The inner rotor has four lobes which mesh with the five lobes of the outer rotor. When the inner lobe rotates, the distance increases between the lobes of the outer rotor and the lobes of the inner rotor in order to create suction. Then, the space between the lobes is filled with oil. When the distance decreases between the lobes, pressure is created. This pressure forces the oil into the chamber for the engine oil relief valve.
Lubricating oil from the oil pan flows through a strainer and a line to the suction side of the engine oil pump. The lubricating oil flows from the outlet side of the pump to a relief valve. The relief valve is installed near the bottom of the left side of the timing case.
When the engine rpm increases, the output of the oil pump increases. This increase in output from the oil pump causes the pressure to increase. The relief valve on the engine oil pump opens if the oil pressure is too high. When the oil pressure on the plunger of the relief valve is greater than the spring force of the relief valve, the relief valve opens. The lubricating oil which flows through the relief valve is returned to the oil pan.
The lubricating oil, which flows around the relief valve, flows through a passage. This passage is drilled along the length of the cylinder block to the oil filter. This oil gallery is drilled through the total length of the left side of the cylinder block. The oil filter is installed on the right side of the cylinder block or on the top rear of the cylinder block. Different machine models have different locations of the oil filter.
Lubricating oil flows from the oil filter through an oil gallery. This oil gallery is located above the lower oil gallery and parallel to the lower oil gallery. The lubricating oil flows through drilled holes in the upper oil gallery to passages in the main journals of the crankshaft. Then, the oil flows to the main bearings of the crankshaft. Also, the oil flows through passages in the crankshaft to the large end bearings of the connecting rods. The piston bearings, the pistons, and the cylinder bores are lubricated by the splash and the mist of the oil.
A hole is located in the bore of each main bearing. This hole allows oil to flow through passages that lubricate the journals of the camshaft for the valves. The bearing for the front journal receives oil from the front main journal of the crankshaft. The camshaft for the fuel injection pump is lubricated by the splash and the mist of the oil.
Lubricating oil flows from the upper oil gallery to a passage in the front of the cylinder block. This passage connects with a vertical passage to the front of the cylinder head. Then, the oil flows to a small hole in the first bracket of the rocker assembly. This small oil hole acts as a restriction in order to reduce the oil pressure to the rocker assembly.
The oil passes through the rocker shaft to the bore of each rocker lever. Then, the oil flows from the rocker levers through holes that are located in the top of the rocker levers. The valve stems, the valve springs, and the lifters are lubricated by the splash and the mist of the oil.
The hub of the idler gear is lubricated by oil from the oil gallery. The timing gears are lubricated by the splash of the oil. Lubricating oil from the timing case returns to the oil pan.