So gonna change my coolant expansion tank next week as just ordered a cheap one of eBay  with out silicon and  with a cap( why do so many sell them without cap??)
Unfortunately my existing tank is re inforced with extra plastic so no chance of getting it out with plyers.
I've always used Prestone for coolant and have a few litres worth in my shed, was hoping that would suffice if I was to flush all the old stuff out ???
What's the best way to flush it out on a VAG ?? Last time I did similar was about 10 years ago on a Mondeo. Just detached one of the pipes and ran water thru it for 15 mins to clear out as much of the old stuff. Would that method suffice this time around ??? 

Cheers for reading and thanks in advance for any advice given 👍👍

Hi,

As i understand ,coolant change in mk3s should be done with a vacuum/pressure device that prevents air in the coolant system. Seems complicated. I suck a half liter of coolant out from the expansion tank with a hose everytime i change oil and filter. 

20 hours ago, Octavia64 said:

ordered a cheap one of eBay 

Why replace a decent genuine part with a cheap one that could and do just split for fun along their seams? A genuine one with no silicat bag is only £30

 

20 hours ago, Octavia64 said:

why do so many sell them without cap

They are two separate parts and dont fail together, why change both when only one is the problem? Also be wary of fitting an aftermarket cap as they may have different pressure ratings than what is meant for the car. 

 

20 hours ago, Octavia64 said:

Unfortunately my existing tank is re inforced with extra plastic so no chance of getting it out with plyers.

Annoying that some are like this, have you double checked the bottle says 'mit silikat' as some dont have the bag if you cant see it

 

20 hours ago, Octavia64 said:

I've always used Prestone for coolant and have a few litres worth in my shed, was hoping that would suffice if I was to flush all the old stuff out

Why would you get rid of all the genuine coolant that offers the maximum protection and replace it with some universal stuff that definitely will not offer the same protection. Instead just clamp the pipe off when you replace the bottle and top up with 1L of genuine G12evo coolant which is the newest revision and saves you draining all the good coolant to replace with non compatible stuff. (Also mixing certain coolants can cause a world of problems). you would have to fully flush the system  with water before adding a different coolant. 

 

20 hours ago, Octavia64 said:

What's the best way to flush it out on a VAG

Using the above method will prevent any need to bleed the system. But if for some reason you still go ahead with a full drain, then it depends what engine you have. If you have a 1.6 or 2.0 tdi then you will need to correctly bleed it with a vacuum bleeder followed by running the diagnostic bleed routine. Similar process for the 2.0 tsi, for the smaller engines it varies but isn't as complicated. 

2 hours ago, BerkCo said:

Hi,

As i understand ,coolant change in mk3s should be done with a vacuum/pressure device that prevents air in the coolant system. Seems complicated. I suck a half liter of coolant out from the expansion tank with a hose everytime i change oil and filter. 

Why?

Because i dont have the knowledge or tools to accomplish a complete coolant change. So I change it by small amounts on a wider time frame

5 hours ago, ApertureS said:

Why replace a decent genuine part with a cheap one that could and do just split for fun along their seams? A genuine one with no silicat bag is only £30

 

They are two separate parts and dont fail together, why change both when only one is the problem? Also be wary of fitting an aftermarket cap as they may have different pressure ratings than what is meant for the car. 

 

Annoying that some are like this, have you double checked the bottle says 'mit silikat' as some dont have the bag if you cant see it

 

Why would you get rid of all the genuine coolant that offers the maximum protection and replace it with some universal stuff that definitely will not offer the same protection. Instead just clamp the pipe off when you replace the bottle and top up with 1L of genuine G12evo coolant which is the newest revision and saves you draining all the good coolant to replace with non compatible stuff. (Also mixing certain coolants can cause a world of problems). you would have to fully flush the system  with water before adding a different coolant. 

 

Using the above method will prevent any need to bleed the system. But if for some reason you still go ahead with a full drain, then it depends what engine you have. If you have a 1.6 or 2.0 tdi then you will need to correctly bleed it with a vacuum bleeder followed by running the diagnostic bleed routine. Similar process for the 2.0 tsi, for the smaller engines it varies but isn't as complicated. 

