What is gbts. cylinder head

26.09.2019

Not many new car owners who have sat behind the wheel for the first time know that the cylinder head is one of the most important parts of the engine.

In this article we will talk about the cylinder head, what it is in the car, the device of the head and the processes taking place in it. We will also consider the main signs of a breakdown of the cylinder head, which will help you notice a malfunction of the power unit in a timely manner, as well as monitor its performance.

Cylinder head, what is it in a car?

The cylinder head or simply the cylinder head is an important part of the engine, located directly above the cylinder block. Every car owner should know this. Since it is in the head that the thermal energy generated from the combustion of fuel is converted into mechanical energy of movement. It is in it that the main mechanisms that carry out this process are concentrated. For this, many mechanics call the cylinder head - "head" or "head", implying that it plays a leading role in the entire engine block.

What is the GBC made of?

According to its structure, the cylinder head consists of a cover and a head housing:

The head cover protects the internal components and mechanisms of the cylinder head from external influences, and also prevents engine oil from leaking. From above it has a hole for filling the motor with oil. The connection of the cover and the body of the head is carried out with the help of screws and a special reusable rubber gasket that does not allow oil to seep between the two components.
In turn, the head housing is the basis in which a large number of important engine components are located. The simplest in structure are cylinder heads in engines with lower valves. Overhead valve motors have a more complex design.

There are many important components in the cylinder head housing, without which starting the engine and its operation is simply impossible. Let's see what functions it performs and what it actually has:

Partially or in full, combustion chambers are located in the cylinder head.
The channels of the lubrication and cooling systems pass.
There are flanged holes for the intake manifold, which, depending on the type of engine, can supply either a fuel mixture or just air.
Also in the cylinder head housing there are holes for the exhaust manifold, through which exhaust gases are discharged.
In the head housing there is a platform and holes for the elements of the gas distribution mechanism, camshaft transmission elements and other components.
There are threaded holes for spark plugs or injectors.
Engines with an overhead camshaft have additional supports.

All these important components interact directly with the head housing, which also has another name - the cylinder head crankcase.

Where the head housing meets the cylinder block, the inner surface is smooth and slightly expanded. This allows the cylinder head to be tightly connected to the cylinder block, as well as to withstand the heavy loads that occur during engine operation.

In addition, a gasket is provided between the joints of the two components. It is made of reinforced asbestos, since it is this material that is able to withstand gas pressure drops and temperature differences, while maintaining a high level of tightness of the oil pipeline channels, the cooling system and the combustion chamber. However, such a gasket is disposable and is no longer suitable for reuse.

What loads are subjected to the cylinder head during engine operation?

During operation of the motor, the head is subjected to the following loads:

Large temperature difference;
Exhaust gas pressure;
Serious mechanical impact.

During the combustion of fuel in different parts of the head, temperature differences can reach up to several hundred degrees. For example, in the area of the combustion chamber, the heating of the metal can be about 300 degrees. In the same place where the channels of the cooling system are located, the temperature will be in the region of 90-95 degrees.

The same can be said about the pressure of gases formed during the combustion of fuel. Uneven loads acting on different parts of the cylinder head can lead to deformation of the metal. To prevent such an outcome, special requirements are imposed on the cylinder head, in particular:

High structural strength;
Long service life;
Strictly adjusted dimensions of the combustion chamber and channels;
Good sealing of gas joints;
Simplicity of design, allowing for the necessary repairs;
Minimum weight and dimensions.

Cylinder head materials

The necessary rigidity of the cylinder head is provided by the power frame, as well as the material from which it is made. In particular, the head is made of aluminum or high-quality cast iron by precision casting.

For carburetor and injection engines, the principle of operation of which is based on forced ignition, aluminum alloys are used. Since this alloy is much lighter than cast iron, it cools better and is also able to dampen detonation.

In diesel engines that operate on the principle of compression ignition, the cylinder head is often made of cast iron. This is done so that the main parts of the engine are resistant to high loads and strong mechanical stress. Although for low-power diesel engines, the cylinder head can also be made of aluminum to reduce the total weight of the engine.

