Tighten the bolt? What is the problem: a wrench and ... go ahead, tighten it all the way.

This is what a person who has a poor idea of ​​how important the correct order of tightening the cylinder head bolts will be will think. And what kind of engine malfunctions can a violation of the order and technology of tightening the cylinder head bolts lead to. In fact, this is a very sensitive question, so let's figure it out.

Why should a motorist know the procedure for tightening the cylinder head?

Naturally, if you have a bunch of banknotes and even shake out the ashtray in the cabin, you go to a car service, then there is no need. But for those motorists who want and can repair a car in general, and in particular, this information will not be superfluous.

It is important! Before we share with you the features of the cylinder head tightening procedure, you should draw your attention to the fact that each engine model has its own bolt tightening parameters.

In no case should you, especially when working with the cylinder head of modern cars, rely on your knowledge and experience gained when repairing the cylinder head on other engines. The procedure for tightening and pulling the cylinder head bolts is carried out in strict accordance with the manufacturer's requirements for this engine. You can easily find these parameters in the engine repair and maintenance manual.

Knowing the order of tightening and retightening the cylinder head is not so often necessary for you. In the case when it is necessary to replace the cylinder head gasket or when repairing the engine.

What are the general features of the cylinder head tightening technology

To begin with, according to the old memory of the operation of domestic car models, many motorists are worried about the need for preventive broaching of cylinder head bolts. Especially after an engine overhaul or cylinder head repair.

Cylinder head broaching is not required in modern engines. This is due to the fact that for attaching the head to apply
self-tightening bolts or so-called "spring bolts".

Their characteristic is such that after the first tightening they no longer need to be pulled during the period of operation. Moreover, pulling the cylinder head in this case can only damage the quality of the bolts.

If earlier, broaching the cylinder head was one of the mandatory points of vehicle maintenance, today this point can only be applied to outdated models of engines of Muscovites, GAZ and VAZ.

Rules for tightening the cylinder head

With different parameters and characteristics, the general rules for tightening bolts, in principle, apply when working with all types of motors.

• Mandatory use of the manufacturer's parameters according to: the order (diagram) of tightening the cylinder head bolts and the tightening torque.
• When tightening the cylinder head, use only a serviceable and proven torque wrench, not a simple wrench. In this matter, the eye and the hope for muscle memory are not helpers.
• A prerequisite is the ideal condition of the cylinder head bolts: in no case use old bolts, do not put cut bolts, check the condition and cleanliness of the thread before tightening. Reapplying the "spring" bolts will no longer provide the required tightening force, which will eventually lead to oil leakage from under the cylinder head gasket.
• It is strictly forbidden to tighten or tighten the cylinder head with TTY bolts (this type of bolt is used mainly on aluminum cylinder heads). The TTY bolts are not tightened to the tightening torque, but to the specified degree. This information should be in the manufacturer's instructions.
• When buying a cylinder head gasket, it must have a manufacturer's specification, which indicates which tightening torque is applicable to this particular type of gasket. This must be taken into account so that the figures for the tightening torque of the engine and the tightening torque of the gasket do not differ dramatically.
• If the hole for the cylinder head mounting bolt is "blind", then pouring oil into it before tightening the head, try not to overflow. Otherwise, the bolt will not reach the end. If the hole is through and goes into the cooling system, then before screwing in the bolt, lubricate the thread with a plastic sealant.

If you nevertheless decided to tighten (broach) the cylinder head bolts, then take into account that it is done: for an engine with a cast-iron cylinder head - to "hot", ie. minimum 80 0 engine temperature, for an engine with an aluminum cylinder head on "cold".

A number of repairs to the power unit of the car are associated with the removal of the block head. Dismantling the cylinder head does not cause any particular difficulties, but planting the unit in place when assembling the motor requires full compliance with the installation technology, in particular, tightening the fasteners.

Consequences of improper installation of the cylinder head

Correct tightening of the block head is very important, since the performance of the motor directly depends on it. The cylinder head acts as a cylinder cover, and any violations in its fit affect the processes taking place inside the power unit.

