The wear of the liners leads to a decrease in oil pressure in the engine lubrication system. We can see this when reading the oil pressure gauge in the engine. If the connecting rod or main bearings are worn, they must be replaced with new ones, as this can lead to significant wear of the crankshaft.
If the crankshaft is damaged from wear, then it must be removed and given for grinding on the machine. The most common causes of bearing wear are metal chips, dirt, debris, normal bearing aging, poor system oil lubrication, etc.
The inserts are not recoverable, they are simply replaced with new ones. You can replace the liners yourself if you have engine repair experience and the right tool for this.
Liners are plain bearings, there are two types of them, main and connecting rod. They withstand heavy loads during engine operation. The liners are made of tin-aluminum alloys.
The insert consists
steel base gives the insert rigidity and tight fit in bed, keeps its shape at high temperatures.
Intermediate layer
consists of lead bronze, designed for anti-friction coating substrate, and also serves to prevent scoring of the working coating of the liner.
Nickel underlayer lays down on top of the intermediate layer. Its thickness is 1-2 microns. The nickel sublayer has anti-corrosion features to keep the liner from rusting.
Anti-friction coating - this is the working surface of the liner, where the friction of the surfaces of the knees of the shaft and the liners occurs. This coating has a low coefficient of friction. It is made from lead alloy.
Liner wear detection
To determine the wear of thin-walled bearing shells, use a brass plate to check the clearance between the bearing shells and the crankshaft journals. The cover is removed from the bearing under test and cleaned of grease, and a brass plate lubricated with oil is placed on the liner.
Then the cover is put in place and tightened to failure with bolts. The bolts of the remaining covers must be loosened, the crankshaft is turned with the crank. With a gap of normal size, the shaft turns with difficulty, or does not turn at all.
If the shaft rotates easily, then the liners are subject. replacement. After replacing the liners, the bolts are tightened with a torque wrench. The allowable gap between the shaft journal and the bearing is provided by selecting the bearing according to the journal size. It is impossible to reduce the gap by sawing off the bearing caps or by placing gaskets between the liners and sockets.
It is also impossible to increase the gaps by scraping the liners; this may expose the steel band of the liner and damage the crankshaft journal. The taper and ovality of the crankshaft journals, as well as the presence of scratches and scuffs on them above the permissible value, are eliminated by grinding them to the repair dimensions with the installation of liners of the corresponding repair dimensions.
Signs of wear on the liners
Entry of foreign bodies. Foreign bodies can get into the engine in most cases when we repair it, and we do not see when something accidentally enters the engine crankcase. This usually gets dirt, sand, debris. Dirt will quickly spread through the engine and cause great damage to it. Sand particles will scratch in all rubbing areas of the engine, and the engine can quickly fail.
Elimination methods.
If dirt gets on the surface of the liner, there is scratching, scoring, it is necessary to drain the oil and change it. Check oil and air filters for integrity. Flush the engine with flushing fluid to remove all dirt particles.
Corrosive wear
Corrosion abrasion occurs on the back surface of the liner. In this case, there may be several reasons.
1 When repairing the engine, the mounting bolts were loosely tightened
2 The engine often ran at high speeds
3 Foreign bodies are on the surface of the support of the liners
4 Wrong size earbuds fitted
Troubleshooting methods are also varied.
1 Tighten the bolts with a manometric wrench to the required torque.
2 Try to save the engine and not squeeze the last juices out of it at high speeds.
3 Always check the cleanliness of the assembly of the liners.
4 Inserts use the appropriate size.
metal fatigue
Signs. With metal fatigue, the delamination of metal particles in the middle of the liner, where the maximum load occurs, will be clearly visible on the liner. The same will happen with long-term use.
There are several reasons.
1 Uneven load on the liners when the engine is running.
2 The inserts do not meet the requirements of the manufacturer (marriage).
3 Troit the engine, its uneven work.
4 Engine vibration.
Elimination method
1 Check the visual condition of the inserts.
2 Check the crankshaft, take measurements, replace the liners.
3 Eliminate the causes of uneven engine operation.
4 Measure the compression in the engine cylinders.
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It leads to a decrease in the efficiency of the engine lubrication system, which, in turn, can lead to significant wear of individual parts of the power unit, as well as to a decrease in its working life. Therefore, if even slight wear is detected on the connecting rod and / or main bearings, corrective action must be taken.
Usually the causes of wear are their natural aging. However, in some cases, dirt or debris gets on their working surface, corrosion occurs, insufficient lubrication, axle misalignment and other reasons. As a rule, the liners cannot be restored, so they must be replaced with new ones. The procedure is quite complicated, so its independent implementation makes sense only if the car owner has the appropriate work experience and the necessary tools.
Description of the inserts
Before proceeding to a description of the signs, causes and methods for eliminating wear of the liners, it is necessary to understand their purpose, types and principle of operation.
There are two types of crankshaft liners - indigenous And connecting rod. In fact, the liners are plain bearings, and their task is to withstand significant loads that occur between the connecting rod and the crankshaft journal. In modern machines (in most cases) liners are made of ductile aluminum alloys (usually aluminum with tin). From above they are covered with an anti-friction compound.
