Compression is the most important indicator of the engine status. Interested in buying a car "as a door", we mean this particular parameter. From its magnitude will depend such indicators as the dynamics of acceleration, fuel consumption and oil. What is compression in the engine cylinders rate for engines and the reasons for its decline about everything in this article.

What is compression

Compression is the pressure being created in the cylinder when the piston in the compression tact reaches the NMT (upper dead point). Compression unit - kg / cm 2 (kilogram divided by centimeter in square) or atmosphere. In the former times, the engine compression was the amount of their separation into the infamited (6-7 kg / cm 2), medium-affiluted (7-9 kg / cm 2) and the forced engines (above 9 kg / cm 2).

The higher this value, the more economical and more powerful motor.

Compression and compression, what's the difference

In everyday life, talking and saying compression, we mean compression, in reality it is not the same thing. So the degree of compression and compression in what the difference.

The most visual prove it is a mathematical calculation. Look at the drawing below as it can be seen from here that the degree of compression in the simplest interpretation of the formula is the ratio of the working volume to the volume of the combustion chamber.

In reality, for more accurate measurements of the formula, it has this kind:

ε \u003d v1 + v2 + v3 / v1 + v3,

where V3 is the volume of the compressometer. For calculation, a coefficient of 1.2 - 1.3 is used (determined by the Poisson equation) and the formula has the form p \u003d ε * 1.2. From here we have that with a compression ratio of 10 kg / cm 2 compression should be within 12-13 kg / cm 2. Ideally, the values \u200b\u200bobtained by the compressometer should coincide with the calculated one.

Norm for different engines

The pressure in the engine cylinders depends on its type. The compression in the diesel engine should be no less than 28 kg / cm 2, although the pressure of 20 kg / cm 2 was considered normal in normal models 2. At the same time, the variation of values \u200b\u200bbetween the cylinders should be no more than 2-3 kg / cm 2.

On most gasoline imported cars and domestic, normal engine compression should be within 10 - 13 atmospheres, including on VAZ 2107, and on the VAZ-ox models of the "tenth" family, it is slightly higher, from 11 atmospheres. The compression difference in the cylinders should be no more than 0.5-1 kg / cm 2.

Signs of bad compression

The friction between the piston with rings and the cylinder leads to an increase in the gap, and as a result, it will be:

• increased oil consumption, as it will be easy to gather masonry rings and burn in the combustion chamber;
• an increased amount of smoke, due to the combustable oil, which follows from 1 point (in some cases it can be associated with faulty oil-challenged caps);
• as a result, power is reduced. This fall will be especially noticeable on engines with small litters;
• an increased amount of smoke from the Sapuna. Sapuna is both on carburetor and injection models.

Causes of low compression

As mentioned above, the decline in compression occurs for several reasons, it is:

1. engine life;
2. violation maintenance (unreasonable replacement oil);
3. the use of low-quality oil;
4. engine overheating;
5. riding on a cold engine (thermostat malfunction).

There are and reasons for which additives will not help and need repair, it is:

• piston exercise;
• valve exercise;
• rurate gaskets between cylinders;
• rings lay (sometimes "treated").

Furious piston

Such faults are practically visible immediately, but some can only be determined after diagnosis.

Engine diagnostics

With the booster piston, the tightness in the cylinder is broken, the engine is poorly started and unevenly works "Troit" as, and during the burnt valve. It is bad to start (or not even start) the motor when the rings "lay down".

Aligned rings

Check without device

You can check compression without compressometer. If it is necessary to reveal what kind of cylinder is faulty, it is enough to unscrew the spark plugs and scroll through the starter motor, and closing the hole with the finger to monitor the suction and release of air. With a big malfunction (frightened piston or valve), you will define this cylinder at once, as it will be weaker to suck and push the air.

In other cases, for accurate diagnosis of compression, it is better to use a compressometer.

Check compressometer

To check the compression in the cylinders with your own hands you need to have a compressometer. This is the device measuring pressure (from Greek manós, loosely), may have different nozzles for different holes.

