The engine in its technological understanding is a rather complex installation, a unit that consists of many individual parts designed to fulfill certain goals. The full functioning of every detail allows for the smooth operation of the entire mechanism. Some elements are characterized by the performance of some narrowly focused functions, others receive a higher “honor” and work on converting one type of energy into another. That is, for example, to turn the fuel in the tank into the force of movement.
So what is a cylinder head? The decoding is quite simple, this is the cylinder head. This detail is one of the most important and basic in the coordinated work of the entire mechanism called the engine. It is to this node that the process of fuel combustion belongs, here the waste elements are released, in our understanding these are gases. To understand how everything is arranged here, it is necessary to study and consider the entire constructive core of the device and understand the main functions.
Design features
Previously, cylinder heads were made of cast iron metal, but now they are gradually abandoning it, in favor of lighter and simpler aluminum-based alloys. But, all the same, it is not possible to completely eliminate cast-iron cylinder heads from the automotive industry, because there are types of motors where the temperature regime itself does not allow the use of light alloy. After all, there is a high probability that thermal shrinkage and, accordingly, deformation will occur. And with such processes, heads made of cast iron are most effectively handled.
The heads are superimposed on top of the cylinders, and are attached to its base through ordinary bolts or studs. The type of attachment may differ even for one engine specification, it all depends on the modification and types of the device. Considering that the landing plane itself has a large area, there are several basic rules for installation, how to properly screw and install the head, so that an even distribution and connection is obtained. Due to the fact that there is a difference in design solutions, individual rules and mounting schemes are developed for mounting different motors.
In motors arranged in rows, one head is able to cover the entire cylinder body. But more productive motors, the so-called V-shaped ones, require their own cylinder head for each row. To ensure maximum sealing between the head and the block, a gasket is made in an exact copy with the head. As a rule, gaskets are made from a special asbestos sheet, which is fireproof, no matter what the level of heating, thereby maintaining the tightness of the chamber.
The main mechanisms of the cylinder head
Among the main mechanisms and elements of the cylinder head are divided:
- 1. The main body of the head, the so-called crankcase, where the main mechanisms of the system are placed.
- 2. The required number of threaded holes, in which, as planned, candles or nozzles are installed.
- 3. Asbestos gasket.
- 4. The combustion chamber, where the fuel is burned and converted into a working mixture.
- 5. Discharge and gas distribution device.
- 6. Mounting points for the intake and exhaust manifolds.
In addition to removable head elements, there are also non-removable ones that are required to maintain the tightness of the gas distribution mechanism itself. These devices include valve seats. They are hot-pressed into the head crankcase. But to change them, you will need a specialized tool.
I would like to clarify that it is not recommended to remove and replace valve seats on your own in garage conditions. Indeed, with uneven heating of the head, it can simply simply change its geometry. That is, the main plane of contact with the cylinder block is broken, and the tightness is lost. In this case, the cylinder head cannot be repaired, and a new cylinder head will have to be purchased.
All components and elements in the design of the car need maintenance, and often repair. The head in this case is no exception. Particular attention is paid to those parts that receive a large load. Namely, this is a gas distribution mechanism, it includes valves, seals, both valves and a camshaft, head gaskets. Many factors affect wear and function, but the main ones relate to maintenance and diagnostics. The owner is faced with the important task of constantly monitoring the engine, preventing it from overheating, and controlling the flow of oil or coolant that breaks through. When oil leaks appear, be sure to contact the service.
Damage to the head, in addition to the above overheating, can be affected by the use of a tool during screwing and installation, without a special measuring element, such as a dynamometer. Tightening bolts and nuts without control will warp the body, which will of course render it unusable. There is a whole range of activities and repair operations, where you need to take into account all the nuances.
Often, the car owner is faced with the problem of replacing, removing the head in such cases: cylinder boring, new crimping of bushings and seats, valve replacement, refinement, grinding of seats, grinding of the plane.
I hope the presented article gave an understanding of what the head is. What are the main details, parts, its components.
The cylinder head is the most important part of any car engine. Does it require a cylinder head? What does it consist of? What is the purpose of the cylinder head? How is the cylinder head diagnosed, repaired and replaced? Today we will try to answer all these questions.
The use of the first head has been carried out since the birth of the very first engine. Without this component, it is impossible to operate any engine.
Cylinder head device
The cylinder head is the top part of the engine that fits over the block and covers the top of the block.