After casting, the head is subjected to a process of milling, drilling, as well as special machining. This procedure allows you to reduce the stress of the metal that occurs during the manufacture of the cylinder head.

The main processes taking place in the cylinder head

Having dealt with the question of the cylinder head, what it is in the car and what it consists of, it is worth talking about the processes and mechanisms that it controls when the engine is running.

As you know, the fuel mixture emits exhaust gas during combustion, it must be removed in a timely manner. This function is carried out by a gas distribution mechanism located in the head housing. It consists of a valve system that opens sequentially at different stages of cylinder operation using a chain drive.

The cylinder head also houses a mechanism for controlling the supply of fuel to the working combustion chambers, as well as a mechanism for removing exhaust gases from the cylinders. This whole process is carried out by the intake and exhaust manifolds.

In turn, during the combustion of fuel, not all of the energy released is converted into energy of motion. Part of the fuel is converted into thermal energy, which to a greater extent heats up the engine parts. In order to cool it, cooling is provided in the head housing, which is a system of channels where the coolant circulates.

To lubricate moving parts in the engine, an oil pipeline system is provided that passes through the cylinder head. And to ensure the tightness of the system, valve stem seals and camshaft seals are placed in the cylinder head.

Design features of the cylinder head

In turn, the shape of the cylinder head for each engine is individual and may vary:

Depending on the location of the combustion chambers.
Ignition parts and their relative position to the cylinders.
The location and total number of parts of the exhaust system.
Various design features of a particular engine.

For example, the classic shape of the in-line engine head closes several cylinders at the same time. The V-shaped engine design uses several separate cylinder heads in one engine, where each row of cylinders has its own head. This design practically prevents deformation, since each head has a fairly small size.

Cylinder heads also differ in the type of formation and supply of a combustible mixture to the combustion chambers. Due to this, the heads for carburetor and injection engines have a slightly different design and differ:

The shape of the combustion chambers;
intake manifold design;
The diameter of its valve and channels.

There are also design features in the cylinder head of diesel engines.

Features of engine assembly after head repair

The necessary rigidity in the head provides a power frame. It consists of vertical bosses that have recesses for bolts and a main base plate located underneath.

During factory assembly, unacceptable deformation of the cylinder head is prevented by a strict sequence of tightening bolts or fastening studs with certain tightening torques. Therefore, after any cylinder head repair, it is important to follow these strict rules. Since any misalignment violates the tightness of the connection and leads to damage to the gasket or damage to the head itself, which subsequently has to be changed.

If, when checking the engine after installing the cylinder head, smudges of oil or coolant are found, then this indicates an incorrect tightening of the bolts and a violation of the tightness of the system.

In turn, the tightening of the bolts is carried out using a torque wrench that controls this process.

Each stud, each bolt must be tightened in a strict order and with control of the fit. Moreover, the tightening torque for different engine models may vary. This data is rarely found in the instruction manual, but they will definitely be in the repair manual for a particular engine.

What happens when the cylinder head malfunctions?

We will not describe all the nuances of this issue, since this topic is for a separate article, but we will still touch on the main problems associated with cylinder head problems. In the event of a breakdown of the gasket or the head itself, the following phenomena can be observed:

Oil can enter the cooling system. You can identify such a problem by antifreeze, it will have a dark, cloudy color with obvious oil deposits, and also have a specific smell.
In addition, antifreeze can enter the lubrication system. As a result, the level of coolant in the reservoir will constantly decrease, and the oil in the engine will become more and more. When checking the oil level in the engine on the dipstick, you can also observe the presence of white foam, an emulsion.
Due to leakage, coolant can also enter the combustion chamber. In this case, white smoke from the exhaust pipe will go constantly, and the level of antifreeze in the tank will gradually decrease.
In addition, exhaust gases from the combustion chamber can enter the cooling system. You can identify the problem by exiting exhaust gas bubbles from the expansion tank while the engine is running.
Also, exhaust gases can enter from one cylinder to another or escape through a crack in the head of the block or if the cylinder head gasket is damaged. If there are no problems with identifying the problem in the second case, then with the first option everything is much more complicated, since there are no visible external damages in this case. However, the first signals of such leaks are a decrease in engine power, increased fuel consumption, and difficult starting of the engine.

