Lubrication circuit (BMW 3 Series E36)

BMW engines have a so-called circulating lubrication system. The oil pump takes oil from the oil sump through the oil intake and supplies it to the main oil filter. There is a pressure-reducing valve at the outlet of the oil pump. The valve opens when the pressure is too high and some of the oil flows back into the oil sump. The oil enters the main channel along the central axis of the oil filter cartridge. When the oil filter is clogged, the bypass valve opens and supplies unfiltered oil to the main channel.

A bypass valve is installed behind the oil filter (oil pressure control valve), which maintains the oil pressure at approximately 4 bar. When the pressure increases, the valve opens and some of the oil flows back into the oil pan.

The main channel branches off into the crankshaft bearing lubrication channels. Through inclined holes in the crankshaft, oil flows to the connecting rod bearings and from there is sprayed onto the piston pins and cylinders.

At the same time, engine oil is supplied through inclined channels to the cylinder head to the camshaft bearings, rocker shafts and rocker bearings. Check valves ensure that sufficient oil is constantly supplied to lubricate these parts in the cylinder head.

If there is a chain drive, oil is also supplied to lubricate the timing chain and the oil pump drive chain.

[Information taken from this resource: BMWMAN.RU]