A cooling system for an engine includes a coolant tank, a heat exchanger, and a drain valve. The coolant tank holds a fluid coolant and is coupled with a tank conduit through which the coolant flows from or to the coolant tank. The heat exchanger is fluidly coupled with a supply conduit. The drain valve is fluidly coupled with the coolant tank by the tank conduit and with the supply conduit. The drain valve is fluidly coupled with a drain conduit that directs the coolant out of the cooling system and alternates between a closed position and an open position. The drain valve prevents the coolant from flowing out of the cooling system through the drain conduit when in the closed position and permits the coolant to flow from the heat exchanger and out of the cooling system through the drain conduit when in the open position.