How To Flush A V6 Cooling System

[Nuggetzz]

My VT V6 was getting over-hot when sitting at the lights with aircon on, and if you revved the engine in neutral the temp would go back down really fast. I was wondering if the circulation was piss poor, so I thought I would do the pump at the same time as flushing the radiator.

So anyway I pulled the whole thing apart got the water pump out and noticed a slight corrosion problem. I wonder if you can spot it in the picture below:

 

[Sean880]

Very Good thread with helpful pictures. Just a couple of things:

1. Definitely use the bleeder screw, with everything back in place and tight, as the means to rid the system of air like most recommend here. Bleed a few times after running the car on different occasions to ensure you have all the air out. (Clearly you cannot fully bleed air from the system by running the engine with the top radiator hose disconnected as air is only trapped in that hose once it is re-connected and you can potentially create an air lock).

2. Don't use any old coolant. Use the one specifically designed for the V6 Commodore such as is shown in the picture on the "how to do" post. The one pictured is the Castrol 350 concentrate which meets the GM spec for the VY V6 and various other V6 models. You can get this at supercheap auto and plenty of other shops. About $44 for 5 litres of the concentrate.
SEE:--
Castrol Australia - Cooling System Products

3. Don't just pour the castrol 350 concentrate from the 5 ltr container into your radiator as is shown in the picture in the "how to do" post. This will result in a poor mix. The mix must be 50% water and 50% coolant concentrate. Mix up the coolant with demineralised water at 50/50 proportions in another clean container and add the mix. Then you will not end up with too much or too little of the coolant in the engine and cooling system. Castrol considers that too much coolant concentrate (like a 60% ratio) will result in over heating. Too little will not protect the engine and cooling system. Bear in mind that your cooling system takes more than 10 litres of fluid ( when emptied fully)so you will need more than 5 litres of the coolant concentrate. Refer to your handbook for the capacity of your car's system.

4. If you have a VY - GM recommends you add the 3 pellets to the cooling system. If you have another model check the handbook. Use the 3 brown colored pellets (GM part 92140053) if so recommended for your vehicle (about $12 currently). Crush these in the plastic bag into a powder and add to the coolant mix when filling the system. Apart from other functions, this product will seal any tiny leaks in the system. GM designed the engine and the cooling system so don't think you know better. One friend at a GM dealer( parts dept) told me that many service centres of other manufacturers buy these radiator pellets from GM dealers because they work well and they don't have anything like them for their cars available from their manufacturer.

 

[sweefu]

hey mate how much did it cost all up for the coolant, gaskets, cap etc? All the parts?
Cheers!

 

[Sean880]

Castrol 350 Coolant concentrate (commodore V6 engines)- 5 litre - $43.70 at supercheap auto (or about $47 at your holden dealer for a like correct spec concentrate product for the V6 engines).
At 50/50 mix you will probably need more than 5 litres of coolant concentrate if you properly drain your system. You can also buy smaller containers of the correct coolant concentrate but do NOT mix brands just to save a couple of dollars.
Don't dilute the mix with added water below 50/50 ratio just to save a few bucks. Do it properly and you won't need to do it again for 2 years and your engine and cooling system will be optimally protected.

3 Pellets - add to the mix - $12-13 at your Holden dealer
Use these if recommended for your model of commodore(such as for VY) otherwise you might find you have a tiny pinhole leak somewhere that the pellet material would have nicely sealed.

Distilled /demineralized water - 5 litre container - approx $6 at your supermarket. You may need a little more than 5 litres. (Also comes in smaller 2 litre containers - at $4.00 approx). Don't use tap water in your cooling system when for a small $ amount you can use clean distilled/demineralized water. (It's surprising how much rubbish is produced from using tap water in your domestic steam iron. That's why they tell you to only use distilled water).

Thermo housing gasket - have not priced and this is only necessary if you remove the housing and thermostat as part of the flush procedure. Check pricing with your local dealer.

If you have an older/high km car you should desirably replace the thermo with a new one if you are going to remove the housing and thermo for the flush. It makes no sense to open it all up and leave the old thermostat there unless you know it was very recently replaced. Check pricing with your local Holden dealer.

Radiator cap - while you are at it check condition and replace the cap if necessary. If in doubt - replace it.

 

[Kernal]

This might be a stupid question. My mate and I were arguing where to fill up when topping up the coolant level. I say fill it from the radiator filler thing (dont know exactly what its called lol) and my mate says to fill it into the overflow bottle. So which one is it?

 

[Nuggetzz]

This might be a stupid question. My mate and I were arguing where to fill up when topping up the coolant level. I say fill it from the radiator filler thing (dont know exactly what its called lol) and my mate says to fill it into the overflow bottle. So which one is it?