The main bearings are located between the crankshaft and the place where the crankshaft passes directly through the engine housing, in seats, the so-called "beds". The main bearings have holes in their design for better oil drainage. That is, the main bearings are plain bearings for the main journals of the crankshaft. And in fact, it keeps and rotates on the main bearings.
The connecting rod bearings are located at the bottom of the connecting rod head. And the connecting rods, in turn, are fixed with the help of connecting rod bearings on the connecting rod journals of the crankshaft. The function of the connecting rod bearings is that they are plain bearings for the lower heads of the connecting rods and the connecting rod journals of the crankshaft.
The wear of the liners implies a significant increase in their gaps (the larger the increase, the worse). As a result, the pressure in the engine lubrication system drops. Usually in such cases, a light (oiler) lights up on the dashboard, symbolizing that the oil pressure has dropped significantly. Especially often this manifests itself on a hot engine, when the oil viscosity is minimal. Drivers in such cases say that "the bearings do not hold oil." Liner wear is a very dangerous problem that can lead to a lot of wear on other parts of the engine and the motor as a whole. And this can lead to a significant decrease in their resource and damage.
The sound from the knock of the main bearings is usually muffled, with a metallic tint. It is easy to identify when the engine is idling, and after that the speed increases sharply (sharply press the gas pedal). At the same time, a large load is placed on them and a knock appears. Similarly, you need to do with the connecting rod bearings.
It is easy to find, and in which cylinder the liners are knocking. To do this, turn off (unscrew) the spark plugs on a gasoline engine or fuel injectors on a diesel engine. If, with any unscrewed candle, the mentioned knock disappears, then there is a problem in this cylinder.
Signs and causes of wear
Now let's go directly to the types of damage that contribute to the wear of the liners and their failure.
Ingress of foreign bodies
signs. A sign of ingress of foreign bodies or dirt is the situation when there is a local damage to the working surface on the liner. In some cases, there may also be slight (smaller) damage on the back of the part. Typically, debris or dirt on the surface of the liner is the root cause of further wear. Therefore, it is necessary to identify the indicated malfunction as early as possible. Otherwise, the wear will spread further and a significant surface area will be damaged, up to 100%.
Causes. As stated above, the reason for this situation is the ingress of dirt or debris between the liner and its support. This also results in the formation of places with high oil pressure, in which the oil film is destroyed. In turn, this leads to the destruction of the surface of the liner during its operation.
Elimination Methods. First of all, it is necessary to check the bearing surfaces of the liner and shaft for damage. If they exist, they must be eliminated. After that, you need to make sure that the surfaces are clean. This is especially true when new inserts are installed.
mud erosion
signs. A sign of mud erosion is the presence of burrs or inclusions of dirt. Sometimes both. In especially advanced cases, mud erosion can move to areas near oil holes.
Causes. The reason in this case is low-quality oil, which contains dirt impurities or abrasive materials.
elimination. It is necessary to check the operation of all moving parts of the engine. Especially carefully it is necessary to check the lubrication system. It also makes sense to check the oil and air purification system (primarily filters). When assembling the engine, do not allow dirt to enter it. After all, it is necessary to change the oil to a new one.
Corrosion abrasion
signs. We are talking about the presence of corrosive abrasion on the rear steel surface of the liner. As a rule, traces of corrosion are located closer to the connection of the halves of the liner body.
Causes. In this case, there may be several reasons. Among them:
- Reduced pressing force. This leads to minor movements of the body of the liner relative to the surface of their support.
- The mounting bolts were loosely tightened during installation.
- There are foreign bodies on the contact surfaces of the support of the liners.
- Prolonged operation of the engine at high speeds (especially if this occurs often).
- Using earbuds with the wrong size (width).
elimination. According to the different causes of the problem, the troubleshooting methods may also be different. In particular:
- Tighten the mounting bolts to the torque recommended by the vehicle manufacturer.
- Inspect the fit diameter of the bearing support.
- Check the cleanliness of the mating surfaces between the bushing and the support.
- Use an insert of the prescribed size (width).
- Try not to use the engine at high speeds for a long time.
metal fatigue
signs. Fatigue can be caused not only by long-term use of the earmold, but also by excessive load on it. Signs of its failure will be a situation when particles of material are literally torn out of its body, especially in places of significant load.
Causes. There may also be several:
- Use of inappropriate or poor quality earbuds. This leads to their significant overload.
- The main load during operation falls on the edges of the liners.
- Incomplete combustion of fuel in the combustion chamber.
- Incorrect tuning of the car engine.
Elimination Methods. Accordingly, the elimination methods may also be different. Need to check:
- axial shape of the shaft.
- the shape and geometric dimensions of the liner supports.
- engine assembly conditions, and in particular, the installation of liners.
It also makes sense to install a new quality liner that fits the size.
Wear due to penetration of tin
signs. A significant layer of tin in a certain place on the surface of the steel base. This is usually accompanied by very strong localized wear in that area.
Causes. The occurrence of small movements of the liner in its seat, which arose due to the low pressing force.
