A rotor-type apparatus for centrifugal cleaning of crankcase gases from a combustion engine. The rotor is hydraulically driven by pressurized oil by means of a turbine wheel located in an oil collection chamber. A pressure equalizing and gas discharging conduit, which extends into the collection chamber and has an upper aperture located above a liquid level of the oil in the collection chamber during the operation, is connected to an outlet conduit for the propellant oil from the collection chamber.