Engine Lubrication: Description and Operation

The oil pump is of a trochoid type, and mounted on the crankshaft at the crankshaft pulley side. Engine oil is drawn up through the oil pump strainer, the oil pump and to the oil filter. The filtered engine oil flows into two paths in the cylinder block. In one path, engine oil reaches the crankshaft journal bearings. Engine oil from the crankshaft journal bearings is supplied to the connecting rod bearings by means of intersecting passages drilled in the crankshaft and then injected from a small hole provided on the large end of the connecting rod to lubricate the piston, piston rings and cylinder wall. In another path, engine oil goes up the cylinder head and lubricates the HVL adjusters, valves and camshaft, etc., after passing through the internal oilway of the rocker arm shafts. There is a check valve in the path from the cylinder block to the cylinder head. It serves to keep the oil gallery and cylinder head filled with engine oil even when the engine is not running. An oil relief valve is provided on the oil pump. This valve starts relieving oil pressure when the pressure increases over 300 kPa (42.7 psi). Relieved engine oil drains back to the engine oil pan.