8V A3 Coolant Bottle Revisions

[Blade9759]

2018 A3 2.0T

I want to replace coolant bottle. I ordered the latest revision (5Q0121407M), and it does not have the silica gel bag in it nor does it have the G13 coolant sign. The car came with 5Q0121407T, and does have the silica gel bag and the G13 coolant sign. (I cannot order 5Q0121407T because the M revision replaced it) I'd like to have a bottle with the silica gel, but can I use the latest revision with the vehicle? If so do I need to revert to G12? I called my dealer's parts and according to them, I should have no problem. I just wanted your guy's thoughts. Thanks.

[Blade9759]

Ive been running G13 no silica bag since 2015...Zero issues.

How often do you change coolant?

[kevin#34]

Audi coolant is "lifetime" fill. Doesn't need to be changed.

only the G13 is given for "lifetime" (and providing the silica bag is inside the tank), not the G12 or lower.

[kevin#34]

Here's the issue if your looking to "change" the coolant...
There's no drain for the engine block...ya have to turn the engine upside down to drain the block.
Also on the S3...the two side radiators have to be turned upside down to drain them.

to completely drain (and to refill as well) the coolant, a vacuum pump must be used (VAS 6096)

[XMetal]

Funny...my 2015 Audi S3 with G13 never came from the factory with a silica bag in the tank...neither did my 2018 S3

TTRS is a 5 cylinder thats a different motor from the S3 4 cylinder

That is really odd. My 2018 S3 does have a silica bag in the tank. There doesn't appear to be a rhyme or reason for fitting different expansion tanks to these cars?

[XMetal]

Thanks for posting that - I'll need to change out my expansion tank one of these days to get rid of that silica bag!

[XMetal]

The level sensor in mine corroded and gave me a light on the dash...so I ordered by Audi part number and Audi told me it was

NLA as of 06/09/20:

Please order 5Q0-121-407-M as the direct replacement

Then what arrived was a different part number!

Its installed...seems to work fine...no silica bag.

So when you ordered 5Q0-121-407-M, what part actually showed up? Where did you ordered it from?

I went ahead and ordered 5Q0-121-407-M from FCP Euro...so let's see what actually show up. However, the part checker from FCP indicates that 5Q0-121-407-M "May Not Fit" my S3? So, we shall find out about that as well.

[Blade9759]

Thanks for the helpful information. I ended up ordering 5Q0-121-407-M from FCP Euro and installed it. FCP said that it might not fit, but shopDAP said it did. So far so good, and install was super easy.

[MNAudi101]

I just did this, went to VW picked up a new tank, no bag, fresh G13 to refill. have about 10k miles on it no issues. I feel better not having that bag in there thats for sure.

[kevin#34]

Audi gives the G13 for "lifetime" only if silica bag is present. If the silica is removed, better to replace G13 with G12 that is glycol based (and must be replaced periodically)

[kevin#34]

G13 is glycerin-based (less harmful for the environment, that's why mnufactures abandoned glycol-based coolants), glycerin alone is not capable to protect aluminium parts (radiators, engine head etc.) from corrosion, that's why they add a bag containing silicates (check any vehicle G13 equipped, and you will see "mit silica" printed on the coolant tank).
The fact that you can't find any statement from Audi regarding cooling loquid replacement on TT models is exactly for this reason: G13 with silica bag is considered lifetime (does not need to be changed periodically, unlike older glycol-based coolants).

Regarding the coolant draining process on EA 855 engine, check Elsawin @ DRAINING AND FILLING COOLING SYSTEM in 5-cylinder direct injection (2.5 ltr. 4-valve TFSI); Rep. gr. 19: cooling system coolant; Draining and filling coolant system

[kevin#34]

in post #23 you referred several times to TT-RS, that's why I mentioned TT-RS engine, however the same, identical draining procedure is described for EA 888 engine...
regarding Elsawin, it's where I took the info I posted....

[kevin#34]

the fact that you can't drain 100% of the coolant it's obvious, as for engine, gearbox or transmission oil... unless you take the engine apart...
anyway nothing stops you from flushing the system several time with distilled water (good also for cleaning) before a final refill with the proper coolant...

this said, EA 888 and EA 855 engines share exactly the same coolant draining procedure, if you don't trust me, compare the 2 procedures in Elsawin or via Erwin (as I have done), and you will understand...

[kevin#34]

if you have both EA 888 and 855 service manuals you can easily see that the only difference between the 2 engines when draining the coolant is the hose(s) that must be detached (due to the cooling pipes passing from the gearbox on the EA 855), while for the refilling exactely the same procedure and tools (VAS 6096 vacuum pump and VAG 1274/8 adaptor) is prescribed; for the bleeding, again same procedure: 2 minutes @1500RPM, with air conditioning system in OFF, LED in AC button not lit, and heating at HI, with the lowest possible blower speed (= 0).

...and it's not a matter if you work (or not) on your own vehicle that makes you a good mechanic, but following what is recommended by who engineered the vehicle, I think...