How to check the compression in diesels
How to check the compression in diesels
Compression is one of the main indicatorsTechnical condition of the diesel engine. Compression check is carried out at service stations with the help of special instruments - compressometers and compressors.
Compression is the pressure thatIt is created in the propulsion cylinder during its rotation by the starter, when the fuel supply system has not yet entered into operation. Compression is one of the main indicators of the viability of the engine. The nominal compression values for various engines under normal atmospheric conditions are 28-40 atmospheres. The verification of the compression of the diesel engine assumes the diagnosis of the cylinder-piston group, which is performed by a special instrument-a compressometer or a compressograph. The device has in its composition a shut-off valve that prevents the pressure from dropping when the crankshaft is cranked. The difference between the two devices is in a different way of outputting information. In the compressorometer for these purposes serves as a dial gauge dial, and the compressor allows you to display data on a computer monitor or print a test report on paper.
Compression check order
1. Disconnect the high pressure pump stop valves. Disconnect the high-pressure pump dispenser. Remove one of the glow plugs. To connect to a flange of a candle накаливания the compressometer or компресграф. 5. Measure the compression with the starter on. Measurement is considered complete when the readings of the compressometer cease to increase. Repeat the measurement by placing the device in place of the next candle. Record the results of each test.7. Install the spark plugs in place. Connect the connectors of the fuel shutoff valves and switch on the high-pressure pump dispenser.Checking conditions
Nominal value of compression and valuethe maximum tolerance can be seen in the operational documentation for the car. The compression test should be performed at a crankshaft speed of 200-250 rpm. Also a prerequisite for the accuracy of the measured values is the state of the air filters. With a clogged filter, the compression readings can be distorted. The compression range is made in those temperature conditions in which the engine actually starts. There is a direct relationship between the ambient temperature and the minimum compression at which the engine can be started. This characteristic for a specific engine can be obtained from a series of tests conducted in a maintenance station.
