Coolant issue?

[Peller]

After a a decent drive in my 2018 290 (GPF) Cupra, I had to top up the windscreen wash bottle.

I noticed that there was very little coolant in the reservoir but dismissed it as it was I had the car on a good run and it would settle when cool.

Upon checking after sitting for 24 hours the coolant is still well under the minimum mark. No dash warnings or visible leaks.

The car has only done 13000ish miles and was serviced before 11k with no issues.

I've unfortunately been through similar issues (as many of you guys) with my old 280 SC and the pump was replaced under warranty.

Does anyone else have this issue with the newer GPF engines?




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[Slickric21]

Got exactly the same thing this week on an 11 month old car that has done 4k miles.
Topped it up a few days ago and doesn’t seem to have lost any more.
Will keep an eye on it.

Was out for a drive with another Cupra owner (car of a similar age) last week and he had the low coolant warning come on during the drive (which I why checked mine actually !!!). He had to top his up with distilled water at the time as his reservoir was almost dry.

No sign of any visible leaks on either car.

 

[Peller]

Got exactly the same thing this week on an 11 month old car that has done 4k miles.
Topped it up a few days ago and doesn’t seem to have lost any more.
Will keep an eye on it.

Was out for a drive with another Cupra owner of a similar age last week and he had the low coolant warning come on during the drive (which I why checked mine actually !!!). He had to top his up with distilled water as his reservoir was almost dry.

No sign of any visible leaks on either car.

It's quite worrying tbh. I hoped the coolant problem was sorted with the new engine.

I've topped up with official coolant I had left from my old 280. I'll keep an eye on it daily.

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[SRGTD]

Quite a few mk7 / mk7.5 Golf owners on VW forums have had the coolant level drop in the expansion tank. It seems that quite often, there’s an air lock in the cooling system from the factory, and the air lock works it’s way out and into the expansion tank during the first few months / first few thousand miles. The air lock - once expelled - will be replaced with coolant from the expansion tank, so the level in the expansion tank will drop as a result.

I had this happen in my VW a few months after I got it. I topped up the level with G13 coolant and it‘a been fine ever since.

 

[Slickric21]

I’m hoping it’s just going to be the airlock also.

 

[Peller]

I’m hoping it’s just going to be the airlock also.

I'm hoping the same. I've topped it up to the max so hopefully after a few drives I can monitor the the coolant level.

I'll report weekly and hopefully get some comparisons.

I really thought that the VAG group would've sorted any previous issues with the latest engine spec.

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[RUM4MO]

I think that the key here is to check your under bonnet once a week, ie check all fluid levels and make sure everything else looks okay, with cars becoming more reliable it seems that too many people never lift the bonnet unless an issue forces them to - not smart or a clever way to operate.

 

[Mr Pig]

It could be a leak obviously but you want to be sure of that before you start spending money.

Fill the tank up to the full mark, exactly and, this is important, make sure the lid is on tight! Sounds stupid but the lid is a bit crap and some can be crazy hard to tighten so you might need to really crank it on. If the lid is not tight you can lose coolant through it.

Then just check to see if it's still dropping.

 

[Slickric21]

Found a good summary on a Golf forum that seems to match what I’ve read about this ‘issue’ recently.

- Coolant level dropping after a shortish period with a new car. This seems to be caused by an initial build air lock finally being purged. Most cars don't need extra coolant (but some do) and the level stabilises after that.

- Low coolant level due to a leak (coolant sensor or thermostat housing fault seems to be the most common culprits here)

- Low coolant level that mysteriously goes back up after the engine cools down (or if you undo the filler cap) - I haven't read any good explanations for what is happening here (yet).

The obvious advice here is to check your coolant levels regularly.

 

[bgb]

Had this on a brand new Cupra 290 recently, Technicians were almost certain air lock, topped up and since then I've been golden!

Maybe worth unscrewing cap and letting engine run till up to temp to 'Burp' the system - hopefully get rid of any airlock?

