that's very honest and kind of you.
but I would sell it on
sold as seen and all that
either that or trade it in.
without spending big money you aren't going to get to the bottom of the issue as its trial by error
Coolant loss from tank on motorway journeys or high speeds
- Thread starter YKFR
- Start date
but I would sell it on
sold as seen and all that
either that or trade it in.
without spending big money you aren't going to get to the bottom of the issue as its trial by error
I know myself and @black_sheep have advised before, but did you ever contact the trader/dealer? By now, i would have returned the car or at least kicked up a stink for a fix to be provided etc?
Where is the leak coming from? Is the bottle cracked, a hose leaking, the cap not sealing?
At least you're starting to narrow it down.
At least you're starting to narrow it down.
The OP’s car was pressure tested, and held the pressure which would have identified a leak in those components quite easily (less the expansion cap, which is where the pressure rig fits). I swapped my expansion cap after the same diagnosis, but it made no difference.
There is an overflow in the expansion reservoir; if the system pressure increases, either due to an airlock some where in the coolant system or exhaust gases over pressuring the coolant system, it ditches excess coolant out of the bottom centre of the tank - if the car is moving, there is obviously turbulent airflow around the engine bay which causes it to spay all over the place, which is what it looks like has happened in this instance.
When my water pump catastrophically failed it, dumped the entirety of the coolant, steam came out of the engine bay, but most of the coolant was on the sound proofing/oil pan cowling underneath the car.
I was replacing my Octavia regardless of this fault, but the heater matrix lost performance on the driver’s side only a few days before it was traded in, so had the entire system flushed and bled, which resolved the problem before it was traded in - all of the bills and paperwork for the numerous coolant related checks were presented with the service history when I handed it over.
My opinion was that the heater matrix (on my car) was the most likely cause, and I would have DIY replaced it for peace of mind if I had retained the car; since trading in the car, there has been a significant increase in the number of cars suffering with heater matrix issues and the matrix is c.£100 for the part.
@YKFR Was the journey different from from those previously where you hadn’t experienced coolant loss?
For example - short journeys (30 mins) vs a long journey(2 hrs)? was the outside temperature cooler, resulting in the climate control heating the cabin as opposed to cooling it? Was the engine load higher on this particular journey - extra passengers/weight/towing or higher engine revs?
I've just double checked the manual. The coolant overflow system is sealed, an inlet at the bottom, an overflow at the top and the pressure cap. It will not spray coolant where the OP's has unless there is a leak.
Exactly how can that work, these coolant systems are designed to run at slightly elevated pressures to suppress boiling of the coolant, so they must get fitted with a system safety pressure release device, that pressure release device is the reservoir cap, so it lifts to release excess pressure and that normally means that there is a concealed/protected "dump" tube/channel that controls the direction of the air/steam/fluid being released in a safe manner - unless the newer shape of that reservoir permits safe release directly from the reservoir cap out onto the bowled top of the reservoir.
The journey just included me driving up to 90+ mph in 4th gear for like 10 seconds or less... Then I parked up and found the area surrounding the bottle all wet. It was also night time around 10:30 pm. But I didn't have heating on, I never do. Not yet anyway
I have never caught it in action like this so until now i didn't know where it was leaking from...
PS: I drive around doing urban travel so it's fine for that (as it held coolant for 18 days before drop), just can't take it anywhere far...
At high speeds of around 90+ mph it leaks out if the bottle otherwise there is no leakage
well stay within speed limits and car will be fine
Haha true but it's very unreliable, before this time it leaked during normal driving so can't just leave it...
As I said, the only two inlets/outlets connect to other pipes in the system. You are right, there has to be a pressure release, but normally that is a pipe that dumps on the ground not into the engine bay. This is a very complex cooling system, for sure.
This may be some new environmental protection requirement, who knows?
Y
You could mount a camera and light, then take it for a blast. Useful things those cellphones. I used one to see what damage was done to the Arona impact beam when it was tail ended. I wish I had them way back in the day.
The heat in cabin wast strong enough. So i decide to change the matrix on my own i paid £66 for parts and £20 for coolant and water to flush it out.
I used OBDeleven to check output temperature for each side of heating system
Hi all,
Another update...
So its been a while. And now I think I am beginning to understand the pattern of coolant drop more. I had the car taken to separate VAG specialist. Paid £200 to had the car stripped and looked for leaks. The car was left overnight as nothing could be found during the initial hour. They ruled out the heating matrix as the car isn't showing symptoms of a faulty matrix. According to them, symptoms such as smell of coolant in the cabin or uneven output of hot or cold air isn't present. When I drive at night during rain, windsheild gets misty; but when hot air is given out it clears pretty quick.
