This is pretty much how I would do it, although I use deionised water as the mains supply here is very high in calcium (hard):



If you feel the need to properly flush the radiator you really have to remove it and 'back flush' putting water through from the bottom hose to top (the reverse direction the coolant normally flows). Just running the motor with water in it as in the video will not do much for the radiator as the thermostat will be closed and it will not circulate. You can pour water in from the top (like he does) which will flush some of old coolant, but it won't shift any debris that might be in there unless you go in the reverse direction.

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