Insufficient tightening of the head leads to a fall due to loss of tightness at the junction of the cylinder head with the cylinder block, burnout of the gasket, breakthrough of working gases from the cylinders and their ingress into the channels of lubrication or cooling systems, penetration of technical fluids into the combustion chambers, which in turn negatively affects on the functioning of the power unit and can cause very serious damage.

Excessive tightening also does not bring anything good, in this case, damage to the head often occurs - cracks appear, or fasteners collapse - bolt rupture, thread failure, etc.

Uneven or incorrect tightening often causes the head to warp, due to which gaps appear at the joints between it and the block, which leads to the same consequences as insufficient tightening.

Part features

The cylinder head is a structurally rather complex part. It is a massive plate in which channels are made for the circulation of fluids of the lubrication and cooling system, and technological holes - candlesticks, for injectors (in diesel engines), fastening.

Also on top of the cylinder head there is a so-called "bed" of the camshaft - a seat for its installation.

Despite its massiveness, the block head is a fragile part due to voids inside, so excessive tightening force often leads to cracks in the walls and bridges.

For the manufacture of cylinder head, two types of metals are used - aluminum (the most common) and cast iron.

To secure the latter, steel bolts or studs with nuts are used. For example, the head of the UAZ 31519 block is attached with pins.

The difference in the materials of manufacture of the head and its fasteners has one negative factor - the different thermal expansion of the components during heating, especially with regard to the aluminum cylinder head.

Uneven tightening of fasteners (nuts, pins, etc.) during thermal expansion leads to the appearance of excessive stresses in the metal structure, as a result of which the head warps.

Bolt Tightening Conditions

When installing the block head, it is important to adhere to the tightening technology, which includes a number of criteria:

• Tightening order;
• An effort;
• Condition of fasteners (for example, studs with nuts);

Each motor has its own tightening order, which must be followed in order to ensure that the head is evenly attracted to the block and to eliminate the occurrence of stresses on any parts of the surface. For example, on a VAZ 2105 it looks like this.

Effort is another important factor for the correct attachment of this engine element. The plate is pulled in several approaches (on different motors their number is different), each of which is performed with its own effort.

The block head fasteners are tightened with a sufficiently large force, which leads to their pulling. Therefore, on many motors, bolts are not allowed to be reused, they must be replaced. But there are also motors in which replacement of fasteners is not needed and their re-installation is possible.

All information regarding the cylinder head tightening technology is indicated in those. documentation for the car, it is also often indicated on the packaging of the head gasket and fasteners.

General rules for performing work, methods used

There are a number of general rules that must be followed when installing the block head:

Despite the fact that each engine has its own characteristics of tightening the block head, the general technology of this operation is the same. In general, two methods are used to tighten fasteners:

• In several approaches, bringing the tightening force to the required value;
• Tightening the fasteners to a certain force (in one or more approaches), and then twisting the bolts at a certain angle.

The tightening method is selected based on the type of bolt.

The first method is used when using non-stretching bolts (these are not used now, but they can be found on old cars). But often this type of fastener requires tightening after a certain period of engine operation in order to compensate for the shrinkage of the cylinder head gasket. But such fasteners are allowed for reuse, and more than once.

The second method of tightening the block is relevant for most modern cars. And all because of the use of tension bolts (the so-called TTY type).

Due to elastic deformation, such fasteners are able to compensate for thermal expansion of the head and shrinkage of the gasket, but for this they must be brought into deformation mode (in fact, just stretch a little).

For this, it is necessary to turn the bolts twice at a certain angle. On some cars this angle is 45 degrees, on others - 90 degrees.

But after the elements are brought into the elastic deformation mode, they will no longer be able to return to their original state, therefore, their reuse is not allowed due to the high probability of destruction.

General order of work

Although the tightening of the block head has many nuances and features, the general technology of the operation is not difficult, it is only important to comply with the conditions.

