An internal combustion engine has an engine casing. A shaft, having a shaft axis, is disposed in the engine casing. At least one bearing supports the shaft in the engine casing. A separator wheel is disposed on the shaft for rotation therewith. The separator wheel has a first opening in fluid communication with the crankcase, a second opening, and a channel extending radially from the second opening to the first opening relative to the shaft axis. A suction tube is permanently affixed to a portion of the engine casing. An end of the suction tube has a unitary abutment surface. A gasket is disposed between the unitary abutment surface and the second opening of separator wheel. The gasket is also disposed at least in part on a separating plane of the engine casing.