Elimination Methods. Typically, you need to do the following: The first is to check the bore diameter of the liner support. The second is to check the cleanliness of the mating surfaces of the liner and support. Third, check the bolt torque and adjust it according to the manufacturer's recommendations.
Surface corrosion
signs. Corrosion, depending on its degree, always damages the surface of the liner. It becomes porous and loses its color.
Cause. As a rule, the described phenomenon is caused by the use of low-quality oil, during the decomposition of which acids are released, which cause corrosion.
Elimination Methods. It is necessary to revise the engine, and especially the lubrication system. If there are significant damages on the shaft and the bushing, they must be repaired. At the end of the repair work, it is imperative to buy a high-quality new one recommended for this machine.
Not enough lubrication
Liner wear diagnostics
signs. Little or no oil can cause chafing and/or melting of the bearing face. And this, in turn, is the cause of metal fatigue and damage.
Causes. Destruction of the lubricating film between the bushing and the shaft. Because of this, friction and temperature increase significantly during operation. Materials melt. The cause may also be a failure of the engine lubrication system. If the liner bearing is deformed or the surface of the shaft journal is damaged, then there is a high probability of destruction of the lubricating film.
Elimination Methods. It is necessary to revise the engine lubrication system, including the purity of the oil. It also makes sense to check the condition of the surface of the shaft journal and the bearings of the liners. If necessary, make repairs. It is also possible to install new liners.
Incorrect processing of the crankshaft journals
signs. The inner surface of the liner contacts the shaft journal on one or both sides of the liner body. It is also possible that the material of the inner surface is very worn from the ends along the circumference.
Causes. The reasons for this situation may be:
- The size of the insert does not correspond to the required value, usually a large width.
- The inner lock of the liner case is small in size.
- Shaft journal installed incorrectly.
- The fillet (or fillets) necks have a very large width.
- Thrust bearings have very large clearances.
- Thrust bearings incorrectly adjusted.
Elimination Methods. Elimination methods can also be as follows, you need to check:
- type of insert case, its width, size and shape of the lock.
- the shape of the shaft neck fillets.
- axial clearance of the crankshaft.
scratches on the surface
signs. There are some scratches that do not look like working scuffs from the operation of the mechanism.
Causes. On the working surface of the liner for some reason (most often due to lack of cleanliness during their installation) there are small foreign particles. Perhaps their formation is caused by casting or drilling technologies.
Elimination Methods. Flush the engine with new clean oil using an external oil pump. It is best to flush after assembling the engine and before the vehicle is run in.
Excessive erosion due to cavitation
signs. The material from which the liner is made has local washout points. They are usually located symmetrically or centrally on the working surface of the liner. It is also possible that they occur on the reverse side of the oil channel.
Causes. There are several possible reasons for this:
- ingress of coolant into the oil system;
- increased oil flow rate in the system;
- detonation;
- incorrect bearing clearances.
Elimination Methods. Elimination methods can be as follows, you need to check:
- the presence of coolant in the engine lubrication system;
- gaps on liners;
- oil flow rate;
- operating parameters of the ignition system, as well as to revise the engine.
Misalignment
signs. If misalignment occurs, excessive wear occurs only in the region of the upper part of the liner body towards the edge. In this case, the wear zones are diametrically opposite on the circumference.
Causes. Misalignment of the central axes of the liners and the neck.
Elimination Methods. The following options are possible:
- Check the big diameter of the connecting rod. In this case, ideally, the central axis of the “bed” of the connecting rod should be located exactly perpendicular to the thrust planes. In this case, it is necessary to check that both thrust planes are parallel.
- For the main bearing, you need to check the alignment of the “beds” of all the main bearings on the engine.
Prevention methods
As mentioned above, partial failure of the liners leads to increased wear of the engine, and in particular, its lubrication system. Therefore, in order to prevent such a situation, it makes sense to carry out periodic preventive measures. So, first of all it is necessary use the engine oil recommended by the car manufacturer. This is especially true for its viscosity. You should not buy very cheap oil, since it is highly likely that it will contain abrasive particles that negatively affect the engine as a whole, and the liners in particular.
It is also worth periodically checking engine parts, their condition, geometry, cleanliness. When carrying out repairs, always make sure that no dirt gets into the engine and/or lubrication system (oil). There is a so-called "golden rule" of the minder, which says that it is better to have a gap of 0.03 mm more than 0.01 mm less. In this case, the liner is guaranteed not to fail, melt or knock. Keep an eye on the condition of your car's engine and it will serve you for years to come.
It is better not to wait for the situation when the light on the dashboard lights up, signaling low oil pressure. Ideally, you should periodically check the pressure value yourself or in a car service. After all, the light bulb of the oiler glows (that is, the emergency sensor is triggered) as a last resort, when the pressure has dropped to critical. This is best avoided, especially on engines with significant mileage.
Conclusion
It is necessary to periodically check the condition of the liners, since these seemingly insignificant parts can lead to big problems with the engine's oil system, thereby significantly reducing its life. And the sooner it is possible to identify a breakdown and eliminate it, the lower the cost in the future the car owner will have to face to carry out. The replacement procedure can be carried out both independently and at the service station. However, if you decide to carry out the repair yourself, then you must be 100% sure that you can complete the job, since the replacement involves a large amount of both dismantling and installation work.
