Abstract: An integrated coolant pump and transmission fluid heat exchanger comprises a single module bolted to the engine block. A primary liquid coolant circuit takes pressurized coolant from the pump, through the block, to the radiator and back. A small, separate heat exchanger sits within the module, within a parallel liquid coolant circuit that by passes the primary coolant circuit. Liquid coolant is picked off from the pump outlet by an inlet to the heat exchanger, and, after running through the heat exchanger, is returned to the main flow downstream of the radiator. Concurrently, transmission fluid is counter flowing through the same heat exchanger. Consequently, the parallel liquid flow through the heat exchanger does not interfere with the pressure in the main engine cooling flow. The direct, continual heat exchanger relationship between the two fluids in the heat exchanger allows the transmission to be either heated or cooled by the engine coolant, depending on the relative temperatures thereof.