Crankcase ventilation valve
Controls how crankcase gas returns to the intake.
In the cylinder-head cover or a connected separator assembly, depending on engine.
Pressure regulation and oil separation limit crankcase pressure and oil carried into the intake.
A pressure-managed breathing valve for the engine.
Whistling, oil leaks or rough idle can arise from ventilation leaks and need measured checks.
Usually condition-based rather than a routine replacement. Lubrication, overheating and the exact engine affect wear.
Internal-engine work is usually labor-intensive. Diagnosis and the engine code determine the repair scope.
BMW crankcase-ventilation arrangements vary; some valves are integrated into a larger cover assembly.
BMW petrol and diesel engines; petrol-only systems are identified individually.