The vehicle engine is a complex unit, consisting of thousands of different parts. In order for the internal combustion engine system to work in a balanced way, all elements of the unit must function properly. In this article we will talk about liners for crankshaft repair: what is their purpose, what marking and how to replace components.
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Description of crankshaft bearings
All main and connecting rod journals of the crankshaft have their own dimensions, we are talking about the parameters that the journals take after the grinding process. The dimensions of these elements must fully comply with the dimensions that the crankshaft repair liners have. Accordingly, when buying such spare parts, it is necessary to take into account the parameters of your vehicle, because each individual motor has its own dimensions.
For example, if you own a classic VAZ car, you should keep in mind that domestic cars have four different sizes of liners. This means that the crankshaft can in principle be bored no more than four times. You also need to take into account that the crankshaft liners also have an outer size that never changes, but the inner one can be adjusted due to an increase in the thickness of the elements.
Purpose of inserts
In fact, the main bearings of the crankshaft, regardless of the marking, act as bearings designed to improve the sliding of the connecting rods. Connecting rods, as you know, are designed to rotate the crankshaft under the influence of a microexplosion of the combustible mixture in the combustion chambers of the engine. Since the elements wear out periodically, the motorist must remove and replace them in a timely manner, which should also be accompanied by a shaft bore.
It is no secret that when the engine is running, internal components are subjected to high loads and rotational speeds. This means that the motor simply needs to reduce friction, otherwise the unit may fail almost immediately. In order for the friction force to be significantly lower, all the necessary components inside the motor function in a micron film, which is oil.
This layer, which envelops the metal components of the unit, is formed only with sufficient pressure of the working fluid. In particular, the film must always be between the crankshaft main journal and the liner, as a result of which the friction index is not as high as it could be. Accordingly, the liners, which are made of metal, are a reliable protection that allows you to increase the service life of the shaft as a whole.
Design
It would seem that the crankshaft liner is a common part, but its manufacture is carried out using several different metals.
Accordingly, the liner consists of several layers, which we will consider below:
- the first layer is made of copper, its percentage can be from 69 to 75%;
- the manufacture of the second layer is carried out from lead, its percentage is from 21 to 25%;
- the third layer is tin, about 2-4%.
In general, the total thickness of the liner is 250-400 microns. It should be noted that sometimes not copper, tin and lead are used for the manufacture of the liner, but a specialized aluminum alloy. Marking in this case will depend solely on the manufacturer.
Kinds
As for the types, the marking here will depend on the type of component.
In general, liners for the crankshaft are divided into several groups:
- Indigenous. Regardless of the marking, the main bearings perform similar functions. They are mounted between the crankshaft and the place where this shaft passes through the motor housing.
- Connecting rod. The connecting rod components are located directly between the connecting rods and the shaft journals.
In principle, liners, both connecting rod and main, are produced for each type of motor, but they all differ in inner diameter. Depending on the engine model, the diameters of the elements will be different, even for one engine. As a rule, the difference in diameter, that is, the pitch, is 0.25 mm. This means that the size range of parts is as follows: 0.25 mm, 0.5 mm, 0.75 mm, etc.
Checking and replacing the earbuds
When do you need to change?
Since the crankshaft operates under conditions of high temperature and physical stress, only bearings can keep it on its axis. The necks, both main and connecting rod, play the role of internal clips, but the liners are external. Like other engine components, liners wear out over time, which leads to the need to replace them.
Physical wear is an important condition in which it becomes necessary to remove and replace elements. As much as the motorist would not want to avoid wear and tear, this is impossible. Operating a vehicle with worn parts can result in engine failure.
However, the need to remove and install new parts may arise in other cases. For example, often domestic motorists are faced with such a problem as turning the liners. A thin plate of the element is mounted in a special groove, and from the outside, the protrusions abut against the end parts of the bearings. In some cases, when the loads are very high, the protrusions are not able to hold the liner, causing the latter to rotate.
In this case, further operation of the internal combustion engine will be impossible, this malfunction occurs for the following reasons:
- as a result of using a very viscous oil;
- in the absence of lubricating fluid or ingress of abrasive into it;
- with very low interference when mounting bearing caps;
- if the oil is not viscous enough;
- if the engine is regularly operated under conditions of high loads and overloads.
signs of wear
If you have already understood that the repair of the motor of your car is inevitable, then you will probably be interested in identifying the wear of the elements. To determine the measurements, you will need a micrometer, but you can also visually identify the breakdown. During the inspection, you will also need to evaluate the possibility of subsequent boring of the shaft.
But if the liners began to rotate, then their removal and installation of new ones should be done as quickly as possible. One of the signs of wear is a loud knocking of the shaft, a decrease in engine power, as well as its regular attempts to stall.
