As you know, for the normal functioning of the VAZ-2114 engine, there must be normal compression in the cylinders. But, not all motorists understand how to measure it and what should be the norm. This article will talk about the compression rate in the engine cylinders, as well as the reasons for the increase in the indicator and the measurement process.
Video about measuring compression on the VAZ-2114 with your own hands:
The video will tell you how to measure compression in a car.
The process of measuring compression in engines
According to the regulatory and technical documentation, a limiting compression index in the cylinders of the VAZ-2114 engine has been established. So, an increase or decrease in the indicator is not considered the norm, since excessive compression of the air-fuel mixture in the engine can lead to not very good consequences.
Also, it is worth noting that the compression in all cylinders should be relatively the same. Different indicators are not the norm and these are the first bells for an overhaul of the engine.
Normal compression in the engine cylinder
As practice and many years of experience of motorists show, the compression in the cylinders should be 14 bar, but at the same time, the lower limit indicator should not fall below 11 bar .
When measuring, the difference in compression between the cylinders should not exceed 1 bar.
An example of a bad and normal compress
Let's take an illustrative example: 12-13-12-13 - this is normal compression for the engine, but 12-11-12-8 - this is not normal and it is believed that the engine needs diagnostics and overhaul.
Reasons for increasing compression
Compressor to change compression
It becomes clear that a decrease in compression in the engine is associated with wear of the main elements, such as: pistons and compression rings, main and connecting rod bearings, as well as valves. But, what are the reasons for the fact that the compression has increased?
So, let's look at the main ones:
- When performing repair operations related to the gas distribution mechanism, it was allowed adjustment error , which changed the order of operation of the unit, and, accordingly, the compression in the cylinders.
- Glow on the valves , as well as the accumulation of soot on the walls of the cylinders and the throttle assembly leads to an increase in the degree of compression due to a decrease in space in the nodes.
- Also, the reasons for increasing compression in the cylinders can be attributed.
- The last reason for the occurrence of increased compression is. A malfunction is diagnosed quite simply - oil wells are unscrewed and examined. An oil film indicates that there is an excess of oil, and the need to change the valve seals.
Do-it-yourself compression test
It is necessary to measure the compression in the cylinders using a special device - a compression gauge. There are many types of them, but threaded ones are considered the best and most accurate.
- So, to measure the compression in the cylinder, it is necessary to unscrew the spark plug and screw in the compression gauge fitting.
- Then, turn the ignition key until the engine starts to crank the crankshaft.
- The engine should start and the motorist adds gas so that the engine runs a little.
- So, the compression gauge measures the most accurate value.
Compression should not be lower than 11 bar, otherwise, it is necessary to understand the causes of the malfunction.
conclusions
It was found that the normal compression for the VAZ-2114 engine is to show 11-14 bar. An increase or decrease in this indicator, as well as a gap of more than 1 bar between the cylinders, is not considered normal and is subject to diagnosis. Measurement of compression in the engine is carried out using a compression gauge.
Compression in a VAZ engine is the pressure that occurs at maximum compression while the piston is at its lowest point. The stronger this pressure, the higher the ignition temperature of the mixture, respectively, the less fuel is spent on this process, and the higher the performance and efficiency of the engine.
Compression test
Compression depends on the following factors:
- From the amount of gas supplied, which depends on the position of the throttle valve and the throughput of the air filter;
- From the temperature of the internal combustion engine;
- From the gaps between the inner walls of the cylinder and the valves.
The gaps between the nodes of the piston group in the cylinder depend on a variety of factors:
- Incorrect adjustment of the gaps between the valves and the cylinder walls;
- The degree of burnout and wear of the walls of the piston and cylinder;
- Oil on the cylinder walls helps seal and increase compression, but if gasoline is injected into the cylinder for some reason, it washes away the oil from the walls, which increases the gap between the piston and the cylinder.
According to these parameters, the driver or car mechanic makes a preliminary assessment of the state of the engine - its performance, power, efficiency.
WHAT THE COMPRESSION IN THE ENGINE SHOULD NOT BE
At first glance, it may seem that the higher the compression parameters of the air-combustible mixture, the better. But actually it is not. The compression has an upper threshold that cannot be crossed, as this will cause the engine to overheat, and, as a result, carbon deposits, excessive load on the pistons, rings, as a result of which engine parts may fail.
