The correct operation of crank mechanism bearing nodes is the one of engine reliable run decisive factors. The need for detailed analysis of bearing run conditions results from high demands that should be met by modern engines. Since mating surfaces of journal and shell as well as dividing oil film constitute an integral whole, all problems concerning this assembly should be analyzed taking into account their interdependence. The paper deals with some problems encountered during crank mechanism run, i.e. problems concerning the choice of material, structure of mating surfaces, kind of friction, viscosity of applied lubricant in order to reduce wear and guarantee the reliable operation within the whole engine life. Presented examples of problems mentioned in the paper originate partly from bearing manufacturers and from simulations based upon the hydrodynamic theory of lubrication. However, authors are of the opinion that these problems are merely the part of wider subject of friction, wear and lubrication.