Expansion bottle replacement

[OldBoyScout]

19 hours ago, varaderoguy said:

As far as I can tell, the issue of whether you have a Silica bag in your header expansion tank seems to be completely random.

 

On the Golf thread it says:  "this silicon bag is only found in cars with climate control fitted from the factory"

[varaderoguy]

Yerr...in the land of Mlada, I think this may not always be true. All our vehicles have Climate Control, only two have Silicia bags in them.

[varaderoguy]

9 hours ago, Dellbert said:

Maybe diesel only cars ?

 

I am begining to wonder if there is a problem with sand left in the castings ?

Err nope....the VRS is a petrol car. Sorry.

[Bap33]

On 18/08/2020 at 18:33, Bap33 said:

Hi all,

We've been doing the oil replacement with my father on his Octy 3 1.8 TSI engine (MY2018). Everything went fine until I noticed a very dirty coolant tank 😨:

 

 

The coolant looks strongly contaminated:

 

 

Unfortunately, the warranty has ended up during the lockdown in may.

 

I've read the 8 pages of this thread. The P/N of the tank is 5Q0 121 407G. I haven't plunged my finger in the tank to check if there's any residue of the silikat bag. After a quick glance, there don't seem to be any bag at all. The tank seem to be like this:

 

 

But the level sensor has plastic covered electrodes. 

 

I've checked on ifinterface.com (online ETKA), the coolant tank P/N has been replaced by 5T0 121 407T

 

I've several questions:

1) We intend to completely flush the coolant system to get rid of the contaminants and to clean it proprely, before replacing the coolant fluid. Does this make sense to you guys?

2) What would be the gain, to change the coolant tank by a newer version, since there's no bag anymore on this G version?

 

Please advise. Thanks.

 

Hi all,

 

Getting back to this post... Here are some news. My father has finally replaced the coolant tank and changed the coolant fluid.

Step 1: poor some cleaning agent in the tank and follow instructions (usually drive ~50km)

Step 2: scavange the old dirty fluid. Note: Use of a compressor (set @ 1.2 - 1.4 bar max) will help a lot to flush the remaining coolant in the radiator completely.

Step 3: remove the old coolant tank and clean it (white alcool vinegar helps removing the main deposits on the tank walls.)

Step 4: Put old tank back in place.

Step 5: Fill the cooling system with demineralized water.

Step 6: Run the engine long enough to let the demineralized water go into all parts of the system

Go to step 2 and repeat 2-3 times. (steps 3 & 4 can be skipped, when repeating the process).

Step 7: Remove the old tank

Step 8: Install the new tank (5Q0 121 407T - without any silikat bag in it).

Step 9: Fill with 7.6l of G13. Note: Actually P/N of a 5l can is G12E 040 A3. It's already diluted to resist down to -25°C. That's fine four our west european latitudes. 

 

Everything looks OK now. He will still check the coolant color some time to time... 

 

Some pics:

Old tank before cleaning:  

 

Old coolant (No, it's not apricot juice! ):

 

Old tank, and its bl**dy silikat bag:

 

New tank ('mit Silikat' indication has disappeared):

 

New coolant can:

 

Hope this helps...  

Take care and stay safe.

 

 

 

 

[Dellbert]

notice the coolant is now g12 again after the upgrade to g13  ....

[MeteorOcty]

Just had my tank replaced (2014 diesel vrs) as a precaution. Couldn't be bothered to do it myself so got the dealer to do it whilst it was in for service, cost me £70. Its the 'M' revision and doesn't even have to G12 or G13 stamped on it anymore!

[varaderoguy]

10 hours ago, Dellbert said:

notice the coolant is now g12 again after the upgrade to g13  ....

Okay - I don't know why folk are going to G12 again; that doesn't seem right.

G13 can be used in place of G12 and its variants.  You can mix G12+ and ++ with G13 without any issues too.

Edited 12 October, 2020 by varaderoguy
updated info

[bigade1]

@Bap33

 

On 11/10/2020 at 22:35, Bap33 said:

I've checked on ifinterface.com (online ETKA), the coolant tank P/N has been replaced by 5T0 121 407T

 

Being curious and a bit confused with the part number revisions I took a look at Ifinterface.com and even though logically the letter T comes after M in the alphabet I have concluded that 5Q0121407M is in fact the latest part revision. Well according to Ifinterface.com that is. If you locate the original part number 5Q012140G on Ifinterface.com it states " Dropped on 01/02/2019 please use as replacement " : 5Q0121407T  but more importantly if you then click on the part number 5Q0121407T ( which I suspect is what you failed to do ) a further message states " Dropped on 01/02/2020 please use as replacement " : 5Q0121407M. So the T revision was introduced in February 2019 but the M revision was introduced exactly a year later in February 2020. Hopefully there's not a lot of difference between them. Perhaps it's just the outside wording. My M revision doesn't have the words " Mit Silikat " or  " G13 " embossed on it. 

[Bap33]

@bigade1 You may be right for the M version being the latest version. However the « mit Silikat » mention had already disappeared on the T version, which seems to me the most important. 😉.

[Dellbert]

UPDATE ON MY ISSUE .

 

My car had a flush and replacement heater matrix and water pump . Unfortunately the coolant went a very muddy brown colour again resulting in the car going back to the dealer  on 24th October

The car has been flushed numerous times (i was told 4 ) and the problem is still occuring , i was told that it was reccomended by Skoda to flush the system up to 14 times to to remove contaminants (can anyone confirm this )

The silica bag is intact (i have checked this ) so the only thing i think it can be is silica (or sand ) in the block from the casting process .

