What compression should be on a VAZ-2109 car

All owners of domestic cars know the first symptoms of problems with the VAZ-2109 engine: poor dynamics, increased gas mileage, partial or almost complete lack of response to the gas pedal, lack of traction, the car moves with great effort, black smoke comes from the exhaust pipe .

First, an experienced driver blames the spark plugs, and then the piston system comes into question. To check the condition of the piston rings, an independent diagnosis of the operation of machine parts is carried out.

To do this, you need to determine the engine compression.

Even if the carburetor is acting up, you need to check the compression first - this approach will allow you to accurately detect faults in the VAZ-2109, eliminate them and proceed to regulating the carburetor.

About LADA 2109 engines 1st generation (1987 - 2011)

VAZ 2109 (Lada Samara), popularly known as a nine, is a five-door hatchback, a continuation of the Samara line. It was developed in 1987 using the three-door hatchback VAZ 2108 as a basis. The nine itself became the basis for the creation of the VAZ 21099. The car became widely popular thanks to its rapid design, good engines for those times, as well as a practical five-door body. All this, coupled with its low cost, as well as a wide selection of spare parts, made the VAZ 2109 very attractive. This attractiveness was passed on to its successor, the VAZ 2114. In contrast to the VAZ, the injector was installed as standard on the 2109 engines (power unit 2111).

In addition to the injector, the 2109 was equipped with a carburetor with a displacement of 1.1 l, 1.3 l and 1.5 l. Such engines can be seen if you look under the hood of the 2108.

In the article we will look at the engines themselves for the VAZ 2109, their characteristics and weaknesses.

ENGINE VAZ 2108

The 1.3 engine is the base for the eight, it was developed from scratch, and is structurally similar to the 21011 1.3 liter engine. there is nothing in common. This engine became the basis for the creation of power units for installation on the Samara family with a displacement of 1.1 liters and 1.5 liters. This is an in-line carburetor type engine, has 4 cylinders and an overhead camshaft. The timing drive uses a belt.

Regarding the service life of the engine, it is fair to say that careful and quiet operation, proper and constant maintenance will allow you to exceed the official 120 thousand km and the service life can be 180-200 thousand km.

In terms of disadvantages, the following are most often noted. The parts of the cooling system wear out quite quickly. Frequent oil filter replacement and valve adjustment will be required. Oil leaks often occur due to unreliable seals of the valve cover, fuel pump and distributor sensor. It should be noted that unreliable Solex-type carburetors in general, and EPHH in particular.

If the timing belt breaks, the valves may bend. Also, over time, problems with ignition and engine tripping may occur. In addition, due to ignition problems, the engine may detonate. Another reason for this may be low-octane, low-quality fuel. Detonation is indicated by black smoke coming out of the exhaust pipe and loss of power.

ENGINE VAZ 21081

Engine VAZ 21081 1.1 l. is an analogue of the power unit 2108 1.3. However, it has a crankshaft of less stroke, and as a result, reduced traction. This is an in-line carburetor-type engine with four cylinders, an overhead camshaft, and a timing belt. As for the resource, if you ensure careful operation and quality maintenance, you can count on an official 125 thousand km.

Compression in the cylinders of a VAZ 2114 engine 8 valves

The very concept of “compression” denotes the amount of pressure that the engine piston develops at maximum compression of the working mixture, that is, when it is at its lowest point. The higher this parameter, the higher the temperature the fuel-air mixture will burn, which means its consumption will decrease and the overall efficiency of the engine will increase.

Compression measurement for VAZ 2114

The compression of the VAZ 2114, in fact, like the compression on any other car, depends on the following indicators:

1. on the size of the clearance between the cylinder walls and the valves;
2. on the volume of the incoming mixture, which, in turn, depends on the position of the throttle valve and the characteristics of the air filter;
3. from the current engine temperature.

In turn, the size of the gaps between the cylinders and the elements of the piston group can also have a number of reasons:

1. high degree of wear or burning of their walls;
2. incorrectly set clearance between the cylinder walls and the valves;
3. the entry of liquid gasoline into the cylinder (not in the form of a mixture), which causes the oil to be washed away from the walls and the clearance to increase.