The specialist thought it may have been the EGR cooler so their tests were done to diagnose that. But it came back negative. Once the car was left overnight to get hotter, it was checked and there was no sign of coolant leak around there.
So in the end they have deemed it to be either headgasket fault or there is a crack in the engine head it self. That's what they think anyway. I asked them what other tests can they do, but they said; they wouldn't do anymore tests as they are pretty sure its one of those two things.
Now that's that... But I recently realized another thing. The coolant only drops out of the expansion tank when it's getting past the max line. However, I am not filling it even near the max line. I keep it in the middle. But when driving the car, coolant level is rising (how fast depends on speed and duration). And after a certain level past max, its all forced out of the bottle.
The coolant is being forced into the bottle for some reason which I don't know why. And that's causing my leak problem.
I parked on a quite steep incline facing upwards. It wasn't super steep but it was still a hilly road. And after half hour when I started the car, the coolant light came on and all the ccoolant was gone.
I have filled it up to literally minimum. If I see it rising again a lot, its gonna confirm by doubts.
Sorry for so many words... But that's all for now.
Another update...
So its been a while. And now I think I am beginning to understand the pattern of coolant drop more. I had the car taken to separate VAG specialist. Paid £200 to had the car stripped and looked for leaks. The car was left overnight as nothing could be found during the initial hour. They ruled out the heating matrix as the car isn't showing symptoms of a faulty matrix. According to them, symptoms such as smell of coolant in the cabin or uneven output of hot or cold air isn't present. When I drive at night during rain, windsheild gets misty; but when hot air is given out it clears pretty quick.
The specialist thought it may have been the EGR cooler so their tests were done to diagnose that. But it came back negative. Once the car was left overnight to get hotter, it was checked and there was no sign of coolant leak around there.
So in the end they have deemed it to be either headgasket fault or there is a crack in the engine head it self. That's what they think anyway. I asked them what other tests can they do, but they said; they wouldn't do anymore tests as they are pretty sure its one of those two things.
Now that's that... But I recently realized another thing. The coolant only drops out of the expansion tank when it's getting past the max line. However, I am not filling it even near the max line. I keep it in the middle. But when driving the car, coolant level is rising (how fast depends on speed and duration). And after a certain level past max, its all forced out of the bottle.
The coolant is being forced into the bottle for some reason which I don't know why. And that's causing my leak problem.
I parked on a quite steep incline facing upwards. It wasn't super steep but it was still a hilly road. And after half hour when I started the car, the coolant light came on and all the ccoolant was gone.
I have filled it up to literally minimum. If I see it rising again a lot, its gonna confirm by doubts.
Sorry for so many words... But that's all for now.
The coolant will be forced back through the system if head gasket etc as probably confirmed. That’s why the level will go over max.
The reservoir is just that, it’s whats extra to what is flowing round the system. If is your gasket I’d be surprised no back flow oil, sludge under cap and possible sweet smell.
With all your new knowledge though, I’d be going back to your trade seller under consumer rights. You do not want to be laying out for this, it’s expensive!
The reservoir is just that, it’s whats extra to what is flowing round the system. If is your gasket I’d be surprised no back flow oil, sludge under cap and possible sweet smell.
With all your new knowledge though, I’d be going back to your trade seller under consumer rights. You do not want to be laying out for this, it’s expensive!
Three things I know of that can cause that.
Thermostat, Water pump, head gasket/head failure.
Thermostat can be ruled out if you're getting hot air through the heaters.
I'd argue the head gasket could be ruled out if you've had a pressure test without any failures? Youd also be getting a misfire.
Water pump could be sitting without the fins on the back of it, yet not bad enough to leak. The water will be sitting still, overheating due to not being pushed through the radiator, and then boiling up in the header/expansion tank much like how a kettle works.
The header/expansion tank has a "leak off" at the very top, which allows coolant to drain out if the level reaches the cap. You can see this if you remove the cap and pour water down the thin groove where the caps screws into.
Can you, OP or anyone else say if that engine utilises one of these variable flow coolant pumps like VW Group used in the 1.4TDI, you know the type - the ones with the sleeve bypass valve built in?
Edit:- one thing though, if that was the case the radiator would not be getting very hot during a run neither would the cabin heater give out much heat.
If the thermostat jammed closed, I think that you would get a engine high coolant temperature warning, maybe same if the water pump impeller had come off.
Edit:- one thing though, if that was the case the radiator would not be getting very hot during a run neither would the cabin heater give out much heat.
If the thermostat jammed closed, I think that you would get a engine high coolant temperature warning, maybe same if the water pump impeller had come off.
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