Low pressure in the engine entails excessive consumption of fuel and oil. It is unacceptable that in individual cylinders it differs sharply from neighboring ones. Different compression in the cylinders indicates serious problems in the motor - wear and tear and defects that require replacement or repair of parts.
So bad compression is:
- elevated,
- low,
- different.
All these signs of poor compression are a signal that the heart of the machine needs to be repaired.
CORRECT COMPRESSION
How much compression should be in the engine for its long and trouble-free operation? Long-term practice of car operation 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 scheme of 11-12-11-12 is considered acceptable, and 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 to be repaired.
What compression should be on the VAZ 2114 8 valves also depends on how long and under what conditions the car is operated. The ideal pressure, as a rule, is with a new engine, or one that has just come out of a major overhaul. During the operation of the car, the compression may drop by 1-2 barrels. And this will also be within the normal range.
The new engine is the key to good pressure REASONS FOR INCREASED COMPRESSION IN THE ENGINE
Consider the main reasons:
- Incorrect adjustment of the timing belt leads not only to increased compression, but also to reduced, depending on the direction of regulation.
- The appearance of scale on the valves, which appears due to the use of low-quality gasoline, oil or other automotive chemicals. Carbon deposits on the throttle assemblies and in the combustion chamber also appear due to engine overheating. Thus, overheating of the internal combustion engine is not only a consequence, but also the cause of the high pressure of the air-combustible mixture. The operating temperature of the VAZ 2114 8 valve engine should not exceed 85-90 ° C.
- High compression can be provoked by the "occurrence" of the oil scraper covers. This reason is easy to find. You just need to unscrew the candles and examine the cylinders. The appearance of an oil film on their walls will indicate an excess of oil in them, and the need to change the caps.
Compression is also affected by the rate of oil pressure in the engine. If it is overestimated, then this entails an increased pressure of the air-combustible mixture.
Low pressure occurs if the rings are worn out or the valves are burnt out. The operating temperature of the engine is also affected. If it is below normal, then this will also affect the pressure of the air-combustible mixture.
The reasons for the lack of compression in the engine lie in improper operation, untimely preventive maintenance. Sometimes air breaks through from several sides at once - for example, through valves, and at the same time through pistons with rings. Then the pressure disappears completely. Bringing the car to such a state is simply unacceptable
PREPARATION FOR MEASUREMENTS
Compression measurement in the engine is carried out with a fully charged battery. After you have charged and installed the source of electricity in place, check the starter. It shouldn't cause any problems either. Then warm up the engine. Its temperature during measurements should be 70-90 ° C.
From all holes it is necessary to unscrew all the candles. Also unscrew the fuel hose to cut off the fuel supply. Prepare the compression tester for work.
ENGINE COMPRESSION MEASUREMENTS. COMPRESSOMETER
The device, consisting of a pressure gauge and a rubberized tube, which measures the compression in the engine, is called a compression gauge. The following devices are used:
- pressure,
- universal,
- flexible
- threaded.
Experts believe that of all types of compression meters, it is better to use threaded ones. They provide more accurate information. It is necessary to measure the compression in the engine in each cylinder separately. The gauge hose is inserted into the spark plug socket.
Now that everything is ready for measurements, start the engine and squeeze the gas all the way, let the engine run a little. Check the pressure gauge reading and write it down. Move the compression gauge hose to the next spark plug hole, and measure the second and subsequent cylinders in the same way. Write down all the results and compare them.
PRESSURE IN THE INJECTOR ENGINE
Below you will learn how to correctly measure compression in a VAZ 2114 engine with an injection type of power supply.
If at least in one cylinder the pressure gauge showed a pressure below 10 barrels, then it is necessary to look for the reason for such a low figure. Otherwise, very soon it will fall in other cylinders.
Draw about 10 milligrams of oil into a medical syringe and spray it into the cylinder. Take the measurement again. If the pressure gauge readings increase, then the piston rings are worn out and require replacement. If it remains at the same low level, then it is necessary to adjust the clamped or change burnt valves.
WHAT TO DO IF THERE IS NO COMPRESSOMETER AT HAND?
Is it possible to measure compression without a device? Practice shows that yes, it is possible. But this method will give relative and approximate readings. To measure the compression index without instruments, turn out the candles from all cylinders, except for the one under test. Turn the crankshaft manually until the compression stroke ends (watch the marks - they must match). Repeat this operation with all cylinders one by one. Where the pressure is low, it will take less effort to turn the crankshaft. In this way, of course, you will not get accurate compression readings in the engine. But you can understand the presence of problems.