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The cylinder head (cylinder head) of a modern car engine is a rather complex assembly. Its purpose is not only to serve as a cover for the engine cylinders, it is a kind of base on which parts of the gas distribution mechanism, intake and exhaust manifolds, are installed. It also has channels for and engine oil, for supplying the fuel mixture to the intake valves and removing exhaust gases.
As a rule, the head is made of an aluminum alloy, but some of its parts, such as guide bushings and valve seats pressed into the cylinder head housing, are made of steel alloys.

Cylinder head (cylinder head) of the VAZ 21083 engine

The cylinder head serves not only as a cover for the engine cylinders, but also as a kind of base on which various components and engine parts are installed.

In photo 1 - a cylinder head assembly with a VAZ 21083 engine cover. The fitting in the cover, which you see, is connected by a pipe to a breather. This is done in order to clean the crankcase gases entering further into the intake manifold from oil.
By removing the valve cover, you get access to the timing parts (photo 2). Please note that the lower part of the camshaft bearing housing is made in one piece with the block head housing, while the upper part consists of two parts. is supplied through oil channels made in the head housing.
Photo 3 shows the cylinder head of the VAZ 21083 from the side of the surface mating with the upper plane of the cylinder block.
The supply of fuel and the release of exhaust gases from the cylinders occurs due to the timely opening of the intake and exhaust valves, also installed in the cylinder head. The working edges of the valves and their seats are made of heat-resistant steel, as they work directly in the combustion chamber.

Given the high pressure and temperature that occur during engine operation, special requirements are put forward to the sealing gasket under the cylinder head (photo 4). It is made from asbestos reinforced with metal.
It should be noted that the head gasket is a one-time use, as it “shrinks” during installation, which makes it impossible to reuse it.

The cylinder head gasket is disposable, as it “shrinks” during installation, which makes it impossible to reuse it.

The use of a head gasket of dubious origin is undesirable, since even a slight change in the thickness of the cylinder head gasket can adversely affect engine power. This is especially true for diesel engines when.
In order to ensure the tightness of the cylinders and channels at the junction of the head and block, it is required to observe not only the tightening force of the cylinder head bolts, but also the sequence, that is, the order.
This information must be indicated in the auto repair manual.

Cylinder head malfunctions

The most common reason for replacing the cylinder head is the appearance of cracks in the body or a violation of the shape of the mating plane of the head as a result of overheating.

In the event that there is a slight curvature of the surface of the head, the defect is eliminated by grinding the surface. High-quality repair of cracks in the cylinder head is impossible in garage conditions. Attempts to fill cracks with "cold welding" compounds are generally ineffective due to the fact that the materials used to fill the cracks have a thermal expansion coefficient that differs from that of the head alloy.

Replacing the cylinder head gasket

When replacing the cylinder head gasket, it is required to observe not only the tightening torque of the cylinder head bolts, but also the sequence of their tightening.

Often, motorists are faced with the need to replace the cylinder head gasket, due to its burnout. Such repairs are quite affordable, of course, with the necessary tools and information regarding the torque and order of tightening the cylinder head bolts.
The most characteristic signs of a gasket burnout are increased exhaust smoke when the coolant is ejected into the expansion tank. In addition, the motor will overheat, and its power will be significantly reduced.
If you are changing the cylinder head gasket for the first time, then you will need a torque wrench - to control the tightening torque. Cylinder head bolts are made of steel, which has a high tensile strength, but there is still a risk of breaking them. Therefore, even experienced craftsmen always use a torque wrench when replacing the cylinder head gasket.

The engine of any vehicle is a fairly complex technical unit, consisting of many mechanisms. And each of them performs its own function, aimed at ensuring the movement of cars. We invite you to find out what a cylinder head is, why it is needed and what elements it consists of.

