in is performed for 3 minutes at a water temperature of 85 ... 90 ° C and tested according to the regime.

Each repaired pump is checked for tightness at a pressure of 0.12 ... 0.15 MPa. Leakage of water through seals and stud threads is not allowed.

Possible fan parts defects the following: wear of seats in the pulleys for the outer rings of rolling bearings, wear of the streams in the pulleys for the belt, loosening of the rivets on the cross, bending of the cross and blades.

worn out seats under bearings are restored by ironing, chrome plating. Worn pulley streams (up to 1 mm) are machined. Loose rivets on the cross of the blades are tightened. If the holes for the rivets are worn out, they are reamed and rivets of increased diameter are installed. The leading edges of the blades after riveting should lie in the same plane with a deviation of no more than 2 mm. The template checks the shape of the fan blades and their angle of inclination relative to the plane of rotation, which should be within 30 ... 35 ° (if necessary, correct).

The fan assembled with a pulley is statically balanced. To eliminate the imbalance, unbalance recesses are drilled, recesses are drilled in the end of the pulleys or the blade is made heavier from its convex side by welding or riveting the plate.

If in drive fluid coupling the fan leaks oil through the seals, there is an axial clearance and jamming of the driven and driving shafts when the impeller blades and pulley rotate by hand, repairs are needed.

Defects in fluid coupling parts are similar to defects in fan parts. This also leads to similar ways to eliminate them. Fluid coupling ball bearings must be replaced if the axial and radial clearance is more than 0.1 mm.

When assembling, the gap between the driven and driving wheels of the fluid coupling should be 1.5 ... 2 mm. The fluid coupling drive pulley with a fixed fan hub and, conversely, the hub with a fixed pulley must rotate freely. The thermal power sensor of the hydraulic clutch switch is regulated by setting the shims to turn on at a coolant temperature of 90 ... 95 ° C and to turn off at its temperature of 75 ... 80 ° C.

Radiators of the cooling system made of: upper and lower tanks and tubes - brass, cooling plates - copper, frame and brass; oil cooler tanks - steel.

Radiators can have the following main defects: scale deposits on the inner walls of tubes and tanks, their damage and contamination of the outer surfaces of the tubes, core, cooling plates and frame plates, tube leaks, holes, dents or cracks in the tanks, leakage in soldering points. After removal from the car, the radiator enters the repair site, where it is washed from the outside and defective by external inspection and leak testing compressed air under pressure of 0.15 MPa for oil coolers in a bath with water at a temperature of 30 ... 50 ° C. When testing, sealing with rubber plugs, the water radiator is filled with water and excess pressure is created by the pump: within 3 ... 5 minutes, the radiator should not leak. If leaks are found, the radiator is disassembled, the core is placed in a bath of water and, by supplying air through the hose from the hand pump into each tube, the bubbles determine the location of the damage. Pollution and scale are removed in installations that provide heating of the solution to 60-80 ° C, its circulation and subsequent flushing of the radiator with water. The holes are closed with rubber plugs, through one of which it enters through the hose for defects. When radiators are repaired without dismantling (without removing the drums), the leak test is carried out after descaling.

Leakage pipes are eliminated by soldering. Damaged tubes located in the inner rows are soldered (muffled) from both ends. It is allowed to solder up to 5% of the tubes, with a larger number of damaged tubes are replaced. Replace with new plugged tubes and tubes with large dents. To do this, hot air is blown through the tubes, heated to 500-600 ° C in a coil mounted on a blowtorch. When the solder is melted, the tube is removed with special pliers with a tongue of size and shape corresponding to the cross section of the tube opening. You can solder the tubes with a ramrod heated to 700-800 ° C in a furnace, or pass electric current through it from a welding transformer. Old tubes are removed and new or repaired tubes are inserted in the direction of the cooling plate antennae. The tubes are soldered to the base plates with solder.

According to another technology, a defective tube is expanded to a large diameter (a square-section ramrod is used for round tubes or a knife-shaped one with a broadening at the end for flat ones) and a new one is inserted, soldering it to the base plates at the ends.

The total number of newly installed or sleeved tubes for diesel engines should not be more than 20% of their total number, and for carburetor engines — 25%.