It has a rather complex design, which is usually made of aluminum alloy or special alloyed cast iron. Inside there are many perfectly smooth surfaces - this once again confirms its importance in the engine of any car. To achieve the most tight connection with the engine, its width from below is made larger, and a special gasket is installed between the engine and the head.
The head of the block is a separate part on which other nodes are attached. These include: a camshaft (or shafts, if it is not one), valves and their mechanism, spark plugs, various nozzles and much more. The combustion chamber is located directly in the cylinder head, which indicates that the intake and exhaust manifolds are mounted on it.
The number of heads may vary depending on the block type. If the block has a V-shape, then, accordingly, the number of heads will be two. On conventional, single-row engines, one cylinder head is installed.
A cylinder head cover is installed on top of the head, which protects all its components from dust and other foreign particles. For connection, a special sealing gasket is also used. On the top of the cover is a filler hole through which oil is poured. This suggests that the oil enters the crankcase through the cylinder head.
Almost all processes occurring in the engine are carried out precisely through the cylinder head. All the mechanisms that drive the piston mechanism are located on the cylinder head. These are spark plugs designed to ignite the mixture, a valve mechanism, through which fuel is admitted, exhaust gases are released, manifolds and, most importantly, a camshaft. It is located on the cylinder head and actuates the valve mechanism. All this is protected from external influences precisely with the help of the cylinder head.
In addition, combustion chambers are located inside the head, in which the mixture is compressed and ignited. This place has a close connection with the cylinder block in which the pistons move.
The cylinder head has two gaskets that seal the connections to the block and cover. The condition of the engine largely depends on these gaskets and the cylinder head itself.
Diagnostics of malfunctions and repair of a head of the block of cylinders
During operation, the block head experiences heavy loads. This is the mechanical effect of the parts, and the high temperatures formed in the combustion chamber. Most often, all malfunctions come down to the fact that the engine stops developing the required power and starts to work unstably. If the adjustment of the mechanisms related to this does not give the desired effect, then it's time to repair the cylinder head.
Fault diagnosis begins with an external examination of the gas distribution mechanism, as well as the head housing. It should not have all possible cracks, chips and other defects.
Speaking of cracks. This is the most terrible malfunction of the cylinder head. It can be formed as a result of exposure to high temperatures. Most often, this happens due to frequent overheating of the engine. At first, it will be a microcrack, which will gradually grow. Its presence will be indicated by the presence of oil residues in the coolant and the appearance of corresponding bubbles in the reservoir. A crack in the block will break the seal of the valve train, which will lead to a loose fit of many parts. As a result, a decrease in engine power, a drop in compression, etc. Repair of a block with a crack, as with any other mechanical damage, is not permissible, therefore it is subject to replacement.
When removing the cylinder head, check the lower plane of connection with the cylinder block. To do this, a special ruler is applied to it diagonally across the entire length of the cylinder head. Gap control is carried out using a measuring probe. The norm of measurements can be considered a gap not exceeding 0.06 millimeters. If this value is greater, then the plane is subjected to grinding.
Checking the wear of the journals of the camshaft support and its bearings is carried out using a micrometer. The measurement results must be compared with the standards that are valid for your particular engine model. If there are certain deviations, then, based on the values, a decision is made on the method of repair.
The condition of parts such as rocker arms, saddles and levers is determined by external inspection. In the case when the chamfer is "recessed", but the rod, at the same time, is in order, then it needs to be processed. After that, the valve can be used again.
All kinds of external defects in the form of scratches, burrs, etc. are eliminated by grinding. This procedure, first of all, concerns those places where sealing of joints is necessary.
This procedure is performed when serious damage to the cylinder head housing is detected. As mentioned earlier, these include various cracks and broken off parts. In addition, replacement will be required in the case when the deviations of the gaps from the norm significantly exceed the permissible values and in any other cases when it is impossible to carry out repairs.
Together with a new head, it is necessary to immediately replace the cylinder head gasket, as well as the gasket of its cover. These elements are always replaced with new ones when installing a new head.
To carry out the replacement, it is necessary to disconnect all parts that prevent the dismantling of the cylinder head. They can be - an injector, a carburetor, intake and exhaust manifolds, ignition distribution mechanisms (candles, armored wires, a distributor), elements of the cooling system (pipes), as well as various plugs and sensors. After that, the timing belt or chain is dismantled. On some engine models, there is also a fuel pump.