Verification of compression in the engine cylinders is carried out together. So that the readings are correct before starting checking the engine, the cold values \u200b\u200bwill be lower. Further:

• remove the spark plugs and alternately insert the compressometer into the holes;
• the air damper must be open (gas pedal squeezed);
• hold the device in the hole until the testimony stops.

Do not "chase" a starter for a long time, otherwise it can burn. For most machines, a normal compression ratio in cylinders from 10 to 12 kg / cm 2 is considered.

Check oil

If the check showed low values, then it is necessary to determine what is guilty in the following way. To each cylinder pour 25-35 ml clean oil And check again. At the same time if:

1. values \u200b\u200bincreased almost to normal, then on the face of the wear of the cylinder-piston group or after overheating "lay" rings "
2. there is no compression in 1 cylinder or two, it can talk about the root of the piston, the valve, the destruction of the rings.

Methods of recovery

Raise compression in the engine, if you are confident or suspect that the rings lay, it is possible to bay in every 100 grams of clean oil and give time to them to "fold." Sometimes turning the crankshaft in both directions for several degrees. The procedure can be repeated.

The second is a more efficient way, you need to take: 1 part of pure motor oil, 1 part of acetone and 1 part of kerosene. Mix and pour into each cylinder 50 ml, tighten the candles and leave the clock to 10. Remove the candles and scroll through the engine starter for a few seconds. We set the candles, bring up and warm it up to 40 degrees no more. We drain the oil, rinse the system, change the filter and pour new oil.

There is I. special means They are also used when dealing with high compression that occurs with larger nagar on the piston and in the combustion chamber.

The second method is the pressure reduction by additives added to the oil. They appeared a lot with different efficiency on the market. I wrote about the use of additive, the effect of the application is positive.

What is being done primarily when the motor power drops, the fuel consumption increases, oil is consumed above the norm, and on idling Engine strongly vibrates? In such cases, you can define a malfunction by measuring the compression of the aggregate. Diagnostic specialists know what kind of compression in the engine should be, and the correct diagnosis is made by testimony. About the compression I heard something, probably every car enthusiast. Let's deal with what it is that compression affects how to measure it and how to enlarge.

What is compression in the engine cylinders

In a broad sense, this is the force that appears in the combustion chamber when compression tact ends. This is the pressure generated in the combustion chamber when the ignition is turned off (or when there is no fuel supply - in the case of a diesel engine). In this case, the piston is in the uppermost position.

What should be the compression of the gasoline engine?

Consider Read more Engine compression indicators for some car models. The standard formula for determining compression looks like this: compression \u003d compression ratio x coefficient x The compression ratio is indicated in technical documents DVS, while each model has its own degree of compression. The coefficient x is also defined separately for each group of engines, for example, 4-stroke gasoline engines with ignition from sparks have a coefficient of 1.2-1.3. For clarity, we give an example, how compression is calculated in the VAZ engine relating to 4-stroke engines using this formula. The degree of compression of the car VAZ 2112, indicated in the documents - 10.5. Substiving the desired values \u200b\u200bin the formula, we obtain the following: Compression in the VAZ 2112 \u003d 10.5 x 1.2 \u003d 12.6, compression indicators in other VAZ models, subject to the health of all systems and aggregates: car compression, kg / cm2 VAZ 2106 07 11 VAZ 2109 11 VAZ 2110 13

Compression in gasoline engines of some other models of cars of various manufacturers is listed in the table below:

What is the difference between compression compression

It is possible for a long time to theorize, explaining the difference between the compression and the degree of compression, to bring formulas, scientific calculations, that's just good from all this will, there will be no much. For usual, let's say, the rank user car motors The degree of compression is not so important. This parameter is struggling, it is laid during the creation of the engine and is unchanged while those or other changes will be made to this engine. This is for example, motor forcing, overhaul, etc. But all this, as a rule, make experienced masters, and therefore, taking into account the degree of compression, these are their headache. Let's just say that the degree of compression is the ratio of the combustion chamber volume to the total cylinder volume. In fact, this or that the importance of compression tells us how many times the air-fuel mixture will be compressed in this particular model of the motor.