Normal compression and its deviations

General cylinder diagram

According to generally accepted standards, the compression of the VAZ 2114 8 valves should ideally be 14 bars (almost 14 atmospheres). The maximum permissible deviation to the lower side is 3 bars (that is, the compression value should not be lower than 11 bar).

True, this is only allowed if the compression value in different cylinders differs by no more than 1 bar. That is, the following compression schemes are acceptable in four cylinders: 12-12-11-12, 12-11-12-11 and so on. If the pressure difference exceeds 1 bar, then such an engine must be urgently repaired.

For example: 11-14-12-8.

Also, it should be remembered that increased compression is no less evil than low compression or compression with a large variation in the cylinders. Thus, increased pressure in the cylinders of the VAZ 2114 can cause high load on engine components, deposit of carbon deposits on the cylinder walls, and ultimately lead to complete engine failure.

Thus, the normal compression should be in the range from 14 to 11 bar, and have a variation from cylinder to cylinder of no more than 1 bar.

In most cases, only new engines have an ideal compression of 14 atm. Even after short-term use, it can quickly drop by 1-2 units - this is considered quite normal. With further wear, it will begin to sag even more, and the wear itself will proceed differently in all cylinders, which will ultimately lead to a large variation in pressure in them.

Deviations from the norm: reasons

If after the measurements it turns out that the compression of the VAZ 2114 engine is lower or higher than 10 bar in at least one of the cylinders, it is necessary to establish the cause and make repairs. To determine the cause of low compression, you will need a 10 cc medical syringe filled with motor oil. Use it to spray oil into the cylinder bore and measure the pressure again. If after repeated measurements the pressure rises, we can conclude that the problem lies in the wear of the rings. If the result does not change, the problem is in the valves: they could burn out or become jammed. A high compression rate threatens to damage the engine pistons and rupture the cylinders. The reason for this malfunction may be the following: 1

The valve stem seals or oil scraper rings have become over-worn. These problems inevitably lead to increased oil consumption; pay attention to its consumption. If it turns out that the oil consumption is increased, then, together with the pressure readings, this will clearly indicate over-wear of the caps or rings. 2

Formation of carbon deposits in the cylinders. You can get rid of it by decoking.

When else is this method useful?

Perhaps piston wear in one cylinder is rare, but the valve is pinched - this is a fairly common occurrence. And when the engine heats up, the clamped valve will simply burn out. And if it turns out to be understretched, then strumming sounds will be heard. This is where this method of checking compression without tools comes to the rescue.

Therefore, if you have been adjusting valves, but do not have much experience in this matter, then after adjusting the valves, perform the described operation twice, once on a cold engine, the second time, heat the car to 85-90 degrees and repeat the procedure. When the valves are adjusted incorrectly, but on some cylinder the compression disappears, there will be almost no compression, this means that you have overtightened the valve. We urgently open the lid, adjust the valve and go.

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There are compression tester readings, you need to put them into practice

If low compression is visible in one cylinder and the engine idle is unstable, then there is a high probability of wear on the camshaft cam, which controls the exhaust valve.

If the compression is different according to the diagram: low in two adjacent cylinders, then most likely the gasket between them has burned out.

And finally, after you added a little engine oil to each cylinder and repeated the compression test, the readings increased - the piston rings were worn out.

Poor compression in the engine

The car's behavior has changed. The engine does not start from the first crank with the starter or requires prolonged rotation, and at sub-zero ambient temperatures it may not start at all. If you unscrew the spark plugs and inspect them visually, the reason for the failure to start becomes clear - the spark plugs are “wet” due to an excess of fuel entering the cylinders. These are symptoms of poor compression in the engine.

Signs

• the engine starts, after warming up it idles smoothly, but when driving there is a loss of power;
• failures during acceleration and increased fuel consumption;
• works with misfires - “troit”.

What to do if the above symptoms are identified

In order to avoid further and rapid wear, it is necessary to establish the causes as soon as possible and identify components that need to be repaired.

Based on the results of compression measurements, the following indicators are possible:

• high - more than 15;
• low - less than 12;
• no - 0.

An increase in compression in the engine is visible in the exhaust gases - the color becomes bluish-white and oil consumption increases. When accelerating, the piston pins ring. High compression causes an increase in carbon deposits on the valve plates and guides, and a layer of coke forms on the walls of the combustion chamber, reducing the volume of the chamber and accordingly changing the compression ratio of the cylinders.

