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Radiator Drain and Flush

Radiator Drain and Flush

Paul Gover

Here is an easy way to drain and flush.

  1. Remove the filler caps, and turn the aircon or heater to defrost. Turn the ignition on to allow the aircon servo to move to the right position, then turn off again. This allows the heater matrix to drain.
  2. Drain the radiator. There is no radiator drain cock on the series III, though there was on the series II. On the Series III, loosen the circlip (hose clamp) around one of the bottom hoses (very loose).
  3. Insert a medium screwdriver between the hose and the pipe, and waggle about a bit until the water starts to flow up your sleeve. Don't apply too much force, or you'll bend the end of the pipe and don't scratch the pipe with the screwdriver.
  4. The engine drain plug is on the side of the engine block approximately above the dip stick. It's similar to the sump (crank case) drain plug.
  5. To do the complete flushing job, you're supposed "reverse flush" the system, with the engine running, by removing the top hose and directing a stream of tapwater into it towards the thermostat housing, so it goes through the engine and comes out of the radiator at the top. Continue this flush until the water comes out clean.
  6. Refill, as per the manual, with antifreeze or anticorrosion agent and water. Run the engine for 5 minutes at 1000 rpm with the heater/aircon on defrost. Stop, allow to cool.
  7. Remove the expansion tank cap, then the header tank cap, and top-up (the 5 minutes allows the pump to suck air from the heater matrix, and it collects in the header tank). Close off, and you're done.
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