Coolant flush guide

[xPeTeRx]

Hi there

I would like to change the coolant in the system but don't know which hose I need to disconnect from the radiator as there are 3 I see, 2 on the driver's side and 1 on the passenger's side.

Is there a guide or a video showing me which hose I need to disconnect and the steps I need to take to flush it with water before refilling the tank with coolant?

Thanks in advance for any responses I receive

 

[SuperV8]

Have a read of the official workshop engine manual found here:

General maintenance - Leon Mk3 Official Seat Workshop Manuals Link

Hi All! I obtained these a few months ago, and they've been a great use so far. Here's a link to all of the Seat Workshop manuals for the Leon Mk3 3dr/5dr. https://drive.google.com/drive/folders/1M4ofxxMgsFjE7hNWg6l4KuifelmdMUu0?usp=sharing...

www.seatcupra.net

Cooling system 19 - 1.6 & 1.7 flushing cooling system.

 

[xPeTeRx]

Wow thanks for this, there are several documents there and I can't find the one you're suggesting...

Cooling system 19 - 1.6 & 1.7 flushing cooling system

Any ideas where I can find it ?
Thanks

 

[SuperV8]

The cooling system is covered in the 'engine' manual. Pick the one that suits your engine. TDI or TSI - guessing TDI?

 

[xPeTeRx]

The cooling system is covered in the 'engine' manual. Pick the one that suits your engine. TDI or TSI - guessing TDI?

TSI..

There are so many manuals there...and within each manual there is a lot of info.

I'm starting by looking at which hose to remove from the radiator to flush the coolant...is it the hose on the passenger side of the radiator or the drivers side...

 

[SuperV8]

Which TSI?

 

[xPeTeRx]

1.2

 

[SuperV8]

So looking at this manual:
Just remove under-tray, both lower hoses, and the filler cap.
To flush some water through I would connect my hose upto the lower pipe from the header tank.

 

[RUM4MO]

I'd suggest that you buy new O-rings for any "quick release" hose you remove, the retaining spring should still be okay though, these hose ends might not be as easy as you would think to get back on and locked in place - well that was the case for me on my 2011 Audi S4, after refitting these hoses really do pull them well enough to dislodge any that are not fully locked in place.

Ideally all these newer engines need the coolant system to be vac'd down by coolant refill vacuum kit, then that kit is used to reflood the system, I've just done that job on my 2011 S4, it all went very well except for getting the "quick release/quick fit" to lock correctly first or even 10th time, very annoying!

You really should spend some time reading through that workshop manual document as it will advise you exactly how to achieve this with minimum possibility of ending up damaging your engine due to localised overheating, coolant changing, it seems has become a bit more of a "fine art" than what it used to be.

Personally, I'd just try to rinse out the base of the radiator as that is where any iron fall out will have landed and stayed out of suspension in the coolant.

VW Group parts departments sell the genuine latest G12evo in one litre containers premixed to 50% for £7.13 inc VAT a container - well that price was from a month ago, the previous coolant, G13 should now not be available from VW Group outlets, which is a good thing - I think.

I can't advise you on the capacity of that system, but if I was you, I'd be doing what I did and that was to collect all the coolant you drain out and measure it, I'm suggesting that you do that for two reasons, firstly you will know how much new coolant to buy, and secondly, you will know when you have managed to get enough coolant back into the system so that you can safely run the engine to let it purge out the remaining air still lodged in the system.

 

[xPeTeRx]

So looking at this manual:
Just remove under-tray, both lower hoses, and the filler cap.
To flush some water through I would connect my hose upto the lower pipe from the header tank.
View attachment 27920

View attachment 27921

View attachment 27922

Thanks so much for your help...I did eventually find those pages prior to you posting but nevertheless I'm grateful for you validating my findings. Couple of questions for you.

In the first diagram you posted

I assume thats me looking at my bonnet head on? As that is where my expansion bottle would be, ahead of the steering wheel?

If #11 is the actual radiator I need to remove the hoses from, what is #13? Is that to do with AC system?

In the step by step pictures, presumably that's showing item #11 in the diagram? As both item #11 and #13 have two hoses on them.

Regarding flushing the system with water, I understand I cannot use tap water to do this, just distilled water that I need to purchase?

