For reception of exact results of check of a compression the engine should be heated-up to normal temperature, and the storage battery is completely charged.
Results of check of a compression in engine cylinders allow to judge a condition of group of details in the top part of the engine (pistons, piston rings, valves and a lining of a head of the block of cylinders). Namely, compression reduction can be caused not tightness of chambers of combustion owing to deterioration of piston rings, damage of plates and saddles of valves, a burn-out of a lining of a head of the block of cylinders.
Check make in a following order:
– Clear sites near to spark plugs for what blow compressed air (in the absence of the compressor blow sites automobile, or even bicycle, the pump). It is necessary to exclude dirt hit in cylinders at compression measurement;
– Turn out all spark plugs;
– Completely open throttle заслонку;
– Put out of action ignition system, having disconnected electric sockets from ignition coils. Also disconnect an electric socket of giving of pressure to the fuel pump;
– Insert компрессометр into an aperture for a candle;
– Include a starter and turn a cranked shaft at least on seven steps of compression, watching indications компрессометра. On the serviceable engine pressure should accrue quickly. Low pressure after the first piston stroke and slow increase at the subsequent steps of compression specifies in deterioration of piston rings. If after the first piston stroke pressure low and at the subsequent steps of compression does not increase, the reason is leak in valves or негерметичность linings of a head of the block of cylinders (the reason formation of cracks in a head also can be). Compression decrease can be caused also deposit adjournment on undersides of plates of valves. Write down the greatest value of a compression;
– Repeat procedure of measurement for other cylinders and compare results to specifications.
If a compression in cylinders more low is minimum admissible value, through an aperture for a candle enter into each cylinder of a few engine oil, then repeat check. If after introduction of oil the compression has raised, it is possible to draw an unequivocal conclusion that piston rings are worn out. If the compression has increased slightly leak occurs through valves, or a lining of a head of the block of cylinders. Leak through valves can be caused a burn-out of saddles and / or working edges of valves, and also deformation of cores of valves, or formation on them of cracks.
If a compression equally low only in two next cylinders most a plausible reason is the lining burn-out between these cylinders. As acknowledgement occurrence in chambers of combustion or the oil pallet of traces of a cooling liquid is possible.
If value of a compression in one of cylinders more low than in the others and the engine unstably works on frequency of idling deterioration of cams of camshafts can be the reason.
If value of a compression exceeds rating value, means, the combustion chamber is covered by deposit adjournment. In this case a head of the block of cylinders it is necessary to remove and remove a deposit.
If the compression in all cylinders low, or strongly differs for different cylinders it is necessary to conduct tests of chambers of combustion for tightness for what it is necessary to address in a specialised workshop. As a result of tests places of leaks should be precisely established and the quantitative characteristic of leak is given.
After compression check, release throttle заслонку and restore system of ignition and fuel system.