Coolant – purge air or drain and change?

[otter148]

Hello,

I've got a Seat Leon Mk3 2014 1.4TSI ST.

I wasn't getting any hot air through my vents so tried purging air out of the system by removing the expansion tank cap and idling the engine for 15 minutes. This seemed to have worked a bit but the coolant fluid began to rise to the brim of the expansion tank so I stopped to prevent any of it overflowing.

Does any overflow matter or should I try removing some of the fluid first? I read that you probably need to top it up whilst purging, due to air escaping, not remove any!

Also, I noticed the coolant is not really pink/purple (G12/13) but pretty watery and not much colour. Is it worth draining the system and refilling with new coolant (I've got 5l of G40 from Halfords)?

Researching this there's loads of mixed stories about how easy/successful this is to do. And not much straightforward info on how to drain the system (which hose/s to remove etc)...

So maybe leaving what's in there is a safer bet and topping up if necessary?

I'm confident in changing the coolant but only with some clear, foolproof instructions!

Thanks in advance for any help.

Cheers

 

[RUM4MO]

For what it is worth, my personal advice would have been to buy a G65 product, which is what VW Group G12evo is and conforms to TL744 - L.

Anyway, from taking the official way of doing this from VW Group for the similar (hopefully) 2015 1.2TSI, engine, remove the main coolant circuit bottom radiator hose followed by the two charge cooler hoses which are at the opposite side of the car, remove the coolant fill cap before doing this, and allow all the coolant to drain out, then refit the hoses, pressure test the system to 1 atmosphere just to make sure that there are no leaks, fit a vacuum coolant refill kit and pull a vacuum on the system, then allow the new coolant to flood the system. Start the engine and run at moderate rpm until the cooling fan runs, top up coolant if necessary.

I'm making the assumption here that your engine is a EA211.

That is meant to be the only way to do this job and avoid ending up with trapped air in the system.

The other thing that I do, is to try to catch all the draining coolant and measure it so that I know how much MUST get loaded back in, as I don't currently have an air lock in the 2015 VW Polo coolant system, I also fit my pressure testing test to the cooling system while it is an ambient temperature and check apply a pressure of 1 atmosphere - and check to see how much the original coolant level gets depressed while that pressure is applied, doing that is another way to work out if you have refilling the system with coolant as trapped air can get compressed - coolant can't.

 

[nd-photo.nl]

Also remove the silica bag in the coolant expansion tank if its still there. See my howto here:

How to remove the Silica bag from the expansion tank

Follow this POV video if you want to remove the silica / silicat bag from the coolant expansion tank. They are known to rupture, where the silica beads will run through the coolant system and clog up the heater matrix. This will result in costly and unnecessary repairs. When you remove the...

www.seatcupra.net

 

[otter148]

For what it is worth, my personal advice would have been to buy a G65 product, which is what VW Group G12evo is and conforms to TL744 - L.

Anyway, from taking the official way of doing this from VW Group for the similar (hopefully) 2015 1.2TSI, engine, remove the main coolant circuit bottom radiator hose followed by the two charge cooler hoses which are at the opposite side of the car, remove the coolant fill cap before doing this, and allow all the coolant to drain out, then refit the hoses, pressure test the system to 1 atmosphere just to make sure that there are no leaks, fit a vacuum coolant refill kit and pull a vacuum on the system, then allow the new coolant to flood the system. Start the engine and run at moderate rpm until the cooling fan runs, top up coolant if necessary.

I'm making the assumption here that your engine is a EA211.

That is meant to be the only way to do this job and avoid ending up with trapped air in the system.

The other thing that I do, is to try to catch all the draining coolant and measure it so that I know how much MUST get loaded back in, as I don't currently have an air lock in the 2015 VW Polo coolant system, I also fit my pressure testing test to the cooling system while it is an ambient temperature and check apply a pressure of 1 atmosphere - and check to see how much the original coolant level gets depressed while that pressure is applied, doing that is another way to work out if you have refilling the system with coolant as trapped air can get compressed - coolant can't.

Thanks for the detailed advice – much appreciated. Just need to figure out where the three hoses are! Hopefully I can reuse any existing clips/clamps and not have to replace with new ones when refitting the hose ends.

Yes, it is an EA211 engine. I don't own a vacuum refill kit and probably not worth me buying one so I'll see what I can achieve without.

Is flushing the system with distilled water or coolant flush necessary before refilling with new coolant?

Cheers

 

[otter148]

Also remove the silica bag in the coolant expansion tank if its still there. See my howto here:

How to remove the Silica bag from the expansion tank

Follow this POV video if you want to remove the silica / silicat bag from the coolant expansion tank. They are known to rupture, where the silica beads will run through the coolant system and clog up the heater matrix. This will result in costly and unnecessary repairs. When you remove the...

www.seatcupra.net

Thankfully it looks like the expansion tank in mine doesn't have a silica bag and the 'Mit Silikat' isn't printed on the side of it

 

[nd-photo.nl]

@otter148 nice!

 

[RUM4MO]

The hose clips used nowadays are reusable "spring clamps" or "constant tension clamps", annoyingly, well at least on some VW EA211 engined cars, the large main hoses are "latching spring clamps" they will have been used probably to make initial assembly easier, these clamps will be getting supplied latched open, and only need a special shaped tool to unlatch them. What I discovered on my wife's 2015 VW Polo is, that the factory fitted clips are possibly one size down from being the ideal size, so I gave up on removing the hoses last week as time was tight and I wanted to buy in a replacement spring clamp from VW which, comes as the easier to use normal type!! I also bought a "waffle" bladed hose spring clip pliers to try to make life easier when dealing with these latching type!

 

[RUM4MO]

On your question about needing to flush the system before loading up with new coolant, I'll admit that I did not do that when changing my 2011 Audi S4 from G12+/G12++ - or was it G13, to G12evo.
As I don't have any issues with the G13 coolant in my wife's 2015 VW Polo 1.2TSI 110PS, other than it does not have a "Mit Silikat" reservoir and it's now just over 10 years old and so heading towards being acidic, I'm just planning on dropping the old coolant out, vac'ng the system, and then reloading with G12evo.
I'm sure in an ideal world, you should flush with distilled water etc, but not that important to me right now.

 

[otter148]

@RUM4MO Interesting and useful info – thanks. Just need to wait for a bit dry weather and I'll give it a go

 

[RUM4MO]

@RUM4MO Interesting and useful info – thanks. Just need to wait for a bit dry weather and I'll give it a go

I've been checking the parts listing for your engine in your car, and it might be that instead of constant tension spring clamps, for the big main coolant pipe, it might be the same as on my Audi S4, in as much as maybe Audi and SEAT have their own way of doing things, and you might just find there is plastic "quick/fast fit" connector grafted onto the big hose and that has a sliding locking U shaped locking device, which you just slide up and pull the pipe off the radiator stub. The smaller charge cooler pipes will still be the constant tension spring clamps, no doubt you will find out in good time, though always useful to have a "look-see" before starting a job - to avoid inconvenient surprises!