A flap bearing system for a flap shaft in a motor vehicle includes a first radial bearing within which is arranged a flap shaft comprising a flap shaft end. A ratable flap body is arranged on the flap shaft. A flow cross-section of a channel housing is controllable by rotating the flap shaft with the flap body. A first bearing housing surrounds the first radial bearing. A bearing housing cover comprises an opening through which the flap shaft end protrudes. The bearing housing cover closes the first bearing housing. A sleeve radially surrounds a section of the first bearing housing. A circumferential groove is formed at an outer circumference at the section of the first bearing housing surrounded by the sleeve. The flap shaft end protruding from the first bearing housing is arranged geodetically so as to be at a same height or above an opposite flap shaft end.