The fasteners in the oil pump assembly, including the sprocket retaining nut, may loosen and fall off into the oil pan, so it is essential to install these fasteners with Loctite® or an equivalent thread locking compound and torque them to specifications. Begin by removing the lower oil pan, and if applicable, take out the oil pump sprocket cover fasteners before removing the cover. Unclip the crankcase breather oil return line, then remove the oil pump sprocket nut and detach the sprocket and drive chain from the pump. Unbolt the oil pump mounting fasteners and remove the pump, followed by inspecting the oil pressure relief valve. Replace the O-ring seals on the engine oil pipes, ensuring they are lightly oiled, and take care not to damage the O-rings on sharp edges of the engine block during reinstallation. Replace the sealing O-ring in the oil pump and turn the threaded spacer on the pump fully to stop. Reinstall the pump, coating the left side pump mounting fasteners with Loctite® or an equivalent thread locking product before installing and tightening them. Coat the pump sprocket shaft threads with Loctite®, then reinstall the pump sprocket with the drive chain and tighten the mounting nut. Use an Allen wrench to adjust the chain slack by turning the threaded spacer, coat the remaining oil pump mounting fastener with Loctite®, and install and tighten it. The remainder of the assembly follows the reverse order of disassembly. After adding engine oil, start and run the engine, raising the engine speed to 2,500 rpm until the oil pressure warning light goes out.