High compression gradually causes engine detonation knocks, which destroy the connecting rod and piston group.

Reason for high compression

Analysis of the engine revision shows that there is more than one reason. The table shows the reasons for increased compression in the engine:

Reason for low compression

Weak compression is detected when it is started, especially in cold weather, and signs are also found in loss of dynamics and increased fuel consumption.

Low compression increases the rate of engine wear, and if the defect is in one cylinder, then the idle speed is unstable, the car often stalls or lowers the idle speed.

The table shows the main reasons:

If there is no compression in one or more cylinders, then the engine starts very poorly, and once started, it immediately begins to work unbalanced, with strong vibrations and shaking.

If compression is lost in all cylinders at the same time, the engine will not start. One of the reasons may be a broken timing belt while the engine is running and a collision of the piston with the valves. After an impact the valves bend. The gas distribution system loses its tightness, and the compressed air-fuel mixture is directed at high speed into the intake and exhaust manifolds.

Compression also disappears in one of the cylinders due to severe burning of the valve disc. There are examples when from 40 to 50% of the valve disc area is melted and compression is zero. This is easy to determine without a compression gauge. It is enough to wrap a spark plug in this cylinder and when cranked by the starter, the crankshaft will rotate easily and uniformly, without highlighting the compression strokes.

When measuring compression, it is advisable to observe the needle of the pressure meter (pressure gauge) and monitor the dynamics of its increase. By the rate of increase in compression, you can indirectly determine in which group of parts there is severe wear. If on the first stroke the pressure gauge shows low compression (3-5 atm), and during subsequent strokes the rate of pressure increase increases, then with a high probability it can be established that the piston rings are worn out. To double-check the readings, you can use the method of artificially creating an oil film on the cylinder wall by adding 5-10 ml of oil through the spark plug hole. If, with added oil, the compression increases sharply on the first stroke and settles at nominal, then we can specifically state that the compression rings are worn out. If you measure in two adjacent cylinders and obtain a low result without oil and with oil, you can conclude that there is a defect in the cylinder head gasket.

Another option is also possible, when 6-9 atm is reached on the first stroke and on subsequent strokes the pressure gauge needle hangs in the same position. In this situation, it is assumed that the valve or cylinder head gasket is not tight. You can more accurately determine the cause with other diagnostic devices, such as a pneumatic tester or an electronic oscilloscope.

Compression measurement: without a compression meter or using special equipment

So, in practice, only two methods are actively used that allow compression measurements to be taken:

Naturally, the presence of a device allows you to obtain the most accurate readings, however, in emergency cases or to obtain approximate estimated results, the decision to measure compression manually is also practiced.

Let us immediately note that in order to measure compression without instruments, certain skills and knowledge will be required, and the operation does not present any great difficulties, even for novice car enthusiasts.

1. First you need to unscrew the spark plugs, leaving only the spark plug in the first cylinder.
2. Then the crankshaft must be turned so that the piston in the first cylinder is at the end of the compression stroke.
3. To accurately determine that the piston is in the correct position, you need to check the marks.
4. Next, you should approximately remember with what force the crankshaft was turned by hand.
5. After this, the spark plug is screwed into the second cylinder and so on.

Note that although the method is quite primitive, in some cases even it allows you to get a general idea and identify a problem in a particular engine cylinder. More accurate measurements can only be made using a compression gauge.

First of all, you need to study the technical documentation in relation to the specific type of internal combustion engine installed on the machine. Having determined the specific compression value for the engine, you need to start the engine and warm it up until it reaches operating temperature (the cooling fan turns on). Then carefully unscrew the spark plugs

Next, you need to invite an assistant who will depress the gas pedal (an important condition when measuring compression) and crank the engine with the starter. If we talk about the device, the compression meter has a special tip that is tightly inserted into the spark plug hole

After this, the engine is cranked by the starter for about 3-4 seconds. It is also important to take into account that you need to measure compression provided that the battery is charged and the starter itself is fully operational. The fact is that insufficient crankshaft rotation speed can lead to a noticeable decrease in performance, but this will not mean that the compression in the engine has dropped so much. Then, when the readings have been obtained, they need to be compared with the nominal values ​​​​for a particular engine.

