Scion 16401-31480 Radiator Cap Sub-Assembly

To begin with, to drain the cooling system, you can remove the expansion tank and radiator cap, letting the coolant drain. If the coolant is clean, it can be reused. Also, remove the thermostat and flush the engine until you see clean water. When refilling, secure all hoses and clips. You can use an antifreeze mixture and fill the system. If overheating occurs, squeeze the coolant hoses to release air. Check the radiator top hose for heat and release trapped air. Replace the pressure cap if damaged.