How Do You Clean a Clogged Radiator?

Flushing a clogged vehicle radiator involves draining it, connecting it to a garden hose and forcing water through the pipes. The supplies you need to flush your radiator are an empty lidded container for the old anti-freeze, a piece of sturdy wire, a garden hose, clean rags, a glass jar and fresh anti-freeze. This procedure usually takes about an hour and must be performed on a cold radiator with the vehicle turned off.

  1. Drain the cold radiator

    Place the anti-freeze receptacle beneath the radiator and set the radiator temperature control to its hottest setting. Remove the radiator's pressure cap and drain plug so that the anti-freeze drains into the container. If the coolant does not emerge on its own, insert the wire into the drain hole and wiggle it around. Fasten the lid and set the container aside.

  2. Open the drain tap

    Some radiators have drain taps. If yours has one, open it.

  3. Disconnect the radiator hoses

    Disconnect both radiator hoses and insert a garden hose into the top hole. Stuff clean rags around the hose to keep it in place.

  4. Flush the radiator

    Replace the pressure cap and turn on the water. Keep the water flowing until clear fluid emerges from the radiator. Stick a clear glass jar into the liquid stream, collect a small sample and hold it up to the light. If the water is cloudy or contains suspended sediment, dump it out and keep flushing the radiator. Retest the water until it is clear.

  5. Reconnect the hoses

    Turn off the water and remove the garden hose. Reconnect both radiator hoses and fill the radiator with anti-freeze according to the vehicle manufacturer's instructions.

  6. Dispose of the old anti-freeze

    Take the container of old anti-freeze to a hazardous waste dump or ask your mechanic to dispose of it according to local laws.