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The concept of cylinder head

First, let's turn to decryption. The cylinder head is the cylinder head, which is the main unit of any vehicle. Its purpose is to control the process of combustion of the fuel mixture in the engine and the removal of exhaust gases. In fact, the cylinder head is specifically a cover that directly closes the cylinder block.

The cylinder head can be made of aluminum alloy or alloyed cast iron. When the cylinder head casting process is completed, it is subjected to an artificial aging procedure, this is done in order to rid the component of residual stress. In the event that the engine is single-row, then one cylinder head will be installed on it. If it is W-shaped, then a separate block head will be installed on each individual row of cylinders.

It is very important that the head of the block is securely sealed directly to the block. It is for this that the lower part of the element is made slightly wider than the upper one. The cylinder head gasket is used to seal the two parts of the block.

The cylinder head is mounted and fixed using guide pins designed to secure the head. Direct installation is a particularly important procedure, which is carried out in accordance with the regulations specified for each individual car. This regulation is individual, therefore it is highly not recommended to install the head on the Zhiguli and use the instructions from the foreign car. As for the pins themselves, they must be installed and tightened in a certain sequence, while the tightening torque must be observed. For this purpose, a special torque wrench is used.

Remember that when tightening screws, you must be guided by technology, and not use brute force, as this can lead to irreversible consequences.

This may cause deformation of the cylinder head. Inside the head there are many different elements that are hidden by a lid, but we will talk about them later. The performance of this element determines the functioning of the car engine as a whole, this must be known and understood.

The design of the cylinder head and its main parts

With what a cylinder head is, we figured it out. Now I would like to dwell in more detail on the design and main components of this node. Below we will consider the basic information about the parts that make up the block head.

Unlike today's cylinder head, earlier these elements were made of cast iron. In principle, today there are enough cars in the world in which cast-iron heads are installed. This is due to the fact that cast iron cylinder heads are more suitable for those vehicles that operate in difficult temperature conditions. Cast iron can withstand extreme cold and sweltering heat, while aluminum components often warp and shrink.

It looks like the cylinder head disassembled and dismantled

Separately, you should dwell on the gasket of the device. The cylinder head gasket is made from reinforced asbestos. This is done so that it can withstand not only the high temperature that is typical for the operation of the engine, but also the high level of pressure. At the same time, the asbestos cylinder head gasket is able to provide a high level of tightness of the channels of the cooling system, oil wire, and the combustion chamber.

As for the rest of the components, we will talk about this later.

The device and decoding of the mechanisms are given below:

Gasket - as you understand, it plays a very important role in the functioning of an internal combustion engine.
Timing (decoding - gas distribution mechanism).
Carter (decoding - cylinder head housing). All components and mechanisms of this device are located in the crankcase, as well as pipes of the cooling system, oil wire channels and, in fact, the combustion chamber.
Special threaded outlets into which nozzles or spark plugs are installed.
Directly the combustion chamber, in which the process of ignition of the combustible mixture is carried out, which allows the car to move.
Timing drive.
There are also landing planes along with threaded fasteners that allow you to mount the intake and exhaust manifolds.

Let's take a closer look at these components. The cylinder head valves are located in the same row. The angle of their inclination with respect to the plane of the cylinders is 20 degrees. In some modern cars, the arrangement is slightly different, but in most cases the valve arrangement is exactly the same.

Let's go at the front of the cylinder head. If you disassemble it, you will see that it contains a specially designated place for installing the timing chain drive and chain tensioner. Actually, this is where these components are located. As for the combustion chambers, they fit snugly against the block, and for this they are specially processed mechanically. In size, the area of the compression chambers is slightly smaller than the dimensions of the bottom of the pistons. This is done so that during the operation of the internal combustion engine, when the pistons rise up, an intensive swirling of the working mixture of the motor is ensured. Accordingly, as a result of this, the procedure for the combustion of the combustible mixture itself is improved.

On the left side of the cylinder head, you can see four holes for candles or injectors of the ignition system. On the reverse, right side, there is a special flange on which the exhaust and intake manifolds are attached. Next to this flange, the pipes of the cooling system are also mounted, along which antifreeze runs.