After that, unscrew the nuts securing the head cover and remove the cover itself. After that, you can decide to remove the head of the block. Options are allowed when the valve mechanism is disassembled and the camshaft is dismantled after the cylinder head is removed or before it is removed. In the first case, this procedure is much easier to perform, because there are a number of parts that can only be unscrewed with the help of a secure cylinder head fixation.
After complete disassembly and removal of the cylinder head, a new part is installed. It can be performed both with the gas distribution mechanism installed on it, and with the rearrangement of old parts to a new head. In the latter case, it will be necessary to adjust and fit the valves, as well as other elements.
After installing the cylinder head, all removed elements are installed in reverse order. After that, it will be necessary to adjust the ignition timing and gas distribution mechanism.
Video - Tightening the cylinder head
A way to tighten the engine head at home is shown, so as not to stretch later.
Perhaps this is all you need to know about the cylinder head.
Many people call the engine the heart of the car. In fact, this is how it is. It is the motor that drives the car. ICE is the most expensive unit in any car. This node consists of several components. In addition to attachments, there is a block and a cylinder head. Each detail has its own device and purpose. And today we will look at what a cylinder head is in a car, and why the car may not start after replacing its gasket.
Characteristic
Cylinder head stands for cylinders. This is one of the most critical components in a car engine.
It is the cylinder head that is responsible for controlling the combustion of fuel, as well as for the removal of exhaust gases.
Material
For many years, the head was made from the same material as the block. It was cast iron. But since the 1980s, cast iron has been replaced by aluminum. It is from this material that 90% of all heads are made.
But not all engines have the ability to use aluminum cylinder heads. The reason is the high temperature regime, in which deformation and thermal shrinkage of the metal is possible. Therefore, cast-iron cylinder heads are still used on such engines.
Device
Structurally, this node combines:
- Carter. This is the block head housing.
- Spark plug. For them, special threaded holes are provided in the head. Candles are involved in the ignition of the fuel mixture. There are none on diesel engines.
- Nozzles. Designed to supply fuel under pressure.
- gas distribution mechanism. It consists of pulleys, (maybe several) and valves. The latter are further divided into two types. So, there are intake and exhaust cylinder head valves. What is a valve in a car? These elements are responsible for the timely injection of fuel and the removal of gases from the chamber, which are formed after the ignition of the mixture.
- combustion chamber. Each cylinder has its own. Its volume may be different, depending on the configuration of the cylinder head.
Between the head housing (we have already found out what a cylinder head is in a car) and the block, an asbestos gasket is necessarily placed. Also in the design of the head there are non-removable parts. They are installed by hot pressing into the cylinder head crankcase. What is it in the car? Non-removable parts are valve seats. They are installed in the place where the block head contacts the closed inlet or outlet valve. Saddles are a massive steel ring with a conical profile. If they are defective, you must use a special tool for replacement. At home, such an operation is not performed.
How to install
The cylinder head is superimposed on the engine block from above. It is fastened with long bolts or threaded studs. Since the landing area is large, during installation, the sequence of tightening the bolts is observed. This will eliminate structural deformations and possible breakdowns, as well as gas breakthrough.
Note that on in-line power units, the cylinder head covers the entire block. And on V-shaped motors, each row has its own head. But regardless of the type of layout of the cylinder block, a reinforced gasket is installed between the head and it. What is a cylinder head gasket in a car? This is a sealing element. The gasket is made of a hard refractory material that prevents the coolant from mixing with exhaust gases and oil. Such a part is installed on all internal combustion engines. The only exceptions are some sports internal combustion engines. Here the head is ground so evenly and smoothly that its contours completely coincide with the cylinder block.
Car won't start after head gasket replacement
Sometimes it happens that this element loses its tightness. In simple words, the gasket burns out. In this case, when the engine is started, the car smokes. After replacing the cylinder head gasket, everything should return to normal. But if the labels are set incorrectly, then the car may not start at all. But when replacing or repairing the head of the block, you will definitely come across such a mechanism as the timing. It is driven by a belt or chain. The torque comes from the crankshaft of the engine. When dismantling a belt or chain, be sure to mark the location of the pulleys. When installing the drive, it is important to observe the accuracy of the marks. The slightest deviation can cause the car to not start after replacing the cylinder head.
A more serious outcome is a failure of the gas distribution phases. This is fraught with bent valves and damaged pistons. By turning the starter only once, you can fly into a large amount of repairs.