Also when flushing the system with fresh water, where do I put the garden hose? In which one of the two exposed hoses?

Really appreciate your guidance and support. Thanks so much

 

[xPeTeRx]

I'd suggest that you buy new O-rings for any "quick release" hose you remove, the retaining spring should still be okay though, these hose ends might not be as easy as you would think to get back on and locked in place - well that was the case for me on my 2011 Audi S4, after refitting these hoses really do pull them well enough to dislodge any that are not fully locked in place.

Ideally all these newer engines need the coolant system to be vac'd down by coolant refill vacuum kit, then that kit is used to reflood the system, I've just done that job on my 2011 S4, it all went very well except for getting the "quick release/quick fit" to lock correctly first or even 10th time, very annoying!

You really should spend some time reading through that workshop manual document as it will advise you exactly how to achieve this with minimum possibility of ending up damaging your engine due to localised overheating, coolant changing, it seems has become a bit more of a "fine art" than what it used to be.

Personally, I'd just try to rinse out the base of the radiator as that is where any iron fall out will have landed and stayed out of suspension in the coolant.

VW Group parts departments sell the genuine latest G12evo in one litre containers premixed to 50% for £7.13 inc VAT a container - well that price was from a month ago, the previous coolant, G13 should now not be available from VW Group outlets, which is a good thing - I think.

I can't advise you on the capacity of that system, but if I was you, I'd be doing what I did and that was to collect all the coolant you drain out and measure it, I'm suggesting that you do that for two reasons, firstly you will know how much new coolant to buy, and secondly, you will know when you have managed to get enough coolant back into the system so that you can safely run the engine to let it purge out the remaining air still lodged in the system.

Thank you for taking the time to share your knowledge.

Where do you buy replacement O Rings? I'm based in London, UK...

Yes, that coolant refill vaccum kit is £400, whilst I appreciate its benefits and it's security , I'm just a newbie DIYer who has a passion and enthusiasm for learning, that's a lot of outlay for a single that job. And oh trust me, I've spent a lot of time reading these manuals and am enjoying what I'm discovering.

Yes absolutely that's what I'm trying to do to, rinse out from the base of the raidator and then flush the system before refilling.

What measuring device did you use to measure all the dirty coolant you drained out?

Thanks for your help

 

[SuperV8]

Thanks so much for your help...I did eventually find those pages prior to you posting but nevertheless I'm grateful for you validating my findings. Couple of questions for you.

In the first diagram you posted

I assume thats me looking at my bonnet head on? As that is where my expansion bottle would be, ahead of the steering wheel?

If #11 is the actual radiator I need to remove the hoses from, what is #13? Is that to do with AC system?

In the step by step pictures, presumably that's showing item #11 in the diagram? As both item #11 and #13 have two hoses on them.

Regarding flushing the system with water, I understand I cannot use tap water to do this, just distilled water that I need to purchase?

Also when flushing the system with fresh water, where do I put the garden hose? In which one of the two exposed hoses?

Really appreciate your guidance and support. Thanks so much

1# Yes, but bear in mind it's just a schematic showing pipe routing - so actual placement of parts might be off a little.
2# 13 is the charge cooler radiator - also has coolant in it.
3# The official guidance is only use distilled water BUT i'm sure most just use tap water and unless you live in a very hard water area i'm sure it will be fine.
4# With to 2x lower radiator connections removed - I would either put your hose gun in the header tank and fill, or like I mentioned previously disconnect the lower hose from the header tank and connect your hose directly to that hose. I would disconnect each of the 2x lower radiator hoses at a time, then reconnect, to try to minimise air getting in the system.

 

[RUM4MO]

New O-rings from a SEAT dealership, or contact CCP otherwise called Coverdale Car Parts and he will source and send them out to you, I've used Mike quite a few times.

My Coolant Vacuum Refill Kit is a Draper one aimed mainly at DIYers I'd think, so more like £80 which is still a chunk of cash, though I plan to change the coolant on a couple of more cars within the next few years, so still cheaper than paying someone to do it for me! Also, "bonus" is, I've always fancied buying an air compressor, just a small one, buying that cost under £100 it is only fit for air dusting, inflating tyres and for use with this Draper vacuum kit.

