9-3 Coupe (9400) L4-2.0L Turbo (B204) (1999)
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On the turbo engine the thin hose connected after the throttle is fitted with a check valve which prevents the build-up of overpressure in the crankcase.
On the turbo engine a pipe replaces the thick hose connected before the throttle valve on the normally aspirated engine. This pipe carries the crankcase
gases to the turbochargers intake pipe.
Crankcase Ventilation (B235R)
The combustion gases flowing past the pistons and piston rings must be allowed to pass out of the engine. If the gases in the crankcase are not evacuated,
the pressure in the crankcase will continue to rise until something breaks. The crankcase gases must not be allowed to pass out into the engine bay as
they contain a large proportion of unburnt hydrocarbons. A system which recovers the hydrocarbons and prevents the pressure in the crankcase from
rising excessively is used to evacuate the gases.
The crankcase gases are carried to the external oil trap via a nipple on the camshaft cover.
The gases are then evacuated to the turbo inlet pipe where they are mixed with the intake air and burned in the engine.
A drainage hose runs from the oil trap down below the oil level in the sump
The system is water-heated to prevent it from icing up.