In the event that the necks are jammed, then driving a car will be impossible. One way or another, but you will have to carry out a detailed inspection of the elements. If wave-like damage is detected on the necks, which, in principle, can be felt with your hands, then the crankshaft needs to be bored. Accordingly, the replacement of the crankshaft liners in this case will also be necessary. If you are going to buy new parts, then it is better to do this after the motor has been bored out, because if the wear is large enough, then you can miscalculate with the size.
Replacement sequence
To date, the procedure for removing and installing crankshaft liners is not particularly popular among our motorists. Drivers in most cases trust this procedure to specialists, but some still decide to replace the elements at home. We recommend doing repairs with your own hands only if you have at least some knowledge.
In general, the process of replacing the earbuds is described below:
- Before proceeding with the replacement of components, it is necessary to check the presence of a gap between the shaft and the liner. To do this, you will need to use the calibrated plastic wire that is on the neck. Then the cover from the elements is installed and tightened with the necessary force, in this case this figure is 51 Nm. All measurements should be made with a torque wrench.
When the cover is removed, the gap will correspond to the degree of flattening of the wire. To evaluate the desired parameter, you should use the nominal clearance, this indicator should be indicated in the service manual for your car. In the event that, when checking the gap, you find that it is greater than that specified by your automaker, then the liners will have to be changed. The purchase of liners is carried out strictly in accordance with your car model, if the gap is too large, then buy parts only after the shaft has been bored. - When all the gaps have been measured, it will be necessary to dismantle the connecting rods from all necks. Then the crankshaft is removed and its boring is carried out. The grinding process itself should take place on the centripetal. Naturally, such a device is unlikely to be found in the garage of an ordinary motorist, so it would still be better to entrust the grinding procedure to professionals.
When the crankshaft is bored out, proceed to the selection of repair liners. In this case, you will again have to use a micrometer, then try on the shaft liners. When removing old liners, pay attention to their condition - perhaps their failure is due to external mechanical influences. So that the malfunction does not recur after a while, it is desirable to eliminate the cause, of course, if it exists in principle. After all, as you remember, the failure of the liners can be the result of physical wear and tear. - Only after you have finally chosen the parts for repair, you can begin the process of installing the crankshaft. All installation steps are carried out in reverse order, everything must be done correctly and strictly in accordance with the requirements of the automaker. Only when all components are in place can the main bearing caps be screwed on.
- After that, proceed to the installation procedure directly of the shaft liners themselves, as well as the connecting rods. In general, this process should not take much time and effort. Repair liners must be lubricated with engine fluid, after which their covers are screwed on. Actually, the installation itself is quite simple, except for the preparatory processes.
When operating your “iron horse”, always remember that the crankshaft is one of the most expensive in terms of repair and replacement of components. Moreover, it experiences very serious loads during operation. Accordingly, you, as a driver, need to take all measures in order to increase its service life. And an important procedure for this is boring, which must be carried out on time. If the boring process is performed correctly, then all the necks will be smooth, respectively, they will be able to withstand heavy loads during operation.
Also keep in mind that the vehicle's motor is a rather complex unit in its design. And although some experts can disassemble and assemble it with their own hands even with their eyes closed, dismantling and assembling the crankshaft still requires specific skills. Therefore, in the absence of good experience, we do not recommend that you take up this business. After all, by pulling or not pulling the liners during installation, you can again encounter the problem of turning them.
During the operation of the engine, wear of all parts, including the main and connecting rod journals, gradually occurs, therefore, crankshaft repair liners are used to restore their performance. The main journal is the part of the bearing connecting the motor and the shaft, which is the main support of the crankshaft. And the connecting rod neck is also a support, but already for connecting the shaft with the connecting rods. Therefore, the integrity of these parts is fundamentally important.
What are crankshaft bearings?
All connecting rod and main journals of the crankshaft have their own repair dimensions (parameters that they can take after grinding during the crankshaft boring process), which must correspond to the dimensions of similar liners used as spare parts. Both types of liners play the role of bearings, which greatly improve sliding, therefore, when they are worn, timely replacement should be carried out, accompanied by a crankshaft bore.
For most engines, there are several repair sizes of liners. For example, for classic VAZ models there are four of these sizes. Accordingly, the crankshaft can be bored four times. In fact, this is the usual grinding of the surface of rubbing parts to make it smooth and workable again. The outer size of the liners remains unchanged, while the inner size is adjusted by increasing their thickness.. After each replacement of liners, the engine should work for more than one thousand kilometers if it is properly lubricated, i.e. other systems will not act up.
How to determine the wear of the crankshaft liners and help the mechanism?
When repairing an engine, the question often arises of how to determine the wear of the crankshaft liners and their next repair size (which they will have after the upcoming boring). As a rule, a micrometer is used for measurements (measures linear dimensions), but it can be calculated visually with sufficient accuracy. The possibility of further boring of the crankshaft is immediately evaluated.
Replacement is required almost immediately in the case when the crankshaft liners were turned. The loud knock of the mechanism and the constant attempts of the engine to stall will tell you about this, sometimes the necks wedge, then you definitely won’t be able to go further. In all other cases, a thorough inspection is necessary, and if undulating grooves are observed on the necks that can be felt by hand, it is necessary to bore and install liners of the appropriate repair size.
