Cupra coolant issue?

[The-Cupra]

Hi, so recently just bought a 5F cupra 2020 model.

The issue is the coolant level is going lower when its hot. On cold the coolant is at the max line, exactly on it. When im going on a drive and the car is warm the level is dropped to about half way between min and max. I thought coolant expands when its hot and that's how its always worked on other cars iv owned. This is my first VW, so maybe its normal? I dont know.

There is NO coolant loose as far as i can see. If i leave the coolant to fully cool down it returns to the max line. I was thinking the cap could be faulty and not releasing pressure at the stated 23psi? So maybe the system is over pressurizing causing it to push the coolant lower while hot?

In previous cars iv owned the coolant level is a little over the original cool spot while hot. As i said no leaks. No coolant loss. I tried burping the system... fans on full wack when warm to open thermostat. Also pumped a few hoses and raised the revs etc. Went for a drive and checked it. Same thing its dropping while hot... Is it normal.

Could someone check there coolant level cold and then check it when its warm? Does yours drop slightly? For all i know these cars could drop the coolant level when the thermostat opens or something? Cheers

 

[DEAN0]

Yes coolant can expand when hot - BUT - not as much as air expands when hot.

You are running a sealed system and when it gets hot it will be under pressure.
The pressure is so the water in the coolant does not boil at 100c - it will boil at a higher temp.

The only air in the system is in the expansion tank and that air will force the coolant down in the tank.

This is why the book says to check coolant level when cold.

 

[The-Cupra]

Yes coolant can expand when hot - BUT - not as much as air expands when hot.

You are running a sealed system and when it gets hot it will be under pressure.
The pressure is so the water in the coolant does not boil at 100c - it will boil at a higher temp.

The only air in the system is in the expansion tank and that air will force the coolant down in the tank.

This is why the book says to check coolant level when cold.

Thanks for the reply and i do understand that, however i think the fact the coolant is being pushed down it could be under too much pressure.

This phenomenon also happens when a heat gasket goes and exhaust gases are getting into the coolant system. However is also is accompanied with coolant loss. Which i dont have. So its either normal or the cap could be naff. Iv seen a youtube short earlier. Two infact... That suggests the cap is a possibility. However these caps where holding pressure many many hours in advance. Mine isnt quite as bad as that.

My previous two cars where a Megane RS Trophy 2019 and Focus RS Mk3 2018. I mention this because im very over the top with maintenance and checking the vehicle. On both of my previous vehicles mentioned. The coolant level would NEVER drop when hot. Always be a little over mark to which it was when it was cold/cool. This car is doing the complete opposite.

Most manufacturers say check coolant level when cold. This is because coolant expands when warm (to my understanding). So i guess what i want to know if this is normal on this EA888 Gen3 engine. If its normal, my mind will be at ease. If not i need to investigate further. I think im just going to buy a cap from Seat dealers today see if that solves it.

If someone could be as kind to check there coolant today before they set off and check again when the coolant is very warm. See if it drops from your current cold level. Would be very much appreciated

 

[fuzzylogic]

About 10mm lower when hot, on my Cupra R ST. I believe it was the same on my previous Cupra Lux.

 

[DEAN0]

You could do a combustion leak test if you suspect it may be an issue

Combustion Leak Tester Kit, Blown Head Gasket Block Detector Petrol/Diesel Fluid | eBay

After the test has been completed, carefully remove the device. The used test fluid should be disposed of, even if the test result was negative. Combustion Leak Tester Kit. Start the engine (preferably already warm), bring it to a higher speed to obtain a higher combustion pressure.

www.ebay.co.uk

 

[The-Cupra]

You could do a combustion leak test if you suspect it may be an issue

Combustion Leak Tester Kit, Blown Head Gasket Block Detector Petrol/Diesel Fluid | eBay

After the test has been completed, carefully remove the device. The used test fluid should be disposed of, even if the test result was negative. Combustion Leak Tester Kit. Start the engine (preferably already warm), bring it to a higher speed to obtain a higher combustion pressure.

www.ebay.co.uk

There is no need, iv had this issue on my misses Ford Focus many years ago. In this case there is no coolant loss and there would be more pressure in the system when the head gasket has gone (if indeed its blown between cylinder and coolant passage).

There will always be coolant loss with a blown head gasket. Cold VS cold the level doesn't change. Thanks though. I have used them kits before they are good for confirming a blown head gasket.

In my case i was thinking maybe air in the system could be causing it... OR maybe the cap isnt releasing measure like it should.

Here is an issue was that was SOLVED by installing a new overflow cap. I have sent the link below. You can see in the comments the uploaded mentions a new cap solved it. Iv seen another video with something similar. Granted i dont have this much pressure building up...

My issue could be perfectly normal. My drop little drop in coolant coolant might be normal on the EA888. One guy has checked and said both his do it in this thread... Im going to see how the comments progress. Maybe this is normal on this engine. Doesn't line up with any other car iv owned. However, this is my first VW.

