How To Flush A V6 Cooling System

[bhopper]

what temperature are thermo fans suppose to turn on a vt commodore

Hi guy just wondering if any of you guy know what temp the thermo fans are suppose to turn on and off ,just wondering if my is running right.

cheers bhopper

 

[Nuggetzz]

Hi bhopper

The manual states:
a) If aircon is off, fans will come on low when coolant reaches 104 Deg C. It doesnt state when they switch to high speed.

b) Fans are on low speed any time the airconditioning is on. They switch to high speed in an overtemp condition, presumably 104 Degrees C.

c) If the engine is switched OFF, and coolant temp is over 117 DegC, the fans will run on for 4 minutes.

 

[wortus]

If it's VN series 2 up to VY best way to fill and bleed the system after flushing as described is to put all the hoses back on and then get a plastic water bottle like a Gatorade bottle with the larger cap and cut the bum off it and wrap the end where the cap was with electrical tape so it seals into the radiator where the cap goes without damaging the radiator ie not too much tape, next remove the overflow hose from the overflow bottle and clip it so the end is above the top of the bottle as it will not be sealed off by the bottle neck and what you add will just fill up the overflow as well and you do that last.
Fill the system with the concentrated coolant, you will need 6 litres for an ecotech, 5 for a Buick 3.8L, once all that is in fill with water, making sure the heater tap is on so it fills the heater core. Don't pre mix the coolant as you won't get all the water out of the block unless you drain it. I measured what came out and it wasn't 12 litres. Undo the bleed screw and wait until coolant comes out. Once the radiator is full and no more air is coming out of the bleed screw tighten the bleed screw lightly it all that is needed and put the overflow tube back into the bottle and fill it through the plastic bottle with a 50/50 pre mix to a bit above where it needs to be.
Take it for a drive allowing it to warm up and when it is cool recheck overflow level and you can recheck the bleed screw for any trapped air if your worried using the bottlle in the radiator cap hole method. The bottle method gives a head of coolant over the bleed valve to push out any air.
Pellets are only needed with Holden coolant of if small leaks develop after a change. I use the Nulon long life coolant and it states on their web site just this about the pellets. Did my VY a month or so ago and no problems so far. Not sure about VZ's as I have no experience with those engines.

 

[wortus]

How loing since that VT withthe stuffed water pump had a coolant change?

 

[VYMAD]

There is some good advice and knowledge in this how-to. I have always used tap water in my cars' cooling systems, mixed of course with the correct amount of recomended coolant. I admit that most of these have been done with rainwater tank water, now I have no choice but to use town water. I am wondering, though, that if I were to use de-mineralized water, would there not be quite a bit of tap water left in the system due to the flushing process anyway?

 

[Nuggetzz]

How loing since that VT with the stuffed water pump had a coolant change?

It was serviced by Holden, every single log book service, as per Holden recommendations. I presume they do the coolant every time they do the oil.
Maybe the pump was a crappy aftermarket one, the rest of the body is not corroded away, its just the rotor. Who knows.

 

[Nuggetzz]

would there not be quite a bit of tap water left in the system due to the flushing process anyway?

If you remove the block plugs as per the manual there should be no remaining water at all.

If not, you could get another one or two demineralized water bottles so after flushing with tap water you can keep flushing a couple of times with demineralized water.

 

[wortus]

Log book service is meant to check the conductivity of the coolant and replace it every 27 to 30 months regardless. Too much conductivity + corrosion. It seems they have not done that and you should go back and tell them.

 

[green machine s]

If you guys flush the systems out in the way that you have described without removing the knock sensors at the bottom of the engine to drain coolant at its lowest point, wont you end up with a block full of water that might be clean, but will dilute the glycol level in the coolant, because you are actually adding more fresh water into the system than needs to be there?

 

[alex2_s]

If you guys flush the systems out in the way that you have described without removing the knock sensors at the bottom of the engine to drain coolant at its lowest point, wont you end up with a block full of water that might be clean, but will dilute the glycol level in the coolant, because you are actually adding more fresh water into the system than needs to be there?

correct, about 3L of water remains out of a total 12 L system capacity, so after flusihing with water, 3L of water and 6L of coolant needs to be added (to compensate) to create a 50/50 total mix, you can't just add 50/50 coolant mix once the system is flushed/drained (without removing the knock sensors)