It is also important to understand that it is not recommended to continue operating an engine in which compression is reduced in one or more cylinders for a long time. The fact is that the parts in this cylinder will wear out even more, the engine itself will vibrate more strongly and operate unstably, unburned fuel will flow into the oil pan in excess, which will cause dilution of the oil, thereby increasing the overall wear of the internal combustion engine, etc.

Forms of manifestation of technical malfunction

Under normal operating conditions, a vehicle consumes a normal amount of oil and fuel. As the piston rings wear out, the iron horse shows clear signs indicating the need for technical inspection:

• reduced engine speed;
• thick black smoke comes from the muffler;
• increased consumption of fuel and lubricants per 100 km of track;
• a specific hum appears.

The above symptoms require measuring the compression level in the engine using special tools:

• a wrench used to align spark plugs;
• compression gauge;
• syringe;
• 30 ml machine oil.

Before starting the measuring procedure, valves 2109 must be adjusted correctly. If you do not have sufficient experience in this, the operating instructions will come to the rescue.

The slightest inaccuracy will lead to incorrect measurement results. Direct measurement occurs in 2 ways:

1. Manually. This method requires practical experience. The use of devices is associated with the car owner’s ability to correctly assess the dynamics of changes in readings. All spark plugs (except for the first) on the cylinder are turned out. After this, you need to slowly turn the crankshaft until the compression stroke disappears in cylinder No. 1. Then you must sequentially unscrew the remaining candles in the same way. The cylinder where the most effort is put into removal is the defective one.
2. Compressometer. Using the device allows you to quickly obtain the value of the compression level in the cylinders. Measurement begins only after checking the reliability of the connections between the motor and the device. The crankshaft rotation speed when measured is at least 100 rpm.

Even a slight deviation of the indicator from the norm is a reason for investigation. For the most accurate measurements, they are carried out on a hot engine (at a temperature not lower than 80 ºС). After turning it on and warming up, it is necessary to remove the candles as described above. An objective assessment of the compression level can only be made with the throttle valve fully open. In some cases, outside help will be required.

Measuring compression in the cylinders of an injection engine

To carry out the work you will need a compression gauge and an assistant.

— Before measuring compression, it is advisable to check the clearances in the engine valve mechanism and fully charge the battery.

— Warm up the engine to operating temperature.

— Place the car on a level surface, raise the handbrake, select neutral gear.

— We take out the three fuses of the engine management system (ECM) and the control unit (ECU).

The ECM fuse and relay box on VAZ 2108, 2109, 21099 vehicles with an injection engine is located under the instrument panel on the right side and is closed with a lid.

— We turn out all the spark plugs.

The procedure for measuring compression in the cylinders of an injection engine

— We insert the compression gauge into the spark plug hole (either press it or screw it in, depending on its design).

— An assistant presses the gas pedal all the way and turns on the starter for 4–5 seconds.

— We remember, or better yet, write down the compression meter readings and the order of their increase.

— We reset the compression meter readings.

— We check the compression in other cylinders in the same way.

If the engine is working properly, the compression gauge readings should be within 1.0 MPa (10 bar), and the difference in compression between the cylinders should not be more than 0.1 - 0.15 MPa.

Notes and additions

— If the readings on the cylinders are below normal, then we do the following: using a medical syringe, pour 10-15 cubes of engine oil into each cylinder through the spark plug hole and measure the compression again. The indicators have increased - this means the problem is in the rings (stuck, worn out, broken), if not - the problem is in the valves (burnt out, not sealed, large gaps) or in a burnt-out head gasket.

More articles on VAZ 2108, 2109, 21099 engines

Evaluation of the information received

The piston rings form a sealing layer. It is located between the pistons themselves and the cylinder. In working condition, piston rings act as engine protection against gases and oil from the combustion chamber entering the crankcase. Depending on the technical malfunction, the problem is diagnosed at the level of increased oil or fuel consumption.

Experienced car enthusiasts recommend checking the data several times when measuring the compression level in the cylinders. The following formula will help in establishing the truth: the compression level (kg/sq.cm) is equal to the compression ratio multiplied by the engine coefficient (the value is taken from the book on the technical operation of the vehicle).