Its a good idea to fill the system through the radiator filler first when the engine is cold, then fill the coolant bottle to the level specified. Filling through the bottle does not directly add coolant into the system. See later.

If you are filling the system with coolant after flushing or repairs, take off the radiator cap and fill there. When it is full, put the cap on and fill up the overflow bottle to the level indicated in the manual.

If the radiator is already full and you are just topping up, fill using the overflow bottle.

What happens is, during operation the engine pressurizes the cooling system and the coolant gets hot and expands. If the pressure / heat gets too high, the radiator cap will allow some pressurized coolant to flow out into the overflow tank so the pressure doesnt rupture anything.

Later when the car is stopped and it all cools down the coolant will shrink, and there will be a partial vacuum in the cooling system that sucks coolant back out of the overflow bottle back into the radiator to replenish the system.

Note: dont take off the radiator cap when the engine is hot, you can scald the crap out of yourself. Also putting cold coolant directly into the system when the engine is hot can crack the block or head, same thing that happens when you put a frozen glass bottle half in and half out of really hot water. The glass is a tiny bit shrunken when it is cold and when you heat part of it, the hot half expands, the glass cant hack the strain and shatters. Same with your engine block, lets say you have a slow coolant leak and halfway up the mountain your engine overheats, no coolant! So you stop and get that 5litre bottle of tap water out of the boot and pour it in. As it circulates, half the engine is red hot from overheating and the other half is nicely cooled from your (relatively) cold water. CRRRRACKKK. Bad. Dont do it.

Did I get off track there a bit?

 

[Nuggetzz]

hey mate how much did it cost all up for the coolant, gaskets, cap etc? All the parts?
Cheers!

When I did my water pump and flushed the radiator, costs were:

- $37 for 5L of concentrate (Nulon). Make sure it complies with the standard associated with the vehicle. Mine (VT '98 V6) requires coolant adhering to standard HN2043, just look on the bottle for ones that meet this standard.

- $75 for Water Pump including 2 gaskets (only needed one)

- $6 for 5L of demineralized water for diluting concentrate

- $14 for a new thermostat

- $4 for a thermostat housing gasket

- $7 for gasket goo (required for sealing water pump and thermostat housing gaskets)

- $0 for a few hours of my time

Didnt get a cap, mine seemed OK

 

[sweefu]

Cheers for that mate. i'm giving mine a shot on the weekend but not doing water pump.
i'll still do thermostat etc
Thanks for the great guide.

 

[Kernal]

Its a good idea to fill the system through the radiator filler first when the engine is cold, then fill the coolant bottle to the level specified. Filling through the bottle does not directly add coolant into the system. See later.

If you are filling the system with coolant after flushing or repairs, take off the radiator cap and fill there. When it is full, put the cap on and fill up the overflow bottle to the level indicated in the manual.

If the radiator is already full and you are just topping up, fill using the overflow bottle.

What happens is, during operation the engine pressurizes the cooling system and the coolant gets hot and expands. If the pressure / heat gets too high, the radiator cap will allow some pressurized coolant to flow out into the overflow tank so the pressure doesnt rupture anything.

Later when the car is stopped and it all cools down the coolant will shrink, and there will be a partial vacuum in the cooling system that sucks coolant back out of the overflow bottle back into the radiator to replenish the system.

Note: dont take off the radiator cap when the engine is hot, you can scald the crap out of yourself. Also putting cold coolant directly into the system when the engine is hot can crack the block or head, same thing that happens when you put a frozen glass bottle half in and half out of really hot water. The glass is a tiny bit shrunken when it is cold and when you heat part of it, the hot half expands, the glass cant hack the strain and shatters. Same with your engine block, lets say you have a slow coolant leak and halfway up the mountain your engine overheats, no coolant! So you stop and get that 5litre bottle of tap water out of the boot and pour it in. As it circulates, half the engine is red hot from overheating and the other half is nicely cooled from your (relatively) cold water. CRRRRACKKK. Bad. Dont do it.

Did I get off track there a bit?

Nah mate, that was really helpful info

thanks buddy

 

[riki7454]

You guys should probably try and read an actual Holden service manual and not listen to what little timmy from next door's cousin told you. The bleeder screw is meant to be used only when filling with the Holden special tool No. AU425. If it is not available then Holden recommends the disconnecting the top radiator method, as this will take any air voids from inside the engine, air will purge from the radiator side threw the overflow tube when the thermostat opens. If you must use timmy's cousins advice then help yourself by bleeding the system while somehow filling the radiator threw the cap while it is firmly in place, because this is the only other way to do it properly(This is what the special tool achieves). So summing up air in engine bad but in radiator not so bad.