The engine lubrication circuit includes the following:
- 1) Oil sump
- 2) Intake mesh filter
- 3) Oil pump
- 4) Delivery cartridge filter
- 5) By-pass pressure limiter valve
- 6) Pressure switch
- 7) Breather valve.
The oil pump (3) uses gears and is driven by a toothed gear pair on the crankshaft. Its capacity, therefore, depends on the engine speed (see control values in the next section). Any drop in pressure in the circuit is signalled by a pressure switch (6). The oil is taken from the sump (1) (see diagram), through a mesh filter (2) which retains any large impurities which may damage the pump.
One part lubricates the heads. When all the timing components have been lubricated, the oil returns from the heads to the sump through the oilways in the cylinders.
From the pump, the oil passes to the cartridge filter (4), protected internally by an anti-clogging valve which also guarantees correct oil circulation (if opened, however, the oil is not filtered).
After the filter, the oil follows three circuits.
The first leads to the pressure limiter valve (5) which sends any excess oil to the sump.
The second leads to the jets which cool the piston crowns.
The third, which passes through a clutch cover oilway, brings the oil to the crankshaft.
The pressure switch is positioned on this circuit (6).
The oil, now flowing inside the crankshaft, lubricates the big end half bearings.
As it continues to flow through the inner oilway to the shaft, the oil, using holes on the shaft itself, lubricates the timing drive pair, the starter gear inner ring and the starter free wheel.
Finally, coming out the opposite end, the oil lubricates the crankshaft support bearing in the alternator cover. The oil, once it has come out of the circuit under pressure and has lubricated the various components described above, drops into the block and lubricates the primary drive, the gearbox and the gearbox shaft support bearings.
The breather circuit for fumes created inside the block includes a layered breather valve (7) on the top of the right crankcase half, a recovery tank and a connection hose for the air filter box.