In case of large damage, after soldering the support plates, cut out the defective part of the radiator (use band saws and instead install the same part of the radiator from another rejected one, soldering all the tubes to the support plates.

Cracks in cast iron tanks are repaired by welding. In brass tanks, cracks and breaks are repaired by soldering.

The dents of the tanks are eliminated by straightening, for which the tank is put on a wooden blank and the damage is leveled with a wooden hammer. Holes are eliminated by setting patches from sheet brass, followed by soldering them. Cracks are soldered.

Damage to the frame plates is eliminated by gas welding. Wrinkled radiator plates are straightened with a comb.

The repaired radiator is checked in the bath, after pumping air into it.

Repair operations for oil coolers are similar to those for water coolers. Resinous reflections in them are removed in the preparation AM-15. Soldering of tubes to tanks is performed by copper-zinc solder PMC gas welding. Oil coolers are tested at a pressure of 0.3 MPa.

When repairing thermostats- remove scale. Damage to the place of the spring box is sealed with POS-40 solder. Spring boxes are filled with a 15% solution of ethyl alcohol.

When testing the thermostat in a bath of water, the opening of the valve should be 70°C, and the full opening at 85°C. The height of the full valve lift is 9-9.5 mm. It is adjusted by turning the valve on the threaded end of the spring box shank.

Conclusion

Diagnostic methods using electronic equipment are increasingly being introduced into car maintenance. Diagnostics allows you to timely identify malfunctions of the units and systems of the car and eliminate them before they cause serious violations. Objective assessment methods technical condition units and components of the car help to eliminate defects in time that can cause emergency which improves road safety.

The use of modern equipment for the performance of maintenance and repair of vehicles facilitates and speeds up many production processes, but requires the maintenance personnel to master a certain range of knowledge and skills: the device of a car, the basic technological processes of maintenance and repair, the ability to use modern instrumentation, tools and fixtures.

To study the device and the processes of operation of car mechanisms, knowledge of physics, chemistry, and the basics of electrical engineering is required in the scope of secondary school programs.

The use of modern equipment and devices for performing assembly and dismantling of car repairs does not exclude the need to master the skills of general plumbing work, which a worker involved in repairs should possess.

Well-organized maintenance, timely elimination of faults in the units and systems of the car, with highly qualified work, can increase the durability of cars, reduce their downtime, increase the time between repairs, which ultimately significantly reduces unproductive costs and increases the profitability of vehicle operation.

Let's remember a little more about this system cooling.

IN liquid cooling system special coolants are used - antifreezes of various brands, having a thickening temperature of - 40 ° C and below. Antifreezes contain anti-corrosion and anti-foam additives that prevent scale formation. They are highly toxic and require careful handling. Compared to water, antifreezes have a lower heat capacity and therefore remove heat from the engine cylinder walls less intensively.

So, when cooling with antifreeze, the temperature of the cylinder walls is 15 ... 20 ° C higher than when cooling with water. This accelerates engine warm-up and reduces cylinder wear, but in summer time may cause the engine to overheat.

The optimal temperature regime of the engine with a liquid cooling system is considered to be one at which the temperature of the coolant in the engine is 80 ... 100 ° C in all engine operating modes.

Used in car engines closed(sealed) liquid cooling system with forced circulation coolant.

The internal cavity of a closed cooling system does not have a permanent connection with the environment, and communication is carried out through special valves(at a certain pressure or vacuum) located in the plugs of the radiator or expansion tank of the system. The coolant in such a system boils at 110 ... 120 ° C. Forced circulation of coolant in the system is provided by a liquid pump.

Engine cooling system includes from:

• cooling jacket for the head and cylinder block;
• radiator;
• pump;
• thermostat;
• fan;
• expansion tank;
• connecting pipes and drain cocks.

In addition, the cooling system includes a heater for the interior of the car body.

The principle of operation of the cooling system

I suggest you first consider circuit diagram cooling systems.