As for compression, this indicator can change significantly during operation. It shows the real working pressure in the cylinder, and it, as a result of wear of the piston group, violations in the valves, problems with the tightness of the gasket of the motor head and other parts, can change significantly. From here and much greater importance of compression for the owner of a car or a specialist carrying out the repair of this machine.

Low Engine Compression Symptoms

Actually about signs of decline in compression in automotive engines, we have already said. Another thing is that the machine can and shake the machine for other reasons, with the engine compression, in no way connected. However, if the motor began to use oil if the work has become unstable, and even without visible reasons, the compression in the cylinders of your car should be measured. Also a decrease in compression may cause a drop in thrust, increasing the fuel consumption and an increase in the acceleration time of the car. As for the difference in compression in different cylinders of one engine, while this value does not exceed one atmosphere, there is no trouble. If the difference is greater, the motor should be repaired.

How often check pressure?

In prophylactic purposes, diagnostics should be diagnosed with the replacement of spark plugs gasoline motor. Depending on the car brand, the technical condition and quality of products, this operation is carried out with an interval of 25-50 thousand km.

The reason for extraordinary compression checks are such symptoms:

• the power unit began to "eat" oil in an amount of 150 ml per 1 thousand km and more;
• notice sIZY smoke from the exhaust path;
• the car has become bad to start "on the cold";
• on the idling Motor stalls and shakes.

The last feature may indicate a malfunction of the ignition system or failure of 1-2 candles. Before measuring the pressure, such problems is desirable to eliminate. On diesel engines, the wear of the piston group and valves is manifested by similar symptoms, especially difficult cold launch - With the lack of pressure, the diesel fuel simply does not flame.

Procedure for performing measurements

Before checking the engine compression, it is necessary to provide a complete charge of the battery and the operation of the starter. Otherwise you will get lowered indicators and take repair power aggregate Instead of continuing the diagnosis and search for other reasons.

There are several ways to measure pressure - "on the cold", "on hot", with a closed and fully open choke. Practice shows that the most accurate results give a test on a heated motor, performed according to the instructions:

1. Run the engine and bring the temperature of the coolant to 70 ° C.
2. Remove high voltage wires And remove all the candles, on the dieselle - nozzles.
3. Disconnect the nozzles from the controller by disconnecting the appropriate connector. Another option is to de-energize the gas station, pulling the desired fuse.
4. Screw the compressometer nozzle into the hole of the 1st cylinder, open the throttle, by pressing the gas pedal, and turn the crankshaft starter 5-10 times.
5. Remove the readings and repeat the operation on the remaining cylinders.

If you do not want to touch the electronics, you can not disable the injectors of the gasoline engine, it will not affect accuracy, but when diagnosing in oil Carter It will fall a small amount of fuel. The fuel feed on a diesel engine with a mechanical pump is turned off using a cut-off lever.

According to the measurement results, the following conclusions are made:

1. If measurement indicators differ no more than 1 bar and close to the optimal, piston group and valves are good.
2. The same situation, but the indicators are close to the minimum threshold. The resource of the power unit is almost exhausted, you can ride further and add oil, but prepare for repair.
3. When the pressure in one of the cylinders by 2-3 bar below the rest, re-check, bay into the candle hole 5 ml motor lubricant. Compression has grown - it means that the piston group is faulty, since the oil seal the adjacent rings. The testimony remained the same - the burned valve is to blame.

If the pressure in all cylinders is below the norm, you will have to make a major overhaul. Test with the addition of oil to carry out useless - the engine still needs to be disassembled.

Increase engine power with compressor

The compressor is a device, compressed and serving air masses under pressure to the consumer. The largest popularity of the compressors purchased from racers and adherents high-speed modes driving.

For a significant increase in the power of the motor instead of increasing its volume, you can force more air into the combustion chamber. This will entail a larger amount of fuel, which will create increased pressure and enhance the push of the outdated gas. For these purposes, an air blower is used - compressor.

