7A Coolant flush

[cadiddy]

So looking at changing out my radiator and going to do the expansion bottle at the same time. At the moment the cooling system is pretty dirty and I want to clean it up before fitting a nice new expansion bottle.
What's the best way to completely flush the whole system? because isn't the thermostat going to restrict flow if I just poke a hose in top hose and let it run out the bottom?
Cheers
Cadan

[andy10v]

Take out the thermostat, consider replacing.

[cadiddy]

I'll test it and see how it fairs, just want to double check something with whoever might read this, thinking of swapping out the rad due to coolant loss, now I suspect the rad due to seeing pink coolant crystals on the front of the radiator, theres no obvious signs of leaks elsewhere carpets are dry inside the car so don't suspect the matrix, any other known coolant loss issues with the 7A?
Thanks

[macspring]

Might not be leaking, but as you're taking out the rad, replace the small rubber hose from the thermostat hosing to the water rail pipe. # 38 in the diagram.

As it can let go, even on a 7a, if it is still the original.

Also, much easier to do it when the rad is out, regardless of the grief of it letting go when you're driving, and away from the house.

Make sure to fit an oem thermostat, and also check on here for the correct way around, and also the correct orientation for the thermostat. Use a new rubber seal ring also.

[bikerjim]

If there is oil in the system you can flush it through with biological washing liquid. Did a fantastic job on my TDI after the headgasket went.

[cadiddy]

Might not be leaking, but as you're taking out the rad, replace the small rubber hose from the thermostat hosing to the water rail pipe. # 38 in the diagram.

As it can let go, even on a 7a, if it is still the original.

Also, much easier to do it when the rad is out, regardless of the grief of it letting go when you're driving, and away from the house.

Make sure to fit an oem thermostat, and also check on here for the correct way around, and also the correct orientation for the thermostat. Use a new rubber seal ring also.

Thanks for the heads up, I'll report back tomorrow and let you all know what I find (if anything)

[cadiddy]

If there is oil in the system you can flush it through with biological washing liquid. Did a fantastic job on my TDI after the headgasket went.

Thats handy to know as my bro's car had oil in the water when he bought it but after many flushes its just about gone minus the residue.

[Error404]

Oxalic acid is cheap and works really well. Drain coolant, fill with acid dilution, run for a half hour or so then drain - you will be amazed a the **** that comes out.
Flush with clean water mixed with baking soda to neutralise the acid, then flush thoroughly with clean water and refill with coolant

[driftin jo]

This ^^^

[cadiddy]

Well if the above gets it clean enough for Alex it must be good
Would you do it with the thermostat in or out?

[driftin jo]

Do it with it in that way it will warm up quick, without it it would take forever to warm up at this time of year and that is not good for your engine.

[jade]

Oxalic acid is cheap and works really well. Drain coolant, fill with acid dilution, run for a half hour or so then drain - you will be amazed a the **** that comes out.
Flush with clean water mixed with baking soda to neutralise the acid, then flush thoroughly with clean water and refill with coolant

What percentage do you recommend

[cadiddy]

Do it with it in that way it will warm up quick, without it it would take forever to warm up at this time of year and that is not good for your engine.

Right on will do

[Error404]

What percentage do you recommend

Can't remember what I did now, think it was about a cup full of powder, will depend on the strength of the stuff you buy

[Tom_]

Guys, i want to do that on my 7A Coupe aswell, any ideas, if its necessary to use some chemical to flush the system or its enough to only flush the system with water, put the righ ratio of coolant and distilled water? And which parts get off? Only hose of radiator clamp off?