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silica grain in the header tank

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Bendy

Active Member
Aug 10, 2018
149
58
What does it seem like the general consensus is to this issue, are people taking this bag out to prevent issues and changing coolant more often or assuming the people that designed the engine know what they’re doing? Is there any chance of a contribution out of warranty if something goes wrong? I’ve just checked my 2016 184 and it has the bag.
I have a 184 TDI FR. Specialist VAG garage removed my silica bag during service last year, after advising me that they can split and cause blocked heater matrix and expensive repairs. Just remove the bag and forget about it.
 
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Joshua Oakes

Active Member
Apr 30, 2020
55
14
I have a 184 TDI FR. Specialist VAG garage removed my silica bag during service last year, after advising me that they can split and cause blocked heater matrix and expensive repairs. Just remove the bag and forget about it.
What about changing coolant more often? Did they advise on that?


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Joshua Oakes

Active Member
Apr 30, 2020
55
14
The people that designed the concept did not know what they were doing as the bag splits and blocks the heater matrix. It was well intentioned to extend the life of the coolant but newer cars do not have the bag and use a different coolant because it don't work!

Rather than removing my bag on my 184, I just changed the header tank for £20. It's a 15 min job and ensures you don't have any debris already in the tank. Quite happy to change coolant more regularly like we used to in the good old days.

The engine also has/had issues with the variable water pump, which was another bad idea. That now has an improved design that excludes the failure point.

Personally, I'd just change header tank and maybe your coolant.
Perfect thanks mate, how easy is it to change the tank? Also how difficult is it changing coolant?


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Brian Gordon-Stables

Active Member
Jan 16, 2020
189
62
Leicestershire, UK
Perfect thanks mate, how easy is it to change the tank? Also how difficult is it changing coolant?


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Changing tank is dead easy. It's effectively the highest point so you don't really lose any coolant.

You disconnect an electrical connector and 2 pipes I think. I use a syringe to suck out any coolant in the tank (makes less of a mess when you take the hose off). It's just held in place by a couple of clips.

Assuming you have the EA288 engine - its actually has 3 coolant circuits, so it's hard to drain the whole thing without the right kit. The main one runs through the radiator and that contains a large amount of coolant. Some radiators may have a drain point or you just pull off the lower rad hose and drain.

Then fill up with new coolant, run car and check every day before starting and top up if needed (check everyday for a week at least). They can get air locks etc and sometimes take a while to settle.

Coolant system diagram.png
 
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Joshua Oakes

Active Member
Apr 30, 2020
55
14
Changing tank is dead easy. It's effectively the highest point so you don't really lose any coolant.

You disconnect an electrical connector and 2 pipes I think. I use a syringe to suck out any coolant in the tank (makes less of a mess when you take the hose off). It's just held in place by a couple of clips.

Assuming you have the EA288 engine - its actually has 3 coolant circuits, so it's hard to drain the whole thing without the right kit. The main one runs through the radiator and that contains a large amount of coolant. Some radiators may have a drain point or you just pull off the lower rad hose and drain.

Then fill up with new coolant, run car and check every day before starting and top up if needed (check everyday for a week at least). They can get air locks etc and sometimes take a while to settle.

View attachment 17176
Thanks mate, really appreciate this!

What kind of coolant do you use then? Same as before and replace every few years?


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Brian Gordon-Stables

Active Member
Jan 16, 2020
189
62
Leicestershire, UK
Thanks mate, really appreciate this!

What kind of coolant do you use then? Same as before and replace every few years?


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Yeah - had the the same pink stuff put in. Will just change it when my mechanic thinks it is due. Some say every 2 years, some say every 30,000 miles. It's not a big job to do if it's already on a ramp.

No idea what the `correct` interval is!
 
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Bendy

Active Member
Aug 10, 2018
149
58
Changing tank is dead easy. It's effectively the highest point so you don't really lose any coolant.

You disconnect an electrical connector and 2 pipes I think. I use a syringe to suck out any coolant in the tank (makes less of a mess when you take the hose off). It's just held in place by a couple of clips.

