Engine coolant suddenly low

Jsimba

Jsimba

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Hi folks, a bit of an odd one I'd be grateful for thoughfs on. I went to start the car this morning and got an "engine coolant low" warning message on the dash. Opened the bonnet and, sure enough, the coolant level is a good inch below the minimum level.

I say it's odd because I check the coolant every month or so when I'm checking/topping up oil, and a few weeks ago it was totally fine. There were also no warning messages yesterday when I drove the car, so it seems strange to find it so far below the minimum level today.

I've got Roadside Assistance coming out to have a look tomorrow but has anyone got an ideas what could've caused such a sudden drop, could it be the cold weather?! I can't see any obvious leaks from the water pump, but then I know they aren't the most reliable and any leak could be hard to spot.

Cheers!
 
I had this once on both the 8V and the 8Y, vacuum fill from the factory can be a little hit and miss on some cars, topped up and it never happened again.
 
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HM3P said:
I had this once on both the 8V and the 8Y, vacuum fill from the factory can be a little hit and miss on some cars, topped up and it never happened again.
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Thank you I've had the car two years as of this week, do you think that it could take that long to materialise?

The level has never been terribly high and closer to the low mark than the high mark, but it seems to have really dropped in a very short space of time (although it seems to have settled at its current level, about 2 cm below the minimum line, so might be as you say, rather than a leak?)
 
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Jsimba said:
Thank you I've had the car two years as of this week, do you think that it could take that long to materialise?

The level has never been terribly high and closer to the low mark than the high mark, but it seems to have really dropped in a very short space of time (although it seems to have settled at its current level, about 2 cm below the minimum line, so might be as you say, rather than a leak?)
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It can have 'pockets' of air that take time to find there way out into the expansion tank.

I vacuum filled a Golf 7 GTD after changing a cam belt, that did the same thing months later.

colder weather also plays a part.

If no obvious signs of any leaks I'd top up when cold and monitor. temps have taken quite a drop recently.
 
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HM3P said:
It can have 'pockets' of air that take time to find there way out into the expansion tank.

I vacuum filled a Golf 7 GTD after changing a cam belt, that did the same thing months later.

colder weather also plays a part.

If no obvious signs of any leaks I'd top up when cold and monitor. temps have taken quite a drop recently.
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Thanks @HM3P, that's very helpful. I'll do as you suggest and see what happens over the next couple of days.

I've seen from similar/older posts there was a TPI on the water pumps and a few people have reported hairline splits in radiator hoses, so I've booked the car in with Audi for next week, just in case the problem pops up again after topping up the coolant.

Given there was no dash warning yesterday, I can only assume it's something very new and has happened since getting home in the evening. So, with any luck, if there is a leak, a new pump or hose be the extent of the issue.

Fingers crossed...
 
I had the same problem on my 2022 RS3, it happened 6 months before the warranty was out. It was the waterpump leaking, and it was fixed under warranty. The new waterpump installed was a newer revision, and as far as I remember the older version had some design flaw or weakness of some sort...
 
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Jacob79 said:
I had the same problem on my 2022 RS3, it happened 6 months before the warranty was out. It was the waterpump leaking, and it was fixed under warranty. The new waterpump installed was a newer revision, and as far as I remember the older version had some design flaw or weakness of some sort...
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Thanks @Jacob79, that sounds about right and seems to match with a few other posts I've read.

I dropped the car off with Audi yesterday (and cheekily did it through Roadside Assistance, as that guarantees a courtesy car even if the dealership doesnt have any available ).

I mentioned the water pump to them and that it seemed to have affected quite a few other owners, in the hope they would go straight to that, but of course they didn't know what I was talking about So in many ways, I'm hoping that's what they find to be the problem (it's better than some of the alternatives!).

With any luck, it'll be sorted relatively quickly...
 
Yes — cold weather absolutely can cause this, and it’s one of the most common reasons people suddenly see a low coolant warning overnight.
 
Update on this is that Audi topped up the coolant and took the car out to have a look at it (for quite a large number of miles!), but didn't find any visible signs of coolant leaks. Apparently the pressure test suggested that everything was fine too.

The coolant hasn't dropped much/at all since being topped up, so looks like this was a bit of an odd one-off event (I hope!). Still seems a bit of a strange thing to happen.

So I still might just take it along the road to the Audi specialist workshop as well though to see if they have any other thoughts on what it might be, including checking the head gasket, just for piece of mind...
 
Jsimba said:
Update on this is that Audi topped up the coolant and took the car out to have a look at it (for quite a large number of miles!), but didn't find any visible signs of coolant leaks. Apparently the pressure test suggested that everything was fine too.

The coolant hasn't dropped much/at all since being topped up, so looks like this was a bit of an odd one-off event (I hope!). Still seems a bit of a strange thing to happen.

So I still might just take it along the road to the Audi specialist workshop as well though to see if they have any other thoughts on what it might be, including checking the head gasket, just for piece of mind...
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Not sure how long you’ve had it, but I had the same thing on my W212. I was topping up the coolant about once a year. Took it to a mechanic and he said it’s pretty normal for that engine and nothing to worry about, as long as it’s not dropping quickly or leaving any leaks.
 
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I think you are over thinking the coolant loss tbh, just leave it a month and see if it drops again :)

You say you check it 'every month when checking the oil' I imagine you check your oil with the engine hot?
 
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Mike.46 said:
I think you are over thinking the coolant loss tbh, just leave it a month and see if it drops again :)

You say you check it 'every month when checking the oil' I imagine you check your oil with the engine hot?
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Funnily enough, I had the car back in yesterday for its bevel box service anyway and the technician found a small amount of coolant residue under the reservoir, so they're replacing that today. So I wonder if there was a small leak/crack which the residue effectively closed up when it dried. Either way, it's hopefully now sorted..!

