Radiator reserve tank

pinch the return hose going to the radiator, remove any existing anti freeze. using a light detergent clean out the tank. sometime you can get most of the junk out with just flushing it but for heaverier spots you can use a old toothbrush or a brush with a long handle that fits in the tank easily. once the tank is cleaned flush with clean water to remove any soap. flush it out well. then refill with anti freeze