Abstract: A lubricating system for an internal combustion engine includes a crankcase within which are located the rotating shafts, one of which is the crankshaft, and the bearings for these shafts, the crankcase having disposed above it the cylinder block of the engine, and within its bottom portion the sump for the lubricating oil. The oil pump body is radially centered within a cylinder casing by peripheral engagement with a pump seat, formed within one of the end walls of the cylinder casing of the engine crankcase and the pump body serves as the end bearing for the rotating shaft of the engine, the extension of which constitutes the pump shaft.