1 - heater; 2 - engine; 3 - thermostat; 4 - pump; 5 - radiator; 6 - cork; 7 - fan; 8 - expansion tank;
And — a small circle of circulation (the thermostat is closed);
A + B - a large circle of circulation (the thermostat is open)

The circulation of liquid in the cooling system is carried out in two circles:

1. Small circle- the fluid circulates when starting a cold engine, ensuring its rapid warm-up.

2.Big circle- the movement circulates when the engine is warm.

To put it simply, the small circle is the circulation of coolant WITHOUT a radiator, and the large circle is the circulation of coolant THROUGH the radiator.

The device of the cooling system differs in its structure depending on the model of the car, however, the principle of operation is the same.

The principle of operation of this system can be seen in the following videos:

I propose to disassemble the device of the system according to the sequence of work. So, the beginning of the operation of the cooling system occurs when the heart of this system, the liquid pump, is started.

1. Water pump

The liquid pump provides forced circulation of liquid in the engine cooling system. Centrifugal-type vane pumps are used on car engines.

You should look for our fluid pump or water pump on the front of the engine (the front is the one that is closer to the radiator and where the belt / chain is located).

The liquid pump is connected by a belt to the crankshaft and the generator. Therefore, to find our pump, it is enough to find the crankshaft and find the generator. We'll talk about the generator later, but for now I'll just show you what to look for. The generator looks like a cylinder attached to the engine case:

1 - generator; 2 - liquid pump; 3 - crankshaft

So, we figured out the location. Now let's look at its device. Recall that the structure of the entire system and its parts is different, but the principle of operation of this system is the same.

1 - Pump cover;2 — A persistent sealing ring of an epiploon.
3 - Oil seal; 4 - Pump roller bearing.
5 - Fan pulley hub;6 - Locking screw.
7 - Pump roller;8 - Pump housing;9 - Pump impeller.
10 - Receiving pipe.

The operation of the pump is as follows: the pump is driven from the crankshaft through a belt. The belt turns the pump pulley by turning the pump pulley hub (5). That, in turn, drives the pump shaft (7), at the end of which there is an impeller (9). The coolant enters the pump housing (8) through the intake pipe (10), and the impeller moves it into the cooling jacket (through a window in the housing, as seen in the figure, the direction of movement from the pump is shown by an arrow).

Thus, the pump is driven by the crankshaft, the liquid enters it through the intake pipe and goes into the cooling jacket.

The operation of the liquid pump can be seen in this video (1:48):

Let's now see where the fluid comes from in the pump? And the liquid enters through a very important part - the thermostat. It is the thermostat that controls the temperature.

2. Thermostat

The thermostat automatically adjusts the water temperature to speed up engine warm-up after starting. It is the operation of the thermostat that determines in which circle (large or small) the coolant will go.

This unit looks like this in reality:

The principle of operation of the thermostat very simple: the thermostat has a sensitive element, inside of which there is a solid filler. At a certain temperature, it begins to melt and opens the main valve, while the additional one, on the contrary, closes.

Thermostat device:

1, 6, 11 - branch pipes; 2, 8 - valves; 3, 7 - springs; 4 - balloon; 5 - diaphragm; 9 - stock; 10 - filler

The operation of the thermostat is simple, you can see it here:

The thermostat has two inlet pipes 1 and 11, an outlet pipe 6, two valves (main 8, additional 2) and a sensitive element. The thermostat is installed in front of the inlet to the coolant pump and is connected to it through pipe 6.

Compound:

Acrossbranch pipe 1 connects fromengine cooling jacket,

Across branch pipe 11- with bottom diverting radiator tank.

The sensitive element of the thermostat consists of a cylinder 4, a rubber diaphragm 5 and a rod 9. Inside the cylinder, between its wall and the rubber diaphragm, there is a solid filler 10 (fine-crystalline wax), which has a high volume expansion coefficient.

The main valve 8 of the thermostat with spring 7 starts to open when the coolant temperature exceeds 80 °C. At a temperature of less than 80 ° C, the main valve closes the outlet of the liquid from the radiator, and it flows from the engine to the pump, passing through the open additional valve 2 of the thermostat with spring 3.

When the temperature of the coolant rises above 80 °C, the solid filler melts in the sensitive element, and its volume increases. As a result, the rod 9 comes out of the cylinder 4, and the cylinder moves up. At the same time, additional valve 2 begins to close and at a temperature of more than 94 ° C blocks the passage of the coolant from the engine to the pump. The main valve 8 in this case opens completely, and the coolant circulates through the radiator.

