A housing can have a cap, a base member and a mid-portion positioned between and removably coupled with the cap and the base member. The cap and the mid-portion can define a reservoir therebetween and the cap can define a recessed inner wall in fluid communication with the reservoir. The mid-portion can define a recessed impeller chamber configured to receive a pump impeller. The mid-portion can further define a retainer positioned between the impeller chamber and the inner chamber. A resiliently compressible member can be positioned within the inner chamber and configured to resiliently compress in response to a volumetric expansion of the liquid coolant. The retainer can contact the resiliently compressible member to prevent the resiliently compressible member from moving out of the reservoir or into a position blocking a liquid coolant flow through a port. The mid-portion can define a housing wall forming the retainer.