 Because the present coolant is designed to function with a silican bag and am removing it. So want coolant that does the job with out a bag. 

My skoda dealer dealer quoted £37, went to Euro £32, so asked a supplier I've used for years and he sells a few hundred per year. £20 incl pp with a 2 year guarantee. 

Am not for scrimping on good engine or mechanical parts. But a plastic tub am not really to concerned about. 

VAG are trying to make as much as possible in aftermarket with there cars and alot of it is nonsense. 

Was told I had to code new battery in, I didn't and it works fine, was told I would have to do similar with a fuel filter, I used the old fashioned way of priming it myself works absolutely fine. 

If genuine VAG is so superior then why did they use the silican bag method in the first place. 

9 hours ago, Octavia64 said:

 Because the present coolant is designed to function with a silican bag and am removing it. So want coolant that does the job with out a bag. 

My skoda dealer dealer quoted £37, went to Euro £32, so asked a supplier I've used for years and he sells a few hundred per year. £20 incl pp with a 2 year guarantee. 

Am not for scrimping on good engine or mechanical parts. But a plastic tub am not really to concerned about. 

VAG are trying to make as much as possible in aftermarket with there cars and alot of it is nonsense. 

Was told I had to code new battery in, I didn't and it works fine, was told I would have to do similar with a fuel filter, I used the old fashioned way of priming it myself works absolutely fine. 

If genuine VAG is so superior then why did they use the silican bag method in the first place. 

The bag is there to increase the service life of the genuine coolant, it will still function without it there, just means it will need changing earlier (based on testing the coolant first of course)

 

No one has said fitting a new battery won’t work without adaptions - but they are there for a reason and that reason is charging profiles, start stop control, battery capacity management. Basically it is used to keep the agm battery charged properly and also to allow the start stop to work at its best, seems you think the people that designed the car are more on a mission to get you than to actually correctly fix the car with their procedures.

 

Ive seen many a coolant bottle split so just keep that in mind - a 2 year warranty does little to help when you are stuck at the side of the road with no coolant 

1 hour ago, ApertureS said:

The bag is there to increase the service life of the genuine coolant, it will still function without it there, just means it will need changing earlier (based on testing the coolant first of course)

 

No one has said fitting a new battery won’t work without adaptions - but they are there for a reason and that reason is charging profiles, start stop control, battery capacity management. Basically it is used to keep the agm battery charged properly and also to allow the start stop to work at its best, seems you think the people that designed the car are more on a mission to get you than to actually correctly fix the car with their procedures.

 

Ive seen many a coolant bottle split so just keep that in mind - a 2 year warranty does little to help when you are stuck at the side of the road with no coolant 

 

Cheers for the heads up👍  

 

Am no mechanic but my first job when I left school many years ago was in a car dealership so I have some idea of how they operate. What goes on in the workshop is not always what is told to the customer. Every dept in the dealership is so target driven all the staff tend to be a bit brainwashed but their is still some that talk sense.

 

They even have customers slightly brainwashed as everyone refers to the anti freeze as coolant. When it's just antifreeze or antitrust really as it's the water element of any product that provides the cooling to any engine. Better watch out as they have recommended water and screenwash soon to 😃 

 

I will keep an eye on the tub, they tend seep for a good while before they split anyway and in the meantime I'll keep a look out for a cheap genuine one on one of the forums. Wasn't having my pance pulled down by the dealer as it's the manufacturers incompetence that I have to replace it in the first place anyway. 

 

This is my 3rd Octavia having previously had a MK1 and MK2:and they are great cars. The previous models didn't have such nonsense of silica bags, coded battery's, etc etc. The manufacturers think such things are progress when in fact they are regressive of the cars appeal of reliability along with simplicity. As I hear they rightly dropped the stupid bag concept in 2019. 

