Does any one know what symptoms to expect if the bag in the coolant bursts? I’m fairly sure mine has one but can’t see the mit slek (I think) on the header tank. 
if it has exploded is it covered by the cars warranty ?
ive got the 2 litre diesel.  

Edited 8 December, 20205 yr by Stuart-h

I think the main indications are discoloured coolant and lack of warm air from the heater due to blockage of the heater matrix.

Mine says mit Silikat but I cant see a bag in the bottle.

3 hours ago, DC04R said:

Mine says mit Silikat but I cant see a bag in the bottle.

Stick your finger in and give it a wiggle. Mine was in there but i couldn't see it.

 

I managed to persuade mine out without tools

Some expansion tanks are double walled with the silica bag between the two walls.

 

You might be able to see if with a bright light shining through the tank

Tried the light, didn't have a wiggle  will give it a go

 

I was advised by VW to NOT remove the Silikat bag from my 2018 Golf GTI, as I'd be voiding the warranty.  They confirmed any failure would therefore be covered.  My warranty expires next March and the bag will be removed shortly thereafter.

 

Gaz

 

Edited 8 December, 20205 yr by Gaz_

First I don't have a TDI engine in either of our cars, or a Skoda, but, it does seem that 2 versions at least, of these tanks with silicate enclosures in them were used, the original ones had the "tea bags" that could it seems burst, the later ones had a proper enclosure within the structure of the tank and it seems that they were robust enough.

 

It seems that some coolants, maybe only G13 needed these "silicate booster packs" in them to allow for extended protection to the aluminium parts, VW Group's latest factory fill coolant is now G12Evo and these tanks with "Mit Silikat" are no longer fitted to new cars at any VW Group factories.

 

Tanks changed in maybe 01/01/19 and the coolant was changed to G12Evo in 01/0820 - so why the difference in dates if this silicate boosting pack was only needed for G13?

 

For me, VW Group should have made good strong and sound details about these changes available to at least some serious motoring publications as it stands it all sounds a bit like smoke and mirrors being handed out when these questions are being asked.

 

Cars fitted with Mit Silikat  tanks can end up with partially choked  heater cores, and need to hand over £1000 to get the systems  flushed out, heater core and header tank replaced and new coolant added, not clever and it seems money taken without any embarrassment !

 

Also for 2.0TDI engines built over a certain period in time, there is the possibility of ending up with the same heater core choking, but this time being due to casting sand being left in the engine castings, and with time it can move around the cooling systems and settle down in the heater core - same sort of price to repair!

 

Both well documented VW Group design and manufacturing defects so not wear and tear and not user's fault!

Silikat needs regular replacement or what? 

I’m fairly sure I’ve seen a bag in mine unless I’m starting to go mad ! Mine doesn’t have the mit silikat printed on the header tank though ! 

<posting removed>

Edited 10 December, 20205 yr by varaderoguy

I understand your warranty concerns, but the problem arises if the bag splits whilst under warranty and leaks silica into your coolant system and you don't realiase until after your warranty has expired. Then you face a £1000 bill to replace your heater matrix. Sure if I have an issue with corrosion inside my cooling system in the future, I might have to be prepared to have the argument, but the chances of that (with a coolant change every 5 years) are less than the chance of the bag destroying your heater matrix.  I removed mine and I have a warranty and I'll just document a coolant replacement in a few years.

 

Nick

I'm not condoning the removal of the silicate bag on your Skodas but the first thing I did when I got my Leon was remove it.

 

That's speaking as someone who deals with the consequences of them failing on a fairly regular basis.

So can I just ask, g12evo replaces g13?

 

do we know what the difference is and does it still have an extended service life or not?

 

I had a full change with the cam belt change and a swap of an amount when I did the tank swap.

 

Currently I have been removing an amount in the header tank and replacing with fresh every 9-12 months.

 

debating if to use g13 or g12evo come the full coolant change.

Moisture, ok but does it really makes trouble in cooling system? So what is wise on the end to do, after 4 years replace coolant with exp vessel? 

I have just suffered lack of heat on drivers side less than a week after a routine cambelt change. Luckily my garage has recovered it to some degree by hot flushing it twice whilst connected to ODIS diagnostics to run each pump (there are 3 on the tdi) to make sure it was really flushed fully.  Expansion tank has been changed to 5Q0121407M too.  But I suspect the heater matrix may have to come out eventually, we will see.  I'm keeping an eye on coolant colour each day. 

 

Coolant had gone orangey rusty brown after four days should be pink. G13. 

 

I wish I'd replaced the expansion tank earlier in the year for ~£20 hey ho. 

Edited 9 December, 20205 yr by paulski

After how many years and km it happened? 

Here’s one. As I had the garage flush out the coolant the other day as I had to put some green coolant ij. The warning light had come on at 1 am. 
If the car is on hi it’s nice and warm. If I turn it down to 24 it feels like there’s cold air comeing in.

many one got any ideas at all on that ?

34 minutes ago, FrankLK said:

After how many years and km it happened? 

MY2016 65k miles. 

9 minutes ago, Stuart-h said:

Here’s one. As I had the garage flush out the coolant the other day as I had to put some green coolant ij. The warning light had come on at 1 am. 
If the car is on hi it’s nice and warm. If I turn it down to 24 it feels like there’s cold air comeing in.

many one got any ideas at all on that ?

That's sort what mine felt like. Try closing down the passenger vents and then put the air control to front  vents only,  (not in auto ) @24C temperature up the fan dial too. Then feel the difference between each side opening and closing the vents. My hands got cold driving  last week was what I first realised, as although in auto, heat was not coming out the drivers side, (common indication of this fault). But cranking up the heat the passenger side vents in auto provided enough heat for the whole cabin. 

I’ll give it a try. 

On 08/12/2020 at 18:44, varaderoguy said:

Snip   ----

 

The only purpose of the silica teabag is to stop excess moisture getting into the coolant system. In reality, it means instead of Lifetime Coolant ( nonsense statement, because nothing is Maintenance Free) it means you have to replace the coolant after 5 years.

 

Was that meant as a joke?

 

This material that is in these enclosures/bags has got nothing to do with moisture in this application!

On 08/12/2020 at 18:44, varaderoguy said:

Just remove the Silica bag or replace the tank (if double-walled). New tanks are about 20quid.

 

I don't buy the warranty thing with VW. The only purpose of the silica teabag is to stop excess moisture getting into the coolant system. In reality, it means instead of Lifetime Coolant ( nonsense statement, because nothing is Maintenance Free) it means you have to replace the coolant after 5 years.

 

Its been removed on the cars in our fleet.

 

It's not to remove moisture since mix is probably 50/50 coolant/distilled water anyway. The coolant contains silica that coats the metal components preventing oxidation. This is lost over time so the silica bag replaces the lost silica so that the coolant can last the life of the car.

 

Or ditch the bag and just replace the coolant after 5 years.

I prevail to better knowledge - original posting removed.

Is this an issue on earlier (2014) diesel Octavias? 

Is it worth replacing the expansion tank and just regularly changing coolant?