VAZ cars of the 2112 family were produced with. These engines have a different cylinder head with intake ports. There are no other differences, in theory. And therefore it will be the same if we talk about any 16-valve internal combustion engine. The tightening is performed in three steps, although another option is given in the repair books (it is for 8-valve valves).
The part with the name of the cylinder head is attached to the cylinder block with 10 screws. They are unscrewed with a “10” socket wrench. shown in the first photo.
Unscrew sequence (1-10)
Standard screw length - 93 mm. If the screw has been extended to at least 95 mm, it is replaced with a new one (AvtoVAZ requirement).
During installation, a different scheme is used (photo 2). Each screw is lubricated with engine oil, otherwise the efforts will come to naught.
The tightening order of the head is indicated in this photo
Tightening torque for cylinder head cover bolts
For VAZ-2112, the cylinder head tightening torque is normalized:
- The first pass - the force is 20 N * m;
- Each screw is turned 90 degrees to the right;
- Wait 20 minutes, then turn the screws another 90 degrees.
At first, the effort is very small. But at "step 3" it will be difficult to cope with the work. Use lever.
Why do you need guide bushings
Before mounting the cylinder head, perform the following actions: clean the threaded holes, as well as all the holes for the bushings (photo 1). , and only then .
Everything is ready for the installation of the cylinder head
Metal parts adjacent to the gasket must be degreased. We examined the cylinder head tightening scheme, but the cylinder head itself must be installed correctly:
- We place the cylinder head on the cylinder block;
- By shifting the part in different directions, we achieve that the bushings enter the recesses.
After "step 2" the screws can be tightened.
sealant
No sealing compounds are used when installing the gasket! Solidol, CIATIM and other lubricants are not needed all the more. The main thing is that the metal must be degreased. A .
Cylinder head cover and tightening order of its bolts
The metal cover mounted on the cylinder head must not let air through. At points of contact with other parts, tightness must also be maintained. Therefore, a sealant is applied to the edge of the cover. An example is shown in the photo.
Cylinder head cover before installation
Here you need to use materials: Loctite-574, ANACROL, etc. The screws on the cover are tightened with an “8” key.
You can unscrew the screws in any order. Their number is 15 or 14. When installing, it is better to follow the sequence shown below.
The order of tightening the cover is marked with numbers and arrows.
It is not usually necessary to replace the screws - the load is too low. We wish you success.
Common misconceptions
If the bolts are stretched out too much, they are wrapped in four steps. At “step 2”, the tightening torque will be 70-85 N * m. All these are common misconceptions that do not apply to 16-valve internal combustion engines.
All steps in one video: cylinder head gasket replacement
The tightening torque of the cylinder head VAZ 2112 (16 valves) is very important, since deformation occurs when the head is unevenly installed. This leads to the fact that after disassembly, it will be necessary to grind at least 2 mm from the surface of the block head. If you observe all the tightening torques, then you won’t have to sharpen the head, and if you need to do this, then no more than a quarter of a millimeter.
Head design
In order for the hydraulic pushers to work in normal mode, oil is supplied to them from the lubrication system. It is supplied through special channels in the engine block and cylinder head. Oil passes through these channels and to lubricate the journals on the camshafts. There is a valve in the channel with which the oil does not drain from above after the engine is turned off. This allows you to maintain the system in normal mode until it stops completely.
Camshafts
When repairing the head, it is imperative to check the condition of the camshafts. When assembling, follow the instructions and maintain the tightening torque of the VAZ-2112 cylinder head (16 valves). Such a motor is installed on the Priore - it is quite powerful, has excellent characteristics and does not require frequent maintenance. Two camshafts drive the intake and exhaust valves.
The camshafts rotate in special sockets that are located directly in the head. The difference between the camshafts is that there is a small belt on the intake. It is located near the very first support. To prevent axial movement, there are persistent collars - they are located on both sides of the support in front. Ahead on both camshafts there are self-clamping type oil seals.
How to repair
- Valve spring compressor. You can use both "store" and homemade. The main thing is that it is convenient to work.
- Device for pressing out valve stem seals.
- Mandrel in the form of a tube for installing caps.
- Keys on "10", hexagons, tweezers and screwdrivers.
Perform the following manipulations:
- Carry out all the steps to remove the head and camshafts.
- Remove all valves using a special tool.
- Remove oil seals.
- Replace and grind valves. It is necessary to change the valves if there is damage - burnouts, violation of geometry. Be sure to sign on which sockets you grind the valve - otherwise the tightness will be broken.
