Coolant not being held in expansion tank for long?!!! But no leak either. Coolant not being sent back to expansion tank!

[YKFR]

I NEED HELP PLEASE!

Car: Leon fr, MK3, 2014, 2.0 TDI, 184 bhp

Issue: Coolant is not staying in expansion tank properly. All the coolant stays in the system more often than not. Once I fill the tank up, coolant doesn't get sent back to the tank/stay in the tank when Im driving and once I have finished driving.

It's not leaking anywhere either cause when I get a warning for no coolant in the tank, and I top it up to the minimum line. After a while the coolant levels are super high and it goes way past the maximum line, right to the cap. Then it eventually gets forced out as it is too much coolant in the tank.

I also hear water gurgling noises from behind the middle vents (where infotainment system is). This noise will be heard as the ignition is turned on. When the ignition is turned off and key taken out, the noise will go on for 30 seconds or so.

I have no other symptoms of this unknown problem. I have no coolant leak in the cabin, no white sludgy oil on the dip stick or oil cap, coolant is nice and reddish (when it gets back to the expansion tank).

Please help me with this. Has anyone faced this issue???!!!

Or has anyone got any helping words/solutions????!!!

 

[SRGTD]

Have a read of the discussion topic at the link below - in particular post#4; a blocked - or partially blocked heater matrix might be your issue;

Fr 184 coolant issue (yet another)

Hi, I have a 2014 model with 120k on the clock. Recently got the coolant low warning and have since had the timing chain, water pump, faulty aux. water pump and coolant expansion bowl replaced. The car ran without any more leaks for a month but has now started again, several times in the last...

www.seatcupra.net

 

[YKFR]

Have a read of the discussion topic at the link below - in particular post#4; a blocked - or partially blocked heater matrix might be your issue;

Fr 184 coolant issue (yet another)

Hi, I have a 2014 model with 120k on the clock. Recently got the coolant low warning and have since had the timing chain, water pump, faulty aux. water pump and coolant expansion bowl replaced. The car ran without any more leaks for a month but has now started again, several times in the last...

www.seatcupra.net

Hi, thanks for your reply.

I had this issue 5 years ago when I bought the car. It was indeed the heater matrix as I had not much heat coming out the vents. I got a coolant flush and heater matrix replaced. Another symptom back then was the coolant being forced out the expansion tank through the cap.

However, this time around I have no heat issues, coolant stays in the coolant tank (when it actually isn't dropped into the system). When coolant low sign comes up and there doesn't seem to be any coolant left in the tank, I take the cap off and some coolant comes rushing back into the tank.

As a reference:

I did a 17 mile journey yesterday. Some of it involved motorway, maybe 6 odd miles. Before reaching my destination, around 3 miles away from it; I got a low coolant sign. I checked the tank and it was empty. I knew the coolant was in the system, so I drove to my destination for 3 miles with NO COOLANT in the tank. My engine did not overheat, I had no issues driving and there was no white smoke issue either.

I did the same 17 mile journey again today and the coolant is perfectly fine in the bottle. It is at the same level that I topped up to last night (between min and maximum).

Aside from the sloshing water noises behind the middle vents, I can hear noises from next to the driver side wheel, when I get out of the car.

I am thinking what if it is the main water pump that is not pumping the coolant properly through the car?? But I do not know how to get that tested.

 

[SuperV8]

If you can hear gurgling behind the dash - that is air in your coolant/matrix. Air will make your pump cavitate and reduce pumping efficiency.
If your coolant disappears in the header tank - and then reappears then that is air in your coolant. Air is obviously compressible, and water is not.

Are you actually loosing coolant - or is it that it just keeps disappearing and reappearing?

The main coolant pump can leak (external leak) - but the only way for it to stop 'working' would if the shroud gets stuck, which can happen, but you would either get over cooling or under cooling, so would be slow to warm up - or over heat!
EGR coolers can leak, so to can your air to water intercooler cooler. Obviously so to can your radiator, pipes, o-rings etc.

I recently fixed my leaking heater matrix - due to an old o-ring, but I had a wet carpet - so would have thought you would notice this if you had this.

