Changing the antifreeze/coolant

Facade's instructions seem very fine indeed, except for one issue - achieving a proper ratio mix of coolant and water in the end.

If you do a flush like Facade suggests, I don't see when there comes a point when all the fluid is expelled from the entire coolant system (radiator, expansion tank, engine block, heater core)?

That is an issue if the system will be filled with a pre-mixed coolant in the end of the process. Pre-mixed coolants are usually a 50/50 mix (coolant/water).

Now, if at no point in the flushing procedure the entire cooling system can be fully drained, this means that the system will contain say at least 2 l of (almost) pure water before the final new coolant fill.
Now, if you fill in say 4 liters of a 50/50 pre-mixed coolant , that coolant will mix with say 2 liters of water which is already in the engine block or in the heater. This will finally give about only 25% (2 l) of coolant in the entire 6 litre mix. This severely raises the freezing point of the mix, and decreases its corrosion protection capacity.

So, how to resolve this issue when using a pre-mixed coolant to fill the system? I would certainly like to drain almost everything from the entire system before doing a final new coolant fill. How to achieve this? And how to avoid or resolve possible air pockets in the heater core, engine block or somewhere else?


P.S.:
Someone would probably comment "well just use concentrated coolant and control your own mix". I would gladly, but almost all Japanese engines require coolant chemistries which are specific to them and quite contradictory to most European coolants, and having anything Japanese in my country is like having a space ship. It can be quite an endeavor to find ordinary parts for Japanese cars, let alone dedicated coolants. The only Japanese-suitable coolants (non-silicated, phosphated OAT coolant types) which I can find here are already pre-mixed, no concentrates.

Come on guys..

This isn't exactly rocket science. Sometimes some of these fairly easy DIY task gets way overcomplicated due to stupidely long instructions and what not keeping the owner from doing any thinking for themselves.

Drainging the radiator also drains a good deal of coolant from the engine. At least that's what the amount of coolant in the bucket tells me.

Well I drained the radiator and the expansion tank and only about 3.5 l of fluid came out. According to the specifications, cooling system's capacity is 6 liters.

Is there any accessible drain point in the engine block and/or heater core which can be opened to let the cooling fluid out?

Just done my 2009 VVT with aircon as per the manual.
Drained via the radiator tap. Filled and flushed several times until the fluid ran clear. Filled with Halfords Red OAT antifreeze.
Approx 5 ltrs came out each time, 5 ltrs went back in. I measured each time so I was 100% sure I had no trapped air. I allowed for the approx 1ltr left in the system ( now clean due to flush/engine run) when I mixed my antifreeze. I used the concentrate and deionized water from Halfords, so I should have a near perfect 50/50 mix.
Very simple.

As above facades guide is pretty much spot on. Personally I err on the side of a 60-75% mix after a full flush (I ran 5 or 6 full runs of water as my system was properly scummy). Erring for more coolant simplifies the issues bosanek outlines. Coolant mix doesn't have to be an exact science, as long as there is enough water to make it flow well and enough coolant to stop it rusting/freezing.

All I would add is, be careful with the wee drain plug. I would advise unscrewing from the top rather than underneath, and stop unscrewing when it begins to dribble, make sure your basin is as far back from the dribble as possible before unscrewing the rest of the way. The way the Jimnies drain plug is designed when you pop it off it pisses coolant EVERYWHERE, with some force. Not fun when it's at 90C and your face is under the car.

If you can only get pre-mixed coolant, and you know it will mix with what is in there, just drain what you can, and top up with new, run it a few days and do it again, wastes some of the new coolant, but will get nearer what you want.

tbh, anti-freeze lasts pretty much forever, it is the anti-corrosion additives that get used up, so renewing 75% of the antifreeze should be fine.
(50% the first time, then 50% the second time, but half of what was left will be old, so 75% overall- and you will need 25% extra to waste)


When I get around to doing the woeful [strike]Renault[/strike] Nee-San, I will drop what is in the radiator and fill it back up with Prestone, which (apart from using super special Ne-San fluid, not Prestone universal) is how the main agents* do it, leaving 50% of the old coolant there.


*If you find out and query the process, the agent fobs you off with "It is a coolant REFRESH" (according to the boys in the Nee-San club)
Their idea of a flush is exactly as the Jimny, keep adding fresh water, run it and drain, and then they add concentrate and do the final top up with water to get to 50%.