The car compressor enables the engine to add more than 45% of the power, increase the torque by 31%.

Depending on the air supply method, the superchargers are divided into three types:

1. Centrifugal compressor.
2. Two-screw.
3. Rotor.

Thanks constructive features A centrifugal compressor that makes a forced increase in power, it is used more often than other types of superchargers.

The compressor is started using a rotating crankshaft Engine, which creates an additional load on the power unit. When creating motors working in a pair with a supercharger, additionally enhance nodes receiving an additional load during explosions in the combustion chamber. Improving the elements of the power unit significantly increases the cost of the engine and the car as a whole.

To determine the state of the power plant, the automaster is measured by compression in the motor cylinders. During the verification of this parameter, it is possible to obtain only numbers, but this operation allows you to estimate the state of the cylindroport group without a strong disassembly of the engine. Memorial compression is an operation that is performed in minutes, and this procedure provides a lot of information. But not everyone knows what compression is and how it is estimated by the degree of wear and state of the car's power unit.

Compression and compression ratio

Compression is a parameter that shows the pressure inside the combustion chamber when the NWT piston is reached on the compression tact. It shows how shrinking the fuel-air mixture, loaded into the cylinder when the intake tact.

Pressure is one of the factors involved in the combustion process. If you take a diesel engine, then in it ignition fuel mixes It occurs due to strong compression, which is why the mixture is heated so much that self-ignition occurs. Pressure directly affects burning.

In the gasoline engines, the lighting of the mixture comes from the spark of the spark plug. But in such engines it is necessary that the fuel-air mixture is compressed. In the process of this, the fuel evaporates and is better mixed with air, which ensures the ease of ignition, the full combustion of the mixture with a better return of energy. Therefore, compression is considered an important parameter Engine.

Automakers B. technical documentation Indicate the degree of compression. Car enthusiasts perceive this indicator as compression. In fact, these are two different parameters.

The degree of compression characterizes the ratio of the volume of the cylinder when the piston is found in NMT and VMT. This is a geometric parameter indicating how the fuel mixture is strongly compressed. It does not have units. The car documentation indicates that the compression ratio is 10: 1. From here we understand that there is a 10-fold reduction in the cylinder with a compression tact in the cylinder.

But the degree of compression is not a pressure indicator. And the fault of the physical processes occurring in the cylinder. In compression, the fuel mixture is heated, which is in a gaseous state. And the gas with increasing temperature expands, increases its volume. This is the reason that the compression value is higher than the compression ratio, by 20%. As a result, with a compression ratio of 10: 1, we obtain pressure in the chamber at the end of the compression tact at the level of 12 kgf / cm. sq. But this value is not accurate, since compression is changing due to the same physical processes. On the cold engine, the indicator is lower due to lower gas expansion.

Compression in the cylinders directly depends on the degree of compression, but no dependence in the opposite direction. The pressure in the cylinders on the geometric indicator can not affect.

Video: deceptive compression. Diagnostics of the engine without a car

What compression is considered normal?

Excessive pressure in the cylinders, as well as sufficient, negatively affects the processes in combustion chambers. With too much compression, the explosive nature of fuel combustion appears, the detonation of the motor, accompanied by the creation begins high temperatures and shock loads on the CPG and a crank-connecting mechanism.

Therefore, compression in engines is in a specific range. On gasoline engines, the pressure generated in the cylinder varies in the range of 11-13 kgf / cm. sq. But there are exceptions, the power plants of some cars have a compression of 14-16 kgf / cm. cm.

It was noted above that the ignition of the mixture in diesel motors is derived from pressure, and considerable. Therefore, in such motors, the compression indicator is higher than that of gasoline. The workers are considered to have a pressure of 22 kgf pressure at the level of 22 kgf / cm. sq.

What affects the pressure in the cylinders?

Squeeze fuel in the combustion chamber is possible only if it provides tightness in the cylinder. The pistons during the operation of the motor are constantly moving in the cylinders, and where there is a moving connection, there will be gaps there. And at least, seals are applied to eliminate these gaps - piston rings, but there are losses at the point of contact of the pistons with cylinders, since part of the gases breaks through in the poulfry space.

