Draining the radiator gives 3L

[wortus]

Try disconnecting the heater hoses from the engine, with the heater tap in the open position flush out the heater with a hose, once it is clean try and blow out as much water as possible.
I have found that along with draining the block and radiator as far as it will go by removing the hoses results in about 6L or so left in the system. Assuming you have flushed the rest of the system and it's basically clean water you can then reassemble and add the 6L concentrate. You may have a small amount left over in which case just put it in the overflow bottle (which you have previously removed and cleaned and emptied before refitting).
It will eventually all mix but if your worried after a day or so remove some coolant mix from the engine/radiator to a clean container, fill that back up with the contents of the overflow bottle then put the mix you took out of the block into the overflow bottle.
There is absolutely no use in adding an already diluted 50/50 mix to a flushed system that still has around 6L of clean water in it.
I have also been looking after the cooling system on my 2 commodores for a combined 20 years and have always just used clean tap water, unless your tap water has hardness issues for example it is good enough. The coolant/inhibitor will prevent corrosion. I use the Nulon green long life coolant and you do not need Holden pellets in this coolant.
To bleed the system I use a plastic bottle with the bottom cut of and the top wrapped in tape to seal in the top of the radiator. Fill with coolant mix and it will force all the air out of the bleed screw. Any coolant mix left in the drink bottle just lift the bottle up slightly to clear the overflow hose and let it drain to the overflow bottle before you remove it.

 

[Member 1]

Thanks wortus

with the heater tap in the open position

That can be accomplished by having the heater on max?
then put the water hose nozzle inside one of the removed heater hoses opening (disconnected from the engine) and flush with tap water. The pressure has to be small otherwise it will damage the heater core, right? flushing and reverse flushing?

once it is clean try and blow out as much water as possible.

once it's clean, what do you mean by 'blow out' as much water as possible?

I use the Nulon green long life coolant

yes, that's what I want to use...when I get the system as clean as possible.

 

[Member 1]

While motor still running open bleed nipple on thermostat until all air escapes then tighten it . Let motor run for further 5 minutes and repeat .

good tip, thanks

 

[Member 1]

Alright, can't flush the heater core with the water hose. I used long nose pliers to open the spring clamp (the firewall). I can open the spring but getting it to get larger than the hose diameter is a challenge. I think because the hose is old and has swollen. It's not bulged but slightly larger. I will buy Gates coolant kit (heater and radiator hoses). I might as well change the tap. I am thinking about cutting the heater hose (close to the firewall), slide the spring clamp and get it out. Then cut the small piece of the hose connected to the snout. Does that sound right?
Should I use the utility knife to cut the hoses?

 

[greenacc]

You can cut old hoses with whatever, just don't cut yourself.
There was a thread recently about changing the heater tap, forget which model commodore it was but heater taps are all the same.

 

[Member 1]

There was a thread recently about changing the heater tap, forget which model commodore it was but heater taps are all the same.

Thanks
I will search for this thread. I can't find it now, but in the past I found a thread when someone cut the hoses - he included pics of the hoses after they were cut. Of course, because I need this, I cannot find it any more
I need to assemble the tap (heater valve) with connecting hoses outside first and then start installing it from the firewall and then the clamps with the engine, right?

 

[greenacc]

Yeah that's what it said. Disconnect each hose from the engine and firewall then pull out the heater tap with all the hoses still attached to it kind of looking like a spider or grasshopper lol. Then assemble new tap and hoses on the bench to match your old setup before installing it.

 

[wortus]

When I flush my heater core out I just do it by removing the hoses at the engine because it is easy to damage the heater core if your not careful removing the hoses and as my hoses there are fine I don't want to have to cut them.
If you give the heater core pipes too much of a twist you may cause a leak in the core and to fix that it is a big job removing the dash, console and HVAC unit.
If you flush the heater core as I do you need the heater tap to be open (control in max hot position) and may need the engine on so you have vacuum. I then just blow on one hose but you could use gentle air pressure if you have a compressor.
I also think the spring loaded hose clamps on the heater core and heater tap are best because they can't be over tightened. My Commodore still has all of it's original hose clamps and the only hoses that have been replaced are the two radiator hoses and the 2 heater hoses from the engine back to the heater tap, the other two hoses from the tap back to he core are not swollen and are fine so I will leave them.
Don't forget to remove your overflow bottle from the car and give it a good hose out, they are fairly easy to get out just 3 bolts and a few scrivets.

 

[Member 1]

If you give the heater core pipes too much of a twist you may cause a leak in the core and to fix that it is a big job removing the dash, console and HVAC unit.

Thanks

Considering that the heater hoses are old, I think I should get the dealer or a mobile mechanic to change them. I don't want to damage the heater core.
I will have a crack at changing the radiator hoses, they should be easy (the connection I may have a problem with is the lower radiator hose where it connects with the engine - if the hose is stuck with engine, I may not be able to loosen it up easily considering its tight position).
Maybe ask them to flush the heater core. Give them the car with the deminerialised water (not totally clean, but changed from dark brown to light orangy colour). I will then drain the water from the radiator and use the concentrate. I think they would want to add the concentrate themselves and get paid more.

Don't forget to remove your overflow bottle from the car and give it a good hose out, they are fairly easy to get out just 3 bolts and a few scrivets.

Yes, thanks. I have done that. They have three 10mm bolts and one of these terrible scrivets that I had to break (while removing the screw, I wore it out).

 

[Member 1]

From dark brown to this (taken against the window light, not subject to sunlight)
I think if I could flush the heater core it would have been better.