Found an interesting read in the Octavia forum:

 

made me change the reservoir in my Superb 2.0 diesel. 
 

Part nr: 5Q0121407M is a perfect fit and does not contain the bag. 

yes very interesting, and a possible concern, just posted a reply to the link you provided.

maybe vag have changed things, my caddy van has 2 cylinders in the tank instead of the teabag

 

 

I’ve one in my TSI unit as well. Disastrous thing if it leaks. It won’t be staying in mine much longer. If you remove the bottle, most of them can be coaxed out intact. 

Hi, I've also posted in this thread about my father's bad experience on his Octy 3.

Since then, I'm hesitating whether I shall remove the same bag or not on my Superb Mk3 (TDI190 engine). I can't really make up my mind about what to do... since I don't face particular problem at this time... 

Edited 26 February, 20215 yr by Bap33

i have a plan swap to new revision 5Q0121407T

 

couple of pictures, old vs new -

-> https://www.drive2.ru/l/553028236443911915/

Sorry, probably being a bit dense here but what's the intended purpose of the silica bag?

Don't worry, I stopped being lazy and googled it :-). Seems it's to add silica over time to the coolant as the G13 comes with the minimum amount. Is supposed to stop galvonic corrosion.

6 hours ago, MartiniB said:

i have a plan swap to new revision 5Q0121407T

The latest version is 5Q0121407M.  Don't understand the VAG lettering but I got mine from TPS last week.

 

I'll be changing mine when I drain the coolant to do with the timing belt.  The one in my car is the double walled version so no easy way to get the bag out. 

2 minutes ago, jeffl said:

Don't worry, I stopped being lazy and googled it :-). Seems it's to add silica over time to the coolant as the G13 comes with the minimum amount. Is supposed to stop galvonic corrosion.

Skoda tried to make the coolant 'for life'.  If you replace the coolant every 5 years when you do the timing belt you don't need to worry.  G13 has since been replaced with G12evo and there's no G13 marking on the new expansion tank.

12 hours ago, 4StringBass said:

The latest version is 5Q0121407M.  Don't understand the VAG lettering but I got mine from TPS last week.

 

I'll be changing mine when I drain the coolant to do with the timing belt.  The one in my car is the double walled version so no easy way to get the bag out. 

That's what I understood also. The M revision is the latest. A tell tale sign was that my dealer had the tank on stock. And they don't have a lot of parts on stock.

 

Fitting was really easy. Emptied the tank with a brake bleeder. And swapped it over. No mess. After refill I checked the reservoir regularly, but no second refill was needed due to air bubbles. 

I have the singled walled version (visible bag) and I’m now planning to remove it.

Are people going for the new tank revision because they currently have the double walled/inaccessible version or because it has cartridges that don’t leak?

Also, if I remove the bag today on a 3.5 year old car (15k miles) will it give 5 years before flush/replace is needed or does the bag silica dissipate faster?

3 hours ago, Alan_P said:

I have the singled walled version (visible bag) and I’m now planning to remove it.

Are people going for the new tank revision because they currently have the double walled/inaccessible version or because it has cartridges that don’t leak?

Also, if I remove the bag today on a 3.5 year old car (15k miles) will it give 5 years before flush/replace is needed or does the bag silica dissipate faster?

 

I installed a new tank because I had the double walled version. 

3 hours ago, Alan_P said:

I have the singled walled version (visible bag) and I’m now planning to remove it.

Are people going for the new tank revision because they currently have the double walled/inaccessible version or because it has cartridges that don’t leak?

Also, if I remove the bag today on a 3.5 year old car (15k miles) will it give 5 years before flush/replace is needed or does the bag silica dissipate faster?

 

if you have the single walled tank then just remove the bag, you only need a new tank if you have a twin walled tank, as bag cant be removed.

 if you remove the bag on a 3 1/2  year old car, the silica stops doing it's job as it's no longer there, but the anti freeze lasts for 5 years without silica, so you should get 5 years the same as new anti freeze, others may think differently though

3 hours ago, Alan_P said:

I have the singled walled version (visible bag) and I’m now planning to remove it.

Are people going for the new tank revision because they currently have the double walled/inaccessible version or because it has cartridges that don’t leak?

Also, if I remove the bag today on a 3.5 year old car (15k miles) will it give 5 years before flush/replace is needed or does the bag silica dissipate faster?

 

you could also remove the bag and had a couple of cartridges, as in the photo above, this should mean the anti freeze wont need change after 5 years.

but remember the timing belt and water pump will probably need done before then, so anti freeze will be drained anyway

So do new models with a revised tank (no bag or cartridges) get an altered service schedule to include a coolant change?

I just looked at mine says silikat on the side.

 

had a look inside and can’t see anything but I can see something similar to that in the caddy photo.

 

I may have the twin walled one but I still couldn’t see it unless it’s at the back.

 

On the twin walled system is the bag always in the same place or could it be different locations?

3 hours ago, Danoid said:

I just looked at mine says silikat on the side.

 

had a look inside and can’t see anything but I can see something similar to that in the caddy photo.

 

I may have the twin walled one but I still couldn’t see it unless it’s at the back.

 

On the twin walled system is the bag always in the same place or could it be different locations?

In the double walled version there is a holder for the bag in between the walls. But my bag freed itself from the holder and ended up near the overflow connection. 

Replaced 5Q0 121 407 G (5 years 95k Km)

to 5Q0 121 407 M

for minimize risk of silicate bag damage

 

inside picture of 5Q0 121 407 T, no bag version, similar as M

 

On 18/08/2020 at 19:33, Bap33 said:

 

Inspired by the thread I did the 'no silikat' mid at the weekend. Wrote the date of removal on the reservoir so I've half a chance id remembering in 5 yrs time😂  

My car has the bag but having felt it with my fingers it appears adhered at one end to the inside of the tank.  Are they easy to remove if they’re adhered? Presumably I need to take the tank off in case the bag splits when I remove it so I don’t contaminate the coolant?

I removed mine quite easily, it is held to the side my two plastic pillars. I bent the one to the front over with a screwdriver and wriggled the bag past it. I could then pull it out carefully with some needle nose pliers.

Hi Pagan-Image,

 

Yes you're right, mine was actually the same as yours.

 

In the end I had to cut open the bag and suck out the content as the silica was preventing the bottom of the bag compressing to pass the reservoir opening.  I didn't want to rupture it by pulling too hard.  I also found having an extra pair of hands very useful to steady the bag whilst I removed the silica content.

 

Photographs below.

Hi I'm new to this forum.

Would this silicone have any effect on my cabin heating system. I've just had my water pump replaced under warrenty but the heating in the cabin doesn't seem to be working as it use to.

Go back to them, what you should have done ideally is had them replace the header tank with a new one at the same time as water pump as the system would be near empty anyway

Hello, welcome to the forum.

The contents of the bag (or capsule) if fitted are Silicate, and this was fitted to the coolant expansion tank for extended coolant life and corrosion protection for the engine.

The problem comes from the bag splitting and releasing silicate granules into the cooling system, blocking small channels - especially in the heater matrix.

AFAIK, the problem only appears with the bag (if fitted) - later vehicles had a plastic capsule insert fitted instead of the bag. Even later vehicles dispensed with the silicate insert - I believe this may have been when coolant was changed to G12evo.