Header for heat exchanger

A heat exchanger for a motor vehicle, the heat exchanger comprising:

• a core having an open end;
• a header coupled to the core adjacent the open end, the header including a plurality of cavities, wherein each of the cavities is defined by a concave portion of an inner surface of the header;
• and
• a fluid reservoir including a sidewall having an outer surface, a base, and a terminal end depending from the base and defining an opening of the fluid reservoir, the fluid reservoir including a plurality of protrusions extending outwardly from the outer surface thereof, wherein each of the protrusions is defined by a convex portion of an outer surface of the fluid reservoir, wherein each of the protrusions is received in and enclosed by one of the cavities of the header, and wherein each of the cavities has a shape corresponding to a shape of one of the protrusions received therein, wherein a lip is formed on the sidewall adjacent the terminal end of the fluid reservoir and is outwardly offset from and parallel to a lower portion of the sidewall, wherein each of the protrusions includes an engaging surface and the inner surface forming the concave portion of the inner surface of the header includes a receiving surface engaging the engaging surface, wherein each of the engaging surfaces is formed opposite the terminal end, wherein each of the engaging surfaces is inclined with respect to an axis along which a force is applied to assemble the fluid reservoir to the header, wherein a distance from the terminal end to each of the engaging surfaces increases as the distance from the base increases.