Measuring with enough accuracy, I bought a kitchen ware plastic jug - a 1litre capacity one, I already had quite a few ex distilled water 5 litre containers that I saved from going into landfill years ago - I grabbed them initially to save the coolant from my central heating system as it was dosed up with central heating anti freeze which was still under a year old and when I bought this house I wanted to sort out some piping that was not adequate, so some were still empty unused and so available. I marked 3 of them up into litre level marks. Even buying these online is very cheap, I also bought a 10 litre container to dump all the new coolant into because when refilling a system that is under vacuum, you just should not really stop during the process, that was also very cheap.
Collecting the old coolant, I bought a new plastic bucket from Screwfix, I think that it is maybe a 12 or 14 litre one which makes it quite low in height, it was seriously cheap as was the plastic funnel I bought with it for decanting the old coolant into the 5 litre containers - really mainly to quantify the volume and to hold onto it in case I ended up with serious leaks after having taken the pipes apart, ie to use until everything was water tight if it started off not being - really belt and braces approach I suppose - too much time on my hands as I'm retired!

Because I did that job on an Audi S4, I had the extra "bonus" of needing to fabricate a "coolant level raiser" to temporarily raise the coolant level in the reservoir up beyond the supercharger heat exchangers and the cabin heater pipes! That is not an issue on most other cars though!

 

[xPeTeRx]

1# Yes, but bear in mind it's just a schematic showing pipe routing - so actual placement of parts might be off a little.
2# 13 is the charge cooler radiator - also has coolant in it.
3# The official guidance is only use distilled water BUT i'm sure most just use tap water and unless you live in a very hard water area i'm sure it will be fine.
4# With to 2x lower radiator connections removed - I would either put your hose gun in the header tank and fill, or like I mentioned previously disconnect the lower hose from the header tank and connect your hose directly to that hose. I would disconnect each of the 2x lower radiator hoses at a time, then reconnect, to try to minimise air getting in the system.

Thanks for the this...

#2...even though #13 the charge cooler radiator has coolant inside it, that's not be flushed? And looking at it head on #13 would be ahead of the steering wheel on the driver side?

What is the difference between the charge cooler radiator and the radiator? Is the charge cooler radiator for the AC only and the radiator for the heater?

#4 you introduced a new term, header tank, do you mean the expansion tank as referred to in the guide you posted? I don't quite understand yet what you mean about how to connect to the hose...hmmm

 

[xPeTeRx]

New O-rings from a SEAT dealership, or contact CCP otherwise called Coverdale Car Parts and he will source and send them out to you, I've used Mike quite a few times.

My Coolant Vacuum Refill Kit is a Draper one aimed mainly at DIYers I'd think, so more like £80 which is still a chunk of cash, though I plan to change the coolant on a couple of more cars within the next few years, so still cheaper than paying someone to do it for me! Also, "bonus" is, I've always fancied buying an air compressor, just a small one, buying that cost under £100 it is only fit for air dusting, inflating tyres and for use with this Draper vacuum kit.

Measuring with enough accuracy, I bought a kitchen ware plastic jug - a 1litre capacity one, I already had quite a few ex distilled water 5 litre containers that I saved from going into landfill years ago - I grabbed them initially to save the coolant from my central heating system as it was dosed up with central heating anti freeze which was still under a year old and when I bought this house I wanted to sort out some piping that was not adequate, so some were still empty unused and so available. I marked 3 of them up into litre level marks. Even buying these online is very cheap, I also bought a 10 litre container to dump all the new coolant into because when refilling a system that is under vacuum, you just should not really stop during the process, that was also very cheap.
Collecting the old coolant, I bought a new plastic bucket from Screwfix, I think that it is maybe a 12 or 14 litre one which makes it quite low in height, it was seriously cheap as was the plastic funnel I bought with it for decanting the old coolant into the 5 litre containers - really mainly to quantify the volume and to hold onto it in case I ended up with serious leaks after having taken the pipes apart, ie to use until everything was water tight if it started off not being - really belt and braces approach I suppose - too much time on my hands as I'm retired!

Because I did that job on an Audi S4, I had the extra "bonus" of needing to fabricate a "coolant level raiser" to temporarily raise the coolant level in the reservoir up beyond the supercharger heat exchangers and the cabin heater pipes! That is not an issue on most other cars though!

How much coolant does your car take? I'm confused is this your Audi S4 or a Seat Leon MK3 you're referring to?