The approximate price of a device for measuring compression in an engine in the online stores of the capital is from 600 rubles to 2 thousand. Brand models of Western manufacturers are more expensive - up to 8 thousand. In the regions, a device for measuring compression costs no more than in the capital. Its price varies depending on the manufacturer.
Many owners of VAZ cars do not know how important it is to periodically measure compression in the engine cylinders, and do not know what it is. In fact, if the compression is not up to par, it leads to premature engine wear. Accordingly, the risk of its breakdown increases, which definitely leads to costly repairs.
What is compression?
Compression is the pressure in the cylinders. If the compression level is too low, this results in the air/fuel mixture occupying a fairly large volume in the cylinder, being less concentrated and slow to ignite.
Due to this, the level of heat transfer increases and the engine overheats. Everyone understands how harmful an engine overheat is. If the compression level is too high, then the fuel-air mixture ignites too quickly, because the concentration is too high. The mixture simply explodes (this process is also called detonation).
Because of this, engine parts are under a lot of pressure, which acts destructively on them. Simply, this means that the products of combustion of the fuel-air mixture “beat” the details.
A situation may also arise when the compression level in the cylinders is very different. In this case, ignition in one cylinder occurs faster than in the other, due to which the engine runs unevenly. There is a kind of imbalance between the work of pistons and shafts, which also negatively affects their condition.
How to measure compression?
In order to measure the level of compression in the cylinders, you need a special device - a compression gauge. It is relatively inexpensive, at least ten times cheaper than engine repairs.
When choosing it, you need to pay attention to the limit switch that connects to the engine - it can be rubber, or it can be threaded. The second option is preferable, since it is much more convenient to work with it and it is quite possible to measure compression without outside help.
It is best to measure compression "hot". It is also necessary that it be charged and give rated power to the starter. When the engine is warm, unscrew and remove all spark plugs, and then disconnect the wires from the ignition coils.
After that, you need to turn off the fuel pump, if it is mechanical, then you can simply shut off the fuel supply or disconnect the fuel system hoses. If the fuel pump is electric, turn off the relay or remove the fuse to cut off the power supply.
After that, it is necessary to connect the compression gauge to one of the cylinders and start turning the starter (if the compression gauge does not have a thread on the tip, outside help will be required to hold it in the candle seat).
The throttle valve must be fully open, at this point it is worth paying special attention. Compressometer readings will begin to rise, and when they reach a maximum, this will be the compression level in the cylinder. Having fixed the readings, it is necessary to rearrange it to the next cylinder, measure the compression level in it, and so on.
What should be the compression?
The normal compression level for each engine is individual, but there are certain deviation rates. The compression level in the cylinders should not differ by more than 15% (meaning the maximum level and the minimum).
Compression is a very useful method for diagnosing a car engine. We already know how to check the compression in the cylinders of a car engine, and what the compression should be in the most average values. However, we suggest that you now find out more precisely what the degree of compression should be specifically for your car model.
So, we know that compression is the pressure that is created by the piston in the combustion chamber cylinder when it is at top dead center, that is, at the end of the compression cycle. But there is another concept compression ratio- this is the volume of all space in the cylinder at the time when it is at bottom dead center (that is, when this space is maximum), divided by the same volume, but when the piston is at top dead center (when the volume of this space is minimum). What happens if we see in the technical characteristics of the engine that its compression ratio is 10, then this means nothing more than the fact that the maximum volume of the combustion chamber space of one cylinder of such an engine is 10 times greater than the minimum. Those. the fuel-air mixture in such a cylinder is compressed 10 times the volume that enters it.
It turns out that there is a direct dependence of the compression in the cylinder on the degree of its compression, and this dependence is determined by a certain coefficient. It is generally accepted that this coefficient is 1.2-1.3 for gasoline 4-stroke engines. That is, if we know the compression ratio of our engine (and this information is presented in official documents for a car much more often than compression data), then it will not be difficult for us to find out the engine compression.