The operation of the valve is clearly and clearly shown in the figure below:

A - a small circle, the main valve is closed, the bypass valve is closed. B - a large circle, the main valve is open, the bypass valve is closed.

1 - Inlet pipe (from the radiator); 2 - Main valve;
3 - Thermostat housing; 4 - Bypass valve.
5 - Branch pipe of the bypass hose.
6 - Pipe for supplying coolant to the pump.
7 - Thermostat cover; 8 - Piston.

So, we figured out the small circle. We disassembled the device of the pump and thermostat connected to each other. And now let's move on to the big circle and the key element great circle- radiator.

3. Radiator(radiator/cooler)

Radiator ensures the removal of heat from the coolant to the environment. On the cars tubular-lamellar radiators are used.

So, there are 2 types of radiators: collapsible and non-collapsible.

Below is their description:

I want to say again about the expansion tank (expansion tanks)

A fan is installed next to the radiator or on it. Let's now move on to the device of this very fan.

4. Fan(fan)

The fan increases the speed and amount of air passing through the radiator. Four- and six-blade fans are installed on car engines.

If a mechanical fan is used,

The fan includes six or four blades (3) riveted to the crosspiece (2). The latter is screwed to the fluid pump pulley (1) which is driven by the crankshaft via a belt drive (5).

As we said earlier, the generator (4) is also engaged.

If an electric fan is used,

then the fan consists of an electric motor 6 and a fan 5. The fan is four-blade, mounted on the motor shaft. The blades on the fan hub are located unevenly and at an angle to the plane of its rotation. This increases the flow of the fan and reduces the noise of its operation. For more efficient operation, the electric fan is placed in casing 7, which is attached to the radiator. The electric fan is attached to the casing on three rubber bushings. The electric fan is switched on and off automatically by sensor 3, depending on the temperature of the coolant.

So let's sum it up. Let's not be unfounded and summarize on some picture. You should not focus on a specific device, but you need to understand the principle of operation, because it is the same in all systems, no matter how different their device is.

When the engine is started, the crankshaft starts to rotate. Through a belt drive (let me remind you that the generator is also located on it), rotation is transmitted to the pulley of the liquid pump (13). It drives the impeller shaft inside the fluid pump housing (16). The coolant enters the engine cooling jacket (7). The coolant then returns to the fluid pump through the outlet (4) through the thermostat (18). At this time, the bypass valve in the thermostat is open, but the main valve is closed. Therefore, the liquid circulates through the engine jacket without the participation of the radiator (9). This ensures that the engine warms up quickly. As the coolant heats up, the main thermostat valve opens and the bypass valve closes. Now fluid cannot flow through the thermostat bypass (3) and is forced to flow through the inlet (5) into the radiator (9). There the liquid is cooled and flows back to the liquid pump (16) through the thermostat (18).

It is worth noting that some of the coolant enters the heater from the engine cooling jacket through pipe 2 and returns from the heater through pipe 1. But we will talk about this in the next chapter.

I hope now the system will become clear to you. After reading this article, I hope it will be possible to navigate in another cooling system, understanding the principle of this one.

I suggest you also take a look at the following article:

Since we have touched on the heating system, my next article will be about this system.

The engine is almost identical on all machines. Modern cars use a hybrid system. Yes, it is, because not only liquid, but also air is involved in cooling. They blow the radiator cells. Due to this, cooling is much more efficient. It's no secret that at low speeds, the circulation of the liquid does not save - you have to additionally install a fan on the radiator.

radiator fan

Let's talk about domestic cars, for example, about the Lada. To ensure better heat transfer, the engine cooling system ("Kalina"), the circuit of which has a standard configuration, contains a fan. Its main function is to blow air into the radiator cells when the liquid reaches a critical temperature. Operation is controlled by a sensor. On domestic cars, it is installed at the bottom of the radiator. In other words, there is a liquid that has given off heat to the atmosphere. And it should have a temperature of 85-90 degrees at this point of the contour. If this value is exceeded, it is necessary to carry out additional cooling, otherwise boiling water will enter the engine jacket. Consequently, the operation of the motor will occur at critical temperatures.

