coolant expansion bottle

[benterrier]

I have a 2ltr tdi 18 plate with mit silicat on expansion bottle. Cant find bag in reservoir guess it may be different type. Coolant is as it should be, colour/clarity and  no heater issues. What are you guys recommending , do I change the bottle without any silicat additive in, or leave as it is. Recently had a major service by main dealer and when asked about this was told there is no recall on this issue so they have no reason to recommend it being changed it is my decision.

regards 

[ords]

If you are not the first owner, maybe the previous owner had the bag removed.

[Dooge]

Difficult to know, the silicone bags are not the easiest to see even with fresh coolant and I can't imagine an average owner is going to go to hassle of removing the bag. Last time I looked the expansion tanks were about £40 and a 20 min job to replace.

[Gaz]

My 2018 Golf had a bag in it (as did my 2015 vRS), which I removed.  It was easy to find by putting my finger in the hole at the filler cap and fishing around.  If you can't find it, I'd think it's probably not worth worrying about.  No point in replacing a tank that doesn't have a bag in it.

 

Gaz

[benterrier]

Pretty sure there isn't an actual bag in mine, some variations of the bottle held the silicat in a pocket or between double skin bottle. I haven't been on Briskoda for about 2 years and this topic was Hot!

If people have replaced the bottle without any sort of silicat being present and have not encountered problems could they let me know. There are so many after market bottles on the market, they don't say if silicat is added. 

 

[rum4mo]

So these car will have been filled with G13 coolant mix at the factory, it seems to be that someone worked out that at least for some engines, trickle feeding the G13 with extra Silicate is needed to retain the initial corrosion protection.

 

Some years ago I bought a tin of "coolant test strips" these have 2 areas on them, one area for checking %age of coolant-water and the other area for checking the ph of the coolant, ie how it is degrading towards being acidic from initially being slightly alkaline - now these strips are now out with their recommended "use by" date, but as I have them I am continuing to use them, and what I discovered was, the old G12+ or G12++ tended to stay slightly alkaline over a period of 12 years, and the 2 cars that I check that have G13 in them, are moving towards being acidic, even the car that has a silicate pouch still in it - the other G13 car was not fitted with a silicate pouch at the factory.

 

Okay that is only a sample of 3 cars, one with G12+/G12++, one with G13 and no silicate pouch and one with G13 and a silicate pouch.

 

The car with the G12+/G12++ I changed to G12 evo maybe 2 years ago, the car with G13 and no pouch, I plan to change to G12evo as it is 8 years old and 40+K miles, the car with G13 and a silicate pouch - well I've suggested that the pouch might be better being removed and then change the coolant to G12evo, but its owner does not like spending money where it is not absolutely needing to be spent.

 

I'm not sure if I'm pleased or not that I made the effort to buy in from USA these coolant test strips, but as I did buy them, I am using keeping on using them.

 

Back in the "good old days" it was easy to work out when to replace coolant as the cambelts needing replacing frequently and on older engines, the smart money was on changing the cambelt driven water pump at every other cambelt change - and so the coolant was renewed.

Edited 12 April, 2023 by rum4mo
another mess up, wrote "not renewed" instead of "was renewed".

[Crasher]

We use G12Evo concentrate and Quantum mixing water 40/60 as the default fill in everything now. You can get ready mixed but that is 50/50 and technically a little too strong for our climate.

[Gaz]

2 hours ago, benterrier said:

.... and this topic was Hot!

 

Possibly the thread you're remembering:

 

 

G

[rum4mo]

2 hours ago, Crasher said:

We use G12Evo concentrate and Quantum mixing water 40/60 as the default fill in everything now. You can get ready mixed but that is 50/50 and technically a little too strong for our climate.

 

I remember seeing someone selling G12evo 40/60 in bulk, probably 5ltrs on ebay, and thinking that that was what I'd buy when replacing the coolant in my old 2011 S4 - then suddenly became aware that that car left the factory with a 50/50 coolant mix, and so I changed my plan to buying G12evo from my local VW Van Centre by the litre bottle in 50/50 form which was what was being sold - it would have been cheaper if I had just bought premixed 40/60, but at that time I could not find 40/60 pre mixed in the parts listing for VW marques, only 50/50 premixed - so I guessed that VW AG had initially put 40/60 into the market place then had a rethink and only supplied 50/50.

[EnterName]

9 hours ago, benterrier said:

I have a 2ltr tdi 18 plate with mit silicat on expansion bottle. Cant find bag in reservoir guess it may be different type. Coolant is as it should be, colour/clarity and  no heater issues. What are you guys recommending , do I change the bottle without any silicat additive in, or leave as it is. Recently had a major service by main dealer and when asked about this was told there is no recall on this issue so they have no reason to recommend it being changed it is my decision.

regards 

First, establish what the problem is that you are trying to solve?