The interaction of the Elements of the CPG among themselves leads to the wear of contact surfaces, which is why the gaps are gradually increasing, which ensures the seeping of a larger amount of gases. And the more they come out, the less compression will be.

Other elements located in the combustion chamber can affect compression. The injection of the fuel mixture components into the cylinder and the removal of combustion products from it is carried out by valves of the gas distribution mechanism. In the normal state of these elements, their plates due to the springs are tightly adjacent to the saddles. But some negative processes that pass in the cylinders become the cause of burning the saddles and the edges of the valve plates, the formation of a nagar layer on them. As a result, we have another place for leakage of gases during compression.

The gasket is placed between the head and the cylinder block, in which there are cracks for overheating, affecting the combustion chamber tightness.

This reduces compression in the cylinders. And no pressure is not respected by the conditions for the normal combustion of the fuel mixture.

Signs Reduced compression

Reducing compression leads to changes in the operation of the power plant. The fuel is worse with air, so the combustion process is not as needed. The result of this becomes:

• power drop;
• difficult launch of a "cold" motor;
• interruptions in work;
• motor "Troit".

With a critical reduction in compression in the cylinders, the launch of the diesel engine is impossible, gasoline can still get started, but with difficulty. The boundary is considered to fall a pressure of 10% of the nominal indicator. For example, the compression of the motor is compiled 11 kgf / cm. sq. If this value falls to 9.9 kgf / cm. square, the installation will not start no longer.

Video: Engine compression

In addition to natural wear, there are other factors that affect compression. The use of low-quality fuel and lubricant It becomes the cause of nagar inside the cylinder and on the piston. Cocking the elements of the CPG, due to which the piston rings "lie" are jammed in a compressed position. The same Nagar settles on the valves, prevents them from tightly to the plates. These negative factors affect the compression of all cylinders.

Measure compression

Compression measurement is performed by a special instrument - compressometer. This is a pressure gauge with an adapter for installation on the engine.

The measurement technology is simple, but the readings are correct, it is necessary to perform certain conditions. For example, consider how the operation on a gasoline engine is carried out:

1. Before starting work, we are convinced that the battery is fully charged and is able to actively twist the crankshaft.
2. Warming up the power to the operating temperature.
3. Unscrew all spark plugs.
4. I overlap the fuel supply (in carburetor models, we disconnect the fuel pipe from the pump, in the injection - pull the fuse of the fuel pump).
5. We screw the compressometer into the candle hole.
6. Sit down for the wheel, squeeze the accelerator to open the throttle, and we use the starter for 10-15 seconds.
7. We look at the result on the manometer and write it down.
8. We carry out similar measurements in the remaining cylinders.

After measurement, we carry out the testimony based on which we obtain information. And it can be different.

If the readings in the cylinders are the same or there is a difference (there is a difference in the testimony of up to 1 kgf / cm. It is considered normal between the cylinders) and it does not mark the fall below the critical mark - the machine can be further operated.

Compression in the cylinders below the boundary mark is a strong wear of the CPG. The engine requires major repairs.

The pressure in one of the cylinders is significantly less than in the rest - there is a place of severe leakage.

Reveal that it was the cause of a strong drop of compression is easy. To do this, fill 20-30 grams. Oils in it and re-perform measurement. If the compression jumped - the rings lay down or collapsed.

If the fill of the compression oil did not affect - a malfunction we are looking for in the timing valves or laying GBC.. There are more serious breakdowns - the root of the piston or the sample wall of the cylinder, but such malfunctions are manifested not only by the drop in pressure, so they are detected earlier.

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What is the engine compression and how to measure it?

Each vehicle heard in his century such, purely technical concepts, like engine compression and compression ratio. If the engine compression falls, then it is bad - the power decreases, more fuel is used, the car is more difficult to start.

Let's try to deal with this question - what is the engine compression, why it falls, as affects the engine work, as it needs to be measured.

Definition of the concept of engine compression

It is easy to guess that the word "compression" means translated from Latin to Russian "compression".

