The operation of locomotives diesel engines involves aging and physical wear of parts, components and assemblies, which leads to a decrease in the probability of failure-free operation and an increase in the number of failures. To increase the probability of failure-free operation and reduce the number of failures of locomotives diesel engines, a certain maintenance system is applied. To manage of diesel engines maintenance processes in a locomotive depot, it is proposed to use the risks of failures. The article presents mathematical models of the risks of failures depending on the operating parameters of diesel engines. Based on the developed models, it is possible to manage the maintenance processes. Comparison of theoretical and experimental results confirms the adequacy of the developed mathematical models and confirms the effectiveness of the proposed approach to determining the risks of failure of diesel engines for managing maintenance processes in a locomotive depot. As a result, a maintenance process for 5D49 diesel engines in the locomotive depot was developed. By managing the maintenance processes of 5D49 diesel engines in a locomotive depot, it was determined that the optimal mileage is 45,000 km. The resource of 5D49 diesel engines in a locomotive depot in the management of maintenance processes increased by 2.4...5.5% compared to the existing maintenance system.