Author Topic: Replacing coolant tank with Silicon bag  (Read 18452 times)

Offline Finglonga

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Re: Replacing coolant tank with Silicon bag
« Reply #50 on: 09 December 2019, 18:30 »
Do you know the part number of the new tank?

Just take off the old tank, remove the bag, replace the old tank. costs absolutely nothing to do. Absolutely barmy to just buy a new tank without a bag.

Offline Talk-torque

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Re: Replacing coolant tank with Silicon bag
« Reply #51 on: 09 December 2019, 18:34 »
Do you know the part number of the new tank?

Just take off the old tank, remove the bag, replace the old tank. costs absolutely nothing to do. Absolutely barmy to just buy a new tank without a bag.

Exactly right!
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Offline Cecil

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Re: Replacing coolant tank with Silicon bag
« Reply #52 on: 09 December 2019, 19:01 »
Hello, I was at my local Independent VW specialist today having our other car (Up) serviced and mentioned this to him.

He told me that the had a few cars in with the heater matrix becoming blocked. However, this is not caused by the bag in the tank bursting. Apparently, in his words, there is a scale forms similair to limescale that forms on a kettle and he has seen this in both the matrix and on the bag with the bag remaining intact.

Their fix is to flush the matrix and in the main this is succesful but for some only lasts one year then it needs to be done again. Apparently VW had invested in equipment that is used to flush the matrix that neutralises the contents of the bag but have now withdrawn it as it is not believed to be the culprit.

His advice to me was there is not much you can do to prevent this and to leave the bag alone as there does not seem to be a pattern as to what causes this.

Just to clarify the 2 guys who own the garage are ex main dealer trained mechanics and used to work for Audi and VW and have recent experience within the dealership of this issue.

I hope that helps and doesn't muddy the waters too much.

Offline Rob_benton

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Re: Replacing coolant tank with Silicon bag
« Reply #53 on: 09 December 2019, 20:06 »
Interesting info. Thanks
My 6 year old bag had no limescale on it which is good news I guess.

From the videos I’ve seen, either a bag has split or sand from the manufacturing process of the head has been found in the matrix.
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Offline vidman2

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Re: Replacing coolant tank with Silicon bag
« Reply #54 on: 26 January 2020, 14:12 »
Is there a VAG Tech on here that can confirm it is only the tanks with a bag that are the potential problem and that the dual wall 'mit silicat' tanks are burst proof so have no danger of clogging the heating system
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Offline Finglonga

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Re: Replacing coolant tank with Silicon bag
« Reply #55 on: 26 January 2020, 19:09 »

He told me that the had a few cars in with the heater matrix becoming blocked. However, this is not caused by the bag in the tank bursting.

Beg to differ on that, the guy that services my car is ex VW and at leat two that have burst he has fixed himself and showed me a bag and matrix that had split. Personally for a few minutes work I would not risk it.