Crankcase Ventilation: Notes

Crankcase ventilation works to a large extent in the same way as on the N63 engine. However, the N74 has register ventilation, which is also used on the S63 engine.

Fig 1: Identifying Crankcase Ventilation

Courtesy of BMW OF NORTH AMERICA, INC.

INDEX EXPLANATION REFERENCE CHART

Index	Explanation
1	Inlet from oil separator, bank 2
2	Non-return valve
3	Outlet to air intake system, cylinder bank 2
4	Outlet to air intake system, cylinder bank 1
5	Non-return valve
6	Inlet from oil separator, bank 1
7	Orifice for fresh air intake (crossflow ventilation)
8	Non-return flap
9	Outlet to fresh air pipe, cylinder bank 1
10	Connection to fresh air pipe, cylinder bank 1
11	Oil separator, cylinder bank 1
12	Oil return ducts
13	Connection to air intake system, cylinder bank 1
14	Connection to air intake system, cylinder bank 2
15	Oil separator, cylinder bank 2
16	Connection to fresh air pipe, cylinder bank 2
17	Inlet from oil separator
18	Non-return flap
19	Outlet to fresh air pipe, cylinder bank 2

Each cylinder bank has its own oil separation system which includes four cyclone separators.

In naturally-aspirated mode, the cleaned blow-by gas is introduced downstream of the exhaust turbochargers through the non return valves that connect to the intake manifold.

Fig 2: Identifying Bank 1 Non Return Flap And Non Return Valves

Courtesy of BMW OF NORTH AMERICA, INC.

In boost mode it is introduced upstream of the exhaust turbochargers through the non return flaps leading to the fresh air pipes on each bank. In contrast to the N63 engine, the crankcase ventilation systems for the left and right cylinder banks are not completely separate from each other.