Problem Flushing the Cooling System

[VT Dave]

Okay, i split a radiator hose and obviously had to replace it, and at the same time i wanted to flush out the cooling system. So i got the instructions out of my gregory's manual, and proceded to flush the system but i seem to have run into a problem.

I drained the radiator by disconnecting the lower hose and all that, i didn't bother with the Knock sensors because that is just a pain in the arse due to where i am having to do the work on the car. But anyway, i reconected the lower radiator hose, then disconected the top hose from the outlet pipe on the engine. I then ran the hose down this hose and flushed the radiator until clean water was coming out of the radiator cap. But the problem is that i can't flush the engine block which is no doubt full of the same build up of rusty crap that was in the radiator.

So my question is am i missing something obvious with regards to flushing the engine. I would assume the thermostat is closed which is why i can't run clean water through, so if that is the case how do i get around this?

Anyway, that is kind of a long winded explanation of my problem and i no doubt have left out some detail, but we'll see how we go. Also, in case you can't be bothered checking my ride, i am dealing with a supercharged V6 here.
Thanks guys...

[lout]

you have 2 choices, drop the knock sensors and drain all the coolant or remove the thermostat so you can flush it with the hose, I also removed the coolant overflow bottle (couple of screws underneath) and cleaned all the crap out of it. Also don't forget the coolant tablets from holden when refilling (drop the tablets inside your radiator hose before refitting)

[Tree cutter]

Make sure your heaters are at the hottest position so you can flush the heater core as well

[Not_An_Abba_Fan]

The coolant tablets are just crushed walnut shells to circulate in your cooling system to block up any minute leaks you may have. These are used just in case you haven't cleaned all the crap off something when you put it back together.

[IMCRZY]

Disconnect the top heater hose of the block & flush it that way

[Harvs82]

As others have mentioned, just remove the thermostat, and flush it with the hose whilst the bottom radiator hose is disconnected. Then I just bolt up the bottom hose, tip the whole 5 litre concentrate of coolant into the radiator, and then about another 500mL or so into the coolant reservoir, and then top up with water. That way you end up getting the 50% concentrate 50% water mix that you are meant to run with. Once you see coolant appearing in the thermostat housing, put the thermostat back in, and bolt that all up together, but you will need a new thermostat gasket, about 20cents worth.

[pablo]

The thermostat should have a small hole in it to let the air through so as not to have an air lock. When refilling, do it slowly so as to allow the air to escape through the "bleed" hole. If you want to do a good job and flush the block, take off bottom hose at radiator, when coolant flow stops, put hose back on and fill engine with de-mineralised water and go for a burn, to open thermostat up and circulate the water. Alow to cool, take hose off again, drain water, replace hose and fill with 50/50 concentrate & de-min. water.
I had NO trouble, but then, I have no supercharger.

[Lloyd1986]

Ive decided the knock sensors are too much of a pain in the arse to get out and torque right. If I take off the heater hose and flush water through there and do everything everyone else said (except not take out the thermostat because I have a supercharger and that looks like an equally pain in the arse job to remove) Would that be ok?

[accentstencil]

That should be fine. That's the way I do it.

[Lloyd1986]

Sweet, thanks

[Lloyd1986]

Well just finished flushing it now. Certainly easier flushing the block with the coolant hoses than doing it by taking the damn knock sensors out, took me an hour just to get the wires of the damn thing. No ones hands are that small! Anyway im not sure if I got the 50/50 mixture 100% right because I filled it with too much water and it only took about 3l of coolant so I kept draining bits out and now ive put in 7.5 liters of coolant... Anyway im sure its pretty close. I might flush it again sometime soon and do it properly now I know its easy.

[lout]

I premix my coolant before pouring in to engine as I always ended up too thin or thick on coolant. and was never able to calculate it exactly adding one at a time. I spoke to a friend at holden and he told me the coolant tabs are to protect the water pump seal.
Andrew

[Lloyd1986]

Well next time when I have finished flushing the block (I flushed it well with a hose first and then with demin water) I will put a liter of coolant in there before I do up the bottom radiator hose, then pour the other 5 liters of coolant into the rad, and the rest with water. Then I can be pretty confident with my ratio id imagine.

I like the idea of premixing but the problem is there is always a significant amount of water left in the block after flushing it, so if you pre-mix 50:50 it will end up too thin in the car.