Expansion bottle replacement

[CajoLajo]

16 minutes ago, benterrier said:

This design is new to me. When I checked my tank which was labelled mit Silikat l couldn't find any bag. Presuming it had been removed earlier I'll have to check out for this tank design. 

Just to clarify, I said this is what I think I have because I could not locate the bag. As I said earlier, I cannot see that how bag can fit in the area visible once the lid is unscrewed. To me at least, it looks as if there are two chambers separated by inner (ring) wall. The silica bag/container could well be in the outer part of the tank.  I just went for a drive and checked the heating and it is working. It is 27 C here and very humid though. Winter is six months away. Do you expect any coolant colour change at 4 years/40,000km? Mine is definitely not purple. There is no residue at the bottom of the tank and I cannot see anything on the surface of the coolant either. It is still clear. This whole "Mit Silikat" thing got me worried.

Edited 25 January, 2020 by CajoLajo
spelling

[benterrier]

Just been out and checked mine. It appears to be the design with the silikat container built into the expansion tank. There are 2 piped connections, presumably to enable flow of coolant to introduce the silikat. I'm assuming that this design took over from the silikat bag idea which has rupture issues and caused heater matrixes to block.

[caprixpack]

Just read this thread, so decided to go out and have a look at our octavia. 

 

Sure enough. 

 

Was a bit of a sod to get out but and few cuts and scrapes and I managed to fish it out. 

[benterrier]

Hi caprixpack, what model and year is your car. Does the tank have a connection on the bottom as well as the top. Cheers

[CajoLajo]

 

7 minutes ago, benterrier said:

Just been out and checked mine. It appears to be the design with the silikat container built into the expansion tank. There are 2 piped connections, presumably to enable flow of coolant to introduce the silikat. I'm assuming that this design took over from the silikat bag idea which has rupture issues and caused heater matrixes to block.

I really hope your conclusion is correct and that this design cannot cause the issues we are discussing.. It is interesting that there is no mention of the design change that I could find on the net. Perhaps, that would be acceptance of liability for the issues the ruptured bags have caused to Skoda, Seat, Audi and VW car owners.

7 minutes ago, caprixpack said:

Was a bit of a sod to get out but and few cuts and scrapes and I managed to fish it out. 

That is big! Nothing like that in my tank although the "Mit Silikat" stamp is present

[benterrier]

Cajalajo. There would have been a change of part numbers I presume. The acceptance of liability you mentioned would have been covered by the clause; the manufacturers have the right to change the design get out of jail card.

[CajoLajo]

7 minutes ago, benterrier said:

Cajalajo. There would have been a change of part numbers I presume. The acceptance of liability you mentioned would have been covered by the clause; the manufacturers have the right to change the design get out of jail card.

Agree, they are always covered. At this point I don't know what to do. Should one buy the replacement tank without silica or not?

[benterrier]

10 minutes ago, CajoLajo said:

Agree, they are always covered. At this point I don't know what to do. Should one buy the replacement tank without silica or not?

Looking at your video the coolant looks okay for its age, it's clear and has no residue and you say the heater is working fine. I myself would just get the coolant changed with fresh and keep monitoring things for a while

[caprixpack]

44 minutes ago, benterrier said:

Hi caprixpack, what model and year is your car. Does the tank have a connection on the bottom as well as the top. Cheers

 

63 plate 1.6tdi octavia. 

[caprixpack]

Also I'll check the header tank when I get home, just nipped out. 

[CajoLajo]

34 minutes ago, benterrier said:

Looking at your video the coolant looks okay for its age, it's clear and has no residue and you say the heater is working fine. I myself would just get the coolant changed with fresh and keep monitoring things for a while

Thank you benterrier. I will do exactly that.

[allan1888]

The twin walled tank must still have had the same issue. As the new coolant bottle is totally different and without the "MIT Silikat". They would have kept the twin walled tank if there were no issues with it and not revised the part again

[benterrier]

3 hours ago, CajoLajo said:

3 minutes ago, allan1888 said:

The twin walled tank must still have had the same issue. As the new coolant bottle is totally different and without the "MIT Silikat". They would have kept the twin walled tank if there were no issues with it and not revised the part again

 

Good point, so do you think I should replace twin walled bottle on MY18 plate 2L TDI with the revised part or would it void my warranty.

[caprixpack]

15 minutes ago, allan1888 said:

The twin walled tank must still have had the same issue. As the new coolant bottle is totally different and without the "MIT Silikat". They would have kept the twin walled tank if there were no issues with it and not revised the part again

 

That or its just cheaper to make the new revised part. 

[allan1888]

My 2015 vrs had the twin walled tank, I don't know when they changed the design but I wasn't taking the chance with a failure 

[benterrier]

VAG obviously realised that their attempts to up the corrosion inhibitor by dropping a big tea bag full of silikat in the bottle was a pretty poor attempt, basically  a quick cheap fix but a time bomb for a percentage of vehicles. The built in silikat idea overcame the rupture issue. So why have they stopped adding it. Perhaps they've sorted out the manufacturing technique so these harsh chemicals don't affect the complex engines waterways.