The general work algorithm is as follows:

On some cars, it is additionally required to re-tighten the fasteners after a certain period of operation of the car. This information must be indicated in the technical documentation.

Some nuances

Tightening torque is one of the main factors in the proper seating of the block head. But this criterion is influenced not only by the applied force, but also by the fasteners themselves:

• The general condition of the bolts - new or used;
• The presence of grease on the threaded part;
• Thread condition.

The type of power plant (gasoline, diesel), as well as the number of valves, does not affect the cylinder head tightening technology. But this does not mean that the force and tightening order for all motors is identical and before planting the head, it is imperative to study the conditions for performing the operation and all its features.

Common mistakes

Despite the fact that automakers clearly indicate the order and nuances of tightening the cylinder head, many motorists make mistakes when assembling the motor. The most common ones are:

To avoid further problems, you should use only fasteners designed for a specific engine and fully comply with the working conditions.

Features of the performance of work on the example of some cars

As proof of the judgment that each power plant has its own characteristics of cylinder head tightening, we will consider the nuances of performing work on specific models.

VAZ-2112 16 valves

A number of modifications of the VAZ-2112 were completed with two types of 16-valve power plants (factory indices - 21120 and 21124). These two motors, despite some design features, have the same head tightening technology.

These units use 93 mm tension bolts. In this case, the reuse of fasteners is allowed, but on one condition - if their length does not exceed 95 mm (if it is more, they should be replaced). 10 bolts are used to secure the head.

Tightening is carried out in three approaches:

1. The bolts are tightened according to the order with a force of 2 kg / m;
2. Turning over 90 degrees;
3. Repeated extension by 90 degrees.

The drive pattern is shown below.

Between the 2nd and 3rd sets, you need to take a 20-minute break.

Since tensile bolts are used on these engines, additional suspension is not required during operation of the car.

VAZ-2107

On the VAZ-2107, all installed modifications of the power units are 8-valve.

The head of the block is attached to them with 11 bolts, 10 of which are the main ones, and 1 - the auxiliary side bolts (installed in the side ledge).

On this car, tightening the fasteners is also performed in three approaches:

1. 10 main bolts are tightened according to the order with a force of 3.5-4.0 kg / m;
2. The same bolts reach with a torque of 11.5-12.0 kg / m;
3. The auxiliary one is tightened with a force of 3.5-4.0 kg / m.

Additional tightening of the cylinder head during operation of the VAZ-2107 is not required.

"Samara", 10th family, Priora

On models of the Samara family (2108-21099), as well as VAZ 2110-2112 with 8-valve units, tightening is already performed in 4 approaches:

1. Tightening with a force of 2.0 kg / m;
2. Reaching with a moment of 7.5-8.5 kg / m;
3. Turn around 90 degrees;
4. Re-turning 90 degrees.

The break between points 3.4 is 20 minutes.

As for the VAZ "tenth" family, which are equipped with 16-valve motors, their tightening technology is the same as that of the VAZ-2112 (described above).

The same applies to Lada Priora, on 8-valve units, a method with 4 approaches is used (VAZ 2108-21099), and on 16-valve units - 3 approaches (VAZ 2112 with a 16-valve motor).

Volga

On the ZMZ-406 engines installed on the Volga, according to the technical documentation of the automaker, the bolts of the engine block head are tightened in two approaches:

Subsequent tightening of the bolts during operation on this engine is not required.

Operation without a torque wrench

Since the force is precisely indicated on all these cars, then you cannot do without a torque wrench when landing the cylinder head. But on some cars it is quite possible to do without it and use ordinary wrenches and an extension nozzle for tightening.

Immediately, we note that the performance of work without special. the tool is allowed only on "old" engines ("Moskvich", VAZ of the first models).

A special feature of tightening the block head without a torque wrench is the need to "feel" the applied force. For the rest, the general method of work is the same as with the use of specials. tool:

One of the options for tightening without a torque wrench is to double-tighten the fasteners after completing the 2nd approach.