Cooling radiator

It serves to release heat into the atmosphere. The liquid passes through the cells, which have narrow channels. All these cells are connected by thin plates that improve heat transfer. When moving at high speed, the air passes between the cells and contributes to the rapid achievement of the result. This element contains any circuit of the engine cooling system. Volkswagen, for example, is no exception.

Above was considered a fan that is mounted on a radiator. It blows air when the critical temperature is reached. To improve the efficiency of the element, it is necessary to monitor the cleanliness of the radiator. Its cells are clogged with debris, heat transfer is deteriorating. Air does not pass well through the cells, heat is not released. The result - the temperature of the engine rises, its operation is disturbed.

System thermostat

It is nothing more than a valve. It reacts to temperature changes in the cooling circuit. More about them will be discussed below. The scheme of the UAZ engine cooling system is based on the use of a high-quality thermostat, which is made of a bimetallic plate. Under the action of temperature, this plate is deformed. You can compare it with a circuit breaker used in the power supply of houses and enterprises. The only difference is that it is not the switch contacts that are controlled, but the valve that supplies hot liquid to the circuits. The design also has a return spring. When the bimetallic plate cools down, it returns to its original position. And the spring helps her to return.

Sensors used in refrigeration

Only two sensors are involved in the work. One is mounted on the radiator, and the second - in the jacket of the engine block. Let's go back to domestic cars and remember the Volga. The engine cooling system circuit (405) also has two sensors. Moreover, the one that is located on the radiator has a simpler design. It is also based on a bimetallic element, which deforms with increasing temperature. This sensor turns on the electric fan.

On cars of the classic VAZ series, a direct fan drive was previously used. The impeller was installed directly on the axis of the pump. The rotation of the fan was made constantly, regardless of the temperature in the system. The second sensor, installed in the engine jacket, serves one purpose - transmitting a signal to the temperature indicator in the cabin.

Liquid pump

Let's go back to the Volga. The cooling system, the circuit of which contains a circulation liquid pump, cannot simply function without it. If you do not give the fluid movement, then it will not be able to move along the contours. Consequently, stagnation will appear, the antifreeze will begin to boil, and the motor may jam.

The design of the liquid pump is very simple - an aluminum casing, a rotor, a drive pulley on one side and a plastic impeller on the other. Installation is made either inside the engine block or outside. In the first case, the drive is carried out, as a rule, from the timing belt. For example, on VAZ cars, starting from model 2108. In the second case, the drive is carried out from a pulley

Stove outline

Some cars manufactured several decades ago were equipped with engines with air-cooled. There is only one inconvenience in this case: I had to use a gasoline stove, which “ate” a lot of fuel. But if liquid circuits of engine cooling systems are used, you can take hot antifreeze, which is supplied to the radiator. Thanks to the stove fan, hot air is supplied to the cabin.

In all cars, the stove radiator is mounted under the instrument panel. First, an electric fan is installed, then a radiator is installed on it, and air ducts fit on top. They are necessary for the distribution of hot air throughout the cabin. In new cars, its distribution is controlled by microprocessor systems and stepper motors. They open or close the dampers depending on the temperature in the cabin.

Expansion tank

Everyone knows that any liquid expands when heated - increases in volume. So it needs to go somewhere. But on the other hand, when the liquid cools, its volume decreases, therefore, it must be added to the system again. It is impossible to do this manually, but with the help of an expansion tank, this procedure can be automated.

Most modern cars schemes of sealed type engine cooling systems are used. For these purposes, there is a plug on the expansion tank with two valves: one for the inlet, the second for the outlet. This allows the pressure in the system to be close to one atmosphere. With a decrease in its indicator, air is sucked in, with an increase, it is discharged.

Branch pipes of cooling systems

This diagram shows the most common water cooling scheme for a typical internal combustion engine. The vast majority of modern cars work with such systems.

