Operability and efficiency of transport diesel engines significantly depend on periodical diagnosis of its technical condition. The article considers the features of monitoring and diagnostic of transport diesel engines with the help of vibroacoustic analysis of high pressure fuel equipment and gas distribution mechanism. Functional scheme of diagnostic system and analytical method of TDC determination is described. Article gives an example of four-stroke and two-stroke diesel engines diagnosis. Also the article shows turbocharger speed determination and diagnosis with the help of vibroacoustic spectrum analysis. The main feature of the given methods is their high efficiency for diagnosis of transport diesel engines during operation.