On the oil, I generally check both hot and cold (more out of interest than anything else!) but will leave the car sitting when warm before checking rather than immediately after driving.
 
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But I'm definitely guilty of overthinking issues like this too, you're absolutely correct!
 
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Jsimba said:
Funnily enough, I had the car back in yesterday for its bevel box service anyway and the technician found a small amount of coolant residue under the reservoir, so they're replacing that today. So I wonder if there was a small leak/crack which the residue effectively closed up when it dried. Either way, it's hopefully now sorted..!

On the oil, I generally check both hot and cold (more out of interest than anything else!) but will leave the car sitting when warm before checking rather than immediately after driving.
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What mileage was the bevel box service due. On my Audi app there is no details for oil change interval.
 
Jsimba said:
£260ish where I am since the car was in anyway. Otherwise I might have shopped around as prices seem to vary massively around here
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Worth every penny if you cannot attempt yourself.
I did both boxes on my old 8V and the fluid was pretty dark when it came out.
Audi and their sealed for life bo**ox
 
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Japper_ARS3 said:
Read that on a US sight but then said it was sealed for life after first change?
Not seen anything in writing from Audi on this.
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See the samples I took from mine on the 8V thread

www.audi-sport.net

Which oil for transfer/bevel box?

As title really. The 8Y and RSQ3 have a service interval on the oil in the transfer box. The 8V doesn't, it is supposed to be lifetime, but the oil can evap and ... well, we should probably change the oil reguarly based on what I have scoured off the forums. Anyone know which oil it'll take...
www.audi-sport.net www.audi-sport.net
 
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Japper_ARS3 said:
Read that on a US sight but then said it was sealed for life after first change?

Not seen anything in writing from Audi on this.
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They same the same 'sealed for life bo**ox' about the Aisin auto boxes in Q7's and the like yet theres now more than a few companies selling oil change kits (which only changes about 75% of the oil) and a a few companies that have rigs that flush the whole system.

Audi's 'sealed for life' actually means, 'sealed until it's probably out of warranty when it's not our problem'
 
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Mike.46 said:
They same the same 'sealed for life bo**ox' about the Aisin auto boxes in Q7's and the like yet theres now more than a few companies selling oil change kits (which only changes about 75% of the oil) and a a few companies that have rigs that flush the whole system.

Audi's 'sealed for life' actually means, 'sealed until it's probably out of warranty when it's not our problem'
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Yep. mind Boggles.
 
Sorry folks, bumping this back up again. Despite getting a clean bill of health from Audi after they changed the coolant reservoir, I'm probably now over-analysing everything a bit too much, but I had a quick question: does this seem normal to everyone? This was after a short run to the shops. I'd always assumed the bit of steam I could see at the front of the car after driving wt night was from the heat of the headlights, but I've noticed it only seems to appear at the front right of the car. The cold and damp is probably making it appear even more visible than usual but I'd be grateful to know if this is something everyone notices on their own car and is thereforerelatively normal, or if it's something I need to look into more.

Thanks, as ever!

PS: I'd popped the bonnet before filming, so if anyone thinks it looks open that's because it is! //cloud.tapatalk.com/s/697291eac9348/20260122_195758_1.mp4
 
Sorry folks, bumping this back up again. Despite getting a clean bill of health from Audi after they changed the coolant reservoir, I'm probably now over-analysing everything a bit too much, but I had a quick question: does this seem normal to everyone? This was after a short run to the shops. I'd always assumed the bit of steam I could see at the front of the car after driving wt night was from the heat of the headlights, but I've noticed it only seems to appear at the front right of the car. The cold and damp is probably making it appear even more visible than usual but I'd be grateful to know if this is something everyone notices on their own car and is thereforerelatively normal, or if it's something I need to look into more.

Thanks, as ever!

PS: I'd popped the bonnet before filming, so if anyone thinks it looks open that's because it is! //cloud.tapatalk.com/s/697291eac9348/20260122_195758_1.mp4
 
Video not working for me, but I do get steam from the front of the car and the bonnet on occassion. Had this on the 8V too.
 
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Jsimba said:
Sorry folks, bumping this back up again. Despite getting a clean bill of health from Audi after they changed the coolant reservoir, I'm probably now over-analysing everything a bit too much, but I had a quick question: does this seem normal to everyone? This was after a short run to the shops. I'd always assumed the bit of steam I could see at the front of the car after driving wt night was from the heat of the headlights, but I've noticed it only seems to appear at the front right of the car. The cold and damp is probably making it appear even more visible than usual but I'd be grateful to know if this is something everyone notices on their own car and is thereforerelatively normal, or if it's something I need to look into more.

Thanks, as ever!

PS: I'd popped the bonnet before filming, so if anyone thinks it looks open that's because it is! //cloud.tapatalk.com/s/697291eac9348/20260122_195758_1.mp4
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Not an Audi, but I had very similar when owning a scoob. After a spirited run it would steam from one side of the grille. Turned out it was a pinhole in the rad that didn't leak under normal circumstances. Might not explain the sudden loss of coolant but something to get checked maybe.
 
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Had this on last RS3 and also on new one, i'm sure it's just radiators getting hot and causing residual water to evaporate
 
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Thanks both, that's really helpful.

I'll keep an eye on it for the time being to see what happens with the coolant level and, if it looks like it's dropping again or I get higher temp readings, then I'll have Audi take another look.
 
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