You can get more than 3.5 Litres out if you open up a few more pipes start at the thermostat. Flushing is good to remove all the old coolant, use a hose pipe and force tap water through. Flushing is recommended by the coolant manufacturers and it makes sense to remove all the old coolant out before adding the new.soewhaty wrote:Thank you! It's all good then. Only one last problem? Is it NOT possible to flush the whole system completely and remove all 7 liters from the old coolant and put in new 7 liters? I'm asking cos the mechanic said that at most he could empty 3.5 liters. The rest 3.5l he just left in the system cos he could not remove them. Said something is left in the radiators, something left sth else, and so on and so forth. I guess he just left gravity do it's thing. Then he just topped up with 3.5l of the above-mentioned new coolant ready mix.
All that didn't make too much sense to me, though. Isn't Arfur Dent's post #4 from here - citroen-c3-tips/citroen-c3-coolant-t40.html supposed to show exactly that all 7 liters CAN and prolly should be removed and then fresh, new 7l have to be put in?
7 litres for some petrol engines, 6 for other petrols and the diesels are a bit less than 6.