How to solve a problem
Consider the process of labeling on the example of a VAZ-2109 car. For work, we need a good flashlight, a slotted screwdriver, as well as keys for 17 and 19. After installing the timing belt tensioner pulley, you need to turn the camshaft pulley. You need to twist it until the mark matches the bar that is on the engine block. After that, leave the camshaft alone.
Let's move on to the crankshaft. Here, too, there are labels. A bolt must be screwed onto this shaft. This makes labeling faster. Turn the shaft until they are in a vertical position. Next, remove the rubber plug in the clutch housing. After that, we will have access to the flywheel. Why do we need it? There is also a mark here, which ideally should coincide with the slot of the bar that is attached to the cylinder block. If these designations match, then we have correctly set the position of the timing elements. After that, you can safely install the belt. First, it is put on the crankshaft pulley, and then the camshaft.
Finally
So, we found out what a cylinder head is in a car. The head of the block is a very important unit in any engine. At the slightest malfunction, problems arise with the operation of the entire power unit. If the gasket is broken in the engine, do not hesitate to replace it. Otherwise, gases will penetrate the cooling system and mix with antifreeze. And the latter will enter the combustion chamber, due to which thick white smoke will come out of the exhaust when the engine is running.
An internal combustion engine is a rather technologically complex unit, consisting of many parts that ensure the smooth operation of the entire mechanism. Some parts perform narrow technological tasks, others are given a “higher honor” - to perform functions leading to the conversion of one type of energy into another, that is, to convert the fuel in the tank into motion energy.
Of the large number of abbreviations that are found on the pages of technical documentation for a car, the cylinder head abbreviation is probably the most common. Why and what is a cylinder head in a car worth finding out more.
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.
The cylinder head is the upper part of the engine, located above. Depending on the design of the engine, it can perform a different number of functions: in typical modern engines, it closes the upper parts of the cylinders, forming a combustion chamber, and also contains channels for oil and coolant and the main part - (one or two), inlet and outlet , inlet and outlet ports, and in many cases, fuel injectors. In some cases, the cylinder head not only forms the top cover of the combustion chamber, but also has its own part of this chamber or special injection chambers - or.
Since a lot of pressure is created in the combustion chamber during engine operation, the cylinder head must be tightly drawn to the cylinder block. To ensure the tightness of their connection, a cylinder head gasket is installed between them, and the head is evenly attached to the block along the entire length with a large number of bolts.
The cylinder head material can be different: modern heads are mostly made of aluminum, but there are also steel and cast-iron cylinder heads. The main advantages of aluminum are lighter weight and good heat distribution, however, aluminum heads are somewhat inferior to steel and cast iron heads in terms of strength and reliability.
The cylinder head of a modern engine, in which the valve mechanism is located, is covered from above with a special one. The valve cover covers the valve mechanism, and it is made removable to provide access to the valve mechanism for its repair and maintenance - for example, for the so-called valve adjustment, when the gap between the camshaft cam and the valve actuator is adjusted. Like the surface between the cylinder head and the cylinder block, the surface at the junction of the cylinder head and the valve cover is sealed with a special gasket.
How many cylinder heads can an engine have?
The number of cylinder heads may vary depending on the engine. For example, motors have one cylinder head, they also cost one head, but, by virtue of their design, motors necessarily require the presence of two cylinder heads. The reasons are clear: in them the cylinders (and in them) are located at an angle to each other, and the upper parts of the combustion chambers are significantly removed from each other (in the boxes - literally on the opposite side of the engine), so each of the cylinder groups has its own cylinder head.
More exotic options are radial motors and heavy equipment. In radial engines - those where the cylinders move away from, forming a "star" - the number of cylinder heads corresponds to the number of cylinders, that is, each cylinder has its own individual head. Axial engines were widely used in aviation - one can be seen on aircraft with a nose propeller.
The scheme with individual block heads for each cylinder is also used in engines of large volume for heavy equipment - for example, giant diesel engines used in shipbuilding, mining trucks, railway locomotives and so on. These engines usually have a conventional in-line layout, but the use of individual cylinder heads for each cylinder is justified from the point of view of repair and maintenance: it is much easier and cheaper to remove one smaller head to carry out these works than to dismantle a huge common cylinder head entirely. In addition, this scheme allows you to build engines with a different number of cylinders (and, accordingly, displacement and power), without changing the design of the cylinder head.
