Engine Lubrication: Description and Operation

The oil pump is a trochoid type and is mounted on the crankshaft at the crankshaft pulley side. Oil is drawn up through the oil pump strainer and passed through the pump to the oil filter. The filtered oil flows in two paths in the cylinder block.

In one path, oil reaches the crankshaft journal bearings. Oil from the crankshaft journal bearings is supplied to the rod bearings by means of intersecting passages drilled in the crankshaft. It's then injected through a small hole in the connecting rod to lubricate the pistons, rings and cylinder walls.

In the second path, oil flows to the cylinder head and lubricates the rocker arms, valves, camshaft, etc., after passing through the internal oil passage of the rocker arm shafts.

A pressure relief valve is provided on the oil pump to relieve oil pressure should it become greater than 392 kPa (56.9 psi). As oil pressure is relieved, oil is diverted through the valve back to the engine oil pan.