Ideally, the cylinder compression level in new cars is always at the level set by the manufacturer. If after the first visit to the service station the value is very different, then you need to return to the auto center. In some cases, factory defects become the reason for inflated performance of a new car. That is why it is recommended to carefully evaluate a potential purchase at a car dealership.

It would not be amiss to compare the data stated in the book on the technical operation of the vehicle with the actual data.

A test drive will help you do this. Any self-respecting car dealership will offer the client the opportunity to sit behind the wheel of an iron horse before making a purchase. A sharp start, a constantly burning oil level lamp, increased emissions - all of the above indicates existing technical problems.

If the seller does not provide the opportunity to make a test circle, you can use a compression meter to conduct a quick assessment of the technical indicators. If the figures from the measurement results and the data specified in the technical specifications differ, then the purchase should be abandoned.

If there are any fluctuations in the compression level, turn off the engine and carry out a technical inspection. The vigilance of the car owner and constant monitoring of the condition of the car will eliminate the need for lengthy and expensive repairs.

Source: korchim.ru

COMPRESSION – WHAT IS IT AND WHAT SHOULD IT BE?

Compression is a measure of the maximum pressure in the combustion chamber that the piston can create when it reaches TDC during the compression stroke. Measuring this indicator gives an idea of ​​the tightness of the chamber, which in turn depends on the condition of a number of elements - the piston and compression rings, valves with seats, head gasket, and the installed thermal gap in the timing belt. Since the compression measurement technology itself is simple, and the data obtained as a result of its implementation makes it possible to estimate the remaining life of the power plant and identify a number of malfunctions, this diagnostic operation is quite common.

Although car power plants have a common design principle, they are structurally different, which also affects compression indicators. Each engine has its own specific maximum pressure values ​​in the combustion chambers, which must be indicated in the technical specifications. documentation for the car. For example, for a VAZ-2106 a compression of 11 kgf/cm2 is considered normal, but for a VAZ-2110 this figure is already 13 kgf/cm2.

Note that when measuring, it is not necessary that the device should show values ​​that correspond to the norm. As engine components wear, compression readings will drop. Moreover, if they drop below a certain value, this will be a signal of extreme wear of the power plant’s CPG, and the need for major repairs. Some variation in readings between cylinders is also allowed. However, it should not exceed 1 kgf/cm. sq. That is, if measurements on a VAZ-2115 showed that the compression in the cylinders was 12 kgf in the 1st, 11 kgf in the 2nd, 12 kgf in the 3rd, 12 kgf in the 4th, then the power plant of the car will be considered to be in working order.

REASONS FOR COMPRESSION FALL IN ONE CYLINDER

It also happens that a pressure drop occurs in one of the cylinders, and significantly (in some cases, compression can drop to 3-4 kgf/cm2). And such diagnostic results are a reason to worry, because there are malfunctions in the power plant.

The reasons for a drop in compression in one of the cylinders above normal may be:

COMPRESSION RINGS. These elements play one of the most important roles, since their task is to ensure tightness in the piston-cylinder pair. If the rings are damaged (burst) or stuck, they will begin to leak working gases into the sub-piston space, which is why a significant drop in compression occurs;

VALVES. Through these elements, the components of the combustible mixture are admitted and exhaust gases are removed. But during the compression stroke, the valves are closed, which seals the combustion chamber. But if, due to a violation of the combustion processes, the edge of the valve plate and seat are burnt, or the thermal gap is broken, and it turns out to be slightly pressed, then the tightness of the chamber is not maintained, which affects the compression;

PISTON. This element is rarely to blame for a drop in pressure in the cylinder, but there are still situations when the reason lies precisely in it. As a result of the same process changes, the piston crown may burn out. This usually happens due to a violation of the ignition angle. And if the piston burns out, then there will be no tightness;

BLOCK HEAD. Although rare, it does happen that cracks and other defects appear in the combustion chamber, affecting the loss of compression. Also, the head can cause a loss of pressure in some cylinder if it fails due to overheating. Due to changes in geometry, the head in some places simply does not fit tightly to the gasket. Even a simple insufficient tightening of the cylinder head bolts can affect compression;

cylinder head gasket. Due to internal defects or overheating, a breakdown of this gasket may occur. As a result, one of the cylinders is connected to a channel of the cooling or lubrication system, another cylinder (in this case, a strong drop in compression is observed in two cylinders), and the breakdown can also lead out of the engine.