In simple language, avoiding complex physical terms and formulas, we are talking about pressure in the combustion chamber in the highest dead point of compression tact. The higher the compression, the stronger the fuel-air mixture is compressed, no gases are cut into the engine crankcase, respectively, the engine operating action coefficient is higher.

If the level of compression corresponds technical characteristicsThe manufacturer is stated, the engine works in optimal mode: when the piston moves down to the combustion chamber, the required amount of air is sued, and when the piston rises up, the gasoline portion is injected into the chamber, the spark is given to the chamber, and the whole mixture is detected and burns without a balance. Minimum amount of exhaust gases.

Compression is measured in the atmospheres, pascals, kilograms per centimeter, but the most common unit of measurement is the atmosphere.

For example, in KAMAZ engines, the compression level ranges from 29 to 38 atmospheres, and in the Vazovskaya "nine" - it is approximately 9.5-13 atmospheres.

On the pages of our portal, we somehow considered as well. So, in diesel engines The level of compression should be much higher, which we see on the example of KAMAZ, because detonation occurs due to the addition of DT to preheated under high pressure air.

This can also be said about the difference between various stamps Gasoline - A-76, A-80, A-92, A-98. Octane number just determines at what values \u200b\u200bof pressure and temperatures this type Gasoline begins to detonate. That is, if you board in the benzobak lawn A-95 instead of A-80, the engine may simply get startedbecause the engine does not create required conditions For detonation.

Compression is associated with such a concept as "compression ratio". The compression ratio is not measured in some specific units, such as an atmosphere, a bar or paskal. It simply shows how many times the size of the combustion chamber is less than the total volume of the cylinder.

Based on the degree of compression is determined octane number Gasoline:

• gasoline A-92 must be poured with a compression degree less than 10;
• A-95 - 10-12;
• A-98 - above 12.

Causes of compression reducing

As is known, the piston moves inside the cylinder, and even at the inner walls, a protective film is formed, it is still with a time from the cylinder walls, a layer of layer is removed, and the inner volume of the cylinder increases. Accordingly, gaps are formed between the piston rings and walls, through which the gas under pressure can be broken into the crankcase, that is, the entire fuel and air mixture will be burned, but only its part.

In such cases, they say that compression has decreased.

This is displayed at the engine operation:

• make the car more complicated;
• there are failures in operation in all modes;
• increases oil and fuel consumption;
• grows pressure in the cooling system nozzles;
• black smoke from the pipe;
• cotton and shots are clearly audible.

Compression is reduced for other reasons:

• nagar formation on the walls of cylinders, in the combustion chamber;
• due to high temperatures, the bottom of the pistons goes;
• roasted and deform valve;
• cracks in the head of the cylinder block;
• it is required to replace the block gasket;
• brown air filter.

An experienced car mechanic can call you many more reasons. But if you start notice any of the signs listed above, then the time is sent to the diagnosis.

Repair tightening can lead to significant costs in the future.

Measuring engine compression

Specialists advise measure the level of compression every 3-5 thousand kilometers (for domestic cars) or after 10-20 for foreign cars. This procedure is simple and under the power of any motorist, the truth must have a special tool - the compressometer. It must be selected for a specific car model.

The compressometer measures the pressure in the combustion chamber.

To do this, you will need:

• warm the engine to a temperature not lower than 80 degrees;
• remove the coil and all the candles;
• if there is a computer - remove fuses;
• spin the foot of the compressometer into the candle well;
• press the gas pedal until the stop and rotate the crankshaft using the starter;
• repeat the operation for all other cylinders.

The data obtained must be compared with each other - they should not differ more than ten percent.

It is clear that for measurements, the battery must be fully charged, and the starter is in good condition, so that he could scroll through the crankshaft at least up to a hundred revolutions per minute.

Auto mechanics measure compression different ways and compare the testimony of the compressometer when open or closed throttle valve. If the compression is low, then proceed to search for the reason: piston rings, valves, boosted pistons and so on. Repair may pour out in a large amount, and it may only be necessary to replace the gasket or air filter.