If the problem is the risk of a split silica bag causing an expensive repair, if the expansion tank says "Mit Silikat", then the car would have had a silica bag and G13 (or earlier) coolant originally.

If the previous owner had the sense to fish the silica bag out, but lacked the sense to mark the expansion tank as having had the silica bag removed, then I'm guessing they didn't change the coolant.

Example, pic attached is my expansion tank. It's pretty clear what coolant is in the system. (Or at least is claimed to be in the system.) I also wrote (NO SILICA) on the tank, but the permanent marker was not so permanent. 😞

G12evo coolant is pretty pricey, so the additional parts cost of changing the relatively cheap expansion tank isn't prohibitive, if you're going to change the coolant anyway. However if you're 100% sure the silica bag was removed intact and without having leaked any silica into your coolant system, it's a cost you could potentially avoid.

Of course it might be that the previous owner replaced the coolant with G12evo when they removed the silica bag, in which case you don't need to do anything.

 

If I were you, I'd get a torch and have a very good look inside that expansion tank. I'd be looking for the silica bag, but also for any evidence of any sediment of any description in the tank. I've uploaded a pic of my expansion tank with the silica bag in-situ prior to me fishing it out, but the silica container can vary. (Just for the hell of it I've also uploaded a pic of my engine bay, because it's so clean and lahverly. )

If there was no silica bag and no sediment, I'd play it safe and change the coolant to G12evo and be glad someone else fished the silica bag out so I didn't have to.

If I found the silica bag, I'd uhm and ahh about deciding whether to fish the silica bag out or just change the expansion tank for one without a silica bag. Then I'd go with whatever I decided after all the uhming and ahhing and also change the coolant to G12evo.

If there was any trace of sediment in the expansion tank, probably be asking for advice on whether it was worth flushing the coolant system before changing the coolant to G12evo.

 

Edited 12 April, 2023 by EnterName
Corrected spelling of "Silikat"

[benterrier]

Checked bottle again definitely no bag, although says G13 mit silikat.

Think mine is a revised bottle, small tube running vertical could be the silikat reservoir.

[benterrier]

Although the car has done 28k miles it is coming up to 5 years old and Skoda dealer recommended cambelt and water pump change. Be interesting to see if they put what kind of coolant they use 

[EnterName]

43 minutes ago, benterrier said:

Checked bottle again definitely no bag, although says G13 mit silikat.

Think mine is a revised bottle, small tube running vertical could be the silikat reservoir.

Maybe it's this type of expansion tank?

 

[benterrier]

Hells bells, so the bag is not accessible from the filler cap. Will see about getting a replacement I think.

Thanks Enter 

[RoddersUK]

Oh wow, I thought the bag was visible in the middle and mine was removed! 

How have people been removing theirs?!

 

I guess I won't be able to see where that person's was....

 

Spose I better get a new expansion bottle....

 

 

Just to clarify, no silica bag means you need g12evo, or the new expansion bottle has silicat in a vertical plastic tube, which someone mentions could be the case above?

 

Edited 12 April, 2023 by RoddersUK

[hhcd80]

Didn't I read somewhere on here or elsewhere that the double skinned tanks were less likely to simply dump silica into the heater matrix or am I misunderstanding?

For the record, I can't see any sign of the silica bag in the coolant tank in my Octy Mk3 and the coolant is still a vibrant pinkish-orange but it does look like the double skinned tank variant.

[benterrier]

Got to say from the video of the cut in half bottle that the bags strength looks substantial.

As long as reports about using a bottle with no bag and switching to G12 Evo coolant haven't thrown up any problems I will be taking this option.

My opinion, if this bag does rupture a bill for replacing the heater matrix will be very expensive.

The manufacturer will not say there is a problem here but have thought it necessary to upgrade bottles to keep this bag in the system and prevent major engine corrosion. 

[EnterName]

9 hours ago, benterrier said:

Hells bells, so the bag is not accessible from the filler cap. Will see about getting a replacement I think.

Thanks Enter 

 

8 hours ago, RoddersUK said:

Oh wow, I thought the bag was visible in the middle and mine was removed! 

How have people been removing theirs?!

There really are a variety of expansion tanks and silica bags, and it might be that @benterrier's bag isn't the same as the one in the video.

I mean, they all look pretty much the same.

But back to my original question: "What is the problem you're trying to solve?"

I submit that the problem is worrying about the silica bag splitting.

