Oil Circulation

Oil circulation

The type 2000 engine has dry-sump lubrication. The circuit contains two independent oil pumps, housed in the crankcase. One pump draws oil completely free from air bubbles from a separate oil tank, where ft has been allowed to settle, and distributes it by the way of the main oil circuit to the main bearings. The other pump extracts contaminated oil from the crankcase through a strainer and delivers it to the oil tank via a filter. This pump is suitably enlarged to operate at lowered efficiency, since its function is to pump oil containing air bubbles.

A thermostat is placed at the entry to the main oil circuit, and regulates the flow of oil. If the oil temperature falls below 80° C (176° F) a flap operated by the thermostat closes to prevent oil from circulating through the oil cooler. When this occurs the oil passes directly to the bearings. When the temperature rises above 80° C (176° F) the flap opens and oil is passed through the cooler before reaching the bearings.

A pressure release valve (7) and safety valve (4) are built into the main oil circuit. The pressure release valve comprises a spring and piston located in the right half of the crankcase. If oil pressure in the circuit rises above 6.2 ± 0.8 atu (88.2 ± 11.3 psi) the pressure release valve opens and oil is allowed to pass directly into the crankcase.

In addition to the pressure release valve a safety valve is mounted in the left crankcase half immediately after the oil pump. This operates in the event of a defective pressure release valve to prevent damage to the oil cooler and possibly to the filter or lines.

Each main bearing is supplied with oil by a separate passage from the main oil circuit. Main bearings 1 and 8 are designed to supply oil continuously under pressure to the drilled passage in the center of the crankshaft so that oil can reach the connecting rod bearings.

Another oil passage leads to the front bearing of the intermediate shaft. From here a drilling through the center of the shaft supplies oil to the rear bearing. A small drillway on the rear face allows oil to reach and lubricate the axial location bearing.

The oil supplied to the camshafts is taken from the far end of the main circuit. An oil line leads to a central inlet point on each camshaft. The oil passes from the cylinder head to the rotating camshaft by way of an axial sealing ring.

The three camshaft bearings are supplied with oil under pressure from the central inlet point. Drillways in the cam faces provide lubrication at the points of contact between cams and rockers. Oil splashed from these points serves to lubricate the rocker shaft and valve stems.

Oil is collected in the lower part of the camshaft housing and returned to the crankcase by two oil return pipes. The extractor pump then returns ft to the oil tank through a flexible line. A tube in the oil tank adjacent to the line connection point conveys the oil through a pipe to the base of the throwaway type oil filter.

Inside the filter the oil passes between the housing and the element, then flows under pressure through the element toward the center of the filter and is purified. It is then returned to the oil tank.

As a safety measure, bypass valves are built into the filter base and filter body. Should the flow pressure through the filter exceed 2 atu (28.4 psi) oil is directed by way of these valves directly into the oil tank, and any interruption in the oil supply caused by contamination or the filter or blockage of the outlet passage is thereby avoided.