How to fix wrong coolant fluid level; selfrefilling Skoda Octavia😂😂

www.youtube.com

 

[RUM4MO]

For me, this sounds a bit weird, yes the air in the system will expand when the system is hot, but it is compressible, the expanded coolant isn't.

Although, if there is trapped air somewhere in the system, ie deep in the system well away from the reservoir, I would expect the coolant level to increase more while that trapped air is in the system, than it would be after I'd managed to get rid of that trapped air.

So - hummmm!

Maybe these engines routinely get extremely hot at certain points in their systems and none of my cars (with other engines) do, that might expand the air more - but again also the coolant, I'll need to check my daughter's 2019 Cupra sometime.

 

[The-Cupra]

About 10mm lower when hot, on my Cupra R ST. I believe it was the same on my previous Cupra Lux.

Do these pictures correspond with yours? I just always thought coolant expands when warm? Would love someone to look at there and confirm this is indeed the case.

 

[The-Cupra]

For me, this sounds a bit weird, yes the air in the system will expand when the system is hot, but it is compressible, the expanded coolant isn't.

Although, if there is trapped air somewhere in the system, ie deep in the system well away from the reservoir, I would expect the coolant level to increase more while that trapped air is in the system, than it would be after I'd managed to get rid of that trapped air.

So - hummmm!

Maybe these engines routinely get extremely hot at certain points in their systems and none of my cars (with other engines) do, that might expand the air more - but again also the coolant, I'll need to check my daughter's 2019 Cupra sometime.

please check if its not too much trouble. Im under the same impression as you and all previous cars iv owned. Coolant is a little higher when warm. Not a little lower. Iv posted some pictures in my previous post. Also another member has posted saying his does the same. If you could also confirm if yours does this or not that would be very helpful!

 

[fuzzylogic]

Do these pictures correspond with yours? I just always thought coolant expands when warm? Would love someone to look at there and confirm this is indeed the case.

Do these pictures correspond with yours? I just always thought coolant expands when warm? Would love someone to look at there and confirm this is indeed the case.

I will try to get a couple of photos next time I use it. Maybe tomorrow, liquid lunch today so the car stays at home

 

[The-Cupra]

I will try to get a couple of photos next time I use it. Maybe tomorrow, liquid lunch today so the car stays at home

Thank you, its very much appreciated and will put my mind at ease.

 

[TheSwede]

I will take a pic of my expansion vessel today cold/hot. Will get back to you.
It is a Seat Leon mk3 Cupra R 2018, 310 hp. As standard one extra cooler on the right side (sitting in car) in front of the wheel arch. I dont know if just some Cupras have it. My Mk7 Golf R had it. No fog lights, no room on both of the mentioned cars.

 

[The-Cupra]

I will take a pic of my expansion vessel today cold/hot. Will get back to you.
It is a Seat Leon mk3 Cupra R 2018, 310 hp. As standard one extra cooler on the right side (sitting in car) in front of the wheel arch. I dont know if just some Cupras have it. My Mk7 Golf R had it. No fog lights, no room on both of the mentioned cars.

Much appreciated mate. Legend!

Im unsure if my Cupra would have it. However it is the 2020 model so if some Cupra's have it, i imagine mine would have.

 

[TheSwede]

The pictures are from the same ground conditions, my parking lot in the garage.

Cold= 12 c today. About the same outdoor temperature.

Hot =After a 20 km drive just after ignition turned of.
A little less coolant than "cold".

Hot last pic= About 5 minutes after ignition turned of. The electrical circulation pump take 4-5 minutes to shut down. You can see if there is coolant the filler hose on top of exp vessel (pink before it closes down).
Slightly more coolant than "cold". Very little diff..

 

[The-Cupra]

The pictures are from the same ground conditions, my parking lot in the garage.

Cold= 12 c today. About the same outdoor temperature.

Hot =After a 20 km drive just after ignition turned of.
A little less coolant than "cold".

Hot last pic= About 5 minutes after ignition turned of. The electrical circulation pump take 4-5 minutes to shut down. You can see if there is coolant the filler hose on top of exp vessel (pink before it closes down).
Slightly more coolant than "cold". Very little diff..

Thank you for taking the time to do this, so it might be looking like this is completely normal.

Coolant level being lower when engine is hot.

In all other cars iv owned it always went a tad higher when i checked.

 

[TheSwede]

Yes, but if you open the cap it will expand.
On my 2018 Golf mk7 Alltrack (engine EA888 1.8) it works about the same as in the Cupra. The Alltrack have not any extra cooler. (Have fog lights in the cooler grill).

 

[RUM4MO]

I was sure that the coolant levels in my 2011 Audi S4 did not change by very much between COLD and HOT, but, after changing from G13 to G12evo, the level rise when HOT is 0.5 inch, and that change worried me as I considered that it meant that there was trapped air in the system somewhere.

So, when the coolant was COLD, I fitted my "coolant pressure tester" to the reservoir and applied a pressure of maybe 16PSI(I've forgotten the actual pressure but I will have recorded it somewhere!), then noted/recorded the level change when that typical system pressure was applied.