- Assemble all valve drive mechanisms - hydraulic pushers, springs, fix them with crackers.
All actions for assembling the assembly are carried out in the reverse order, only one feature must be taken into account: adhere to the recommended torque values \u200b\u200bof the VAZ-2112 cylinder head (16 valves). The photo shows the tightening sequence.
How to tighten cylinder head bolts
Be sure to tighten according to the scheme given in the article. In order to tighten the bolts, you need to follow a few simple steps:
- Install a new head gasket, place it on the centering bushings.
- Install the head and bait the bolts of its fastening.
- Start tightening with a torque of 20 N * m. If the scale is in "kgf / m", then divide by 10.
- In the second run, you need to tighten all the bolts according to the scheme by 90 degrees.
- For the third run, they turn another 90 degrees.
Do not use bolts with a length of 95 mm or more. In general, the procedure is quite simple, but a torque wrench is required - without it, it will not be possible to maintain the correct tightening torque for the VAZ-2112 cylinder head (16 valves).
There are many parts to an engine, but the cylinder head is one of the most important, so broaching the cylinder head is an important task for any car owner.
Broach modern cars do not need. Previously, it was necessary in order to successfully pass the first technical inspection, but now even the engines of VAZ cars do not need to broach the cylinder head. It is necessary for old engines, for example, Muscovites, UAZs and the same VAZs. The most common reason for the need for turning work is the presence of moisture in those places where the head is attached to the block. Also, the cylinder head broach is needed in case of breakage of its gasket, its warpage, or incorrectly tightened bolts. After repair work, it is advisable to align the tightening torque after a thousandth run.
Scheme and broach rules
First of all, in order not to make fatal mistakes, you need to carefully read the car's manual for its operation. In order for the broach to be successful and without problems, this manual must be original, since only in it the manufacturer provides the consumer with detailed information about all the important nuances and features of the operation of a particular model. Also, successful broaching of the cylinder head requires knowledge of the scheme and algorithm for tightening the bolts. They must be selected for each motor individually, because the correct choice depends on whether their tightening will be successful or not. In case of incorrect actions, first of all, the cylinder will suffer.
Spring bolt technology has been implemented in modern motors. With them, an additional broach of the cylinder head is not needed at all, since the first and last are carried out at the factory. Pulling the cylinder head with them with your own hands can lead to their stretching and subsequent breakage. To start the repair, gaskets are installed that exclude the possibility of shrinkage.
In fact, the cylinder head broaching scheme is quite simple, but you can’t do without a car manual. Although the characteristics of different motors are also different, this does not mean that the scheme for carrying out the corresponding work is individual for each of them. Basically, they are in the same order.
First of all, a high-quality torque wrench is needed, since a simple wrench will not work. Since broaching the cylinder head is a rather responsible matter, it is necessary to approach the repair accordingly and you should not do everything “offhand”. The most important element of the process is the best fastening bolts. Obsolete, downed and cut will not work here. It is strongly not recommended to reuse the spring type, since in this case the broach will be doomed to failure. In addition, such an error can cause oil to leak through the installed gasket.
TTY type bolts are not suitable as they are specific to aluminum cylinder heads. It should be remembered that for their tightening, not a moment of force is needed, but a prudently set degree. All the necessary information about this is in the car manual.
It is important not to forget about the figures for the tightening torque of the gasket itself and the same engine value - the discrepancy should not be allowed to be too significant. Each type of gasket has a different tightening torque.
Stretching requires the utmost attention. If the cylinder has bolts with a blind hole, then during the injection of oil (which should be carried out before tightening), care must be taken to ensure that it does not spill. Otherwise, they will ruin the cylinder block due to the fact that they simply do not reach the end. The through hole to which the motor cooling system is connected requires additional thread lubrication with a special sealant with plastic properties before the bolt can be screwed in.
A groove can also be an element of repair, and if you still decide to start this repair process, then you must not forget that it is carried out only on a hot motor in which there is a cast-iron head. If this head is made of aluminum, then repairs should only be carried out with a cooled engine.
Cylinder head pull torque control
There is a special technique for controlling the tightening of the bolts themselves, which simplifies the repair procedure. It is for this case that the aforementioned torque wrench is required. As for the bolt to be tightened, a moment equal to the same characteristic of its movement must be applied to it.
As the bolt begins to turn, keep the speed of its screwing under control. It should not increase, otherwise there will be no stretching. When you see that the moment gradually increases, this means that you should tighten it until it stabilizes.
