Cylinder compression check

Compression check is one of the most important diagnostic operations. According to the compression value and its change after several cycles, as well as the difference in values for individual cylinders, it is possible to determine the technical condition of the engine cylinder-piston group and its valve mechanism without disassembly with a high degree of accuracy. Preheat the engine to operating temperature.

To check compression, do the following:

- unscrew the spark plugs with a spark plug wrench (subsequent work must be carried out taking into account the model of the installed engine);

- fully open the throttle valve;

- Install the compression pressure sensor in the first spark plug hole;

- ask the assistant to turn on the starter;

- Turn the crankshaft of the engine until the arrow shows the maximum pressure;

- In the same way, check the rest of the cylinders one by one.

pressure drop (about 20%) in one of the cylinders, accompanied by engine vibration at idle, may be due to increased wear of the camshaft lobes. Low and uneven compression can be caused by worn piston rings, which can also be detected by excessive engine oil consumption. See appendix for normal compression values for a new engine.