How to Flush Radiators

A car’s radiator and cooling system should be cleaned regularly to keep them functioning properly. Over time, solid deposits can build in a car’s radiator, which can clog the cooling system. Flushing these clogs from the radiator helps keep a car’s cooling system in shape.

Materials Needed

  • Wrench or phillips head screwdriver
  • Rag or cloth
  • Radiator flush solution
  • Coolant
  • Funnel
  • Receptacle (for used coolant)

Steps to Flush a Radiator

  1. Locate the radiator’s drain plug, which can be found anywhere along the bottom of the radiator. The plug may appear as a screw plug, a bolt plug, or a petcock drain valve.
  2. Place the coolant catcher beneath the drain. Unscrew the plug and drain the coolant until the receptacle is completely empty.
  3. Replace the plug after emptying the coolant.
  4. Remove the radiator cap.
  5. Pour all of the radiator flush solution into the radiator. Fill it to the brim with water.
  6. Replace and tighten the radiator cap.
  7. Start the car. Let the engine run until it gets to its operating temperature.
  8. Turn the heater on. Move its temperature control to the hottest position. Leave the car running for 10 minutes with the heater on.
  9. Turn the engine off and wait for it to cool down. Do not open the radiator cap if it is still too hot to touch.
  10. Open the radiator once the engine has cooled down. Drain the entire contents of the radiator into the coolant receptacle.
  11. Refill the radiator with fresh coolant. Fill it with a 50/50 mixture of water and coolant.
  12. Replace the radiator drain plug or fully close the petcock valve.