Aircon and heater doesn't work

[Jeroen1000]

Any news on where the coolant is going?

Hi Dan,
I missed the thread updates somehow.
Car is going in for repair tomorrow. But yes, I did find out where it goes. It gets pushed out of the expansion bottle. A little history:

1) I had to fill up about once a week (500 ml or so)
2) It noticed on March 15th or so the level was about 1 cm above max with a warmed up car. Never filled it up that far though. I was surprised it was still this high...
3) After a longer drive home on the 26th (+ high way) I noticed the fan spinning and upon inspecting the levels the next morning, I saw coolant on the edges of the overflow bottle. I only decided to inspect the levels because filling up was past due
4) So I started the car, moved it about 20 metres to get to level ground and opened the bottle. Coolant got sucked in (so the level dropped).

I do hope it is not the gasked and just the core...

 

[Jeroen1000]

For those wanting to know, the part number for the heater core is 5Q0819031B

 

[Dan Mansfield]

Hi Dan,
I missed the thread updates somehow.
Car is going in for repair tomorrow. But yes, I did find out where it goes. It gets pushed out of the expansion bottle. A little history:

1) I had to fill up about once a week (500 ml or so)
2) It noticed on March 15th or so the level was about 1 cm above max with a warmed up car. Never filled it up that far though. I was surprised it was still this high...
3) After a longer drive home on the 26th (+ high way) I noticed the fan spinning and upon inspecting the levels the next morning, I saw coolant on the edges of the overflow bottle. I only decided to inspect the levels because filling up was past due
4) So I started the car, moved it about 20 metres to get to level ground and opened the bottle. Coolant got sucked in (so the level dropped).

I do hope it is not the gasked and just the core...

Mine goes in on Thursday! & I suspect that the exact same thing is happening to mine - coolant is being pushed out of the expansion bottle - my theory is that the heater core/ matrix blockage is causing a build up of pressure and the expansion bottle - designed to be the weakest link - is where the coolant is escaping ... it sounds as though we have a very similar experience as I have had to fill up the expansion bottle every 6/ 7 days ...

 

[Jeroen1000]

Mine goes in on Thursday! & I suspect that the exact same thing is happening to mine - coolant is being pushed out of the expansion bottle - my theory is that the heater core/ matrix blockage is causing a build up of pressure and the expansion bottle - designed to be the weakest link - is where the coolant is escaping ... it sounds as though we have a very similar experience as I have had to fill up the expansion bottle every 6/ 7 days ...

I cannot say I'm 100% sure yet. I also smell a bit of coolant through the vents on (cold) startup but only for 2 minutes tops. I can't find any wet carpet near the matrix though. So this might be the coolant that's on the expansion bottle that I'm smelling or an additional very small leak. It's a bit weird I stop smelling it after 2 min.

Nevertheless, an overflowing reservoir is often connected to the head gasket pushing combustion gasses into the coolant circuit. But we both have an additional variable (the blocked core) so any investigation into this would involve either fixing the core or temporarily bypassing it. It is possible the coolant boils (or very close to) and causes the extra pressure (so what you are saying)
It is said that if you open the bottle after the car has been idle over night, it should not be pressurised hard anymore when you open it. So a small whoosh would be ok whilst a big woosh is bad.

Let's update this thread when we know more. After the core replacement, I'd say it will take a week or 2 to make sure the issue is gone.

 

[Scott_FR]

Same was happening with mine, where the coolant level was actually dropping on the car, as I guess a vacuum was building up somewhere in the system due to the blocked matrix. The coolant level would rush back up to where it should be when opening the lid.

Not happened again since fitting the new matrix.

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[Dan Mansfield]

Ho

I cannot say I'm 100% sure yet. I also smell a bit of coolant through the vents on (cold) startup but only for 2 minutes tops. I can't find any wet carpet near the matrix though. So this might be the coolant that's on the expansion bottle that I'm smelling or an additional very small leak. It's a bit weird I stop smelling it after 2 min.

Nevertheless, an overflowing reservoir is often connected to the head gasket pushing combustion gasses into the coolant circuit. But we both have an additional variable (the blocked core) so any investigation into this would involve either fixing the core or temporarily bypassing it. It is possible the coolant boils (or very close to) and causes the extra pressure (so what you are saying)
It is said that if you open the bottle after the car has been idle over night, it should not be pressurised hard anymore when you open it. So a small whoosh would be ok whilst a big woosh is bad.

Let's update this thread when we know more. After the core replacement, I'd say it will take a week or 2 to make sure the issue is gone.

Well, I have today picked my car up from the main dealers - matrix replaced and coolant system flushed ... and so for the first time since buying it two months ago, I drove home lovely n toasty!

 

[Jeroen1000]

Same here. Nice and hot! The original matrix was completely blocked. I only picked it up last Monday. Parts got delayed. It is too soon to tell whether the overflowing coolant issue is also gone but fingers crossed.