Assuming you have the EA288 engine - its actually has 3 coolant circuits, so it's hard to drain the whole thing without the right kit. The main one runs through the radiator and that contains a large amount of coolant. Some radiators may have a drain point or you just pull off the lower rad hose and drain.

Then fill up with new coolant, run car and check every day before starting and top up if needed (check everyday for a week at least). They can get air locks etc and sometimes take a while to settle.

View attachment 17176
Genuine question, not really understanding why you are recommending replacing the header tank and draining and then refilling some coolant when the bag can simply be removed?
 

Brian Gordon-Stables

Active Member
Jan 16, 2020
189
62
Leicestershire, UK
Genuine question, not really understanding why you are recommending replacing the header tank and draining and then refilling some coolant when the bag can simply be removed?
Good question.

Basically, it's hard to know if the bag is already split/degraded or not and whether it will leave any deposits in the header tank. It's sort of belt and braces approach to spend £20 on a new tank to remove/reduce any future issues. My header tank was quite opaque and a bit mucky, so for £20 I thought why not. The OP could just fish out the bag and that might be all good.

Not saying you have to do it, but I consider it prudent to do so.

If there is any silicant gunk already in the cooling system, it's also worth considering changing your coolant as it may well have lots of crud already floating around. The other issue with blocked heater matrix's isn't just from the split silicant bag but also from casting sand that was left in the engine block. This is constantly circulating and will stop at the narrowest or lowest points. I had loads of crud/sand in my blocked matrix and it also accumulated inside my thermostat housing. Again - it's preventative maintanance but IMO it's cost effective compared to the b*ll-ache and cost of other issues with your cooling system.

My view is that assume the header tank and coolant are compromised and replace. I did of course have a blocked matrix and also replaced thermostat & housing and water pump (and header tank & coolant!) so I'm slightly biased.
 
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RUM4MO

Active Member
Jun 4, 2008
6,160
423
South Scotland
@Brian Gordon-Stables , now that you seem to have done a lot of leg work on this, I have a question about this all:- during this period of manufacture VW Group would have filled cars with G12++ followed by or replaced with G13 followed by or replaced with G12evo, so where in all this coolant type wise did the "mit silikat" bags or the need to fit them - and conversely where/when coolant type wise did the need to add "mit silikat" disappear - also was some of these changes introduced only too some engine types, or even fuel, like DERV.

My personal interest in this is purely to get into my head all of the what/why/when surrounding this as I have a 2011 Audi S4 which was filled at factory with G12 and has chain drive so until something fails, no urgent need to dump the coolant(and so fill with new or a newer version), my wife has a 2015 Polo 1.2TSI which is belt driven and so at 8 years might get a new belt, but the water pump is located at the other end of the engine, so replacing the cambelt will not require the coolant to get dumped and as far as the header tank is concerned is filled wit G12++, my older daughter has a 2019 Leon Cupra which has "mit silikat" and G13 marked on the header tank.

Thanks!
 

Brian Gordon-Stables

Active Member
Jan 16, 2020
189
62
Leicestershire, UK
@Brian Gordon-Stables , now that you seem to have done a lot of leg work on this, I have a question about this all:- during this period of manufacture VW Group would have filled cars with G12++ followed by or replaced with G13 followed by or replaced with G12evo, so where in all this coolant type wise did the "mit silikat" bags or the need to fit them - and conversely where/when coolant type wise did the need to add "mit silikat" disappear - also was some of these changes introduced only too some engine types, or even fuel, like DERV.

My personal interest in this is purely to get into my head all of the what/why/when surrounding this as I have a 2011 Audi S4 which was filled at factory with G12 and has chain drive so until something fails, no urgent need to dump the coolant(and so fill with new or a newer version), my wife has a 2015 Polo 1.2TSI which is belt driven and so at 8 years might get a new belt, but the water pump is located at the other end of the engine, so replacing the cambelt will not require the coolant to get dumped and as far as the header tank is concerned is filled wit G12++, my older daughter has a 2019 Leon Cupra which has "mit silikat" and G13 marked on the header tank.

Thanks!
@RUM4MO thanks for thinking I might know the answer! I don't!

I have read up on it before and this web-site offers some good information and also shows what coolants can be mixed if needed.