That is something that I regret not thinking doing BEFORE I replaced the coolant, so, I repeated that test on my wife's 2015 VW Polo 1.2TSI and recorded it, so when I replace its coolant, I will have a "before" figure to compare with the "after".

My logic being, the more air that is trapped in a sealed system, the more the coolant level will get depressed when you apply 16PSI to the COLD reservoir. Obviously there will always be a slight drop in level when 16PSI is applied due to expansion of hoses etc.

 

[The-Cupra]

I was sure that the coolant levels in my 2011 Audi S4 did not change by very much between COLD and HOT, but, after changing from G13 to G12evo, the level rise when HOT is 0.5 inch, and that change worried me as I considered that it meant that there was trapped air in the system somewhere.

So, when the coolant was COLD, I fitted my "coolant pressure tester" to the reservoir and applied a pressure of maybe 16PSI(I've forgotten the actual pressure but I will have recorded it somewhere!), then noted/recorded the level change when that typical system pressure was applied.

That is something that I regret not thinking doing BEFORE I replaced the coolant, so, I repeated that test on my wife's 2015 VW Polo 1.2TSI and recorded it, so when I replace its coolant, I will have a "before" figure to compare with the "after".

My logic being, the more air that is trapped in a sealed system, the more the coolant level will get depressed when you apply 16PSI to the COLD reservoir. Obviously there will always be a slight drop in level when 16PSI is applied due to expansion of hoses etc.

My cupra is on G12evo from factory and without the silica bag as im sure they did away with it in the later models (2020). My level is dropping when hot not rising. I do have a coolant pressure tester. Im also thinking there could be air in the system. However it might also be normal. Replaced with a new cap yesterday but it made no difference. Im going to take the car out for a good run today and then check then level before and after on cold make sure it indeed is not loosing any coolant. Im 90 percent its not loosing anything. I think the fluctuation (going 1cm lower roughly) when warm is normal.

If you do get a chance to check this on your Cupra that would be brill! Iv just bought the car a few weeks ago so im high alert with everything. Got 2 years warrenty from Seat. If it does have an issue i wont delay it going in. But need that reassurance its normal really.

 

[RUM4MO]

It will be some time before I get back with information on my older daughter's 2019 Cupra as she lives 12 miles away.

Yes, when G12evo was introduced, the need for the Slicate pouch would disappear - so it would get deleted as maybe that product (Silicate) was not compatible with the chemistry of G12evo.

Edit:- I seem to remember what annoyed me most about the coolant level change on the Audi S4 was, the workshop manual stated that the coolant must be filled up to the MAX level - as opposed to maybe midway between the MIN marks and the MAX marks, that model of Audi has a VERY BIG, high volume coolant reservoir, so, the typical expansion of coolant, after the change to G12evo, was causing a small amount of coolant to get dumped out of the reservoir when the engine was HOT, and that was annoying me, it is okay now especially after I dropped the normal COLD coolant level down to between the MAX and MIN. One annoying aspect of that model of Audi is, as well as the cabin heater hoses being higher than the coolant reservoir, the supercharger's air heat exchangers are also higher than the reservoir, which means that I needed to fabricate a "|coolant level extender" using a new Febi pressure cap and bonding a vertical tube of plastic piping on top of it after cutting out the pressure element - AND raising the rear of the car onto jack stands, when bleeding the coolant system after back filling it while it was under vacuum. Also needed to feed a pipe down into the "sort of separate" supercharger heat exchanger coolant circuit, and vacuum out air/coolant from that section while letting coolant take its place, in a bid to get rid of all the trapped air!

 

[The-Cupra]

It will be some time before I get back with information on my older daughter's 2019 Cupra as she lives 12 miles away.

Yes, when G12evo was introduced, the need for the Slicate pouch would disappear - so it would get deleted as maybe that product (Silicate) was not compatible with the chemistry of G12evo.

Edit:- I seem to remember what annoyed me most about the coolant level change on the Audi S4 was, the workshop manual stated that the coolant must be filled up to the MAX level - as opposed to maybe midway between the MIN marks and the MAX marks, that model of Audi has a VERY BIG, high volume coolant reservoir, so, the typical expansion of coolant, after the change to G12evo, was causing a small amount of coolant to get dumped out of the reservoir when the engine was HOT, and that was annoying me, it is okay now especially after I dropped the normal COLD coolant level down to between the MAX and MIN.

Thanks for the help mate. Is the proper cold level at the tip of the upside down triangle situated between the min and max line. Admittedly iv been filling to the actual max line when cold. I did look this up but couldn't find any forums or threads mentioning this. I did have a suspicion though. I do have miles and miles of b-roads at my doorstep so the car could certainly throw the coolant in the expansion tank around somewhat.

However i dont feel thats the issue or that there even is one. Im hopeful. Im a stressful car buyer, each time i buy a new car rather than getting excited im wondering what hidden problems there might be. Im currently still in that stage.