Periodically, the cylinder head gasket may fail due to wear of its material or its burnout. The main signs that it is time to replace the gasket with a new one are the appearance of local leaks of oil and coolant at the point of contact between the cylinder head and the motor.

It should be remembered that when replacing the gasket, not only the tightening torque of the cylinder head of the VAZ 2114 is important, but also the entire sequence of operations - after all, the replacement itself is a very important and serious procedure, errors during which can lead to engine malfunction.

Required tools and process

In order to do it correctly, you will need:

• set of socket heads;
• extension;
• ratchet / crank;
• torque wrench.

The replacement process itself should be performed according to the following scheme:

1. Disconnect the wires suitable for the emergency oil level and coolant temperature sensors.
2. Drain off coolant.
3. Dismantle the thermostat.
4. Remove the air filter housing.
5. Disconnect the inlet exhaust pipe from the manifold.
6. Remove the casing, as well as the camshaft belt itself.
7. Disconnect both damper rods from the carburetor.
8. Disconnect the wires suitable for the cylinder head.
9. Disconnect hoses suitable for cylinder head by loosening their clamps.
10. Remove the cylinder head.
11. Remove worn gasket.
12. Clean the contact surface of the cylinder head from the remnants of the gasket material.

The installation of the gasket and the installation of the cylinder head in its place is carried out in exactly the same sequence, but in the reverse order. At the same time, it is worth paying close attention to such a factor as the tightening torque of the cylinder head of the VAZ 2114 8 valves - we will talk about it below.

How to tighten the cylinder head bolts correctly?

Before proceeding with the installation of the block head, you should first pay attention to the condition of its bolts. They must be well threaded and in length meet the required standards.

The normal overall length of the cylinder head bolt is 135.5 mm. If the bolts removed during the replacement of the gasket meet this parameter, then they can be reused. If the bolts have lengthened during engine operation, then they can no longer be used and new ones should be purchased.

Having dealt with the bolts in this way, and installing them in place, you should proceed to tightening. It is performed without fail only with a torque wrench. Tightening the bolts "by eye" can lead to very serious consequences, up to and including damage to the engine itself.

And so, how to stretch the head on the VAZ 2114 correctly? First, remember to start tightening the bolts from the center outward.

This diagram looks like this:

• 7 3 1 4 9
• 8 6 2 5 10

Secondly, tightening should be performed in four stages (each of which is performed in exactly the same sequence as indicated in the diagram above).

At the first stage, we tighten each of the bolts with a torque wrench with a force equal to 2 kgf / cm2.

At the second stage, we tighten all the bolts with a force of 8 kgf / cm2.

At the third stage, we tighten the bolts, turning each of them at an angle of 90 degrees.

At the fourth stage, we again turn each of the bolts (still adhering to the diagram at the beginning) at an angle of 90 degrees.

After all four stages are completed, the tightening of the cylinder head bolts can be considered complete.

Tightening the cylinder head bolts should be taken as seriously as possible. It is necessary to perform all its stages strictly in the same order and with equal effort on each of them. Failure to observe this rule can lead to rapid wear of the gasket and the appearance of oil and coolant leaks.

Correct operation with a torque wrench

A tool such as a torque wrench, which allows the bolts to be tightened with equal torque, requires great care and skill.

The approximate sequence for tightening the bolts with such a wrench is as follows:

• set the holder to the "zero" position;
• start a smooth rotation of the instrument, while monitoring its readings;
• if the rotation of the tool (especially at the initial stage of tightening) occurs without changing the torque on the indicator, then this may indicate a slight internal tension of the fasteners. This phenomenon is completely normal and the rotation of the instrument should be continued;
• when reaching the tightening torque corresponding to the required, the movement of the tool should be stopped.

Instead of a torque wrench, you should not use any other tool (including a mechanized one with the ability to normalize the tightening force). After all, only a key can achieve absolutely precise and smooth tightening of the bolts, due to which the gasket will be evenly pressed over the entire surface of the block. This will help to maximize its service life, to avoid burnouts, oil leaks and coolant leakage.