Special holes are installed on the upper part of the cylinder head, into which guide bushings, support washers, lever support devices, and the distribution pulley bearing housing are installed. A special cover is installed on top of the cylinder head itself, which is fastened with eight screws.

It should also be noted that non-removable components are also located in the head:

first of all, these are valve seats, the purpose of which is to ensure tightness;
as well as valve guides.

It is important to understand that these components are installed by pressing into the cylinder head structure. Accordingly, at home, replacement will be impossible - this can be done exclusively with the use of the necessary thermal equipment, as well as specialized tools.

Some garage "craftsmen" still practice this repair process at home, but this is highly discouraged, since uneven heating can lead to consequences:

The cylinder head can change the geometry of its structure, as a result of which the plane of its contact with the block itself will be violated.
The cylinder head will simply become unusable from improper heating.
Microcracks may appear in the structure of the head, which will be very difficult to get rid of.

In general, carrying out such work at home is fraught with the fact that the device will simply become unusable and there will be nothing left but to hand it over for scrap. Of course, a competent specialist, with the necessary equipment, can try to fix the problem, but this is not always possible. Therefore, we recommend that you listen to our advice.

Maintenance and diagnostics

As you know, all vehicle mechanisms will sooner or later need diagnostics and maintenance. In this case, the cylinder head is no exception. The primary task of any motorist in this matter is the periodic diagnosis of those head components that need it most. In particular, those that are subject to the greatest stress.

This is about:

valve performance;
checking the performance of valve seals;
distribution pulley oil seals;
and, of course, the cylinder head gasket itself.

May cause oil in the coolant. And vice versa - getting antifreeze into the oil system. As a result of oil entering the cooling system, the antifreeze will seethe (but not boil), which will lead to engine tripping, and over time, the impossibility of starting it. In this case, the refrigerant will come out of the expansion tank, and the engine temperature gauge on the dashboard will show the engine boiling. In turn, the ingress of refrigerant will cause the spark plugs to flood, which can be guessed by unscrewing the candle and assessing its condition.

In general, many factors affect the failure of head elements and their correct operation, but most of them relate to timely diagnosis and repair. Even such a trifle as (incorrect tightening torque or non-compliance with the order) can cause deformation of the head, which can lead to engine failure.

What are the renovations for? There are many occasions when head removal is unavoidable.

the need for boring cylinders;
the need for pressure testing of valve bushings or their seats;
failure of valves, which implies the need to replace or repair them;
grinding of saddles or work on their completion;
the need to replace the head gasket (if it is broken or leaks);
or, if necessary, sealing microcracks (this operation can be carried out without dismantling the cylinder head).

The cylinder head (cylinder head) is the most important element of the internal combustion engine, which closes the cylinders from above and is attached to the cylinder block with head bolts or guide pins. The cylinder head, in fact, is a cover that covers the cylinders.

The cylinder head performs a number of important functions:

the cylinder head cover performs a protective function;
there is an oil filler neck in the cap;
the cylinder head gasket provides a seal where the cylinder head fits;
the block head is a place to place the chain tensioner and camshaft drive in a separate cavity in front of the cylinder head;
threaded holes for spark plugs and injection nozzles are located in the head housing;
combustion chambers are wholly or partially located in the cylinder head;
the head is the installation site of the gas distribution mechanism ();
holes are provided in the head housing for installing the intake and exhaust manifolds;

The cylinder head is made by casting from cast iron or aluminum alloys. After the casting is completed, the cylinder head is subjected to an artificial aging process using a special technology. This is done in order to remove residual stress from the element, since the cylinder head experiences serious loads during operation. For an in-line engine, one cylinder head is installed. On V-shaped engines, a head is installed on each row of cylinders. There are cylinder heads with lower valves, as well as heads with upper valves. The first type has a simplified design compared to the second.