Of course, in practice, the compression data will differ from those officially declared by the manufacturer, if only because this compression depends on the process of natural wear of the piston group, and the greater this wear, the less compression will be. But what is the line when compression is so low that engine components can be considered excessively worn out? It is generally accepted that this criterion is approximately 10-12% of the degree of compression declared by the manufacturer or obtained by calculations. That is, if according to the documents the compression rate should be 12 kg / cm 2, then it is easy to calculate that an engine with a compression of less than 10.56 to 10.8 kg / cm 2 is considered to be faulty.
And now let's look at the most popular brands and models of cars among Russian motorists and find out what compression should be in the cylinders of their engines!
Table: What should be the compression of cars
| Automobile | Compression, kg / cm 2 |
|---|---|
| VAZ 2106-07 | 11 |
| VAZ 2109 | 11 |
| VAZ 2110 | 13 |
| Audi A4 (2011-2019) 1.8-2.0/3.0 | 12/12.5 |
| Chevrolet Cruze 1.6/1.8 | 14/13 |
| Chevrolet Lanos 1.5 | 12 |
| Chevrolet Lacetti 1.6/1.8 | 12/12.5 |
| Chevrolet Aveo 1.6 | 13.5 |
| Daewoo Gentra 1.5 | 12.5 |
| Daewoo Matiz 0.8 | 11 |
| Daewoo Nexia 1.5/1.6 | 10.5/11 |
| Ford Focus (2014-2019) 1.0/1.5-2.0 | 12/Too many different options |
| Ford Focus (2011-2014) 1.6/1.6 Turbo/2.0 | 13.5/18/14 |
| Honda Civic (2008-2019) 1.8/2.4 | 13/13 |
| Hyundai Elantra (2013-2019) 1.6 | 13 |
| Hyundai Solaris (2011-2019) 1.4/1.6 | 13/13 |
| Kia Sportage (2011-2019) 2.0 | 13 |
| Kia Sportage (2004-2010) 2.0 | 12.5 |
| Kia Cee "d 1.4 / 1.6 | 13 |
| Kia Rio (2005-2011) | 12.75 |
| Kia Rio (2011-2019) | 12.5-13 |
| Mazda 3 (2010-2019) 1.5/1.6/2.0 | 16/12/16 |
| Mazda 6 (2011-2019) 2.0/2.5 | 16/15 |
| Mitsubishi ASX (2010-2019) 1.6/1.8/2.0 | 13/12.5/12 |
| Mitsubishi Lancer (2007-2019) 1.5/1.6/1.8 | 12.5/12.5/12 |
| Nissan Juke | 12.5 |
| Nissan Qashqai 1.6/2.0 | 12,5/12 |
| Opel Astra 1.4/1.6 | 11/13 |
| Opel Corsa 1.2/1.4 | 12.5/12.5 |
| Toyota RAV4 (2006-2019) 2.0/2.2/2.5 | 12/18/12 |
| Toyota Camry (2009-2019) 2.0/2.4/2.5/3.5 | 11.5/12/12/12,5 |
| Toyota Corolla 1.3/1.6/1.8 | 13.5/12/12 |
| VW Tiguan 1.4/2.0 | 12/12 |
| VW Golf (2009-2019) 1.2/1.4/1.6 | 12/12/12.5 |
| VW Jetta (2010-2019) 1.4/1.6 | 12/12.5 |
During the working cycle of the VAZ 2114 internal combustion engine, four stages occur.
The first stage is intake or compression, during which the piston moves from top dead center (TDC) to bottom dead center (BDC), at which time the intake valve opens to supply the fuel-air mixture.
On the second, the piston from BDC rises to TDC, compression occurs, that is, the pressure rises sharply, because all valves are closed, the temperature rises and the mixture is ready to ignite. The higher the compression, the higher the power and efficiency of the engine.
The ignition of the mixture occurs in the third stage, when the piston reaches TDC. Due to the released energy, the piston moves towards the BDC.
At the fourth stage, when the piston reverses, the exhaust valve opens and the burnt gases are pushed out of the working cylinder. When TDC is reached, all valves close and the piston is ready to repeat the entire four-stroke cycle.
Compression in an engine is the pressure generated in a cylinder as the piston moves from BDC to TDC.
Normal compression in the VAZ 2114 engine
Compression is affected by many different things.
- The pressure inside the volume is determined by the amount of incoming gas. In an internal combustion engine, this is influenced by the throttle valve and the capacity of the air filter. Therefore, it is so important to change the clogged filter element in a timely manner.