Types of cooling systems

In modern engines, there are two mechanisms and three (or four) systems:

• the mechanism for distributing the flows of the air-fuel mixture and exhaust gases - called timing;
• crank-connecting rod (KShM) - this is a mechanism for "coordinating" the movement of pistons in cylinders with the operation of power systems and, if provided for by the design, the ignition system;
• supply system;
• Lubrication system;
• ignition system - only for gasoline (injector and / or carburetor) and gas ICEs, this system is not needed in diesel engines;
• heat dissipation system, i.e. cooling.

In modern automotive industry, two systems have found application - liquid and air. They also call the third - combined, but this, as they say, "according to science" - in theoretical mechanics and car theory.

At the moment of ignition of the working mixture, the temperature in the cylinders can reach above 2000 ° (two thousand degrees) Celsius, and the cooling system is designed to maintain the calculated temperature balance, which ranges from 90 to 120 degrees. From the point of view of theoretical mechanics, the liquid systems used in modern internal combustion engines are, in fact, hybrid or combined. However, in practice, and even the servicemen themselves, they call it liquid, and more often - water, although antifreezes have long been used instead of water.

Liquid cooling systems - specifics

Why water? Why a water-cooled engine? The answer is obvious, in automobile engines it was just that. Even today, cars of old designs are driving on our roads, in which an expansion tank was not even provided. For uselessness. BUT working temperature fluctuated around 70-90 degrees. In modern internal combustion engines, the so-called hermetic system is used, and increased pressure (up to 1.4 atmospheres) allows modern antifreezes not to boil at temperatures up to 120 degrees and - of course - not to freeze to minus 70-80 degrees Celsius.

The vast majority of liquid cooling systems operate from a centrifugal water pump (pump), as well as under the influence of the natural laws of physics - convection, heating and cooling.

The main components of the liquid cooling system

These systems are single-circuit, double-circuit and multi-circuit. The device of the engine cooling system is not difficult, in its " standard list» includes:

• cooling jacket of the cylinder block itself;
• cooling jacket of the head (or heads) of the cylinder block, both have so-called cooling fins, they are external, which is why the theory of the car calls this system combined;
• one or more cooling radiators;
• one or more fans for forced cooling of radiators (or a radiator, if there is one);
• a fluid pump, which mechanics among themselves call a water pump or pump; structurally, it is a centrifugal type pump, drives are gear, belt or electric;
• thermostat (in double-circuit systems old type of motors without the use of electronics);
• expansion tank with a lid not sealed, but calibrated under a certain pressure;
• connecting pipes of the engine cooling system;
• interior heater heat exchanger (or heat exchangers for heaters of interior parts in multi-zone climate control systems);
• coolant temperature sensor (or sensors);
• electronic control unit for cooling, as well as ventilation and heating of the passenger compartment.

The mechanic has the same notorious thermostat in his hand, dividing the system into two circuits. When the engine warms up, the coolant circulates in a closed, so-called "small circle", without getting into the radiator. Warming up of the cooling jackets of the block and the cylinder head to operating temperatures is faster.

Cooling system diesel engine does not fundamentally differ from the gasoline system. The differences are in designs, volumes, capacities and some other parameters, but not in the type of fuel used.

Oil cooling

The lubrication system in modern automobile engines, in addition to its main task - the lubrication of rubbing parts, - performs another one - heat removal: motor oil removes some of the heat from the working mating parts of the motor. Many modern engines even have their own oil cooler, which in other technological maps and instructions and is called - an oil cooler.

Is air cooling used today?

Yes, it does, and quite successfully. In modern motor building, two types of them are distinguished: natural (by blowing incoming air) and forced (with the help of fans).

Natural cooling is more often used in motor aviation. Forced - for example, in such structures as water and wheeled scooters (motor scooters), in walk-behind tractors and other agricultural and communal units and mechanisms.

In the automotive industry, one can recall some Volkswagen models Group - Porsche, Beetle, aka Kafer, as well as the Italian Fiat-500, the French Citroën 2CV, the Czech passenger car Tatra-613 or the native and painfully familiar national car of the USSR - Zaporozhets.

The history of engine building can also recall air-cooled tractor engines, as well as trucks with multi-cylinder diesel engines. The same, for example, the Czech 12-ton Tatra was produced until 2010 and is still "in service". By the way, the driver's cabin of this dump truck is heated by a special electric heater, and the interior of Zaporozhets is heated by an autonomous ... gasoline.

