Low Coolant warning today!
 

Haven't used the S8 for a couple of weeks and starting it today got a low coolant warning.
Indeed it was low, and as an emergency measure I topped up with softened water. It took about 750ml to get up to the correct level. :-(

Now I have to confess I haven't checked this in ages, so it could have been low for a while, though I think I would have noticed. So I'll monitor it regularly.

But what do I get to put in it now, assuming it will be OK for a while as is? The label says G12, but looking online it appears that G12+, G12++ or G13 supersede that.

Where would you recommend going and for what, to top up? I have a VW dealer not far away who ought to have coolant in the parts department.
Looking on ECP they recommend TRIPLE QX Antifreeze (Red (Concentrate) Antifreeze/Coolant 1Ltr) Product Code: 523770482, which is only £5/litre.

And would you syphon some out of the tank and top up with concentrate?

The usual culprits for coolant escaping are the radiator, oil cooler pipe and heater core bleed screws.

750ml of water isn't a lot in terms of diluting whats in there (10 litres). I'd grab a couple of litres of concentrate from wherever and put that in neat for the next top-up then use the old container to make a 50/50 mix. Any modern red / pink coolant will be compatible.

Thanks MJ, useful advice. +++
I'll pop along to my nearest ECP sometime and get a couple of litres of that red stuff then.

I'm old enough to remember topping up radiators on almost every journey so losing a pint or so over an unknown period doesn't worry me much!

Edit: Can't be bothered to drive to ECP so ordered online using whatever the current discount is; should be here Tuesday and just over £10 for 2 litres delivered isn't bad.

ECP seem to be on a go-slow; shipped today and due tomorrow now. At least they've said I'll get a refund on the next-day delivery charges so it's even cheaper now.
I was expecting to need the S8 this evening, but don't now, so fortunately not a problem. :cool:

Cracked coolant expansion pipe where the small hose connects also leads to slow coolant loss and is a common problem, mine has been replaced twice and is cracked once again. Another thing could be valves sticking open in the expansion tank cap so water is slowly evaporating or can be pushed out if car gets too warm (also happened to mine, failed electric fan meant it was getting a bit warm and stuck valves in cap meant coolant was disappearing.)

Mmm good point on the coolant bottle. I forgot about that one.

There's no reason to not drive it as long as the level is correct. That 750ml of water will make no measurable difference to anything since its diluted the coolant by only a few percent. It might freeze at -29 now instead of -30 ;) Since you have no idea of the concentration that was in there, just add 750ml of neat coolant next time it needs some and you know you've averaged out what you added to be 50:50 ish.

Yup, that's exactly what I plan to do MJ. +++
I don't use it much at this time of year, so it's just a case of monitoring for now then investigating once I see some change or detect a leak.

Edit: Pink stuff arrived so I topped up a bit more from just below Min to around Max (tricky as car isn't totally level) - half a litre of neat coolant.
Not exactly the weather for checking for leaks but there's nothing obvious around the header tank, it all looks good.
The cap wasn't "that" tight when I opened it to top up the other day; it's on firmly now.

Finally been for a short drive today, enough to warm up thoroughly then drive back home a few miles.
All seems well and on popping the bonnet on return coolant levels were fine, risen a bit due to heat expansion.

The only thing I noticed, and I think I've heard this before, was a gentle fading soft hiss from near the ECU bay. It faded away in less than 30 seconds.
It was definitely NOT coming from the area around the Auxiliary Coolant Pump, more behind/below and outboard (adjacent to the wing), I think the only pressurised stuff there is aircon piping?

I'll check again when the engine has cooled; I wasn't brave enough (this time) to loosen the coolant cap to see if it was holding pressure. :tuttut:

That hiss is normal. Its the aircon bleeding off pressure from the pump side through the choke which is just next to the ECU box, exactly where you describe.

Thanks MJ, I thought that was it, good to get confirmation. +++