- In the process of adjustment or repair work, car mechanics may make inaccuracies in establishing the valve timing. As a result, the closing moment of the intake valve changes. The cycle is broken and this leads to a change in pressure in the cylinders.
- Incorrect adjustment of clearances in the valve drive also leads to deviations in compression from the maximum effective one.
- Engine power, which directly depends on the degree of compression in the cylinders, is affected by the temperature of the internal combustion engine. If for some reason it is significantly lower than the established working one, then the compression in the cylinders will be less and, accordingly, the power will decrease.
- Due to the burning of valves and cylinder walls, the development of rings, and some other mechanical damage to the piston group, leakage of the mixture from the cylinder occurs during the compression stroke. As a result, compression is reduced.
- For some reason, excess fuel enters the cylinder, gasoline settles on the inner walls and washes oil from them, reducing the seal, and leads to additional air leaks, as well as a decrease in the power of the power unit.
In its turn:
- the correct oil layer on the cylinder walls leads to sealing of gaps and reduction of leaks;
- an increase in engine temperature heats up the parts, the metal of which expands and they fit closer to each other, preventing unnecessary gaps from forming, as a result, engine power increases;
- the higher the crankshaft speed, the sharper the piston movement and more efficient compression occurs, this also increases the pressure in the cylinder and, accordingly, the engine power.
Signs of low compression and how to measure it on a VAZ engine
Compression on the VAZ 2114 should be measured every 30 thousand kilometers. This is usually done in conjunction with valve adjustment. However, signs of low compression may appear not only during a routine check. During the operation of the car, signs of poor compression are detected quite simply, you just need to carefully monitor your engine. These are things like:
- the power of the internal combustion engine drops sharply;
- the engine troit, this can happen when low compression is formed in one cylinder;
- significantly increases the consumption of oil and gasoline.
Having found such signs, it is necessary to measure the compression in the engine. To carry out this procedure, you need to prepare:
- before measuring the compression in the engine, it is required to fully charge the car battery and check the performance of the starter, it should work without comment;
- prepare a device for measuring compression, it is called a compression gauge. It consists of a pressure gauge and a rubberized tube at the end of which there can be a threaded connection for screwing into the candle hole or a conical rubber tip, like a plug plugging this very hole;
- warm up the car immediately before work, because it is necessary to measure the compression in the engine correctly on a warm engine;
- unscrew and remove all the candles from the holes, spreading them side by side, in an accessible place. It is necessary to remove all the candles, because if you unscrew only one and measure in this position, the compression level will not correspond to the true one;
- Turn off the fuel supply to the injectors by unscrewing the fuel hose.
When starting such work, you need to know what compression should be on the VAZ 2114. The normal pressure in the cylinders during compression should correspond to 1.0 MPa, for an eight-valve engine in ideal condition it will be 1.4 MPa.
Having prepared properly to find out what the compression in the cylinders should be, install a compression gauge in the first cylinder.
Fully depress the accelerator pedal to fully open the throttle valve and thereby ensure maximum air flow. Then, turning the ignition key, use the starter to crank the crankshaft from 100 to 200 rpm for ten seconds. At this time, knowing what compression should be in the engine, it is necessary to monitor the readings of the pressure gauge of the measuring device installed in the spark plug hole:
- if the pressure initially increases slightly, and then increases, then the piston rings are worn out. To verify this, it is enough to pour a little oil into this cylinder and measure again. The oil should plug the leak and the compression will return to normal. This is a confirmation that the replacement of the rings is necessary;
- if the pressure rises to 0.8 MPa and then grows very slightly, then leaks in the valve are likely or the cylinder head gasket is broken.
Perform a similar procedure with measurements on all cylinders and record all readings. Upon completion of work, install the candles in place, connect the fuel hose and low-voltage wires. After removing the workplace, it is necessary to analyze the records.
The pressure in the cylinders should not be lower than 1.0 MPa, this is the minimum compression index. The figures for the cylinders should not differ greatly, no more than 0.2 MPa. If the compression in at least one cylinder is less than 1.0 MPa, a complete check of the engine is required and, most likely, its repair.
All these works can be done independently, or you can turn to specialists, you just need to find out in advance how much it costs to measure compression in the engine.
There are ways to increase the compression in a VAZ engine without disassembling it. You can adjust the valves or make the engine decarbonized.