In the photo - "the same" 8-cylinder V-shaped diesel power unit Tatra with direct air cooling. Displacement 12.7 liters with turbocharger and intercooler, power - from 312 to 442 hp, with torque - from 1400 to 2100 Nm, within the framework of compliance with the requirements of standards from Euro 2 to Euro 5.

Evaporative cooling systems

It has not found wide application in modern automotive industry. The mechanics of its work is that the water is brought to a temperature well above the boiling point, and the temperature drops as a result of its evaporation. It was used in experimental aircraft construction models at the very beginning of the 20th century, and today a similar design can be found on diesel engines with a power of up to 20 hp. - on minitractors, in mobile walk-behind tractors, etc.

Malfunctions of the engine cooling system

The weakest link in most systems is the radiators. As a rule, they are installed in the front parts of the car, even if the engine is installed in the base or behind rear axle. This is done so that the coolant gives off heat to the oncoming air flow.

Radiator cells become clogged with fine dust, insects and other road pollution, as a result, the thermal conductivity of the radiator drops, and the temperature regime of the engine is disturbed. In addition, radiators are subject to mechanical damage on high speeds, which is why, for example, a hallmark of a powerful and high speed machine is a fine mesh in wide and huge air intakes.

Cavitation destruction of a liquid pump of classical design.

The most costly malfunction of auto mechanics is called a breakdown of the water (liquid) pump. It is worth the driver to miss the pointer in the red zone of the temperature gauge or the indicator on the instrument panel that lights up in red, and the consequences can be very sad. Up to overhaul engine.

In engines of older designs, a particular headache for car owners was the loss of thermostat performance.

Also periodically fail:

• sensors and indicators;
• the pipe may leak or loosen the clamp on the pipe connections;
• cooling fans do not turn on in time;
• sometimes the pressure valve in the plug of the expansion tank fails.

These and many other malfunctions lead to loss of antifreeze, overheating of the block and its head (heads) and, in the end, to engine failure. Any suspected malfunction in the cooling system must be immediately identified and repaired by the driver.

Symptoms of engine overheating or insufficient heating

During critical overheating occurs:

• periodic departure of the arrow of the temperature indicator on dashboard to the red sector (or the appearance of a red indicator in those cars where the indicator is not provided);
• loss of engine power in seemingly "innocuous situations";
• inadequately high heat in the area of ​​\u200b\u200bthe engine compartment.

In case of insufficient heating:

• the arrow "does not come off" from the lower sector of the temperature gauge on the dashboard;
• the yellow (or, in some designs, white) indicator of the temperature indicator does not go out;
• as a result, the engine "dulls", does not develop the proper power - and especially when "when it is needed" - on the rise, when overtaking, during emergency maneuvering and / or acceleration.

These, as well as many other, very specific and obscure to the driver, "inadequacy" in the behavior of the engine, its units and the car as a whole.

Diagnosis of leaks in the cooling system

One of the main causes of system failure is a drop in the level of antifreeze in the expansion tank. In addition to banal leaks in leaky connections, the cork on the tank with a calibrated pressure control valve may also fail. Coolant, or rather water from a solution of ethylene glycol (propylene glycol), simply evaporates, and the coolant level drops, the engine overheats.

It is not difficult to monitor the level of coolant in the expansion tank. This is constantly reminded and mentioned: both teachers in driving schools, and various instructions for drivers ... and the engines both boiled and continue to boil. To the delight of mechanics and motorists ...

Coolant level control

This level should be constantly monitored. By the way, during operation (during the working day) it can (and should) change in the tank. This is fine. Abnormal - when this level drops below the lower mark, which means a loss of fluid, or higher, which may mean, for example, a breakthrough of crankcase gases into the cooling system. And this is already a very disturbing call.

In the conditions of a specialized service station, level and pressure control in the system is carried out using special equipment and tools. An ordinary car owner has only one trick in his arsenal - systematic visual control of the level in the upper tank of the radiator (on older cars, without an expansion tank) or - in the expansion tank for special risks - max and min.

Missing - trouble!

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