A rotary engine casing having at least one end wall of an internal cavity for a rotor including a seal-engaging plate sealingly engaging the peripheral wall to partially seal the internal cavity and a member mounted adjacent the seal-engaging plate outside of the internal cavity. The member and seal-engaging plate having abutting mating surfaces which cooperate to define between them at least one fluid cavity communicating with a source of liquid coolant. When the casing includes a plurality of rotor housings, the end wall may be between rotor housings. A method of manufacturing a rotary engine casing is also discussed.