 

[bgb]

Found a good summary on a Golf forum that seems to match what I’ve read about this ‘issue’ recently.

The part about the coolant returning after engine cools is due to pressure in system decreasing - fluid is able to push back into tank

 

[Slickric21]

Maybe worth unscrewing cap and letting engine run till up to temp to 'Burp' the system - hopefully get rid of any airlock?

I’m going to do this today just for peace of mind.

Is it best to run the heater on full also whilst doing this ? Sure I’ve read that somewhere !!

 

[RUM4MO]

That heater comment I'd think is aimed at cars with heaters that have a valve controlling the flow of water through the matrix, these cars like most modern cars use "air blending" to adjust the cabin air temperature, so keeping the heater set on Hi should not make any difference - use extreme caution if you plan on removing the pressure cap when the coolant is hot, better to run the engine and let it heat up with the cap off, though I hate running an engine just to heat it up. I thought that your car had managed to move some or most of its air bubble through into the reservoir, I'd just keep the coolant topped up ie keep an eye on it and it should stop needing more coolant added as all the air moves into the reservoir - or have I missed something.

 

[Slickric21]

Ahh ok thanks for the detailed info.

You are absolutely right, my car appears to be fine since the one time I had to top it up, although it’s not been driven that much since then granted. Level does look like it’s ok, not dropped at all.

I was just aiming for the ‘gold standard’ as it were that’s all.

 

[RUM4MO]

As lots of modern cars have by design a "sort of" self purging coolant system, ie they return some of the coolant flow back into the reservoir, they tend to sort out a lot of the getting rid of trapped air, there are some engine types that are known to have trouble doing this, one of VW Group's being the old 1.4 16V 86PS petrol engine, it needs the engine coolant sensor removed if replacing the entire coolant contents so that that area is purged of air while continuing to refill it then refitting that sensor while continuing to refill the coolant - I found that out the hard way, intermittent or permanent loss of any heat from the cabin heater!

It does sound a lot like VW Group do not try very hard to end up with a properly filled coolant system at initial fill - Skoda Fabias with the later 1.2TSI tended to suffer from this a lot, my wife's 2015 VW Polo's coolant level has not moved over its almost 5 years from new. Similarly Audi B8 S4's suffered from this, but my 2011 S4 coolant level has not moved at all. My daughter's 2019 SEAT Leon Cupra did need "2 inches" of coolant adding after a few months.

 

[bgb]

I’m going to do this today just for peace of mind.

Is it best to run the heater on full also whilst doing this ? Sure I’ve read that somewhere !!

I had to for my old GTD due to a heater matrix issue, (doing this causes the coolant to flow through the heater capillaries) - unsure for a general Burp!

 

[RUM4MO]

I had to for my old GTD due to a heater matrix issue, (doing this causes the coolant to flow through the heater capillaries) - unsure for a general Burp!

Had you or someone else fitted a physical valve to the water flowing through the heater matrix?

Older cars like Audi B5 A4 and VW B5 Passat had holes drilled in the heater pipe(s) so the plan when refilling the coolant was to slacken off the hose(s) and ease it/them back to open this/these holes and let the trapped air out - as part of the initial filling process.

 

[bgb]

Had you or someone else fitted a physical valve to the water flowing through the heater matrix?

Older cars like Audi B5 A4 and VW B5 Passat had holes drilled in the heater pipe(s) so the plan when refilling the coolant was to slacken off the hose(s) and ease it/them back to open this/these holes and let the trapped air out - as part of the initial filling process.

Unsure on re-filling.. I'm talking about what i was advised to do to try and increase heat as if the system had scolding coolant but air vents were blowing cold even when on full, it pointed towards blocked capillaries, ie heater matrix. (I sold the car prior to a full fix as it was dong my head in chasing the issue!)

For a burp, I don't believe its required, you are keeping the cap off so pressure doesn't build up and allowing an 'air bubble' to work its way round and out the tank.