the invention relates to improvements in heat exchangers of the type having a container which defines a cylindrical cavity and a cluster of parallel cooling tubes extending through the cylindrical cavity . the housing is provided with a fluid inlet , a fluid outlet , and a center baffle dividing the cylindrical cavity into an inlet compartment and an outlet compartment . the inlet and the outlet are located on opposite sides of the center baffle , but near one edge thereof . an opening is provided near the opposite edge of the baffle , such that fluid must circulate through a nearly circular path within the cylindrical housing between the inlet and the outlet conduits . a second fluid such as cool air , may be blown through the parallel tubes for removing heat from the fluid in the cavity . the present invention improves over the known heat exchanger structure by providing a number of deflector flanges attached to the cylindrical housing wall and extending radially inwardly therefrom towards the interior of the heat exchanger cavity . the deflector flanges direct fluid away from the housing wall and towards the interior of the coolant tube cluster .