The cylinder block requires certain efforts, and if the moment of force applied to the bolt is 20 kgcm, but the elasticity itself (its moment) does not appear, then this indicates its excessive strength - it is not suitable for drawing. But if during the control of the moment of force you observe its decrease, then this means that it is simply destroyed.
Such severe requirements for bolts are due to the fact that they tend to cool and heat up during their difficult mode of operation. To keep the cylinder safe, you need to do everything according to the instructions. If its block, or rather its head, includes poorly tightened bolts, this is fraught with serious negative consequences for the engine.
Video “Tightening the cylinder head”
The recording shows how to tighten the engine head at home, so that later you don’t have to stretch it anymore.
The cylinder head plays an essential role in the operation of the engine. Its correct position affects the operation of the gas distribution mechanism. Also together with it forms a combustion chamber. Therefore, when repairing, the correct tightening is important.
The structure of the cylinder head
Every internal combustion engine, with the exception of the Stirling engine, has a cylinder head. It serves to accommodate the gas distribution system in it: valves, camshaft and its drive.
The cylinder head is an aluminum part with many holes for installing intake and exhaust valves, channels that form the engine cooling jacket. Depending on the number of cylinders and engine type, the cylinder head may have one or two camshafts.
Also in the head are channels for timing lubrication.
In the upper part there are holes for spark plugs in gasoline engines and holes for injectors in diesel engines.
Consequences of incorrect assembly
The head is attached to the cylinder block with steel bolts or studs screwed into the block. It is known that steel and aluminum have different values of thermal expansion. When heated, aluminum expands more than steel, so this point must be taken into account when tightening the cylinder head. That is, if the head expands when the engine is heated, and the fasteners prevent expansion, then microcracks can form in the cylinder head. They will subsequently lead to failure of the entire engine.
For example, coolant can enter the combustion chamber through cracks. Or a crack in the channels of the lubrication system will cause the valve system to operate in the "oil starvation" mode. Also, non-compliance with the tightening torque of the cylinder head leads to clamping of the camshaft and wear of its bed.
How to properly assemble the cylinder head
To assemble the head you will need:
- New pad.
- Torque wrench with head. The key scale, showing the tightening torque, can be either in Newtons or in kilograms. Therefore, we must remember that one kilogram is equal to approximately ten Newtons.
- Engine oil. It is necessary to lubricate the bolts before installation.
Before starting work, you need to check the new gasket for breaks, as well as the exact correspondence of the holes with those in the engine. Then, if the cylinder head is after repair, you need to check it for compliance with the side adjacent to the engine. To do this, the head is applied to a flat cast-iron slab and see if there are any gaps between the slab and the adjacent surface.
After that, the gasket is laid on the upper plane of the cylinder block. The cylinder head is installed on top of it. Then you can start tightening the cylinder head. Before starting work, do not forget to lubricate the bolts with engine oil.
Features of the cylinder head installation
There are differences when working with engines that have a different number of cylinders. The tightening order of the cylinder head will also be different. But the principle is the same. It lies in the fact that the bolts are tightened from the center to the periphery of the head. This is necessary so that when tightening, the resulting stresses go away from the center beyond, and not vice versa. This will preserve the tightness of the gasket and reduce the stress of the metal during engine operation.
The tightening torque is controlled by a torque wrench.
It is a crank with a long flexible handle. On its handle there is an arrow that deviates at the moment of applying force. The arrow points to the scale, which is fixed motionless. There is also an electronic version of the torque wrench. It is more reliable and shows the force more accurately.
After installing the head, all the mounting bolts must be screwed into the holes in the block. Tighten them by hand as far as possible. You don't need to use the key right away. This can lead to the fact that the bolt will go out of thread, after which it will be necessary to restore the threads on the cylinder block.
We work according to the scheme
Then, using the diagram, tighten the head. The most common four-cylinder engines have a similar layout. For example, consider the tightening procedure for the VAZ-2106 cylinder head. Bolts are tightened in two stages. The first stage is pre-tightening with a force of 35-41 N/m. Then the bolts are pulled in a second circle. The final tightening torque of the VAZ-2106 cylinder head is 105-115 N / m.
First, the two middle bolts are tightened, which are indicated by the numbers 1 and 2 in the diagram. Then the bolt to the left of the center and diagonally opposite, are indicated by the numbers 3 and 5. After that, bolts 4 and 6 are tightened in mirror image. Then come the extreme bolts 7 and 8, behind them on the opposite edge 9 and 10.