What compression should be on a VAZ-2109 car

All owners of domestic cars know the first symptoms of problems with the VAZ-2109 engine: poor dynamics, increased gas mileage, partial or almost complete lack of response to the gas pedal, lack of traction, the car moves with great effort, black smoke comes from the exhaust pipe .

First, an experienced driver blames the spark plugs, and then the piston system comes into question. To check the condition of the piston rings, an independent diagnosis of the operation of machine parts is carried out.

To do this, you need to determine the engine compression.

Even if the carburetor is acting up, you need to check the compression first - this approach will allow you to accurately detect faults in the VAZ-2109, eliminate them and proceed to regulating the carburetor.

Boosting with additives: salvation is real, probably confirmed

These additives seem to build up a thin layer on the worn areas of the metal, the thickness of which, however, is sufficient to “replenish” the worn rubbing surfaces of the engine with a certain material, which, moreover, is capable of retaining motor oil. This allows you to further increase the compression in the engine. These additives are available on the consumer market in a fairly wide range, and car enthusiasts can only choose, trusting advertising and the recommendations of friends (if they decide to increase the pressure in the cylinders of their car on their own).

CORRECT COMPRESSION

How much compression should be in the engine for its long-term and trouble-free operation? Long-term practice of operating cars shows that ideally it should be 14 barrels in each cylinder. But a reduction to 11 barrels is allowed, provided that the difference in compression in the cylinders should be no more than 1 barrel. For example, a compression pattern of 11-12-11-12 is considered acceptable, but if the pressure in different cylinders is 11-12-11-9, or another combination of indicators that differs from normal, then the engine already needs repair.

Article on the topic: Replacing the universal joint on a VAZ 2107

What compression should be on a VAZ 2114 8 valve also depends on how long and under what conditions the car is operated. Ideal pressure, as a rule, occurs with a new engine, or one that has just come out of a major overhaul. During vehicle operation, compression may drop by 1-2 barrels. And this will also be within the normal range.

A new engine is the key to good pressure

Malfunctions: Price - quality?

Good day to all. Happy upcoming main holiday, Victory Day! I had to fix another problem myself.

After the capital, the mileage was 1 - 1.5 thousand km. Suddenly, for no reason, a lot of oil began to be thrown into the carburetor. And don’t even throw it, but the carburetor was simply filled with oil. I was honestly shocked. It would seem that I just made a capital investment, but the symptoms seemed to be stuck in the rings. I measured the compression. The measurement showed that in the first cylinder the compression was 12, in the second - 6. An autopsy showed that the QUALITY OF THE PISTONS IS DIFFICULT TO CALL THE WORD “QUALITY”. The spaces between the compression rings on the pistons burst.

As a result, I bought a new set of pistons, pins, and rings. Put.

Tested it out. The traction is good. Consumption is moderate. So far so good. How long.

I’ve never seen a 2-cylinder in-line engine before)) Cool, so miniature.

Are there any problems with spare parts?

All spare parts are from VAZ 2108, but they come in double size.

What do we have to do?

First of all, we install the car downhill, in principle, it doesn’t matter what the angle is, ten to fifteen degrees is enough. The most important thing is that the car rolls easily, but there is no need to choose a very steep descent, the test results may be incorrect

How is it checked?

We stopped the car on a descent, engaged second gear, released the clutch and handbrake. Let's note the time. After some time, the compression tightens, the compression is released from the cylinders, but the car, of course, does not start.

We are waiting, after some time there will be such a failure - OP, that’s it, the car started, OP, until the next cylinder, it stopped. We measure the time interval between these dips

. After a while the compression tightened and the car started moving again. And so you need to measure the time four times - unless, of course, you have a four-cylinder engine.

If this distance is equal, plus or minus 10 seconds is allowed, then everything is normal. If some interval turns out to be shorter, then get out of the car, open the hood, open the distributor (if the car is carburetor) and look at where the slider is, on which cylinder the compression is taking place (in the injector you need to look at the timing marks).