How to put liners on the crankshaft - procedure
In most cases, the replacement of the liners is carried out at the service station, however, if desired, any driver who has repair skills and knows how to use the tool may well try to carry out this operation on his own. To do this, you need to sequentially do the following:
- The first step is to check the clearance between the liner and the crankshaft. To do this, a calibrated plastic wire is located on the desired neck. After that, a cover with an insert is installed and tightened with the necessary force (approximately 51 N m (Newton per meter), this value can be measured by tightening the unit under examination with a torque wrench). After removing the cover, the gap is determined by the degree of flattening of the wire. To evaluate this parameter, there is a nominal gap for each brand of car, and if the wire indicates that the gap is larger, then a repair insert will be required.
- After checking the clearances on all connecting rod journals, it is necessary to remove the connecting rods, dismantle the crankshaft and send it to the boring. Grinding is carried out on a special machine (centripetal), which, of course, not everyone has. Therefore, it is better to do it with the master. After boring, you need to select the crankshaft liners, here again a micrometer will help and further fitting with measuring the gap.
- When the size of the liners is finally selected, the crankshaft is installed in the reverse order. Its elements must be placed in their seats and screw the caps of the main bearings.
- Next, you need to decide how to put the liners on the crankshaft, and install the connecting rods in their places. To do this, they are lubricated with engine oil, their covers are twisted, so that direct installation takes a minimum of time, not to mention preparation. It is important to assemble the crankshaft with the same clutch and flywheel installed in the engine before the repair.
We must remember that the crankshaft is one of the most expensive parts in any car. In addition, it bears the greatest burden. Therefore, it is necessary to take all measures to extend its service life. In this matter, the timely boring of the crankshaft plays a decisive role. After this procedure, all necks become perfectly smooth and ready for further work. It is this factor that determines the quality of the overhaul.
A - Scratched by foreign particles - grains are visible, immersed in the working layer of the liner
B - Lack of oil - the top layer is worn off
C - The inserts are incorrectly positioned during installation - there are shiny (polished) areas
D - The neck is reduced to a cone - the top layer is removed from the entire surface
E - Wear of the edge of the liner
F - Fatigue fault - craters or pockets formed
EXAMINATION
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Insert selection
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The procedure for assembling the engine after a major overhaul
Make sure you have all the necessary replacement parts, tools, and materials before starting assembly. Carefully read the description of the procedure and get ready to perform the work. Among other equipment, sealants will also be required for mating non-gasketed surfaces and fixing threaded connections. The compilers of this Guide recommend using only brand-name materials, tools, fixtures and replacement components (indicated in the text).
In order to save time and minimize the risk of various kinds of difficulties, the compilers of the Manual recommend that when assembling the engine, install the components in the following order:
Engine 1.3 l
a) crankshaft;
c) A head of cylinders (the Part Repair without extraction from the car of the petrol engine of 1.3 l of the present Chapter see);
d) Rocker shaft assembly;
e) Timing drive chain with sprockets (see Part Repair without removing the gasoline engine 1.3 l from the car of this Chapter);
f) Flywheel (see Part Repair without removing the 1.3 l gasoline engine from the car);
g) Oil pan;
h) Mounted components and assemblies.
Engines 1.6 l and diesel
a) crankshaft;
b) Connecting rod and piston assemblies;
c) Oil pump (see Part Repair without removing a 1.6 l gasoline engine from a car or Repair without removing a diesel engine from a car of this Chapter);
d) Crankcase pan (see Part Repair without removing a 1.6 l gasoline engine from a car or Repair without removing a diesel engine from a car);
e) Flywheel (see Part Repair without removing a 1.6 l gasoline engine from a car or Repair without removing a diesel engine from a car);
f) Cylinder head with gasket (see Part Repair without removing a 1.6 l gasoline engine from a car or Repair without removing a diesel engine from a car);
g) Timing belt tensioner, gears and the timing belt itself (see Part Repair without removing a 1.6 l gasoline engine from a car or Repair without removing a diesel engine from a car);
h) Mounted components and assemblies;
i) Auxiliary drive belt(s) with pulleys and tensioners (see Part 1.6L Petrol In-Vehicle Repair or Diesel In-Vehicle Repair).
At this stage, all serviceable and remanufactured engine components to be installed must be absolutely clean and dry. It will be correct to lay out the parts in the order of installation on a clean work surface.
Installing the crankshaft and checking the operating clearances of the main bearings
Engine 1.3 l
Determination of the working clearance of main bearings
3. Useable old liners must be installed in the block and bearing caps in exactly the same order.
4. When installing a machined shaft complete with a set of original Skoda repair kit liners, the need for the checks described below is eliminated.
5. Checking the working clearances of the main bearings should be carried out if there is the slightest doubt in assessing the degree of wear of the shaft, as well as in the case of installing a machined shaft complete with non-branded repair liners. The gap determination can be made by either of the two methods described.
6. The first method, more complicated due to the need to use inside gauges and columbus, requires the installation of main bearing caps (with liners inserted into them) on the block. Tighten the cap bolts to the required torque (when checking bearing clearances, old bolts are used). Now measure the inner diameter of each of the bearings with a caliper / columbus. Next, subtract from the results obtained the diameters of the corresponding main journals of the crankshaft. Compare the calculation results with the requirements of the Specifications.
