the exterior face of the housing 30 a multi bladed fan 38 partially illustrated in fig1 is attached by threaded fasteners 40 to the bosses 36 a plurality of fins 42 is provided on the outer surface of the housing 30 to dissipate heat transferred from a viscous fluid not illustrated contained by the assembly 20 a cover indicated generally at 44 is mounted to a front face of and cooperates with the housing 30 to form a reservoir 46 for the viscous fluid as described below the cover 44 is a dished member having an annular outer edge 48 secured to the housing 30 by an annular retainer lip 50 spun over from the material of the housing 30 an annular seal 52 e g a formed in place gasket is interposed between the edge 48 and a front face of the housing 30 to prevent leakage from the interior of the assembly 20 a plurality of fins 54 is provided on the outer surface of the cover 44 to dissipate heat transferred from the fluid a disk like pump plate 56 is installed in the interior of the assembly 20 the pump plate 56 is positioned on a shoulder 60 of the housing 30 and is drivingly secured to the housing 30 by the cover 44 the pump plate 56 divides the interior of the assembly 20 into a working chamber 62 and the fluid reservoir 46 in the view of fig1 the working chamber 62 is the interior volume to the left of the pump plate 56 while the reservoir 46 is the interior volume to the right of the pump plate 56 for purposes of this specification a first or rear surface 57 of the pump plate 56 is in communication.