Note. To check if the valves are tight enough when they close, if the piston rings are worn or broken, or if there are other problems in the cylinders, it is necessary to measure the compression of all cylinders. To do this, the engine must be at operating temperature.
1. Unscrew the spark plugs.
2. Disconnect the ignition module
3. Open throttle and start air dampers.
4. Insert the compression tester into the first spark plug hole.
5. Ask an assistant to fully depress the gas pedal and turn on the starter.
6. Rotate the crankshaft until the compression gauge shows the highest pressure.
7. In order, check the remaining cylinders in the same way.
8. According to the rules, the compression pressure in any of the cylinders should not be less than 80% of the result of the maximum measurement. Low, uneven compression across the cylinders may be due to worn piston rings, which can also be detected by excessive oil consumption. With good compression, the results should be at least 7.5 atm.
If the values obtained approach or are below the minimum values given, this indicates the need for an additional revision of the engine:
The difference between the compression pressures of the individual cylinders must not exceed 1.0 bar.
The reason for the low compression pressure may be worn piston rings, which must be accompanied by increased oil consumption at the same time.
9. If low compression is detected in any cylinder, a small amount of engine oil is poured into it through the spark plug hole and the pressure is measured. If at the same time the compression pressure rises, then, apparently, the reason lies in the wear of the piston rings. If the compression gauge readings do not change, then the cause is a leaky valve seat. The reason may also be a leaky gasket between the head and the cylinder block. In this case, you need to remove the head and check the pairing.
There are special liquids on sale, the introduction of which into the cylinders increases compression. However, they should be considered as temporary means.
After checking, remove the compression tester, screw in the spark plugs and tighten them to 20 Nm. Connect the spark plug connectors.
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