[caprixpack]

42 minutes ago, allan1888 said:

My 2015 vrs had the twin walled tank, I don't know when they changed the design but I wasn't taking the chance with a failure 

I've not read anything that suggests the tank fails, only that the bag can split. Taking the bag out took 5 minutes and saved £20 odd, the hassle of removing coolant faffing with pipes and making a mess. 

Edited 25 January, 2020 by caprixpack

[allan1888]

There must have been a reason for changing though you cant remove anything from the twin wall tank. i dont know if it was the bag first then switched to the twin wall tank or the other way around. if there was no issues with the twin wall why would they change it and remove the " mit silikat" completely, since im out of warranty there is no way i was taking the chance, Spend £20-30 and save myself £££ in potential costs. 

[caprixpack]

They will have changed the design when they decided to not use the bag as the tanks will cost more to produce with the extra walling, if it's not needed why spend the extra money making then. It's nothing to do with the tanks failing.  How will removing the bag potentially cost you £££? 

Edited 25 January, 2020 by caprixpack

[allan1888]

The tanks don't even have the twin wall design now or the bag, so if the twin walled tank wasn't failing why redesign another tank and remove the MIT Silikat label completely. The coolant hasn't changed so why the tank redesign to remove a part that was causing issues. I never said removing the bag would cost £££, I said I wasn't taking the chance with mine being out of warranty so changed my tank to save £££ from a potential failure

[encephalopathy]

bit fiddly to get out as the silica was pretty solid and the wrong shape for coming out the round hole at the top. the little mosquito forceps were handy to grab an edge, but i went very gently to avoid tearing the bag. overall took less than five minutes to do!

[allan1888]

What model year is your car ? Just trying to figure out when they changed from the twin walled tank to the one with the bag, my 2015 vrs had the twin walled tank with no access to remove anything

[benterrier]

Taken from VW self study program 820433.

 

Expansion Tank with Silicate Repository. The  coolant  expansion  tank contains  a  silicate  repository.   Silicate  is  used  to  protect  the  aluminum  components  in  the  coolant system  from  corrosion.   There are silicates in  the G13 coolant, but  they  are used up  over  time  if  the engine is  subject to  high thermal  loads. To  compensate  for  the silicate  consumption, silicate  is  taken from  the repository  and added to  the coolant.  The silicate repository  provides  additional  protection  against  corrosion  for the  aluminum  components  in  the  coolant  system  over  the  entire lifespan  of  the  engine. 

[allan1888]

46 minutes ago, benterrier said:

Taken from VW self study program 820433.

 

Expansion Tank with Silicate Repository. The  coolant  expansion  tank contains  a  silicate  repository.   Silicate  is  used  to  protect  the  aluminum  components  in  the  coolant system  from  corrosion.   There are silicates in  the G13 coolant, but  they  are used up  over  time  if  the engine is  subject to  high thermal  loads. To  compensate  for  the silicate  consumption, silicate  is  taken from  the repository  and added to  the coolant.  The silicate repository  provides  additional  protection  against  corrosion  for the  aluminum  components  in  the  coolant  system  over  the  entire lifespan  of  the  engine. 

Any idea when the twin walled tank was replaced with the tank that has the bag or vice versa, from all the posts I see the bag came after the twin walled tank going by the vehicles in people's profiles, which means the twin walled tank had issues or was more expensive to manufacture so they switched to the bag that was cheaper but came with its own issues. Now it's removed all together.

[CajoLajo]

I am now even more confused about what to do with mine. My coolant is not purple after 40,000 km. It is reddish/brown. One member posted somewhere here that his coolant is purple after 100,000 km. I am not sure if he has the bag in situ. Does this mean that my coolant tank has contaminated the coolant or the coolant does change colour after a while (normal behavior)? Or perhaps, the silica does change the colour of the coolant after a while. I need to point out that my coolant is clear and there is no visible residue in the tank. Checked numerous other VW forums and they mostly talk about the bag and this bag can rupture (but it can be removed as a preventative measure). The issue is widespread but also associtaed with symptoms such as the loss of coolant, issues with the heater and very contaminated coolant. It alos appears that diesel engines are more affected (or more people are driving diesels in Europe). I do have the silica in my tank in some shape or form, it could be in a bag behind the inner wall. Is this any safer? I don't think so. I just cannot find anybody discussing this design in relation to the issue. How is G13 supposed to last as long as the car I cannot understand. 

10 hours ago, allan1888 said:

Any idea when the twin walled tank was replaced with the tank that has the bag or vice versa, from all the posts I see the bag came after the twin walled tank going by the vehicles in people's profiles, which means the twin walled tank had issues or was more expensive to manufacture so they switched to the bag that was cheaper but came with its own issues. Now it's removed all together.

I could not find any reference to twin-walled tanks on this site and it appears that I was the first one to mention it. Perhaps the combination of key words I used is not fetching anything. I think it is important to establish what design was first in production.  It could be the case that VW had a large stockpile of single walled tanks and decided to use them and just add the silica bag. My friend's VW 1995 Transporter single cab truck has one that to my eye looks the same as the current single walled design.