The high-pressure pump is a component of the automotive common-rail system and has as main assemblies: housing, driveshaft, gaskets and front plate. Literature presents analyses of the threaded fastening assemblies, especially for those with the critical joints with screws, those involving torque and angle. The assembly process that we have studied performs the sealing of the components with the gasket through the screws, thus preventing the fuel from leaking from the pump. Our paper presents an analysis of the influence of the tightening process with screws of the housing, gasket and front plate. The experiment was conducted using the Zeiss measuring system and the screwdriver Janome. The tests analysis demonstrates that screwing process can influence the distortion.