3.4. Check of pressure of compression

Check of a condition of the engine can be made by measurement of pressure of compression in cylinders. If to make this check regularly, then it is possible to learn the beginning of wear of the engine in advance, without waiting for the moment when wear is shown in low overall performance of the engine.

1. Warm up the engine up to the working temperature. At the same time the accumulator has to be completely charged. Unscrew spark plugs.
2. Disconnect electric wires from the ignition distributor. On engines with system of injection of fuel remove the relay of the fuel pump, and on models with carburetors disconnect the electric socket from the fuel cut-off valve.
3. In an opening of a candle of the first cylinder establish компрессометр.
4. The assistant has to press an accelerator pedal against the stop and turn the engine a starter. After a provorachivaniye of a bent shaft by one or two turns pressure of compression has to increase to a maximum, and then be stabilized. Make record of the maximum received result.
5. Similarly check other cylinders.
6. Compression pressure in all cylinders should not differ more, than on 1,5 bars. Pay attention that the size of compression has to increase quickly on the serviceable engine. The low pressure of compression on the first turn of a bent shaft accompanied with gradual increase in pressure on the subsequent turns of a bent shaft indicates wear of piston rings.
7. The low size of pressure on the first turn of a bent shaft which slightly increases further indicates a thinness of a prileganiye of valves, the punched laying of a head of the block of cylinders or existence of a crack in a head of the block of cylinders. Wear of the ends of cores of valves can lead to the low pressure of compression also.
8. If pressure in one cylinder lowered, then carry out the following test. Fill in through a candle opening in the cylinder of a little engine oil and check compression pressure.
9. If filling of oil in the cylinder increases compression pressure, it specifies that the cylinder or piston rings is worn-out.
10. Low pressure in two next cylinders indicates a laying burn-out between cylinders.
11. If pressure in one cylinder is 20% less, than in the others, and the engine idles unstably - it indicates a worn-out cam of the camshaft.
12. If pressure of compression is too high, it indicates that the combustion chamber is covered with a thick layer of a deposit.
13. After this check screw in spark plugs, connect high-voltage wires and install the relay of the fuel pump.