Folks is there a coolant bleed valve on the 6G74? If not, what's the best way to bleed the cooling system?

Did a coolant flush yesterday and I think there's some air in the system afterwards.

No bleed valve.
Fill radiator engine off, will gurgle and drop down, keep filling.
When it appears to be full - radiator cap on, run briefly.
Radiator cap off, top up.
Fill overflow tank to above full.
Run engine to full operating temp, then let cool down.
Check overflow tank. It will be empty. Fill it, keep an eye on its level over the next few days.

There are bolts on the block that are there to release the coolant from the block. Check the service manual as there's multiple bolts and only one of them are meant to be to release coolant.
These bolts are incredibly hard to remove though - well at least in my experiences - I ended up just flushing my system about 3 times instead of trying to remove those bolts because I just about every method possible (WD40, freezespray, air ratchet, even welding a spanner to it).

You can release air by removing the radiator cap when starting the car cold and filling up the reservoir/radiator as the level drops.
Remove cap, start car, turn heaters on full blast, and wait for the level of coolant in the radiator to drop significantly. When it does, then thermostat has opened.
Fill up the overflow bottle with coolant and tighten radiator cap.
Then rev the engine a bit to around 4000rpm for a little bit and drop to idle. Do this a few times. Hopefully you will have hot air coming from the vents during idle when you do the air is gone.
Then fill the reservoir bottle up again and she should be right to go.

*sigh* No need to turn heater on, it has constant coolant flow through it at all times.

These bolts are incredibly hard to remove though - well at least in my experiences - I ended up just flushing my system about 3 times instead of trying to remove those bolts because I just about every method possible (WD40, freezespray, air ratchet, even welding a spanner to it).

I completely agree... Removing these was a nightmare! I don't think those bolts could withstand more than a few removals at that level of tension.

even welding a spanner to it

LOL! Now that's dedication.

There are bolts on the block that are there to release the coolant from the block. Check the service manual as there's multiple bolts and only one of them are meant to be to release coolant.
These bolts are incredibly hard to remove though - well at least in my experiences - I ended up just flushing my system about 3 times instead of trying to remove those bolts because I just about every method possible (WD40, freezespray, air ratchet, even welding a spanner to it).

You can release air by removing the radiator cap when starting the car cold and filling up the reservoir/radiator as the level drops.
Remove cap, start car, turn heaters on full blast, and wait for the level of coolant in the radiator to drop significantly. When it does, then thermostat has opened.
Fill up the overflow bottle with coolant and tighten radiator cap.
Then rev the engine a bit to around 4000rpm for a little bit and drop to idle. Do this a few times. Hopefully you will have hot air coming from the vents during idle when you do the air is gone.
Then fill the reservoir bottle up again and she should be right to go.

Why would you turn the heater on full blast, the heater flows regardless of where the temp is set as there is no coolant tap for the heater

If you want to remove the air from the system after a drain and refill or flush, DONT rev the car, leave at idle until the fans come on, if you dont have a filling funnel set up, once warmed up turn off hte car, let it sit for a while and then top up the radiator, put on the cap and you should be fine. Pays to check it next time the engine has cooled

not doubting your methods Mal as you know more on the magna then 99% of people here or not, but my method which hasnt failed me yet is i take the small hose off the throttlebody which is the highest water hose in the engine bay.... run the car while filling and heater on untill i have constant flow out of the small hose then re attach the small hose to throttle body.
works for me so thats what i do. :)

There's plenty of methods around to flush out the coolant. Pretty much any mechanic I've spoken to has always recommending also running the heaters for good measure.

Relatively simple to get the air out of the system as it generally collects up at the top of the radiator. Revving the engine I'm told allows for the fluid to circulate faster through.

If you've got a spare driveshaft lying around you can use the CV boot as a filling funnel lol

I don't have a filling funnel (or a spare CV boot :P) so will try the radiator cap off method. Changing the coolant was the first "under car" work I've done, it was a good learning experience :D

Thanks all for your help!!

There are bolts on the block that are there to release the coolant from the block. These bolts are incredibly hard to remove though - well at least in my experiences - I ended up just flushing my system about 3 times instead of trying to remove those bolts

I never remove these bolts, even during an engine rebuild. They are probably corroded in, may break off trying to pull them out or damage the block, and may leak once put back in.
Multiple fill and drain until the coolant colour is gone works for me. I use a concentrated coolant which is ok to use with tap water anyway.

The reason why some people turn the heater on would be because the Haynes manual states that, that is the correct way to do it, not everyone knows that the coolant is constantly flowing regardless of whether the switch is flicked or not, so I would call it a good measure unless you know better, hell I only assumed until I had to remove the heater core then I actually noticed how it all worked.

Agreed those bolts are pricks, I have a motor that has never been run before and those bolts still have the sealant (the prevent corrosion) on it from factory still and those bolts are major pains in the backside to remove.

I personally fill up the radiator until it is full, idle the car until the thermostat opens, give the top radiator hose a few good squeezes, to remove any excess air, top it up again, once it won't take anymore I put the cap back on, take the car for a spin, go home check level, done. Its never failed for me before.

The idea of the block drain plugs is to remove any sediment/rust that has settled there. It would be too heavy to flush out. The plugs shouldn't be too hard to come out. Then put them back with loctite 577 on the threads to seal it and make it easier to come out next time.