Page 14 of 55
Downloaded from www.Manualslib.com manuals search engine Crankcase Venting System
The crankcase vapors (a result of combustion blow-by gasses) are led out of the crank-
case and back into the combustion chamber via the intake manifold. The blow-by gasses
contain droplets of oil which must be separated. The oil is returned to the sump while the
blow-by gasses are led into the intake pipe for combustion.
The engine performance is affected by the introduction of crankcase vapors into the com-
bustion process, particularly in idle speed ranges. This influence is monitored by lambda
regulation.
The crankcase vapors are carried from the crankcase and into the cylinder head covers
through labyrinth separators (one per cylinder head). The oil which accumulates on the
walls of the labyrinth separators flows into the cylinder head via a siphon and from there
back to the sump.
The remaining vapors are passed to the engine for combustion via the pressure control
valve (5) in the intake manifold. One labyrinth separator with a pressure control valve is inte-
grated in each of the two cylinder head covers.
The throttle valve is controlled so that there is always a 50 mbar vacuum in the intake man-
ifold. The pressure control valve regulates the crankcase pressure to a low 0-30 mbar.
12
N62 Engine
43-02-12 Cylinder Head Cover
1-4. Opening for Spark Plugs
5. Pressure Control Valve
6. Opening Valvetronic Motor
7. Opening Valvetronic Sensor
Connector
8. Camshaft Sensor
Page 17 of 55
Downloaded from www.Manualslib.com manuals search engine Secondary Air Pump (SLP)
The electrically-operated secondary air pump is mounted to the vehicle body. The pump
draws out filtered fresh air from the air cleaner housing during the warm-up phase and sup-
plies it to the two secondary air Non-return Valves.
Once the engine has been started, the secondary air pump is supplied with voltage by the
ECM via the secondary air pump relay. It remains switched on until the engine has taken in
a certain amount of air.
The O ON
N
period may be a maximum of 90 seconds and it depends on the following engine
operating conditions:
• Coolant temperature (from -10 ºC to approximately 60 ºC)
• Air temperature (NTC sensor in HFM)
• Engine speed
One non-return valve is mounted on each cylinder head (see also Engine Views).
The non-return valves are opened by the pressure generated from the secondary air pump.
The secondary air is led through a pipe to the secondary air ducts (integral in the cylinder
heads) for distribution into the exhaust ports.
The non-return valves are sprung closed when the secondary air pump is deactivated. This
prevents exhaust vapors, pressure and condensation from flowing back into the secondary
air pump.
15
N62 Engine
43-02-14
View From Rear of The Cylinder Head
1. Cylinder Head Lead
2. Non-return Valve (SLV)
3. Secondary Air Pump Connection
Page 23 of 55
Downloaded from www.Manualslib.com manuals search engine Engine Covers
Each cylinder head has a plastic cover for the ignition coil cabling and top of the cylinder
head. The covers “push fit” into rubber grommets on the cylinder head covers.
A sound absorption cover for the top of the
engine also covers the two Valvetronic motors.
This cover is fixed to the intake manifold hous-
ing using four bolts.
The cylinder head covers are made from plastic. The retaining sleeves for the ignition coils
have molded-on gaskets. The sleeves must be replaced if any hardening or damage is vis-
ible on the gaskets. The sleeves are inserted into the cylinder head through the cylinder
head cover (nos. 1through 4).
N No
ot
te
es
s:
:
21
N62 Engine
42-02-21
Engine Covers
Cylinder Head Cover
1. Cylinder Head Top Cover
2. Sound Absorption Engine Cover
1-4. Opening for Spark Plugs
5. Pressure Control Valve
6. Opening for Valvetronic Motor
7. Opening for Valvetronic Sensor Connector
8. Camshaft Sensors (Intake and Exhaust)
43-02-12