7. The second method involves the use of a special measuring set Plastigage. The clearance value is determined by the degree of flattening of pieces of soft calibrated wire from the set when they are compressed between the main bearing shells and the shaft journals. Measurement of the width of the flattened pieces of wire is carried out according to the scale printed on the packaging of the set.
8. Information about suppliers of measuring kits can be obtained from any service station.
9. Insert the upper main bearing shells into their beds in the cylinder block, then carefully place the crankshaft into the block. Do not use any lubricant - the shaft journals must be absolutely clean and dry.
11. Wipe the running surfaces of the lower shells in the bearing caps and lubricate them with a thin layer of silicone compound to prevent the gauge wire from sticking. Install the covers in their regular places in the engine - check the factory markings. Screw in the old fixing bolts and tighten them to the required torque. Do not allow the crankshaft to rotate after laying the calibrated wire on it.
12. Loosen evenly in several steps, then unscrew the mounting bolts and remove the covers, being careful not to break the integrity of the flattened pieces of wire.
14. If the clearance is out of range, check whether dirt or foreign particles have fallen under the back of the liner. Wipe down the backs of the earbuds and their beds and retest. At repetition of negative result check up correctness of selection of loose leaves (the Section Replacement of an epiploon of an intermediate shaft see). If the calibrated wire is more flattened at one end than at the other, then the neck has a taper and must be turned.
15. If the gap is excessive, despite the correct selection of liners, the shaft necks should be machined for the installation of liners of the next repair size (see Section Replacing the intermediate shaft seal).
16. Finally, after making sure that the operating clearance of the bearings complies with the regulatory requirements, remove the traces of flattened wire from the shaft journals by carefully scraping them off with the edge of an old credit card.
Final installation of the crankshaft
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Engines 1.6 l and diesel
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Determination of the working clearance of main bearings
3. Lubricate the upper bearing shells with clean engine oil.
4. Insert the crankshaft into the block so that the cranks of the second and third cylinders are at TDC, and the first and fourth are at BDC.
8. Proceeding in the same order, tighten the bolts to the angle of the 2nd stage of tightening (use a goniometer or a template specially made of thick cardboard).
9. Install the rear oil seal housing assembly with the new oil seal installed.
10. Check up freedom of cranking of a cranked shaft. In the event of jerks and bite points, without delay, investigate and eliminate the cause - re-check the operating clearances in the bearings.
11. Check up an axial play of a shaft (see the Section Removal and installation of a cover of a head of cylinders). If the thrust surfaces of the shaft are not worn out, and the half rings are replaced, the play should be normal.
Installation of piston rings
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Installation of connecting rod and piston assemblies on the engine and checking the operating clearances of connecting rod bearings
Engine 1.3 l
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Engines 1.6 l and diesel Checking bearing clearances 1. As in main bearings, connecting rod bearings must have a strictly defined working clearance, which ensures effective lubrication of rubbing sliding surfaces. 4. The second method is based on the use of a calibrated wire from the Plastigauge set (see Section Installing the crankshaft and checking the operating clearances of the main bearings). All components must be thoroughly wiped and installed without lubrication. |
Final installation of connecting rod and piston groups
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Diesel engines
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The initial start of the engine after the completion of its overhaul
Acting in accordance with the instructions set forth in Section Procedure for assembling the engine after overhaul, install the remaining components on the engine, assemble the power unit and install it on the vehicle (see Section Removal, dismemberment and installation of the power unit). Carefully check engine oil coolant levels. Make sure all communication lines are properly connected. Check the engine compartment for materials and tools left in it.
Petrol models
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| 3. Turn the engine over with the starter until the oil pressure warning light goes off. If the lamp does not turn off after a few seconds of cranking the engine, recheck the oil level and the oil filter is secure. If everything is in order, check the condition of the oil pressure switch wiring. You should not continue trying until you are sure that the oil is properly circulating through the engine. |
Diesel models
All models
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General information and precautions
Cooling system diagram (carburetor engine 1.3 l)
On all models of cars of the brand in question, a closed-type cooling system operating under pressure is used. The system includes a water pump driven by a timing belt on 1.6L models and an auxiliary drive on others, a cross-flow aluminum radiator, an electric fan, a thermostat, a heater heat exchanger, as well as all connecting fittings and electrical switches. . Cold coolant from the radiator through the lower hose enters the water pump, which supplies it to the galleries of the block and cylinder head (as well as to the interior heater heat exchanger). After removing heat from the surfaces of the cylinders, combustion chambers and valve seats, the coolant reaches the bottom of the thermostat, which is initially closed. Next, the coolant passes through the heater heat exchanger, after which it returns back to the water pump.