In which case, the least worry and fewest variables option is to have the expansion tank changed to a non-silica tank, and replace your coolant with G12evo. That's the problem sorted forever.

 

8 hours ago, hhcd80 said:

Didn't I read somewhere on here or elsewhere that the double skinned tanks were less likely to simply dump silica into the heater matrix or am I misunderstanding?
For the record, I can't see any sign of the silica bag in the coolant tank in my Octy Mk3 and the coolant is still a vibrant pinkish-orange but it does look like the double skinned tank variant.

Yeah, I've read that too. Seems reasonable, but I don't know for sure that whatever makes the silica bags split isn't an issue for the double-walled expansion bottles.

Maybe it's because the silica gets trapped in the double-wall construction of the expansion tank when the bags split.

One of the guys at work was telling me about his 2015 Audi A3 that had had the dreaded "Like half my heating in the car don't work." issue. He had the heater matrix replaced under warranty, but then the problem later returned and he had to resolve it at his own cost. He knew his problems were caused by some sort of silica bag issue, but wasn't really interested in the precise cause of the problem or the preventative solution. (For all I know, he now has a new expansion tank with a new silica bag in.)

My point is, that people who are both aware of the issue and look into the cause and preventative options for mitigating the risk, are a tiny subset of VAG vehicle owners, so collecting data on the issue is difficult. I would guess the safest silica option is the cartridge type silica container, and even they fail. https://forums.ross-tech.com/index.php?threads/8529/

Once you're aware of the silica bag problem, for people like me, it's always going to be a little niggling worry in the back of my mind, and I have more than enough of those already. So once I understood the issue, I fished my bag out and replaced the coolant. I understand the "Out of sight, out of mind." perspective with double-walled expansion tanks means fishing the bag out isn't an option. (It can be done, but there's a good chance you'll split the flipping thing trying to fish it out.)

 

The easiest option is to do nowt. There's a fair chance you'll be alright and won't have a problem.

The safest option is to remove the silica bag from the expansion tank (or replace the tank if you can't) and replace all the coolant with G12evo.

 

As Cilla might have said on Blind Date: "Will you go for contestant number one, who's free and easy but offers no guarantees, or contestant number 2, who'll give you peace of mind, at a price? The choice...is yours!"

2 minutes ago, benterrier said:

Got to say from the video of the cut in half bottle that the bags strength looks substantial.

As long as reports about using a bottle with no bag and switching to G12 Evo coolant haven't thrown up any problems I will be taking this option.

My opinion, if this bag does rupture a bill for replacing the heater matrix will be very expensive.

The manufacturer will not say there is a problem here but have thought it necessary to upgrade bottles to keep this bag in the system and prevent major engine corrosion. 

You beat me to it while I was busy writing my latest "War and Peace" post.

 

[EnterName]

Also, while I'm here I'll post this, because it's such a handy graphic.

 

[rum4mo]

@EnterName, where did you get the sticky label denoting that G12evo 50/50 was in that cooling system?

 

Ah, I think that you just cut a bit of the sticky labelling on the bottles, why didn't I think about doing that! (still I do have 4 bottles still in the garage, so I'll consider doing that)

[EnterName]

1 minute ago, rum4mo said:

@EnterName, where did you get the sticky label denoting that G12evo 50/50 was in that cooling system?

 

Ah, I think that you just cut a bit of the sticky labelling on the bottles, why didn't I think about doing that! (still I do have 4 bottles still in the garage, so I'll consider doing that)

That's exactly what I did.

 

[EnterName]

Here's a video of a guy changing his expansion tank. Even with the tank removed, he can't see the silica bag, but it can be heard (he says) when he shakes the removed bottle.

Doesn't look like a big job to simply remove the tank, replace with e new tank and top it up with fresh coolant if needed, with a plan to replace the coolant for G12evo (if applicable for your engine) in due course. This thrifty guy reused his coolant from the old tank, which he'd drawn out before removing the tank. Cost was just the tank.

 

 

Edited 13 April, 2023 by EnterName
Forgot the flipping link to the video!

[RoddersUK]

I'm def going to do this, just in case I can't see the bag!

[RoddersUK]

OE only or something like this ok?

 

 

[EnterName]

2 minutes ago, RoddersUK said:

OE only or something like this ok?

 

 

I'd love to say "Yeah, that looks fine!" but I really don't know enough about any possible subtle differences between the expansion tanks, particularly as there's some sort of a sensor within the tank.

Someone on here is likely to know for sure, but your preferred Skoda dealer should be able to tell you which part you need for your specific vehicle, if you give them a call.

It might well be they're all the same and it's not an issue. But I can't confirm that is the case, and telling you otherwise would expose you to the risk of a wasted purchase.