Thanks for the heads up on the O Rings I will check it out.

Do you have any links to videos of someone using the vaccum kit to flush the coolant on a Leon MK3?

Thanks a lot

 

[RUM4MO]

I was mainly making reference to what I did on my S4, but most of it carries across to all these newish engines.

Maybe you should search using Google for "changing coolant in a SEAT Leon MK3, when I last looked, the internet was awash with these guides, there were quite a few for my B8 S4 and I'd be surprised if there are not any for this SEAT Leon MK3 1.2TSI or maybe even the VW Golf same age or Skoda Octavia same age.

Coolant capacity, I only know the capacity of my B8 S4 and that became obvious only when I drained it down, someone in another forum quoted refilling a B8 S4 with 6 litres so I bought in more than that. I could not find that capacity figure anywhere in the official Audi workshop manual, so I'd doubt if you will find it the one your were given a link to, which I found a bit annoying, why VW Group leave out that bit of info I can't say.

The one reason that I did not perform a full flushing with a hose followed up with reloading with warm/hot water and taking the car on a short trip, then dumping the water and backfilling with G12evo was, I was concerned that for the first time in my life, I could only buy ready mixed coolant from VW Group, and if I had left water in the system after flushing it out, ie did not manage to remove as much of the water as possible, I would have ended up having a lower strength coolant mix than I had intended to have.

By the way, to answer one of the questions you asked SuperV8, the charge cooler is the turbo charged air water/air intercooler on the inlet manifold, it has its own electric fan and it is separated flow wise from the common coolant circuit as the plan is to get the rest of the engine up to temperature as quickly as possible - but dumping accumulated/acquired heat out of the inlet air is desirable at all times.

Edit:- I'd be the first to acknowledge that some people will just be ploughing straight in and opening up these coolant systems and then refilling them with as much coolant as possible - and getting away with it, but why bother to take that risk if you are asking questions on how it is done.

I think that VW Group are quite laid back or secretive about exactly how long the factory loaded in coolant should be left in the system, I bought a pack of test strips in from America to check over my cars as for the first time in my life I've owned a car with a cam belt - and a separate water pump belt, and a car with a cam chain, prior to that all our cars had a water pump driven off the cam belt or behind the cam belt which meant the smart thing to do was to get the water pump and so coolant replaced every cam belt change or every other cam belt - so the coolant ended up being replaced at worst/longest every 8 - 10 years. My 2011 S4 is obviously now over 10 years old, so that is why I chose to replace the coolant. By the way, the test strips ended up getting too old to be trusted but I could see a change in the PH value which indicates that the coolant is degrading from being slightly alkaline towards being acidic and when that happens the corrosion protection has dropped. When you look at any other company selling that same coolant, all of which in VW Group world is manufactured by BASF, every single previous to G12evo product that appears in the aftermarket, quotes a service life of maybe 3 years, now maybe that is just to keep the aftermarket suppliers in business, or is there another reason that we don't know about?

Another Edit:- then for cars that were filled up with G13 at the factory and have not got a "silicate top up pouch/capsule" in the reservoir - what is expected to be going on in these systems, I'd think that there there will be "early" protection depletion and so corrosion will kick in, another reason why I'm considering replacing what will be G13 in the cooling system of my wife's late July/early August build 2015 VW Polo, for the G12evo I seem to have left over from changing the coolant in my early February 2011 build S4 to G12evo. I just need to read through the recommendations for doing that job in my official VW Polo workshop manual - and not just jump in and pull hoses off etc!

 

[SuperV8]

Thanks for the this...

#2...even though #13 the charge cooler radiator has coolant inside it, that's not be flushed? And looking at it head on #13 would be ahead of the steering wheel on the driver side?

What is the difference between the charge cooler radiator and the radiator? Is the charge cooler radiator for the AC only and the radiator for the heater?

#4 you introduced a new term, header tank, do you mean the expansion tank as referred to in the guide you posted? I don't quite understand yet what you mean about how to connect to the hose...hmmm

The charge cooler radiator also uses the same coolant and so should also be flushed. This is just a heat exchanger (radiator) for your inlet air cooler. Nothing to do with your AC.

Yes by header tank = expansion tank - the tank with the cap where you check/fill your coolant.