Lubricating system
The engine lubricating system has forced-flow circulation, with the oil pressure being generated by a gear pump consisting of a pinion and an eccentric ring gear. The pump is located in the timing cover and driven by the crankshaft. Oil is drawn from the sump to the oil pump via an inlet strainer and pipe. A reducing valve in the timing cover limits the oil pressure and returns surplus oil to the suction side of the pump. From the pump the oil then flows through a passage in the cylinder block to the oil filter.
A thermostat in the oil-filter adapter housing opens at 105 C (221 F) to allow the oil to circulate through the oil cooler. After filtering and cooling, if necessary, the oil is carried via a pipe to the main gallery in the cylinder block where the engine oil pressure sensor is located. If oil pressure drops too low, the sensor grounds the circuit for the warning lamp in the main instrument unit, causing it to light up. The crankshaft main bearings and big-end bearings are lubricated with oil via oil ways in the engine block and crankshaft, while oil mist lubricates the pistons and cylinder walls, which are also splash lubricated. A piston-cooling nozzle is fitted at each cylinder to spray a fine jet of oil onto the underside of the piston.
The outer bearing on the exhaust side balancer shaft is supplied with oil through a drilling from the No. 1 main bearing. The inner bearing on the exhaust-side balancer shaft is supplied with oil through a drilling from the No. 3 main bearing. Both balancer-shaft bearings on the inlet side are supplied with oil from the main gallery. From the main gallery in the cylinder block, a rising oil way to the cylinder head also supplies oil for the camshafts and valve mechanism. Through one of the cylinder head bolt holes, oil flows through drilled passages to the camshaft bearings and valve tappets.