The functional diagram of the engine cooling system is shown in the accompanying illustration. The cooling system functions as follows: a centrifugal water pump takes cold coolant from the bottom of the radiator through the lower radiator hose and pumps it under pressure through the galleries of the water jacket of the block and cylinder head, and, if equipped, also through the oil cooler heat exchanger. Having removed heat from the cylinders, combustion chambers and valve seats, the liquid enters the lower part of the thermostat, the valve of which remains closed during the engine warm-up stage and then opens. In addition to cooling the engine, the coolant is also used to heat the car interior. For this purpose, a heater heat exchanger is included in the cooling system path, passing through which the liquid returns back to the cylinder block.
Until the engine has warmed up to a certain temperature, the coolant continues to circulate in a short circuit, passing only through the block and cylinder head, as well as through the heater heat exchanger. As soon as the engine temperature reaches the set value, the thermostat opens, as a result of which a radiator is connected to the fluid circulation circuit. In the radiator, convective heat transfer from the liquid to the oncoming air flow occurs, the efficiency of which is determined by the developed area of the radiator heat exchanger fins and the speed of the air flow around them. If necessary, additional cooling of the radiator is provided by turning on the electric fan of the cooling system. When the liquid reaches the lower cavity of the radiator, the cycle repeats.
An electric fan controlled by a temperature-sensitive cooling system switch is installed behind the radiator. As soon as the temperature of the coolant reaches a certain set value, the fan turns on, as a result of which the airflow to the radiator heat exchanger increases, which leads to an increase in the efficiency of heat transfer.
Precautionary measures
| To avoid scalding, never remove the expansion tank cap or disconnect any components of the cooling path when the engine is hot. If it becomes necessary to remove the reservoir cap before the coolant has completely cooled (such situations should be avoided if possible), excess pressure in the system must first be relieved. Wrap the tank cap with a thick layer of rags, then slowly unscrew until a hiss appears. When the hissing noise indicating release of steam stops, slowly unscrew the lid all the way. If the hissing does not resume at the last stage of unscrewing, the cap can be removed. During the entire procedure, do not tilt your face over the neck of the tank; wear rubber gloves to protect your hands. Try to avoid getting antifreeze on exposed skin and paintwork on body panels. Accidental splashes should be washed off immediately with plenty of clean water. Never leave drained or fresh engine coolant stored in an open container. Collect traces of the strait immediately with rags. Remember that the sweet smell of antifreeze can attract the attention of children and animals. The ingress of even a small amount of coolant into the digestive tract of a living organism is fraught with the most serious consequences, even death. Remember that when the engine is hot, the cooling fan continues to function even after the ignition is turned off - take care of your hands, try not to let hair or the edges of clothing come into contact with the impeller blades. Precautions for models equipped with an air conditioning system are listed in Section Air conditioning system - general information and precautions. |
Disconnecting and replacing cooling system hoses
If during performance of the checks listed in the corresponding Section of the Head Routine maintenance, defects of hoses of system of cooling are revealed, they should be replaced.
Empty the cooling system. If the coolant filled in the path is fresh enough, it must be reused and must be drained into a clean container.
Try to remember the route of the hose to be replaced. To disconnect the hose, loosen the hose clamps on the fittings / nozzles of the corresponding components. Slide the clamps along the hose, completely freeing the sections of the latter seated on the fittings. Carefully remove the hose from its fittings/pipes. To fasten the hoses, two types of clamps are used: standard, as well as spring, to release which, squeeze the free ends with pliers.
Remember that the radiator inlet and outlet pipes are rather fragile elements - do not use excessive force when removing the hoses from them. Rotate the hose on the fitting to facilitate removal. In extreme cases, a strongly “sticky” hose can be cut off from the nozzle with a knife - despite the certain material costs associated with this method, it will still be cheaper to replace the hose than to purchase a new radiator (nevertheless, first make sure you have a replacement hose on hand ).
When installing a new hose, first put on the mounting clamps on it, only then pull the hose onto the fittings / pipes of the corresponding components of the cooling path. Some hoses and their fittings are equipped with landing marks - take care of their correct alignment.
To facilitate the fitting of rigid hoses on fittings, lightly moisten the ends of the latter with soapy water, or preheat the ends of the hose in warm water - do not use any oils as a lubricant.
Pull the hose ends onto the fittings and check the correctness of its laying in the engine compartment. Move the clamps to the ends of the hose, leading them behind the flare fittings / nozzles. Tighten the pinch screws.
Fill the cooling system (Routine maintenance see the Head).
Start the engine, then carefully check the system for signs of coolant leaks.
Removal, check of a condition and installation of a radiator
Radiator of the cooling system
Radiator of the cooling system - general information
Models 1.3 l
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1.6L models without air conditioning
Diesel models without K/V and petrol models 1.6 l with K/V
Disconnect the negative cable from the battery, then empty the cooling system.
Petrol models
3. Turn out bolts of fastening of a radiator to the top transverse beam of a front end of the car (the latch of the lock of a cowl is built in this beam).
Diesel models
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Status check
2. If necessary, a “flow-through” check of the radiator for blockages of internal channels can be carried out at a service station.
3. Repair of a radiator that has lost its tightness should be carried out only in a specialized workshop. Trying to fix the situation with a soldering iron will only damage the plastic components.
4. In an extreme situation, minor coolant leaks