From your side, as from the owner of a car, it is required to fully follow the requirements of the manufacturer: pour the desired type of oil, refueling the gasoline of the said brand, from time to time to undergo diagnostics.

In this video, you will see how to determine the compression of the engine.

Compression is determining the engine durability factor. It is from this indicator that the degree of wear depends on various parts of the engine. Therefore, motorists are trying to support it in various ways. - What is it and how is it measured? In today's article, we will try to describe this phenomenon in detail, and also learn to measure it yourself.

Characteristic

Compression is the maximum degree of air pressure in the combustion chamber, which is achieved at the time of finding the piston in the NTC in the process of compression tact. From the value of this characteristic depends the serviceability of the motor, as well as the durability of all its mechanisms.

Simple words, compression is an indicator of the viability of the engine, that is, the main factor of its health.

What does it affect?

Many processes depend on the magnitude of this value, namely:

1. Complete fuel combustion in the chamber.
2. Oil consumption.
3. Circus service. Low compression class increases the risk of engine trimming.
4. Easy to start the motor. If the value of the compression is lower than normal, such an engine is very difficult to start, especially "on the cold".
5. Power of the power unit. Over time, she can fall. The smaller the compression class, the lower the car's power. Accordingly, it follows weak characteristics Dynamics of movement and overclocking.

Causes of decline in compression

One of the main reasons for low compression is, with a frequency of the motor boosting in the cylinders, there are scales. They can also appear on pistons. The latter as a result melted or roast. Low compression (vases of the "tenth" family including) indicates the wear of the rings partitions. As a result of all these signs, power is noticeably lost, while growing

Also one of the reasons for the compression fall is a malfunction in the GDM system. In this case, there is a high risk of valve progress. Such a part is no longer subject to recovery. The boosal valves should be immediately changed, otherwise the drop in power and the increase in fuel consumption will not cease.

By the way, one of the reasons for the valve progress, and respectively, the compression falls is the wrong adjustment. If there is no necessary thermal gap between them, we can talk about serious malfunctions in the system of gas distribution. In this case, the valves will not be closed completely. But also big Clearance Also fraught with its consequences. For example, it may cause insufficient opening of the valves. Because of this, the cylinder flows less air. As a result - knocks under the valve lid.

Compression falls strongly and due to the progress in this situation, the spent gases will not go out through the silencer and but straight into the oil highway or in

What else can indicate a low degree of compression? The main reason that compression disappeared is wear piston rings and development on the walls of cylinders. Here the problem is additionally accompanied by increased flow Oil and gasoline.

Oddly enough, but even an air filter can cause low compression. The fact is that the scored item does not allow the air to get into the cylinders. As a result, a strongly depleted mixture is formed, almost without oxygen. In some modes of operation, this is normal, but when fuel is mixed in such proportions all the time, there is a reason to beat the alarm.

The last reason for reducing the compression indicator is a crack in the block head. It often happens due to engine overheating. But if you think that due to the low degree of compression, the stockings bridges are rushing, the compression here is nothing to do with it. Most likely, there was an overload in the back of the car, not more.

What is the normal engine compression?

What it is - the phenomenon of compression - we have already found out. Now a little about numbers. But first it should be noted that this indicator is installed on each engine separately, its manufacturer's plant. The exact value of the compression is indicated in the instruction manual for your car. For gasoline engines This indicator must correspond about 9.5-10.5 atmospheres. The compression of the VAZ "Tenth" family is slightly higher - 11 atm. On diesel engines, the runt of compression ratio ranges from 28 to 32 atmospheres. At the same time, the spread between the cylinders should not exceed more than 0.5-1 atm in gasoline and 2.5-3 atm in diesel power plants. Such different classes Compression stockings are a consequence of different types Fuel ignitions. If the gasoline inlet it lights up with the help of the spark, then the diesel engines are compressed. Hence such a different compression. It makes diesel motors more durable and wear-resistant. Practice has shown that the higher the factory degree of compression, the more powerful and more economical engine.

