This paper will discuss results of metallurgical and metrological examinations of cylinder liner and piston ring surfaces before and after 150, 1000 and 4000 hours of heavy duty diesel engine testing. Three different composition coatings and three methods of application were investigated, including electroplating, plasma and HVOF spraying. To examine metallurgical parameters such as porosity, microhardness, microstructure and their changes after testing, scanning electron microscopy and energy dispersive X-ray spectroscopy were used. The cylinder liner and piston ring surface profile and roughness parameters include Ra, Rz, Rk, Rvk, Rvk, skewness, oil retention volume, etc. The mechanisms of scuffing origin and final wear were evaluated for different piston ring coatings and methods of application. The paper will show the correlation between metallurgical and metrological parameters and efficiency of the cylinder liner-piston rings tribological system. The data from these examinations formulates required performance for transformation of abnormal and/or severe type of wear to mild processes.Presented as a Society of Tribologists and Lubrication Engineers paper at the World Tribology Congress in London, United Kingdom, September 8–12, 1997