 

[Jeroen1000]

Alright, I fear some bad news in the making. I have just checked the coolant level after a 15 minute drive and it looks like it has dropped.

It was filled a good cm over the MAX marking on the bottle after the matrix replacement and now the level is between min and max markings.
Granted, the car engine is still hot so I have not opened the expansion bottle yet to see whether the level rises upon opening it. The bottle's edges are not wet from coolant so either it is still being ejected through the bottle but it has dried up already, there's a leak or it's between the ears.

edit: so a slight whoosh when opening the bottle. Level rose a bit. By chance, it now just touches the marker I had set between the min and max indicators on the bottle before I had the matrix replaced.

 

[Jeroen1000]

Alright, so I moved the car to level ground this morning and checked the level again. The level was lower than yesterday (just barely above the printed min level on the bottle) whilst no one has driven the car since last night. Yesterday evening (so on May 3rd) it was between min and max at a pencil marking I had made.

Anyway, I stupidly did not check on level ground yesterday and so I need to be cautious about jumping to the wrong conclusion. I've now topped up about 200 ml of coolant. If it drops again, there's definitely still an issue.

 

[Scott_FR]

As Tom Jones would say... It's not unusual for coolant levels to drop a little after being filled from empty.

You're doing the right thing.

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[Dan Mansfield]

I am about 4 weeks now since work done and coolant has dropped in that time but not at the rate it was previously (was going from full to empty in about 7 days) .. upon last check it was half way between max and min (dealer had filled to bottle seam - inch above above max) I don't know what to make of it ....

 

[Jeroen1000]

Hi Dan,

Well it can be tricky and a mind game. Mine had dropped too after the repair. I'd say I put in 200 ml to get it between min and max again. Mind you, mine was also filled a few cm above max after the repair. So it would have taken more than 200 ml to get to the point to which it had been filled after the repair.

If you don't mind me suggesting a type of approach:

- fill it with the engine cold (at least off for a few hours) to a marking you set between min and max. I used a thick pencil to draw the marker.
Note you need a 50:50 mix of coolant and distilled water. Unless you live in a very cold place
- Make note where you parked when checking the level.
- Check regularly at the same spot where you filled to get the most accurate reading. In the beginning I checked after every 'long' (+30 minutes) ride to make sure it had not borked out the coolant. Especially when motor way was involved.

So since my last refill a month ago, the levels have been stable. IF it has dropped, it cannot be more than a few mm but I think it has not dropped at all.

So in short, a one time drop after the repair is probably ok. Maybe an airlock somewhere. However, if it keeps dropping there IS still and issue.
If it is borking out the coolant, you can only spot if after a drive. It will dry up quite fast in a hot engine bay.

If it keeps dropping this slowly, the only thing I might consider is pressurising the circuit and have them go leak hunting.




I would suggest filling up with the engine cold and actually setting a marking

I am about 4 weeks now since work done and coolant has dropped in that time but not at the rate it was previously (was going from full to empty in about 7 days) .. upon last check it was half way between max and min (dealer had filled to bottle seam - inch above above max) I don't know what to make of it ....

 

[Alan128]

When using a wet vac, I sucked it directly out of the coolant reservoir, and undid a small hose at the top end of the engine.

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Just wondering is the hose you undid the small one on the top of the expansion tank?

 

[Scott_FR]

Just wondering is the hose you undid the small one on the top of the expansion tank?

Did this again recently. Turns out I was wrong, and it was the top radiator hose I pulled off.
You hardly get any loss of fluid onto the ground.

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[Alan128]

Did this again recently. Turns out I was wrong, and it was the top radiator hose I pulled off.
You hardly get any loss of fluid onto the ground.

Sent from my SM-G960F using Tapatalk

Thanks for the post and all the information, I'm having problems with coolant loss from expansion tank like your goodself and a few others. I've made a start by undoing some screws from the interior, will have to drain coolant before undoing the heater matrix. Is it a case of just pulling the pipes from both ends of the heater matrix and when you fit new one pushing the pipes into that? Also how much coolant can I expect to vacuum out from the system?

 

[ben]

Hi Scott. Thanks for this post. I’ve seen a vid on YouTube of a guy changing one on an Octavia which seems very similar to your suggestion -he just removed the blower motor, glove box and side kick board.

My car takes a long time to get warm. I had a coolant leak from the thermostat so thought it was related. That’s been replaced and the system has been manually bled but it’s the same if not worse. It’s going in for a free “mechanical” flush next week at SEAT. Otherwise it’s probs the matrix.

I’d be really grateful if you could re upload or send me your images. The ones from your original post I cannot see - they are blurred out with a photobox watermark.

how did you bleed the system afterwards? I might take mine to my dads mechanic and show him how it can be done with dash intact, and offer a pair of hands if required.

How did you bleed the system after?

Also if you could look at this vid and confirm it’s the same, id be grateful!

Thanks