The conditions have been considered of the environmental effect on the working efficiency of fuel feed system of diesel engines in wintertime. A scheme has been suggested of thermodynamic state of diesel fuel oil in structural components of the fuel feed system of energy-saturated tractors affected by environmental conditions. There is a mathematical description of the temperature changing process in the fuel tank depending on the environmental temperature provided in the study.

Several ways of technical diagnostics have been researched. General aspects have been considered of the mechanism diagnostics by vibroacoustic signals. The assessment of the vibroacoustic engine diagnostics method is provided. On the basis of a laptop computer, a portable diagnostic complex has been elaborated for the pre-assessment of combustion engine mechanisms' condition using parameters of a vibroacoustic signal. For technical assessment of combustion engines a diagnostic scheme has been proposed for mechanical components by vibration parameters.

The author of the article considers the scientific approaches to increasing the longevity of high-loaded operating parts of small agricultural machines by forming the technological repair units when choosing the optimal methods of hardening the functional surfaces with anti-wear low-cost material.