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Hi experienced ones.

I want to do a complete cooling system flush on my 2006 NC, not just a radiator flush. Does any body have any tips as to how I can flush the approx 3 litres in the cooling system held behind the thermostat.

P

If it is anything like an NA/NB, this will drain when you take the plug out of the bottom of the rad? So when you re-fill, you will re-fill the block too, and by some definitions, you have 'flushed' the complete cooling system. What do you want removed that will not be removed this way?

I assume you are using 'coolant', not water in the system. In which case corrosion should be non-existent, and there should be minimal crap in the system, and I would expect that would come out with the old coolant.

You could remove the thermostat, and stick a hose down there, but again, I wonder what you think you are fixing - what is the problem here?

If it is anything like an NA/NB, this will drain when you take the plug out of the bottom of the rad? So when you re-fill, you will re-fill the block too, and by some definitions, you have 'flushed' the complete cooling system. What do you want removed that will not be removed this way?

That has been my experience with cleaning out cooling systems in the distant past, I am just getting back into being a backyard mechanic after a break. Hey when I sed to work on cars a bit there were no ECU's to speak of. The most complex car I worker on had a Bosch K jetronic fuel injection system. My reading on the www re the NC is that only about 4 to 5 litres of the 7.5 litres on the cooling system will drain when simply opening the drain plug on a cold engine. eg http://www.mx5scotland.co.uk/board2/viewtopic.php?t=15598

Was making sure that I was not missing something as I want to make sure that I only have to do this once to minimise the mixing of coolants.

Penguin wrote:only about 4 to 5 litres of the 7.5 litres on the cooling system will drain when simply opening the drain plug

I don't know NC's, but I've had cars like that. Some cars have a drain plug low down on the block.
I would refill with demineralised water & cooling system flush, & run up to full temp. Drain & refill with demin. water & coolant.

It's a time consuming process, but if you remove thermostat & flush with a hose you will be left with 3L of 'tap' water & all it's minerals.

On second thoughts, do the flush run with demineralised water only.

That is what i do. Dump the rad. Fill with water. Run again for a bit. Dump rad again. Refill with your coolent of perference.

Thanks - I will give it a go - may do two runs with distilled water as I think I am on original coolant.

Done my NC coolant about 6 times in the last year. It’s just one drain plug, easy. Takes about 5 litres of coolant.