 

   Any thoughts ?

[PetrolDave]

13 hours ago, Dellbert said:

i was told that it was reccomended by Skoda to flush the system up to 14 times to to remove contaminants (can anyone confirm this )

WOW! 14 sounds a very large and pretty random number?

[Guest J_D]

Just trying to think how many times mine has been in!

September-19 on 2 separate dates for flushing, 1 of the visits the car was with them for a week and was flushed multiple times each day. Heat went again. 

I believe it went back in October for a further flush and coolant refill. Heat went again. 

June 2020 it was back again for a day or two. My understanding is that everything that could come off the car this time was taken off the car and hand cleaned after some more flushing. 

 

The garage were fantastic with redoing the work over and over and the final time in June seems to be working. I still have heat from my vents!

 

It is worth noting that the replaced expansion tank by the garage had the silica bag in it again (likely because that was the given part number at the time) but I've replaced since for the one without. 

 

So I can believe that the flushing takes multiple attempts to get it right!

 

I have a spare matrix at home, Rev B, which I believe has slightly wider channels. However the heater matrix doesn't require replacing atm, although it is likely I'll swap it out when the car coolant is next changed to ensure any final remnant's are removed. 

 

 

 

[foregonereality]

On 18/10/2020 at 10:26, Bap33 said:

@bigade1 You may be right for the M version being the latest version. However the « mit Silikat » mention had already disappeared on the T version, which seems to me the most important. 😉.

 

That was some work Bap! Well done!

 

Was the old silica bag pierced or was it still fully intact? I ask as I've changed my tank to a bagless revision and I'm dreading the same thing happening to my car.

[Dellbert]

2 hours ago, J_D said:

Just trying to think how many times mine has been in!

September-19 on 2 separate dates for flushing, 1 of the visits the car was with them for a week and was flushed multiple times each day. Heat went again. 

I believe it went back in October for a further flush and coolant refill. Heat went again. 

June 2020 it was back again for a day or two. My understanding is that everything that could come off the car this time was taken off the car and hand cleaned after some more flushing. 

 

The garage were fantastic with redoing the work over and over and the final time in June seems to be working. I still have heat from my vents!

 

It is worth noting that the replaced expansion tank by the garage had the silica bag in it again (likely because that was the given part number at the time) but I've replaced since for the one without. 

 

So I can believe that the flushing takes multiple attempts to get it right!

 

I have a spare matrix at home, Rev B, which I believe has slightly wider channels. However the heater matrix doesn't require replacing atm, although it is likely I'll swap it out when the car coolant is next changed to ensure any final remnant's are removed. 

 

 

 

so are you convinced it was a bag problem or a casting sand problem ?

[Bap33]

@foregonereality I deserve no congratulations. It was my dad's work...  

He told me the bag was OK. It has only torn of when he tried to cut the tank in 2 pieces.

Edited 3 December, 2020 by Bap33

[Guest J_D]

I'm convinced it was the bag. The car is from 2014 and didn't have any issues until 2019 with the heating. I imagine casting sand would've been apparent before then. 

[Dellbert]

5 minutes ago, J_D said:

I'm convinced it was the bag. The car is from 2014 and didn't have any issues until 2019 with the heating. I imagine casting sand would've been apparent before then. 

 

 Well mine had no issue for 3 years allegadly

Edited 3 December, 2020 by Dellbert

[Dellbert]

cant add a pic

 

[Dellbert]

This is whats running around my coolant system

[foregonereality]

4 hours ago, Dellbert said:

This is whats running around my coolant system

 

That looks like muck, not silica. Might it be worth getting it analysed at a lab to verify its contents - reason being that if it's a manufacturing defect then surely the onus would be on vag to fix the problem without cost to you?

[cheezemonkhai]

Yep that does look a lot more like casting sand or muck than silica.

 

As above, I would consider sending it to a lab to confirm what it is.

 

Edited 4 December, 2020 by cheezemonkhai

[Tivan]

My car was at the dealer about 4 or 5 times regarding coolant changing color (quickly) from pink to brown. It was already like that when I purchased the car and luckily warranty was still active. Over a year they were trying to fix it. Flushed countless of times, changed thermostat, EGR cooler, expansion tank, heater matrix. Last thing they changed was front radiator and since then coolant color is great. However I did notice that during this last fix they also changed (again) expansion tank and now it has silica bag in it. I am a bit conflicted what to do with it. Car is now out of warranty of course.

Edited 4 December, 2020 by Tivan

[Dellbert]

6 hours ago, foregonereality said:

 

That looks like muck, not silica. Might it be worth getting it analysed at a lab to verify its contents - reason being that if it's a manufacturing defect then surely the onus would be on vag to fix the problem without cost to you?

What sand do you use for casting?

Silica sand

 

Silica sand is the most commonly used sand because of its great abundance, and, thus, low cost (therein being its greatest advantage). Its disadvantages are high thermal expansion, which can cause casting defects with high melting point metals, and low thermal conductivity, which can lead to unsound casting.

[Dellbert]

11 hours ago, Dellbert said:

This is whats running around my coolant system

That was colected by an inline filter in 48 hours after the vehicle was flushed nd clean

[cheezemonkhai]

The silica in the bag was clean almost clear in colour,  hence the thoughts on casting sand.