Silica Bag Colour

[AntFR]

So I recently removed my silica bag as I have the dreaded one side heating issue in my MK3 Leon FR technology 184 TDI. I decided to replace the expansion tank and then remove the bag once I knew my replacement was working for a couple weeks. My old expansion tank was double walled, but interestingly, I could not for the life of me see the bag inside or hear it when shaking. Upon cutting open the tank with a hacksaw I just so happened to cut the silica bag. Now the bag itself was fairly full with no splits on the sealed edges so my guess is the bag never failed. However, the colour of it does concern me as it looks like a teabag (pretty brown). The expansion tank too is pretty stained. My friend removed his bag from his Leon and it appears fairly clean (note his car is 2017 and mine is 2014). Should I be concerned about the colour and what now could be the issue with one side heating in the car if not the silica bag.

 

[TheSwede]

Corrosion, thats why you have heating issues i guess. There are some treads about this problem. One below:

https://www.seatcupra.net/forums/threads/removing-silica-bag-from-coolant-header-tank.470769/

 

[BillyCool]

The silica bag itself does not cause the issue directly - it can contribute to blocking your heater matrix if it splits. This blockage can also be caused by left over casting sand in the engine block that gets stuck in the matrix.

Have you changed your matrix?

 

[AntFR]

The silica bag itself does not cause the issue directly - it can contribute to blocking your heater matrix if it splits. This blockage can also be caused by left over casting sand in the engine block that gets stuck in the matrix.

Have you changed your matrix?

As far as I'm aware the matrix has never been changed. According to the paperwork, the previous owner had a loss of cooling so the coolant was replaced but there was no mention of the matrix being replaced. Judging from the invoice amount the matrix was not changed. I am looking into getting it changed, however, if there is sand / corrosion then I would assume multiple full flushes would be needed to prevent a new matrix being clogged up? I bring this issue up as I have not seen any evidence online of silica bags looking as stained as mine.

 

[BillyCool]

As far as I'm aware the matrix has never been changed. According to the paperwork, the previous owner had a loss of cooling so the coolant was replaced but there was no mention of the matrix being replaced. Judging from the invoice amount the matrix was not changed. I am looking into getting it changed, however, if there is sand / corrosion then I would assume multiple full flushes would be needed to prevent a new matrix being clogged up? I bring this issue up as I have not seen any evidence online of silica bags looking as stained as mine.

Hard to say exactly why your bag is that colour. The idea of the bag in the first place was to extend the life of the coolant ("coolant for life") by topping up it's anti-corrosion powers. The engine had more corrosion sensitive parts and needed the coolant to cope. Not a great idea and gets most of the blame for matrix related issues - although casting sand also play its part in that.

Changing/removing the bag this late in the day won't make a difference to a blocked matrix. The matrix needs to be changed. There are other threads on it if you have a look. If you can dump most of your coolant and maybe run some clean water through that might help. Then new matrix, fresh coolant and go from there. Mine was done in March 2020 and still working okay. I did not do any complicated bleeding but did have the wonderful dodgy water pump changed as well as thermostat and housing, so the car was drained of almost all of its coolant anyway.

 

[AntFR]

Sure thing. I imagine it is general gunk from over the years. The bag removal is simply a precaution and fault finding exercise. The only other answer for the staining could be caused by a different coolant being used? I found the attached info about the mixing of VAG coolants. There is no mention of the type of coolant used when it was last flushed other than 'red' but either way if the old G12 was used or the current advised replaced G12Evo it could cause browning to the factory issued G13 (or the remnants of it). G13 can't be so good if it has been superseded so soon either. My coolant at present appears to be a pale pink. As you say I will get the system worked on soon. Would it be a good idea to use a Cooling System Flush solution in the weeks running up to a coolant / matrix change? That way any surface gunk would also get removed. Ultimately I don't want to go through the trouble of getting a new matrix and it blocking again weeks later.

 

[TheSwede]

About your attached picture.
G13 mixed with the latest one G12evo will NOT be brown. That is wrong information. I have changed from G13 to G12evo on four petrol cars, two VWs/one Seat Cupra/one Skoda without problem the last 3 months. New G13 have the same color as new G12evo.
FYI Before i did the replace i mixed G13 and G12evo 50/50% in a pot and heated it on the stove. No change in color!

 

[BillyCool]

Can't offer any advice on a flush. Most debris seems to get trapped in the matrix. My thermostat housing also turned out to be a good place for debris to settle. I'd certainly get as much coolant out as you can. Someone else may be able to give some more guidance.

 

[Mo_86]

About your attached picture.
G13 mixed with the latest one G12evo will NOT be brown. That is wrong information. I have changed from G13 to G12evo on four petrol cars, two VWs/one Seat Cupra/one Skoda without problem the last 3 months. New G13 have the same color as new G12evo.
FYI Before i did the replace i mixed G13 and G12evo 50/50% in a pot and heated it on the stove. No change in color!

To flush out and replace the old g13, how many bottles of g12 evo will be needed?

 

[TheSwede]

To flush out and replace the old g13, how many bottles of g12 evo will be needed?

The system contains about 8 litres. I prepared 10 litres.

For “flush” (ordinary replacement in this case) I used 9,5 litres of new G13 which I already had stored in my basement. Used the car for some driving and did it again but this last time I used G12evo (Eurolube-D65 equal to Volkswagen G12evo). G13 and G12evo are 100 % mixable.

I didn’t flush with water, want to keep track of the mixing ratio, not possible if I just filled water in the engine in my world ……

If you don’t have any problems, if the coolant is clear and clean as mine was, I doubt you need to flush the car. Just replace the old G13 with new G12evo. The Eurolub D-65 5 litres is concentrated so I mixed it 50/50% with distilled water and got 10 litres.

 

[TheSwede]

Some alternatives to VAG G12evo coolant, has to do with money......

Glysantin g65 BASF
Febi Bilstein 183367
Swag 33108926
Eurolub D-65
Starta G12Evo Longlife (Perhaps just in SE)
Vaico VA-065

 

[bahyr]

Actually inside the VAG G12 evo bottles is Glysantin G65.