How to use oxalic acid to flush a radiator

Written by aram khayatpour
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How to use oxalic acid to flush a radiator
(Thinkstock/Comstock/Getty Images)

Radiators serve as the main cooling mechanism for the fluid in your automobile's engine. Without them, the water in the cooling system would never have any heat removed from it, and the engine would overheat and become damaged. Over time, the radiator becomes contaminated with outside dirt, unclean water, or even sludge. To remove these contaminants and return the radiator to peak efficiency, use an oxalic acid chemical flush.

Skill level:

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Things you need

  • Garden hose
  • Coolant
  • New radiator cap

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  1. 1

    Open the radiator cap on the top of the radiator.

  2. 2

    Unscrew the drain plug on the bottom of the radiator.

  3. 3

    Place a hose into the top of the radiator and turn it on so that water is flowing through the radiator. Continue doing this until the water coming out of the drain plug is running clear.

  4. 4

    Screw the drain plug back into the bottom of the radiator.

  5. 5

    Pour the oxalic acid radiator flush into your radiator and fill the radiator with water, then screw the radiator cap back on. Read the specific manufacturer's instructions for your oxalic acid as they may vary from brand to brand.

  6. 6

    Turn on your engine and allow it to reach normal operating temperature.

  7. 7

    Turn on your heater and place it on the hottest setting, then allow the engine to run for 10 minutes.

  8. 8

    Turn off the engine and wait until the engine has cooled.

  9. 9

    Open the radiator cap and then the drain plug at the bottom of the radiator. Allow all the liquid to drain out.

  10. 10

    Close the drain plug and refill the cooling system with a 50/50 water and coolant solution, then replace the radiator cap with a new one.

Tips and warnings

  • Make sure your automobile is on a level surface before you begin flushing the system.
  • Oxalic acid is corrosive and should not come in contact with the skin or eyes. Always wear protective eyewear and gloves when working with it.

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