Four-cylinder engine models have ten bolts. But not everyone will have the same tightening pattern. There are options when, after the two central bolts, the two lower or upper bolts are tightened in pairs, and not diagonally, as in the case above. It should be noted that the cylinder head tightening schemes for the VAZ-2106 and VAZ-2108 are different. Therefore, you first need to study the circuit for a particular engine.
Common mistakes when installing a cylinder head
In the repair of equipment, one should never neglect the tightening torques of threaded connections. Twisting “by hand” or “by eye” leads either to insufficient or excessive force of fixing the part. If it is such as a cylinder head, then a careless approach will inevitably lead to breakage, and possibly more expensive repairs. Insufficient tightening will cause exhaust gases to blow through the cooling jacket. And excess can either lead to a violation of the threaded connection in the cylinder block, or it will clamp the camshafts excessively.
The next mistake may be using the wrong tool or bolts that are not designed for this connection. Usually these bolts have a specific fine-toothed thread. Therefore, if you replace them with others, you can damage the threads in the cylinder block. In addition, "native" bolts have high hardness due to heat treatment. This is done so that during operation the thread does not stretch and the gap between the head and the block does not increase.
The wrong tool can wear off the edges of the mounting bolts and this will lead to insufficient tightening torque or problems with subsequent loosening.
Finally
Masters advise some time after the repair to tighten the cylinder head again. This is done with a run of 500 to 1500 km. During this time, the head of the block finds its optimal position, as a result of which the fixing bolts are weakened. Therefore, they need to be stretched again. This procedure does not take much time, but significantly reduces the risks associated with insufficient tightening torque.
When carrying out car maintenance, questions often arise that are only casually discussed on forums or in the literature. One of them is the tightening torque of the fasteners of the main components of the car. To find out all the nuances of fastening the cylinder head bolts, let's concentrate on the engine, the "heart" of the car. And with an understanding of the principles of the tightening torque of threaded connections, the knowledge gained will be easy to extrapolate to any vehicle node.
Tightening the bolts correctly
Any threaded connection is designed for a certain tightening torque. It is regulated by industry quality standards, for example, “OST 37.001.050–73 Tightening of threaded connections. Tightening standards ”and the governing documents of vehicle manufacturers. Foreign manufacturers use other standards, but basically they are similar to domestic ones. The information below will be presented based on Russian standards.
To what extent can threaded connections be tightened
Why is it important to maintain the correct tightening torque? Only proper tightening will ensure reliable fixation of the part, on the one hand, and prevent damage to the thread and / or the part itself, on the other hand.
Consider what happens when the tightening torque is exceeded using the example of a bolt with a nut:
- Immediate thread deformation. Due to too much applied force, deformation and stripping of the thread on the part occurs. The bolt or nut is not subject to further use, in addition, certain difficulties will arise when trying to unscrew the nut for replacement. Most likely, you will have to use a drill or a metal saw to cut the nut.
- Metal damage hidden from view. It may seem that the nut is tightened correctly, however, due to the excess of the yield strength, irreversible changes occur in the bolt or nut: deformation, violations of the metal crystal lattice. Such a case is especially dangerous, it is so imperceptible immediately, but after some time a bolt crack can lead to sad consequences.
The yield strength is called the mechanical characteristic of the material, which characterizes the stress at which the deformations continue to grow without increasing the load. Designation σ t.
The unit of measurement is Pascal [Pa] or multiples [MPa].
This is an important parameter by which allowable stresses for ductile materials are calculated.
After passing the yield point, irreversible changes begin to occur in the metal of the sample, the crystal lattice of the metal is rearranged, and significant plastic deformations appear.
Wikipedia
If, on the contrary, the nut is not tightened with the appropriate moment, after a while it will simply unscrew, which can also lead to undesirable consequences. Therefore, it is strongly recommended to tighten the threaded connections not “with all the force”, not by hand, but wisely, using special equipment.
Torque control tools
The main torque control tool is a torque wrench. This is the name of the wrench, which has a built-in dynamometer (a device for measuring the moment of force). There are the following types of devices:
For non-professional use or a small car service, an indicator or limit key is suitable, as the most affordable. Digital will be in demand in a large car service.
How to choose the force to tighten the connection correctly
When working with a key of the limit type, in order to achieve the required moment, one should:
- Before tightening, select the required tightening torque, e.g. 50 Nm. The force is set on the main scale of the device, but not 50, but 48 Nm.
- On the auxiliary scale, a force of 2 Nm is set, which in total will give us the required 50 Nm.
