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Compression rate

The compression (pressure) indicator plays an important role in detecting faults in the VAZ 2106 engine without disassembling it. The word compression in Latin means compression. Compression refers to the pressure in the cylinders at the extreme point of the compression stroke. A significant decrease in pressure indicates wear on the piston rings of the cylinders, as well as the cylinders themselves. If the valve clearances are incorrectly adjusted, the required amount of air does not enter the combustion chamber.

If compression is low, engine response decreases and fuel and oil consumption increases. With low cylinder pressure, engine power drops and the car cannot reach maximum speed. What compression is needed is indicated in special manuals for measuring it. The average compression rate for a gasoline engine is 9.5 - 10 atmospheres. In this case, the difference between the pressures in each of the cylinders should not exceed 10%.

Engine compartment of VAZ 2106

The following factors may affect the maximum cylinder pressure:

degree of throttle valve openness: the less it is closed, the greater the pressure;
Air filter contamination;
incorrectly set valve timing;
incorrectly adjusted valve clearances;
motor temperature;
wear of parts sealing the combustion chamber causes air leakage, which reduces pressure;
the entry of oil into the combustion chamber acts as a seal, which increases the compression value;
lack of tightness of the check valve or compressometer hose.

Diagnostics are performed when engine power decreases and when repairing the cylinder head or overhauling the cylinder block.

What compression should be on a VAZ 2106

Considering that more than 4 million units of VAZ 2106 cars were produced, there are many more of them on our roads. Accordingly, the issue of repairing the famous “classic” still remains relevant. For example, the question of what compression should support six good engines.

The technical data specified in the vehicle's operating manual does not contain such a function. There is a slightly different concept. compression ratio. There is no direct connection between these two parameters; they have only one thing in common. In both cases we are talking about pressure.

The compression ratio is a calculated constant and has no dimensional units. For the VAZ 2106 engine and its modifications it is 8.5. This figure is the result of dividing the total displacement of the cylinder by the volume of the combustion chamber. Simply put, the air-fuel mixture entering the cylinder is compressed 8.5 times, moving the piston upward.
Compression is variable; its value depends on the technical condition in which the engine is located. This parameter indicates how much pressure appears in each cylinder when the crankshaft rotates with the starter. This is determined by a pressure gauge that is screwed in instead of the spark plugs, the unit of measurement is 1 kgf/cm2 or 1 bar, which is almost identical (1 kgf/cm2. 0.98 bar).

Compression is measured to determine the degree of wear of the cylinder-piston group. Its values were obtained experimentally in practice. Extinguishing occurs as follows: All 4 spark plugs are unscrewed and the check valve is turned in place in each cylinder, and by rotating the starter, the maximum pressure that can be supplied by each piston is determined. In the VAZ 2106 engine, the ideal figure is 13 kgf/cm2, but this is a rare case; such pressure is found on new, running-only engines.

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Determination of compression in a cylinder without a compressor

If the measurement range is from 11 to 12.5 kgf / cm 2, this is a normally working VAZ 2106 engine. In addition, it is important that the compression in all 4 cylinders is the same, a difference of more than 0.5 kgf / cm 2 indicates a malfunction of one of them . This is usually a burnt valve, this is a problem when driving on poor fuel and heavy loads.

The measurement results, which showed pressure from 10 to 11 kgf / cm2, indicate early engine repair. These results may not be entirely accurate when the engine is breathing. This is the name for the phenomenon when engine oil begins to flow through the crankcase ventilation hose from the fan to the carburetor along with crankcase gases. The reason is simple: due to wear on the piston rings, excess pressure builds up in the crankcase, which pushes oil droplets through the breathing apparatus into the carburetor.

Oil, combined with fuel, enters the combustion chamber and, after combustion, forms carbon deposits and spark plugs on its walls. When a lot of oil gets into the oil, it starts to fill the gap between the worn rings and the cylinder surface, then the compression readings will be higher and cannot be relied upon. In other words, if the engine is breathing, it's time to change the piston rings.

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Compression values of 9-10 kgf/cm2 indicate wear of the cylinder or piston group or valves. In both cases, engine disassembly is required. Such an engine usually consumes oil and fuel, is unstable, and some energy is lost. However, it can continue to be used for some time, the main condition is. Compression in all cylinders should be the same. If the valve in one of them completely burns out, then the pressure in it decreases greatly and the cylinder completely fails.

compression vase 2106 (solid)

The same fate awaits a unit whose compression is below 9 kgf/cm2. This pressure indicates the need for this minor repair. In such cases, all outboard equipment is removed from the engine in accordance with its capacity, unscrewed from the box and completely removed from its supports so that it can be disassembled and repaired in more comfortable conditions.

