Coolant flush

[SM18]

Removed the silicate bag from my header tank, as it wasn’t looking it great condition. New header tanks don’t have them in, and you can’t seem to replace the silicate bag either. My local Audi confirmed this. He said my Audi requires g12 mixed with distilled water, or ready mixed.

I’m wondering if I need to bother flushing system, haven’t ever before with motors with no isuues. If I get around to it, is there a drain tap, do you have to fill Audis from the bottom . Any help would be great

 

[Crash0090]

I wouldn't bother getting a new silica bag, the purpose of them is to expand the life of the coolant i believe, but half the time they end up bursting and blocking the heater matrix. This very thing happened to me.

As far as i'm aware nothing in Audi servicing says about flushing the coolant system. unless the coolant becomes contaminated i don't see why you would have a need to flush it.

Drain plug is on the back of the radiator on the drivers side if i remember correctly down the bottom, so you'll need to get under the car. couldn't undo mine so just pulled the hose off the rad.

you re-fill from the header tank.

 

[Matt Titanium]

I wouldn't bother getting a new silica bag, the purpose of them is to expand the life of the coolant i believe, but half the time they end up bursting and blocking the heater matrix. This very thing happened to me.

As far as i'm aware nothing in Audi servicing says about flushing the coolant system. unless the coolant becomes contaminated i don't see why you would have a need to flush it.

Drain plug is on the back of the radiator on the drivers side if i remember correctly down the bottom, so you'll need to get under the car. couldn't undo mine so just pulled the hose off the rad.

you re-fill from the header tank.

Does the coolant have a five year life? At nearly six years old, I think it's time to get that silica bag out of mine and replace the coolant. Are there any bleed screws or does all the air vent automatically?
Edit:
Thinking about it, the water pump was replaced under warranty at three years old so assume new coolant would go in at the same time.

 

[SM18]

You can’t buy a new bag, nor does it come with a new tank. When it’s due it’s annual service, if the drain plug undoes okay, I’ll probably change it. But then again, maybe not. I’ve never changed it on the various golfs and A3 I’ve owned. Just worth knowing where the drain is. Some other vehicles I’ve had, recommend filling from bottom with a pressured hose

 

[Crash0090]

Does the coolant have a five year life? At nearly six years old, I think it's time to get that silica bag out of mine and replace the coolant. Are there any bleed screws or does all the air vent automatically?
Edit:
Thinking about it, the water pump was replaced under warranty at three years old so assume new coolant would go in at the same time.

There are a number of bleed screws on the cooling system, or you can run the car with the header tank cap off and heating system on full to allow the trapped air to escape. You'll know it's all out when the reserve coolant in the header tank stops bubbling.

if you've had the water pump done then yes, should have had new coolant done at the same time.

 

[Matt Titanium]

There are a number of bleed screws on the cooling system, or you can run the car with the header tank cap off and heating system on full to allow the trapped air to escape. You'll know it's all out when the reserve coolant in the header tank stops bubbling.

if you've had the water pump done then yes, should have had new coolant done at the same time.

Thanks,
I think I'll still fish the silica bag out in case it leaks.

 

[SM18]

Thanks,
I think I'll still fish the silica bag out in case it leaks.

For the sake of two hose clips, and a plug sensor. Remove take before you remove bag. You’ll be in a world of pain if it busts whilst removing it with the tank in situ

 

[Matt Titanium]

For the sake of two hose clips, and a plug sensor. Remove take before you remove bag. You’ll be in a world of pain if it busts whilst removing it with the tank in situ

Wise words there.

 

[Potterswheel]

Removed the silicate bag from my header tank, as it wasn’t looking it great condition. New header tanks don’t have them in, and you can’t seem to replace the silicate bag either. My local Audi confirmed this. He said my Audi requires g12 mixed with distilled water, or ready mixed.

I’m wondering if I need to bother flushing system, haven’t ever before with motors with no isuues. If I get around to it, is there a drain tap, do you have to fill Audis from the bottom . Any help would be great

You don't say what model A3, I replaced my tank and fluid recently at 5 years old and my tank was clearly marked up G13. (you can just make it out top of image to right of handbook symbol)
Because of all the horror stories about the cooling systems on our cars, I carefully removed the tank complete with the silica bag and then after fitting the new tank replaced the fluid by draining small amounts through a hose clip at the bottom of the radiator and topping up repeatedly. I closed everything up after a while and ran the engine until warm and then allowed everything to cool, I then repeated the drain and top up procedure with the remainder of my mixed fluid. Audi part number G A13 A8J M1, not exactly 100% changed - but 100% full at all times.

 

[MattDC]

Mine didn't have a silica bag in it (apparently the TFSI's don't, or so I was told) but my heater matrix was still blocked. Had it replaced and G12 coolant put in. I've since been told it most likely blocked up because previous coolant was mixed with tap water and not distilled water. I was advised to only use either G12 or G13 with distilled water to avoid the sam thing happening again.

 

[SM18]

Mine didn't have a silica bag in it (apparently the TFSI's don't, or so I was told) but my heater matrix was still blocked. Had it replaced and G12 coolant put in. I've since been told it most likely blocked up because previous coolant was mixed with tap water and not distilled water. I was advised to only use either G12 or G13 with distilled water to avoid the sam thing happening again.

Potentially scaled water then. I think you need de ironised. I think there is a difference in the two? I could be wrong

 

[SM18]

You don't say what model A3, I replaced my tank and fluid recently at 5 years old and my tank was clearly marked up G13. (you can just make it out top of image to right of handbook symbol)
Because of all the horror stories about the cooling systems on our cars, I carefully removed the tank complete with the silica bag and then after fitting the new tank replaced the fluid by draining small amounts through a hose clip at the bottom of the radiator and topping up repeatedly. I closed everything up after a while and ran the engine until warm and then allowed everything to cool, I then repeated the drain and top up procedure with the remainder of my mixed fluid. Audi part number G A13 A8J M1, not exactly 100% changed - but 100% full at all times.

View attachment 253555 View attachment 253556

It’s an a3 8v
I use same coolant, never add water just that when topping up