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7A Coolant flush

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  • #16
    Use chemicals, no way you will get rid of it all other wise.

    Not sure what you mean by your last question? I would get the while system up to temperature without the thermostat in there, this will allow full flow and maximum flushing. Drain when cooled by removing thermostat housing.

    Then run hose pipe through the heater hoses through matrix in both ways, and through block as well, plugging the thermostat housing to fill the block/head and then draining en-masse. Then remove radiator and flush both ways with a hose, again forwards and backwards and allowing it to fill the radiator and quickly empty.


    • #17
      What's Oxalic acid "normally" used for? This would be a good starting point for me so when I google translate it if I have a vague idea of what kind of shop I should be asking in
      1990 CQ20v
      2001 3.0 B6 A4 Avant Quattro Sport


      • #18
        Wood bleach, from memory, but you can get it in reasonable bulk from Ebay no problem.


        • #19
          How to get whole coolant from system? I know to take out thermostat, then disconnect bottom rad hose and than lose one hose from heater to block. But there will be still some old coolant. The filling is easy because of vacuum tool.
          Audi Coupe Quattro 2.3 20V


          • #20
            I would like to add here, this to prevent issues with others in the future:

            Use 1 cup (250ml)of oxalic acid power, mix thoroughly with a large body of water.
            So 5/8 litres water = 1cup (250ml) oxalic acid.
            Special instructions now from my mistake and mishap in experience would be to thoroughly mix this as the powder has a tendency to turn to a slush that can compact itself and block your system, in even 10mm gaps!!!!.

            Use protective gloves (perhaps rubber?) for the acid as it can sting and irritate your hands for days and break down the outer layers of your skin. (My experience also)

            I hope this helps future users