Useful video

You can find additional useful information from the video below:


Well, at the end, it should be reminded once again that before starting tightening, you need to check the length of all bolts (it should be equal to 135.5 mm). If the length differs from the indicated one, especially in a larger direction, then there will be no sense even from the most careful tightening of such bolts.

The cylinder head (or cylinder head for short) is one of the most important components of the entire engine system of your car. The tightening process itself is quite simple, as is flushing the engine cooling system. To do the job well, you only need a special set of tools and the cylinder head bolts themselves.

When is cylinder head tightening necessary?

The need to periodically tighten the cylinder head is characteristic only of car brands that were produced until 2010 inclusive. All other models of modern cars have a completely different engine structure, as a result of which this stage of work is not carried out. However, for those who own the same VAZ-2106 or 2107, this problem is primarily relevant during the annual maintenance of the car.

• Pay particular attention to the selection of the correct tool, in particular the torque wrench. The more accurately you select it according to the size of the head, the less likely it is to knock off the thread. The most accurate torque values ​​are obtained using wrenches equipped with a dial force indicator.

To successfully tighten the cylinder head with your own hands, adhere to the following recommendations:

• Use the vehicle manufacturer's instructions. It indicates the exact values ​​of force and torque, and also sets the specific procedure for installing the cylinder head when repairing the engine.
• Check the original condition of the bolts. If you notice a breakage or distortion of the thread, then buy new samples.
• The surface of the hole and the threads of the bolt must be absolutely clean. The cylinders can be quickly cleaned with a wire brush, which is used when painting stamped discs.
• If you find "blind" holes for the cylinder head bolts, carefully use oil for lubrication. If there is more lubricant than necessary, you will not be able to install the bolt completely.

Advice: after tightening, be sure to lubricate the threads with plastic sealant.

• If TTY bolts are used in the cylinder head block, it is strictly forbidden to retighten them. With maximum force, they can simply rupture and lead to destruction of the gasket.
• When installing a new gasket under the bolt, it is imperative to clarify the information on the amount of force and torque when tightening.
• When tightening bolts of a special type TTY, it will be necessary to set and tighten them to a clear degree. To do this, you need an appropriate tool with an angle indicator in the body.

What is cylinder head bolt pulling used for?

If all the bolts of the cylinder block are in order and do not require replacement, but the torque is much lower than the values ​​specified by the manufacturer, it is necessary to pull the bolts. To do this, you need the following tool:

• Special torque wrench with torque indicator;
• A caliper or any small ruler.

Pulling the cylinder block bolts takes place in 4 main stages:

1. First, using a torque wrench, tighten the bolts in the order shown in the figure below to a force of 2.0 kg / cm.

1. Further, in the same order, you need to go through the second circle and hold out the value of the moment to 8 kgf / m.
2. At the end of the work, it will be necessary to turn the bolts to 90 degrees in the 3rd circle.

Important: If you have a 16-valve power unit in your car, then any type of bolts on it can be reused. The only limitation is bolts that do not exceed the standard size of 95 mm.

Replacing the cylinder head bolts and tightening them is a simple process that only requires the use of special tools and skill. If you are performing this type of work for the first time, then be sure to monitor the accuracy of the torque and setting the correct tightening angle.

Video: tightening the cylinder head

(Cylinder head) depends on the power and condition of the engine. After all, the cylinder head is an integral part of the combustion chamber, therefore it affects all processes associated with the operation of the engine. If the cylinder head is loosely tightened, during engine operation, exhaust gases will break through into the lubrication and cooling systems, changing the quality of the oil and antifreeze or antifreeze. This will cause the oil and coolant to mix. If this happens, the engine must be repaired immediately, otherwise there is a high probability of such damage, after which it will be cheaper to install another motor.

What does the cylinder head consist of?

On any type of engine, the cylinder head is arranged the same. It consists of:

• housing (heads), in which the channels of the oil and cooling systems pass;
• intake and exhaust valves;
• one or two camshafts.

