The invention discloses an internal combustion engine and a coolant pump. An engine cylinder block forms a cooling jacket adjacent to a cylinder and that intersects a deck face adapted to mate with a cylinder head. The cooling jacket has an inlet passage intersecting a mounting face adapted to mate with a coolant pump housing. The block forms a vent passage extending from the cooling jacket to the mounting face. The pump housing forms a volute adapted to receive an impeller. The housing forms a discharge passage that fluidly connects to the inlet passage of the block. The pump housing also forms a vent passage the fluidly connects with the vent passage of the block. The vent passages of the block and pump housing are positioned between the deck face of the block and the inlet and discharge passages when the pump housing is connected to the engine block.