A coolant flow control system (100, 200) includes an integrated coolant flow control and heat exchange device (10, 50). The device includes a valve body part (20, 60) and a heat exchange part (30, 70). According to the system, all the coolant flow from the engine is delivered back to the engine after passing through the valve body part (20, 60) and then the heat exchange part (30, 70) in which it passes over the heat exchanger part (40, 80). The valve body part (20, 60) by positioning of the coolant flow wall (26, 66) allows multiple flow modes and coolant paths to branch out (or converge) from (or to) thereby controlling the flow in all coolant circuit branches.