Experts say that the value of the compression may differ, despite the stable technical condition of the DVS. This can happen due to the difference in the conditions in which measurements were performed.

There are several factors from which the result of the compression measurement may depend on:

1. The volume of air that enters the cylinders.
2. Engine temperature.
3. The rotational speed of the crankshaft.

It is also necessary to allocate that viscous oil, located on the walls of the cylinder, also contributes to an increase in the value of the compression ratio. This phenomenon is observed due to the sealing of the gap between the conjugate elements. And on the contrary, compression is reduced due to an excess amount of fuel that enters the combustion chamber.

Do not panic and wonder if the car mileage is 200-250 thousand kilometers, and the measurement readings are very large (for example, 10 atmospheres at gasoline engine). The reason for this may be the accumulation of a thick layer of carbon on the elements of the combustion chamber. As these deposits accumulates, the volume of the combustion chamber itself is reduced, which leads to such dubious results.

In what cases does the level of compression increase?

In addition to the above factors, this indicator may be an increase due to:

• The presence of oil in the combustion chamber.
• High engine temperature.
• Fully open throttle valve.

Experienced motorists say that when measuring compression, it is necessary to pay attention to only three moments: the temperature of the motor, fuel and the position of the throttle.

How often should measure measurements?

Drivers say that it is necessary to measure the compression ratio every 10-40 thousand mileage kilometers and all values \u200b\u200bare recorded in a notebook. Thus, you will constantly know what state is your engine at the moment. This will avoid troubles such as the overheating of the motor, the mark of the valves, pistons and their location.

In what conditions do you need to do measurements?

It is very important to follow the measurement rules of this indicator, because it depends on the accuracy of the measurement, and accordingly, the further life of the "heart" of your iron horse. So, when working with a compressometer, it is important to pay attention to the following points:

• Engine temperature. Motor to the measurement should be heated, and its temperature fluctuate in 40-60 degrees Celsius.
• Fuel supply must be disabled.
• Charged accumulator battery. Her voltage must be at least 12 and no more than 14 volts.
• Low air humidity. It is not recommended to measure in rainy weather.
• Before measuring, you need to unscrew all the candles from the cylinders.
• Turn off the ignition.

Methods measuring compression

Before proceeding with the work, make sure that this device is really suitable for the engine of your car. Full models of devices have a small tip, so they are difficult to use on 16-valve power plants.

You can measure compression with both open and closed throttle. Specialists recommend measuring in both cases. This will determine the engine malfunctions (if any) with higher accuracy.

If the measured indicator has increased or decreased, you can make a diagnosis - your motor is faulty, and it needs urgent repairs. But do not forget that there is a small scatter of the values \u200b\u200bof the cylinders, which we have said earlier.

In order to produce accurate measurements, you need an assistant. So why start work? Initially, you must press the compressometer to the hole in the cylinder, that is, where you unscrewed the candles. At this time, the assistant includes the starter. The latter should work approximately 4-6 seconds. Next, on the manometer, the arrow will show the values \u200b\u200b- they must be recorded.

After measuring compression in one cylinder, go to the next one. Its verification is made in the same way. Such manipulations should be repeated with all cylinders. In this case, each value is recorded separately in the notebook. It is desirable that the battery gives a voltage to 13-13.5 volts. It will give us a starting current margin, since with each second starter rotation, the battery is dropped at a certain level.

Upon completion of the work, you must install the candles back and re-check the voltage in the battery. If necessary, recharge it into a few volts.

To more accurately determine the current status of the engine, it is necessary not only to focus on the indicators of the measurement compression, but also a number of other characteristics. It can be a level of vibration, noise, fluctuations in power, operation of a motor at idle, and fuel.

Conclusion

So, we found out which compression should be and how it can be measured. Indicators on the instrument make it possible to accurately determine the internal state of the motor, its remaining resource and current malfunctions. And if you found that you have no compression, such an engine should be subjected to more detailed inspection and repair. Otherwise, after a couple of thousand kilometers, he will destroy himself, and no overhaul will save him.