Embodiments of systems and methods for bypassing an aftercooler are disclosed. According to one embodiment, the bypass valve system may include a turbocharger, an air temperature sensor, an aftercooler, a three-way bypass valve, an aftercooler conduit, a bypass conduit, a pipe fitting, an engine, a radiator, an expansion tank, a pump, a bypass control system and a locomotive control system. The temperature of the charge air is measured and sent to the bypass control system. The locomotive control system sends engine throttle conditions, such as engine notch position, to bypass control system. Bypass control system determines whether to circulate coolant through the aftercooler or bypass the aftercooler based on the temperature measurements and the engine throttle conditions. Bypass control system then sends a signal to the bypass valve to either to circulate coolant through the aftercooler or bypass the aftercooler through the conduit.