Abstract: A cooling jacket assembly is made for an electric motor or generator. A hollow cylindrical housing is cast with an outer peripheral surface and an annular axially facing end surface, a plurality of grooves formed in the outer peripheral surface and a radial lip at one end. The outer peripheral surface is machined into a smooth surface having a uniform diameter. Inlet and outlet ports are drilled through the end surface to communicate with the grooves. A pair of sealing recesses are formed in the outer peripheral surface on opposite sides of the grooves, and an O-ring seal is placed in each recess. A cylindrical sleeve is slid over the outer peripheral surface of the housing until it engages the lip and so that the sleeve slidably engages the outer peripheral surface and sealing engages the seals.