How Do You Flush Coolant?

[reganlives]

Seeing as my car has had a new radiator, I had a look at the rad the other day and I think the garage have refilled the system with the old coolant which has got radweld in it so therefore now looks a bit brownish in colour. This has got me thinking and seeing as its a new rad I'd rather flush the system out so its nice and clean and then fill it up with fresh coolant but I how do u flush the coolant? I remember helping my dad do his years ago by undoing the little tap on the rad itself but does the engine need to be running so the pump is running and then should I run water thru the system as well?

If someone can provide me with step by step instructions it would be most helpful then this thread could be made a sticky as well in order to help others ;)

[rig-pig]

there is 2 ways of doing this you can ether pull the bottom rad hose off ( recommended ) as its quicker and you get rid of more water at once or there is a small drain plug on the bottom left of the rad.

drain out water/coolant and fill with fresh water NO coolant take for a run and drain out water REMEMBER WATER WILL BE HOT and repeat till you get clean water then dump water and fill with coolant/water mix.

or you could back flush with a hose but this will make a mess of your engine bay

[Bazza]

to be fair to the garage it is near impossible to get all the old coolant out

best way is to drain the radiator

then take off the thermostat cover and then the thermostat

beware the coolant will come rushing out

then just stick a hose in the rad and the thermostat hole and let it run until clear

then put it all back together and fill up with new coolant

wouldnt advise running it whilst flushing !

[reganlives]

wheres the thermostat mate? also what u mean wouldnt advise running it? u mean emtying and filling with water then running it or letting it drain and constantly fill with water while the engine is running?

[rig-pig]

if you split it at the thermostat housing you will need to replace the gasket that's why i suggested to empty the coolant and fill with water because when you go for a run the thermostat will open and the fresh water will mix with the old coolant and when you dump it you should get rid of most of the old coolant