a lube - oil pump system for a diesel engine &# 39 ; s fuel injection system has a first and second pump . each pump is a multi - plunger swash - plate type pump . the first pump mounts to a neck portion of a front cover of the engine &# 39 ; s crankcase and has a driven gear that meshes with and is driven by gear teeth formed on the engine &# 39 ; s camshaft . the second pump mounts vertically stacked on top of the first pump and has its own driven gear that meshes with and is driven by the gear of the first pump . the second pump is configured to operate in the counter - rotational direction as the first pump .