The body is the main element of the cylinder head. It circulates lubricant and coolant, is the base for camshafts and valves. If the cylinder head housing is correctly attached to the engine block, then all engine systems work normally. If the cylinder head is tightened unevenly, then there is a high probability of cracks in the head housing. The cylinder head is made of aluminum, and the mounting bolts are made of steel. Therefore, the thermal expansion of the head and bolts is not the same. If some part of the cylinder head is tightened poorly, this will lead to the appearance of stresses in it, because one part of the head will increase more than the other.

How to properly tighten the head

The basic rule when tightening the head is to do everything evenly and not overdo it. Therefore, before tightening the cylinder head mounting bolts, you must carefully read the repair instructions (manual) of your car. After all, the tightening force (moment) for cast iron and aluminum blocks is different. It is not uncommon for the tightening torque to differ even on different engine models from the same manufacturer.

To tighten, you need a little engine or transmission oil, a torque wrench and an adapter (adapter) corresponding to the head of the bolts. Whether you are installing a fully assembled head or just a body, the tightening is the same. Insert all the bolts (after lubricating the threads with engine oil) into the holes of the head and block and screw in by hand as far as possible. Then, using a torque wrench, start tightening the bolts to a torque of 1 - 2 kg.m. Then up to 5 - 8 kg.m. Refer to the photograph for the bolt tightening order. If you install the cylinder head on an in-line engine with 5-8 cylinders, then first twist the middle, then gradually move to the edges. This will avoid damage to the cylinder head and gasket.

After tightening all the bolts with a force of 5 - 8 kg.m, in the same order pull them 1 - 2 more times, turning by ¼ turn. The head is tightened. After the vehicle has driven 500 km, all bolts must be tightened again by ¼ a turn (not on all vehicles). If you installed the head on the spring bolts, then this operation is not necessary.

Head tightening errors

The most common mistakes that lead to damage to the cylinder block or cylinder head:

• pouring oil into threaded wells;
• hauling bolts;
• use of an inappropriate wrench attachment;
• Wrong bolt tightening order
• using bolts that are too long.

If the threaded well of the cylinder block could not be cleaned of rust, scale and dirt, then the bolt without lubrication is very difficult to tighten. Therefore, the tightening is weaker than it should. Most minders will lubricate the bolts, but an inexperienced motorist can pour oil into the well for better lubrication. As a result, the well will be destroyed and the cylinder block will have to be changed.

If you tighten the cylinder head without a torque wrench, then the effort is determined by eye. As a result, instead of 16 - 19 kg.m. winding and 25 - 30. This often leads to breakage of the bolts and the need for expensive repair of the cylinder block. The heads of most cylinder head bolts are made for an internal or external hexagon (sometimes a square). If the socket on the wrench has lapped edges, then when tightening the bolt, it can turn. As a result, the edges of the bolt head will also be licked off and it will be difficult not only to tighten it, but also to unscrew it.

Video - Cylinder head tightening torque - torque wrench

Using a different order of tightening the bolts leads to stress in the cylinder head housing. Since the aluminum from which the head is made does not tolerate such loads poorly, cracks appear in the cylinder head housing.

Fuel combustion products leak through these cracks, which leads to a drop in engine power and throttle response, an increase in fuel consumption and a decrease in engine resource. Also, through the cracks, oil and coolant are mixed. When antifreeze, water or antifreeze gets into the oil, they dramatically impair its lubricating properties, resulting in increased wear on all rubbing engine parts. This often leads to cranking of the crankshaft liners and seizure of the engine.

Although most repair instructions allow for reusing bolts, it is advisable to reuse new bolts each time. Indeed, during the tightening process, the length of the bolt increases. Therefore, the manual specifies the maximum length of the bolt, at which it is still possible to use it. If the bolt turns out to be a little longer, it will rest against the bottom of the threaded well of the cylinder block, as a result of which the block will either break or split.