Now get into the car and do the same thing, only in ignition order, for example - first and third, fourth and second. As a result, you will know exactly which cylinder has weak compression.

Repair

As I wrote above, it’s really difficult to make repairs yourself. Unless, of course, you have a blown gasket, it’s possible to repair it, but again, it’s not so easy. How to replace a short video.

Diagnostics are carried out with the cylinder head removed - here the malfunction can be determined 100%. You are unlikely to do it yourself; contact specialists at a service station, or people who understand.

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Instructions for checking compression of VAZ-2109

To measure compression, you need to prepare special tools:

• a compression gauge consisting of a soft bendable hose, a pressure release key and a tip with a measurement panel;
• spark plug key.

When diagnosing yourself, you cannot do without an assistant. Instructions for measuring compression of a VAZ-2109 injector and carburetor look like this:

1. Turn on the car engine and heat it to a temperature of 80 to 90 degrees.
2. Remove the hose from the fuel pump that drains gasoline.
3. Carefully unscrew the spark plugs, first clearing the wells of any build-up of dirt and debris.
4. Remove the armor wire located in the center from the toggle switch cover, fix the spark plug in it and place it on top of the engine.
5. Place the compressor tip in the recess of the first cylinder; the device does not have to be screwed in; it can be pressed against the hole with your hands.
6. Proceed to measure pressure. The assistant must take the driver's seat and press the gas pedal all the way, then turn the key in the ignition and start the starter for at least 3-5 seconds.
7. Watch how the compression meter values ​​change at this time, the dynamics of increasing readings should be recorded, and also write down the maximum position of the arrow. Once locking is complete, release the pressure by pressing the release button.
8. These actions must be performed for each engine cylinder separately, so as not to forget the indicators, record them on a piece of paper.

A popular way to eliminate stuck rings and increase compression

This method does not guarantee that the compression meter readings will change. But, it is actually effective if different compression in the cylinders was formed precisely because of the position of the rings. At a minimum, your conscience will be clear, and you will then exclude this item from the diagnosis.

We purchase high-quality valve cleaning fluid. The instructions for it should indicate that it is added to engine oil. This evening we unscrew all the candles and pour 50-70 ml into the cylinders. this liquid using a bulb or syringe. In the morning, after 12 hours, crank the engine, then clean the spark plugs and adjust the gaps, and only then screw them into place. When starting the engine, do not be alarmed by the quality and quantity of smoke from the exhaust system. You enter the road to pass sections at higher speeds. That is, the task is to give the engine maximum load. Therefore, think in advance where you will do this. Consider the condition of the road surface, weather conditions, traffic intensity

Ideally, this is done on a country road. Important! The previous point must be fulfilled, otherwise the coking products that have come loose overnight will fall under the valve and then disassembling the cylinder head will not be avoided. After running at a speed of 100-120 km/h over a section of 10-20 km. measure the compression in the cylinders again.

There are two options here: joy and a feeling of happiness from seeing numbers of the same compression, which corresponds to the norm. Or bitterness from the upcoming operation with disassembling the cylinder head and diagnosing the engine. There is no third.

Good luck with eliminating compression differences between the cylinders.

Expert opinion Ruslan Konstantinov Expert on automotive topics. Graduated from Izhevsk State Technical University named after M.T. Kalashnikov, specializing in “Operation of transport and technological machines and complexes.” More than 10 years of professional car repair experience.

If in one of the “pots” the pressure is significantly lower than in the others (for example, everywhere is 11.5, and in the only one 6.0 atmospheres), this indicates a difference in compression. Naturally, this negatively affects the operation of the power unit. Often a drop in compression can be observed in several “pots”. However, in this case, we can safely say that the engine needs urgent overhaul. There can be many reasons for a drop in compression; elimination requires dismantling the cylinder head. Here are the main reasons: 1. Broken (burnt-out) cylinder head gasket. One of the most common causes is “treated” by replacing this element. 2. The cylinder head is not tightened enough. Actually, the above reason follows from this: the gasket begins to leak pressure and eventually breaks through. 3. Rings are skipped. This phenomenon occurs if the o-rings are severely worn or broken. If the pressure drops in one “pot”, the rings are guaranteed to be broken. In this case, a major overhaul of the engine is required. 4. Coking. The rings become coated with coke due to the use of low-quality motor oil or due to high mileage. The oil burns out and the rings stick in one place, unable to move along their grooves. Only one side is ground down, which means the engine wears out faster. Coking is indicated by a drop in compression in all cylinders. 5. Wear of the walls of the cylinder block. This is a rare phenomenon and most often occurs due to the manufacturer using low-quality materials. 6. Engine overheating. If the engine overheats, the rings and the walls of the block begin to leak pressure, and with it the oil. Partially can be identified by the bluish smoke from the exhaust pipe. 7. Piston burnout. If the piston is broken, the compression in the cylinders will be virtually zero. It can burn out from both the top and the side. Often, pistons break when the timing belt breaks when, due to a violation of the valve timing, they meet the valves. 8. Valves. Compression may drop due to improper adjustment, burnout or breakage when the timing belt breaks.

