Diesel in the use of process, assembly and spare parts in the mechanical, thermal and chemical factors, and other aspects of the role, because of friction, wear, corrosion deformation and changed the original design and manufacture of parts, the size of precision, geometrical shape and the technical conditions. This makes the original diesel engine to promote the technological status of the use of performance is gradually declining.

As parts wear, that affect the process of working with disorders of the factors, such as the gap increases, sealing deteriorate, the compression ratio change, injection pressure and spray quality changes, and so on. This makes a gradual reduction in engine power, its performance is not strong diesel engine, the speed of automobile and tractor reduced acceleration time and distance lengthened, smoky exhaust and so on.

Diesel fuel consumption economy that rate, there is a change in the process. New diesel engine in the initial stage of the run-in commissioning, as a result of poor contact with the surface, friction losses greater power, fuel consumption rate is high. After adjustment adjustments, the diesel engine to good technical conditions, fuel consumption rate has stabilized at a lower range. Since then, as the diesel engine wear and the technical condition deteriorate, the rate of fuel consumption and gradually increase. At the same time, oil consumption has also increased.

Apart from the decline in horsepower, fuel consumption rate, with the diesel engine working hours increased, the agencies and with increasing gap between the parts and undermine relations with the right. Caused or exacerbated by the impact load, they often damage and failure, the reliability of the diesel engine decline.