1. Disconnect the upper hose from the radiator.
2. Insert a hose into the radiator and flush with a stream of clean water until the water flows out of the radiator drain hole clean. If the radiator is heavily contaminated, remove the radiator and flush it by successively directing a stream of clean water from different sides of the radiator.
3. Flush the heater radiator, having first opened the heater tap and disconnected the hoses from the heater. Connect a hose to one of the hoses and flush with a stream of clean water until the water flows out of the second hose clean.