 

All the other mass manufacturers of main stream cars don't have the bag. They also have stop/start and all the technologies VAG have but their batteries don't require coding in. As the ECU simply self regulates itself for the purpose of recharging and maintaining its battery. 

 

We live and learn 👍

2 hours ago, Octavia64 said:

All the other mass manufacturers of main stream cars don't have the bag. They also have stop/start and all the technologies VAG have but their batteries don't require coding in. As the ECU simply self regulates itself for the purpose of recharging and maintaining its battery. 

 

We live and learn 👍

Every other manufacturer with start/stop or AGM batteries requires adapting a new battery. Everything from Land Rover to Hyundai. Do people do it every time? Nope.

 

some it’s done by a combination of buttons on the dash, others by diagnostic tool.

 

Coolant/anti freeze whatever you want to call it, you are correct it is made up of 2 components - water which actually has the heat transfer abilities and then the additive which contains the anti freeze, rust inhibitors, lubricants, colouring and bitrex. The silicat bag is there to slowly deposit the additives back into the coolant mix to extend the coolant life in some cases to 15 years! Without the silicat bag and using the new coolant g12evo you can expect coolant to last easily 10 years. Whereas old coolants contained acids and needed replacing a lot more often.

 

And what you say about customers and staff in dealers being brainwashed is spot on - a lot of the time the staff will push a sale without actually knowing if it’s what people require, simply because they are told to push it 

I took off the return to tank and put that into a waste pot, then as the coolant went down, put the fresh g12evo in.

 

My understanding is the old stuff needs the bag and the new stuff doesn't and you will be prone to corrosion if you don't change.

 

I'm sure my way hasn't completely changed it, I did run 10ltrs through, did 5lts over 2 weekends, so it all mixed through.

 

I don't have the tools etc... To do a full drain and refill, so this was in my mind, my next best choice.

Sounds like an interesting and DIY friendly  way to change coolant. I guess ypu warm the engine up with the expansion tank cap off al the time? From start? 

Yup, I did it that way.

Also had the heating on max temp to open any valves on that pipework, but I think after, someone said it's a constant flow circuit anyway.

 

It's also quite slow, the return flown isn't fast at all!

 

Okey, interesting! I maybe try it in the future. I read somewhere that turning the heat on makes the thermostat open and makes the coolant circulate in those components that otherwise wouldnt be joining to return pipe. 

It would have the opposite effect, thermostat will only open when the coolant reaches the thermostats opening temperature, if you want the coolant to warm up quicker you do not take heat from the system.

 

19 minutes ago, J.R. said:

It would have the opposite effect, thermostat will only open when the coolant reaches the thermostats opening temperature, if you want the coolant to warm up quicker you do not take heat from the system.

 

J.R. what do you think about chanhing some of the coolant with that method? I mean unplugging the return pipe and filling the expansion tank the same amount 

Never had any issues purging VW cooling systems, especially now they get to operating temperature at tickover if you have euro 6.

 

Get as much coolant in and air out as you can while the engine is warming up at tickover, then start pottering about until everything is hot adding coolant as necessary. Don't be surprised if you are still topping up by small amounts for the next month or so so carry a bottle with you just in case.

 

I believe if you had a totally dry engine/radiator and charge cooler system then using a vac filling adaptor would be worth doing and you can get one for around £75. (obviously you need a decent volume of compressed air for this also) But typically just dropping the radiator hose or taking the water pump out only drains part of the systems anyway.

 

Also, IMO use the G12 evo.

 

Edited 1 August, 20232 yr by SuperbTWM

40 minutes ago, SuperbTWM said:

Never had any issues purging VW cooling systems, especially now they get to operating temperature at tickover if you have euro 6.

 

Get as much coolant in and air out as you can while the engine is warming up at tickover, then start pottering about until everything is hot adding coolant as necessary. Don't be surprised if you are still topping up by small amounts for the next month or so so carry a bottle with you just in case.

 

I believe if you had a totally dry engine/radiator and charge cooler system then using a vac filling adaptor would be worth doing and you can get one for around £75. (obviously you need a decent volume of compressed air for this also) But typically just dropping the radiator hose or taking the water pump out only drains part of the systems anyway.