Cylinder head tuning
Since the cylinder head of a modern engine has many functional roles, containing the timing, part of the intake and tract, part of the injection system and, it is often tuned.
The main improvements to the cylinder head itself usually relate to optimizing the diameter, shape and surface of the channels, especially the intake ones. The correct shape of the channel minimizes turbulence and improves the filling of the cylinder, and an increase in the diameter of the channel allows you to increase the volume of air or air-fuel mixture supplied. However, it should be understood that in the case of an increase in the diameter of the inlet channel, with the remaining parameters of the motor unchanged, the flow rate drops, which negatively affects the filling of the cylinder and the characteristics of the motor at low and medium speeds. Thus, an increase in the diameter of the intake duct should be accompanied by an increase in the volume of air supplied (for example, by increasing the boost pressure of the turbine).
Another characteristic of the motor that can be changed by finalizing the cylinder head is. Since the cylinder head is the upper part of the combustion chamber, by grinding off its lower part, it is possible to reduce the volume of the combustion chamber and thereby increase the compression ratio in the cylinder. Similar techniques are used, for example, to adapt old engines with a low compression ratio, designed for the use of gasoline (AI-80, AI-76 and lower), to the most common AI-92 today.
Cylinder head designs depending on the type of engine design
As mentioned at the beginning, the design of the cylinder head may vary depending on the design of the motor on which it is installed. The simplest cylinder heads on Flathead engines are a metal plate with threaded holes for installing spark plugs. However, as the internal combustion engine improved, it became necessary to transfer the camshaft and valve mechanism to the cylinder head, and as a result, most modern engines have just such a design. However, high-volume overhead valves are still found in American cars. We will look at different cylinder head designs depending on the design of the engine.
Cylinder head of a lower valve lower engine
The design of the engine involves the location of the camshaft in the cylinder block, near the crankshaft, and the drive of the first from the second using gears. At the same time, the valves are driven from the camshaft by pushers and are located with the plates up, and the intake and exhaust fit the cylinder from the side (hence one of the English names for such motors - side-valve engine, which means "engine with side valves").
Thus, and , and are located in the block (and next to it), and only the spark plug could be located in the upper part of the cylinder. Accordingly, the cylinder head of such a motor was the simplest plate (another English name for such motors refers to this - Flathead, that is, "flathead"), in which, if necessary, there were threaded holes for installing spark plugs.
The next step in the development of lower engines was engines with a mixed valve arrangement: in them, the intake valves with the drive were moved up to the cylinder head, and the exhaust valves were left unchanged. This design was called the F-head, since the piston and valves partly resembled the letter F in location. The intake valves were driven through rocker arms. Thus, the design of the cylinder head became more complicated: instead of a simple plate, it became a plate with an intake valve drive mechanism and, as before, a connector for installing spark plugs.
Cylinder head of an overhead valve lower engine
The next stage in the development of engines after the lower valve lower steels: that is, the camshaft in them, as before, was located in the cylinder block, driven from the crankshaft by a gear mechanism, but the valves moved up to the cylinder head. Of course, this led to a noticeable complication of its design - from a plate with holes for spark plugs, it turned into a full-fledged unit with channels for lubrication and cooling, as well as inlet and outlet channels through which the air-fuel mixture was supplied and exhaust gases were removed.
Since the valves were driven from the camshaft through push rods and rocker arms, the design of the cylinder head of such a motor assumed the location of these rocker arms and the actual valve mechanism inside it.
Cylinder head of an overhead valve engine
The cylinder head of a modern engine in the vast majority of cases looks exactly like this: in the diagram, both the camshaft and the valve mechanism are located in the cylinder head. This scheme is the most modern and may have several implementation options.
In the simplest versions, the cylinder head, in addition to the intake-exhaust channels, lubrication and coolant, contains one camshaft and two valves for each cylinder. The valve drive, in turn, can also be different - directly from the camshaft or through rocker arms or hydraulic compensators that regulate the gap between the camshaft cam and the valve head.
More advanced cylinder head options suggest the presence, as well as the presence, one of which controls the intake valves and the other the exhaust valves. However, despite this increase in the number of work items, the functionality and fundamental design of the cylinder head remains the same.
KnowCar is an understandable encyclopedia of car design, where the complex is described in simple language, with illustrations and videos, and articles are sorted into sections. Encyclopedia in the process of filling. If you have questions or suggestions, please contact the team. All contact details are at the bottom of the site.