- Using a socket of the required size, tighten the nut. When a force of 50 Nm is reached, a click will be heard and tightening will stop.
Control over the effort when working with an indicator-type key is carried out visually.
In addition to the torque wrench, you can find torque screwdrivers and screwdrivers on sale, they work on the same principle. When choosing a torque wrench, remember that the tightening torque you need must be 25% less than the maximum allowable for the wrench. Using the key "at the limit", you quickly disable it. And also be sure to read the instructions for its use.
Well, you can check the correct tightening of the connection with a goniometer.
How to work with a homemade torque wrench
As a rule, a torque wrench is a rather expensive tool. Its purchase is unlikely to be justified for private use. However, the simplest device is easy to make yourself. For this you will need:
- conventional spring scales with a hook and a round scale, allowing you to weigh up to 20 kg (the so-called steelyard);
- a piece of a rather thick pipe (2.5 cm) about half a meter long.
Having fixed the hook of the scales at the end of the pipe, insert a wrench into the other end and pull the scales, tightening the nut. In this case, to create a moment of 10 Nm, it will be necessary to apply a force of 2 kg. According to this scheme, you can calculate in advance what effort in kilograms you will need to apply to tighten.
Of course, a homemade key will have a rather large error, but it's still better than nothing.
Video: how to make a torque wrench with your own hands
Standard Cylinder Head Bolt Torques
To know for sure how much torque to tighten a particular threaded connection, you can use the following data.
Table: Tightening torques for connections depending on the thread diameter
| Nominal thread diameter | Turnkey size of the head, bolt (nut), mm | Thread pitch, mm | Strength classes according to GOST 1759–70 | ||||
| Bolt | |||||||
| 5.8 | 6.8 | 8.8 | 10.9 | 12.9 | |||
| screw | |||||||
| 4;5;6 | 5;6 | 6;8 | 8;10 | 10;12 | |||
| 6 | 10 | 1 | 0,5 | 0,8 | 1,0 | 1,25 | 1,6 |
| 8 | 12 - 14 | 1,25 | 1,6 | 1,8 | 2,5 | 3,6 | 4,0 |
| 10 | 14 - 17 | 1,25 | 3,2 | 3,6 | 5,6 | 7,0 | 9,0 |
| 12 | 17 - 19 | 1,25 | 5,6 | 6,2 | 10,0 | 12,5 | 16,0 |
| 14 | 19 - 22 | 1.5 | 8,0 | 10,0 | 16,0 | 20,0 | 25,0 |
| 16 | 22 - 24 | 1,5 | 11,0 | 14,0 | 22,0 | 32,0 | 36,0 |
| 18 | 24 - 27 | 1,5 | 16,0 | 20,0 | 32,0 | 44,0 | 50,0 |
| 20 | 27 - 30 | 1,5 | 22,0 | 28,0 | 50,0 | 62,0 | 70,0 |
| 22 | 30 - 32 | 1,5 | 28,0 | 36,0 | 62,0 | 80,0 | 90,0 |
| 24 | 32 - 36 | 1,5 | 36,0 | 44,0 | 80,0 | 100,0 | - |
Main threaded connections in the engine
The list of the main threaded connections of the engine and the features of their tightening:
- Cylinder head (cylinder head). A very important knot, therefore, when attaching it to the block, it is important to observe not only the tightening torque, but also the order in which the bolts are tightened. As a rule, the cylinder head is tightened with a fairly large moment, starting from the center of the block to the edges in several passes. Be sure to specify this information in the car's operating manual (for each engine model, the numbers and order may be different)!
- Valve lid. Due to the small diameter of the valve cover studs, special care must be taken when tightening them and not to exceed the required torque. Also check the tightening order and torque in the manual.
- Spark plugs and glow plugs. They are tightened in random order, but very carefully, since if the threads in the engine are damaged, expensive repairs will be required.
- When tightening the nozzles, also be careful: due to their small diameter, it is easy to damage the threads.
- The engine mounts should be tightened after the engine is fully installed, when it already rests on them with its weight. If the chocks are tightened before the engine rests completely on them and the jack is removed, the chocks will quickly tear during operation.
So, now you know the basic rules when working with threaded connections. If you don't have a torque wrench but need to tighten something in the engine, it's best to purchase or borrow one from someone. As a last resort, use a home-made one, but do not tighten the nuts “by eye”, this will most likely harm both the engine and your wallet, repairing an internal combustion engine in used cars is not a cheap pleasure.
