New Generation N62 Engine
Chapter 6 P.6
Course Contents/Background Material
© BMW AG,
Service Training
- Expansion tank (29):
The task of the expansion tank is to receive fuel when the fuel
tank is full and has expanded due to heating (e.g. solar
radiation). The activated-carbon filter would cease to function if
fuel reached it.
- Rollover valve (11):
The rollover valve is also a plastic ball valve. When the vehicle is
in its usual position, the rollover valve is open, thereby allowing
air to flow in and out. In the same way, fuel can flow via the filling
vent valve (28) from the fuel tank into the expansion tank, and
from the expansion tank back into the fuel tank.
In the event of an accident in which the vehicle rolls over, the
ball locks the expansion tank inlet and outlet openings and
prevents fuel from escaping.
- Dust and spider filter (12):
The dust and spider filter prevents dust and small insects from
entering the activated-carbon filter, which would thus render it
unserviceable.
Tank ventilation function
During refuelling, the air escapes via the service ventilation into
the expansion tank.
Air molecules in the tank have combined with hydrocarbon
molecules. These must not escape into the ambient air. The air
containing hydrocarbon molecules is fed through the activated-
carbon filter. This filters out the hydrocarbon molecules and
stores them.
The activated-carbon filter is regenerated when the engine is
running. This means that air is passed through the activated-
carbon filter in the opposite direction and is supplied to the
combustion air via the engine's purge air pipe (8). The fuel
evaporation control valve (6), which is controlled by the digital
engine-management, controls the proportioning.