 

Also, IMO use the G12 evo.

 

Cheers 👍

47 minutes ago, SuperbTWM said:

Never had any issues purging VW cooling systems, especially now they get to operating temperature at tickover if you have euro 6.

 

Get as much coolant in and air out as you can while the engine is warming up at tickover, then start pottering about until everything is hot adding coolant as necessary. Don't be surprised if you are still topping up by small amounts for the next month or so so carry a bottle with you just in case.

 

I believe if you had a totally dry engine/radiator and charge cooler system then using a vac filling adaptor would be worth doing and you can get one for around £75. (obviously you need a decent volume of compressed air for this also) But typically just dropping the radiator hose or taking the water pump out only drains part of the systems anyway.

 

Also, IMO use the G12 evo.

 

Great! Do you know a good reliable video tutorial for this procedure?

17 minutes ago, Octavia64 said:

Cheers 👍

Just to clarify, when I said 'start pottering about' i'm refering to driving the car around steadily, not reorganising your stamp collection 😂

 

 

10 minutes ago, BerkCo said:

Great! Do you know a good reliable video tutorial for this procedure?

 

Plenty on youtube that are even VAG specific, there is more than one way to skin a cat mind. If you have VCDS and the 2.0 TDI with the complicated cooling system you can enable the water pump/s manually to try and help burp the system as well.

1 hour ago, BerkCo said:

J.R. what do you think about chanhing some of the coolant with that method? I mean unplugging the return pipe and filling the expansion tank the same amount 

 

I have certainly considered it and its a job I have to do soon as I had to put the wrong coolant in during the confinement after having realised I had filled it with tap water only when I rebuilt the car, the tap water came out clean as a whistle showing that the Silkat works, except my tank is not marked Mit Silkat and I cant see any teabags!

 

My concern is that there would be considerable mixing of old and new, when you start seeing new coolant coming out, if you can even see the difference it will probably be 50/50 new and old, if you do the maths then you could use that method 50 times and still have some of the old coolant remaining, against that when you drain there is a lot left in the engine block etc.

 

I have used the method for adding neat anti-freeze to increase the concentration, I think its what I did last time in fact, if the existing stuff is compatible with the new then I will probably do the same this time.

Thanks for the replies! I was at the dealership an hour ago to buy coolant. Asked them about if they have any  coolant change method( mentioned about the method i refered here as well) or service intervall.  I was baffled by the answer. The service guy told me that i never had to bother changing it, "it is filled for life ". I thought that nothing is filled for life. Life of the car? Is it 10 tears or 15 years? Than what? Junk it? Strange...

2 hours ago, BerkCo said:

Thanks for the replies! I was at the dealership an hour ago to buy coolant. Asked them about if they have any  coolant change method( mentioned about the method i refered here as well) or service intervall.  I was baffled by the answer. The service guy told me that i never had to bother changing it, "it is filled for life ". I thought that nothing is filled for life. Life of the car? Is it 10 tears or 15 years? Than what? Junk it? Strange...

For the TDI's it would be until the timing belt was changed.

15 minutes ago, ords said:

For the TDI's it would be until the timing belt was changed.

I have a 1.6 TDI , cambelt was changed at 140000km , the car is at 180 000 kms So I dont have to think about coolant till next cambelt change at ca 240 000 km ? 

5 minutes ago, BerkCo said:

I have a 1.6 TDI , cambelt was changed at 140000km , the car is at 180 000 kms So I dont have to think about coolant till next cambelt change at ca 240 000 km ? 

In the UK, Skoda recommend a belt change every 5 years, so the water is changed then. I believe that if the car has the silikat bag it extends the working life of the water way beyond 5 years.

The first 5ltr change I did, what returned out pretty much looked like the old stuff. The second lot looked more like the new.

Yes I won't have it all out, but I certainly will have a good % of g12evo in.

 

And it's so easy to do, I could do 5ltr a year when servicing the car, no bother.