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We carry out decarbonization

Since coking of the rings is one of the most common causes of loss of compression in the cylinder, let’s look at how to eliminate everything.

So, let's assume that a pressure drop is noted in one of the cylinders. Pouring oil into it and re-measuring it showed an increase in compression. The verdict is that the rings are stuck or broken.

To carry out decoking, you will need a special washing liquid (for example, “LAVR”).

You can also use the old proven method - make such a liquid yourself by mixing kerosene with acetone (in a 1:1 ratio).

1. Warm up the engine;
2. Unscrew all spark plugs;

3. We install the pistons in a row (using a key for turning the crankshaft and 4 rods of equal length);
4. Using a syringe, pour liquid into all cylinders (the instructions for the product indicate the required amount. Usually this is 50-70 grams for each cylinder);

5. Cover the spark plug holes with a rag and leave the engine to cool for 10-12 hours. It is also advisable to periodically “move” the pistons, slightly turning the crankshaft in different directions;
6. We purge the cylinders (turn the crankshaft with the starter to remove any remaining product);
7. Replace the spark plugs;
8. Start the engine ();
9. After starting, we give it time to idle for 5-7 minutes. At first, engine operation will be accompanied by strong smoke and interruptions, but gradually everything will return to normal;

10. We go out onto the highway and give the engine the maximum possible load to remove carbon deposits from the cylinders.

After the trip we take compression measurements. If the performance has improved and the pressure in all cylinders has approached the same level, we change the oil and continue to operate the car.

In the case where the performance in the cylinder where the drop was noted has improved, but not enough, you can decarbonize again by pouring cleaning liquid only into this cylinder.

But here it is worth noting that by washing the rings were only eliminated, but we still have to figure out what caused this.

If decarbonization does not bring a positive result, or the cause of the fall does not lie in the rings, you will have to carry out serious repair work - remove the cylinder head to restore it or replace the cylinder head gasket.

It may be necessary to remove the pistons and replace damaged rings.

It is important to read: what is the danger of smoke from the exhaust pipe.

Whatever the cause of a drop in compression in one of the cylinders, this problem cannot be left unattended, and it is necessary to carry out all repair work as early as possible so that such a malfunction does not lead to more serious damage.

How to determine different compression in cylinders without a compression gauge.

Source

BG products used for compression restoration

One example of the use of BG products as a preventative measure to keep the cylinder-piston group (combustion chambers, piston, oil rings, valves, etc.) clean is the so-called “great three” BG:

1. Compression restorer working with the oil system - BG 109;
2. Engine oil conditioner BG 110 (BG 115), the task of which is to give the oil thermal and antioxidant stability, protect the required additive package provided by the engine oil manufacturer, and also reduce friction in the engine, thereby increasing the service life;

BG 208 is a highly effective fuel system cleaner for gasoline engines, poured into the fuel tank. Its advantages are that its combustion temperature is much higher than the combustion temperature of the fuel (it does not burn in the combustion chamber). Thanks to this, it cleans the entire fuel system, combustion chamber and exhaust system elements (oxygen sensor, catalyst).

And in conclusion, I would like to remind you that preventing a problem is much easier than solving it. Timely and regular use of auto chemicals when servicing vehicle systems will help you save significantly on its repairs, increase the service life of its components and assemblies, increase engine efficiency, and issues with piston rings will arise only if you communicate with those who neglect these recommendations.

Prevention is cheaper than repair!