Combustion chambers are partially or completely placed in the cylinder head. Inside the head there are inlet and outlet channels, "cooling jacket" channels for the circulation of coolant, as well as oil channels for the engine lubrication system. Inlet channels for supplying the fuel-air working mixture or only air to the cylinders, as well as channels for exhaust gases, lead to each individual combustion chamber. Each of the channels ends with valve seats that are pressed into the cylinder head. The valve seat is made of cast iron or other materials.

The lower plane of the cylinder head, which is adjacent to the cylinder block, is wider. This is done to get the best possible seal with the surface of the block. Additional sealing of the junction of the cylinder head and the block is achieved through the use of a cylinder head gasket. The fastening bolts have a strict sequence in the tightening process, and the tightening torque must also be observed. These bolts are tightened with a torque wrench.

The cylinder head is fastened and the bolts are tightened strictly according to the recommendation of the engine manufacturer. The main task is the need to avoid deformation of the cylinder head.

The upper part of the head of the block is closed with a cover called a valve cover and is attached to the head through a sealing rubber gasket. The cylinder head cover is made of aluminum alloys or sheet steel. The cylinder head of a modern car engine can have a complex design, depending on the characteristics of the gas distribution mechanism.

How is the cylinder head decoded

The abbreviation cylinder head stands for simply. This is the cylinder head - a detail that can be attributed to one of the most important in the entire internal combustion engine as a whole. It is this node that controls the process of fuel combustion and is responsible for the removal of spent elements, in this case gases, to the outside. To better understand what a cylinder head is in a car engine, you need to consider in detail its design and analyze the main functions.

Design features of the cylinder head and its constituent parts

For a long time, cylinder heads were made of cast iron, which is now being phased out in favor of aluminum-based light alloy products. Aluminum cylinder heads are being used more and more often, but cast-iron ones cannot be completely abandoned. There are types of engines where the temperature operating conditions do not allow the use of a light alloy, since the danger of thermal shrinkage and deformation is great, and cast iron heads resist such processes most effectively.

The cylinder head is superimposed on the cylinder from above and attached to its base with bolts or studs (the type of attachment depends on the engine modification and the address of its manufacture). The landing plane of the head is large enough in area, therefore, in order to avoid deformation of the structure, a certain sequence is used during fastening, the sequence of tightening each threaded connection, and certain efforts. The fastening scheme and the connection tightening sequence for each engine are developed individually, due to the difference in design solutions.

In so-called in-line engines, one block head covers the entire cylinder body, and in engines where the cylinders are arranged in a V-shape, each row has its own block head. To ensure effective tightness of the connection between the cylinder and the head, a gasket is placed, which has the exact shape of the head and cylinder, and all the necessary holes for fastening. Gaskets are made of reinforced asbestos sheet, which is a refractory material and, regardless of the level of heating, maintains the tightness of the combustion chamber.

The main mechanisms and parts of the cylinder head

The scheme of the main parts and mechanisms of the cylinder head includes:

block head housing (crankcase), where the system mechanisms are located;
a certain number of threaded holes into which spark plugs or nozzles are mounted;
asbestos gasket between the block head and cylinder;
a combustion chamber where the fuel ignites and turns into a working mixture;
gas distribution and exhaust mechanism;
planes and mountings for the intake and exhaust manifold.

In addition to removable parts, the head also has non-removable ones, which are necessary to obtain tightness of the gas distribution mechanism. These include valve seats. They are hot pressed into the crankcase of the head of the block. If necessary, you will have to use a special tool to replace them.

Repair and maintenance of the cylinder head

Like any part in a car, the cylinder head needs periodic inspection, diagnostics, and if serious problems are identified, it needs to be replaced. Usually, the parts that have to bear the greatest load fail first of all - valve seals, the valves themselves, the head gasket. The wear and tear of the head is most affected by the factors of improper diagnosis and maintenance. Violation of the necessary force when tightening the nuts and the order of tightening the bolts or fastening nuts leads to deformations of the housing, this disrupts the normal operation of the engine.

If these types of breakdowns are detected, the parts will have to be replaced, and this should be done according to a clear scheme, which is given in the technical description of the engine.

Whether it is necessary to change the oil when repairing the cylinder head of a car will show the final measurement of its level and analysis of its structural state.