For obtaining exact results of check of a compression the engine has to be heated-up up to the normal temperature, and the rechargeable battery is completely charged.
Results of check of a compression in cylinders of the engine allow to judge a condition of group of details in the top part of the engine (pistons, piston rings, valves and laying of a head of the block of cylinders). Namely, reduction of a compression can be caused not by tightness of combustion chambers owing to wear of piston rings, damage of plates and saddles of valves, a burn-out of laying of a head of the block of cylinders.
You make check in the following order:
– clear sites near 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 hit of dirt in cylinders at measurement of a compression;
– turn out all spark plugs;
– completely open a butterfly valve;
– put system of ignition out of action, having disconnected electric sockets from ignition coils. Also disconnect the electric socket of giving of tension to the fuel pump;
– insert компрессометр into an opening for a candle;
– include a starter and turn a bent shaft at least on seven steps of compression, monitoring indications of a kompressometr. On the serviceable engine pressure has to increase quickly. Low pressure after the first piston stroke and slow increase at the subsequent steps of compression indicates wear of piston rings. If after the first piston stroke pressure low and at the subsequent steps of compression does not increase, then leak in valves or leakage of laying of a head of the block of cylinders is the reason (also formation of cracks in a head can be the reason). Decrease in a compression can be also caused by deposits of a deposit on reverse sides of plates of valves. Write down the greatest value of a compression;
– repeat the procedure of measurement for other cylinders and compare results to specifications.
If a compression in cylinders below minimum admissible value, through an opening for a candle enter into each cylinder of a little engine oil, then repeat check. If after oil introduction the compression raised, then it is possible to draw an unambiguous conclusion that piston rings are worn-out. If the compression increased slightly, then leak happens via valves, or laying of a head of the block of cylinders. Leak via valves can be caused by a burn-out of saddles and / or working edges of valves, and also deformation of cores of valves, or formation of cracks on them.
If the compression equally low only in two next cylinders, then is the most probable cause a laying burn-out between these cylinders. As confirmation emergence in combustion chambers or the oil pallet of traces of cooling liquid is possible.
If value of a compression in one of cylinders is lower than in the others and the engine unstably works at idling frequency, then wear of cams of camshafts can be the cause.
If value of a compression exceeds nominal rate, so the combustion chamber is covered with deposits of a deposit. In this case the head of the block of cylinders should be removed and removed a deposit.
If the compression in all cylinders low, or strongly differs for different cylinders, then it is necessary to carry out tests of combustion chambers for tightness for what it is necessary to address in a specialized workshop. As a result of tests places of leaks have to be precisely established and the quantitative characteristic of leak is given.
After check of a compression, release a butterfly valve and restore system of ignition and fuel system.