I have no idea about the "mit silikat" being used/discontinued and thought is had been stopped on newer cars and from what you say, that is not the case!

My car has pink coolant so not sure where that fits in! I guess it should be G12++ or G13.

This makes no reference to the much newer G12EVO but this forum has some info on that:


Your guess is as good as mine. From my point of view, as long as I put in G12++ or G13 and change it every 2 or 3 years, I should be fine.

audi_vw_coolant_specs.jpg
audi_coolant_mixing_chart.jpg
 

Joshua Oakes

Active Member
Apr 30, 2020
55
14
Good question.

Basically, it's hard to know if the bag is already split/degraded or not and whether it will leave any deposits in the header tank. It's sort of belt and braces approach to spend £20 on a new tank to remove/reduce any future issues. My header tank was quite opaque and a bit mucky, so for £20 I thought why not. The OP could just fish out the bag and that might be all good.

Not saying you have to do it, but I consider it prudent to do so.

If there is any silicant gunk already in the cooling system, it's also worth considering changing your coolant as it may well have lots of crud already floating around. The other issue with blocked heater matrix's isn't just from the split silicant bag but also from casting sand that was left in the engine block. This is constantly circulating and will stop at the narrowest or lowest points. I had loads of crud/sand in my blocked matrix and it also accumulated inside my thermostat housing. Again - it's preventative maintanance but IMO it's cost effective compared to the b*ll-ache and cost of other issues with your cooling system.

My view is that assume the header tank and coolant are compromised and replace. I did of course have a blocked matrix and also replaced thermostat & housing and water pump (and header tank & coolant!) so I'm slightly biased.

Does this look like the same as what you bought? I’ve found a few with slight differences and can’t get to my car just yet?


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Wastedagen

Active Member
Aug 3, 2017
429
81
Milton keynes
So after reading this and another thread regarding silicone bags in the reservoir tank I went and had a look in mine and there was no bag...

Now I've had the car nearly 2 years now and I only just realised, , I had the wrong coolant in the system....
Printed on my tank is G13 and the manual states to use G13 or G12++. Both of which are purple in colour. I had bright pink in mine....

Anyways I have changed it to G13 now, hoping no damage has been done...

My question is, what tester are people using to measure the coolants potency? Can I use any one or is there a special tester for OAT coolants... Etc...

Thanks in advance....
 

andycupra

status subject to change
So after reading this and another thread regarding silicone bags in the reservoir tank I went and had a look in mine and there was no bag...

Now I've had the car nearly 2 years now and I only just realised, , I had the wrong coolant in the system....
Printed on my tank is G13 and the manual states to use G13 or G12++. Both of which are purple in colour. I had bright pink in mine....

Anyways I have changed it to G13 now, hoping no damage has been done...

My question is, what tester are people using to measure the coolants potency? Can I use any one or is there a special tester for OAT coolants... Etc...

Thanks in advance....
but will you be changing to g13 and then leaving it for the life of the car? then if so you need the silicon bag.
alternatively, if the bag has been removed pink might actually be the way to go as that does need changing.
 

Wastedagen

Active Member
Aug 3, 2017
429
81
Milton keynes
but will you be changing to g13 and then leaving it for the life of the car? then if so you need the silicon bag.
alternatively, if the bag has been removed pink might actually be the way to go as that does need changing.
That's a fair point..... The g13 I bought said only good for 5 years... So i guess I'll change it then every 2 or 3 years...
 
Last edited:

Woody_72

Active Member
May 10, 2020
69
34
Northwest England
Just checked my 184 and yes, it has 'Mit Silikat' on the overflow tank. Just ordered a new one, they're only £20-ish, and gonna replace it. I even think I managed to find one with a G13 pictogram on it, they all seem to say G12 :rolleyes:.
 
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Joshua Oakes

Active Member
Apr 30, 2020
55
14
Just checked my 184 and yes, it has 'Mit Silikat' on the overflow tank. Just ordered a new one, they're only £20-ish, and gonna replace it. I even think I managed to find one with a G13 pictogram on it, they all seem to say G12 :rolleyes:.
That’s my problem at the minute, where did you find yours? Any chance of a link to it? Thanks mate,

Josh.


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