At the same time, they check the condition of the rubber parts of these supports; you may have to change the cushion. Many car owners dismantle the engine directly on the car; this option also has a right to life, especially if you only need to replace the piston rings.

Source

How to measure engine compression?

Required Tools

To take measurements of the VAZ 2106 you need to prepare:

compression gauge;
spark plug key;
instructions for the engine installed on the VAZ 2106.

Compression gauge with a set of adapters
The compression gauge should be selected with a threaded tip so that it is screwed into the spark plug hole and not pressed in. In this case, more accurate values will be obtained. You also need to check that the valve that records the readings is located in the pressure gauge head, which is screwed into the hole for the spark plugs, and is not located under the measuring device. This will make it possible to avoid underestimating pressure readings during diagnosis. The compression tester kit includes adapters that allow diagnostics on any engine.

It is better to carry out diagnostics with an assistant: one person screws or holds the tip of the device, the other presses the gas pedal as much as possible and starts the starter.

Stages

The test is performed with the engine warmed up to a temperature of 70-90 degrees. Before diagnosing, turn off the fuel supply. If a mechanical fuel pump is installed, then you need to disconnect the fuel line through which fuel is supplied. In the case of an electric fuel pump, you need to de-energize its relay. The battery must be fully charged. Measuring pressure in a VAZ 2106 consists of the following steps:

First, you should clean the niches where the spark plugs are located and disconnect the high-voltage wires.
Then you need to unscrew all the spark plugs.

Broken spark plug
The gear lever must be in neutral position.
Now you need to disconnect the central wire from the ignition coil in order to de-energize the car while the starter is running.
Then you should screw the tip of the compression gauge into the spark plug hole.
After starting the starter, you need to turn the ignition key until the readings on the pressure gauge stop increasing, usually 4 compression strokes are enough.
Readings should be taken one by one in each cylinder, resetting after each measurement.

Alternate readings

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Diagnostics of the VAZ 2106 should be performed with the throttle valve open and closed. In each case, this makes it possible to identify your defects.

When diagnosing, you need to pay attention not only to pressure, but to the difference in compression values of different cylinders. The readings between them should not exceed 0.5 - 1 atmosphere. This will make it possible to determine which cylinder is causing the problem. Thus, any car enthusiast can make diagnostics on a VAZ 2106 by measuring the pressure in the cylinders. It is enough to have a compression gauge and an engine maintenance manual. Based on the inspection, you can draw conclusions about malfunctions and carry out repairs, if possible at home.

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Content

Compression in a VAZ car engine 2106

The concept of compression, its measurement

The technical data specified in the vehicle's operating manual does not contain such a function. There is a slightly different concept of compression ratio. There is no direct correlation between the two parameters, they are interconnected by only one, in both cases we are talking about pressure.

The compression ratio is a calculated constant and has no dimensional units. For the VAZ 2106 and its modifications this is 8.5. This figure is the result of dividing the total displacement of the cylinder by the volume of the combustion chamber. Simply put, the air-fuel mixture entering the cylinder is compressed 8.5 times, moving the piston upward.
Compression is variable; its value depends on the technical condition in which the engine is located. This parameter indicates how much pressure appears in each cylinder when the crankshaft rotates with the starter. This is determined by a pressure gauge that is screwed in instead of the spark plugs, the unit of measurement is 1 kgf/cm2 or 1 bar, which is almost identical (1 kgf/cm2. 0.98 bar).

The procedure for measuring compression in cylinders of VAZ 2101-2107

So, before proceeding with a detailed description of this procedure, I would first like to provide a list of the necessary tools that will be needed for this work:

Candle key
Compressometer

A compressor is a device that allows you to measure the pressure in the cylinders of an internal combustion engine on various automotive systems, ranging from diesel to gasoline power units. When choosing such equipment, it is very important to keep in mind that with a threaded fitting, the indicators will be somewhat more accurate than with a regular one (which has to be pressed during measurement). So it is best to use a threaded fitting. My Jonnesway compression gauge has both one and the other type. You can clearly see it in the photo below:

So, below is a detailed list of actions that must be performed to check the pressure in the cylinders. It is worth paying attention that the car engine must be warmed up, preferably to operating temperature, at least 70-80 degrees. After this, it is necessary to shut off the fuel line so that when the starter rotates, gasoline does not enter the combustion chamber. To do this, after installing the fuel filter, you can remove the hose and plug it with a bolt of the required size, for example, or simply clamp it, securing it with a clamp. And then start the engine and wait until it stalls on its own. Next, you need to unscrew all the spark plugs from 4 cylinders.