 

[YKFR]

If you can hear gurgling behind the dash - that is air in your coolant/matrix. Air will make your pump cavitate and reduce pumping efficiency.
If your coolant disappears in the header tank - and then reappears then that is air in your coolant. Air is obviously compressible, and water is not.

Are you actually loosing coolant - or is it that it just keeps disappearing and reappearing?

The main coolant pump can leak (external leak) - but the only way for it to stop 'working' would if the shroud gets stuck, which can happen, but you would either get over cooling or under cooling, so would be slow to warm up - or over heat!
EGR coolers can leak, so to can your air to water intercooler cooler. Obviously so to can your radiator, pipes, o-rings etc.

I recently fixed my leaking heater matrix - due to an old o-ring, but I had a wet carpet - so would have thought you would notice this if you had this.

Hello and thank you for your reply!

I do not think I have been losing coolant because everytime my coolant is disappearing from the expansion tank, I have added water to shut the sensor up. If I was losing coolant, then the amount of times I have added water, any remaining liquid would be more or less clear/see through by now. But when coolant reappears in my expansion tank, it is very reddish (just like how coolant should be). Also when it reappears, there is LOADS; much more than it was before (I assume because of my topping up). This overfills the tank and it is then forced out the tank through the cap.

I have had no over heating or under heating issues. My coolant temperature shows 90°c and there is no issue with the power of the car or white smoke being released or sweet smell from inside the car etc.

Ps. When I got the car 6 years ago I was losing coolant as it was being forced out the expansion tank after a long motorway journey or after a few days of local city travel. I did all tests on the car and it all came back fine. I read somewhere about a silica bag that is kept in the coolant tank to preserve the coolant, this bag can burst inside the expansion tank and all little pieces can travel through the system and block the thin and delicate heater matrix passages. So I got the heater matrix replaced on a whim. And it turned out to be the solve. Also back then my heating in the car was not working very well and both sides had a temperature difference.

 

[nd-photo.nl]

After the repair, did you keep the G13 coolant with silica bag, or did you go G12 EVO without silica? If you kept the G13 with silica, then you might have the same issue again...

 

[YKFR]

So an update on the issue.

Past 7 days or so it was completely fine. Like no issues what so ever. The coolant level looked a bit low but it wasn't completely disappearing.

Then today after driving to work (my usual 17 mile journey). I finished the day and as I was going home I wanted to take a look at my expansion tank.

To my (not so) surprise, the coolant tank was empty again. But this time I noticed that the metal components and area around the coolant tank were wet.

So my coolant IS being forced out the expansion tank after like 7 odd days on AVG.

And the water gurgling noise is still there.

 

[SuperV8]

Was this after a DPF regen? Someone on here had a blocked micro circuit pump

This was the blocked pump - but they also had no heating, so not sure this could be your issue as you still have heating on both sides don't you?

Ongoing Cabin Heat Issues Matrix

Eh up Thought id start a fresh thread as im a little bit miffed with cabin heat problems. A couple of weeks back i switched out my heater matrix as i had no hot air, matrix was blocked when i tested after removal. Flushed the system with DI water till it ran clear fitted a new Nissense matrix...

www.seatcupra.net

I think I would test your coolant for combustion gasses/CO2 - you can get cheap kits, to rule out head gasket or cracked cylinder head?

 

[YKFR]

Was this after a DPF regen? Someone on here had a blocked micro circuit pump

This was the blocked pump - but they also had no heating, so not sure this could be your issue as you still have heating on both sides don't you?

Ongoing Cabin Heat Issues Matrix

Eh up Thought id start a fresh thread as im a little bit miffed with cabin heat problems. A couple of weeks back i switched out my heater matrix as i had no hot air, matrix was blocked when i tested after removal. Flushed the system with DI water till it ran clear fitted a new Nissense matrix...

www.seatcupra.net

I think I would test your coolant for combustion gasses/CO2 - you can get cheap kits, to rule out head gasket or cracked cylinder head?

Hello,

The image in the thread you linked is one of the two auxiliary water pumps on my car. One is for charge cooler and the one in the image is for heater support.

My heating works perfectly fine ATM. It's somewhat less hot at times but when I properly have the setting on highest temp, all 4 vents at the front give out very warm/hot air. If heater matrix was getting blocked I'd see a change in heating temperature???

And going back to your first reply on my thread on Wednesday...

I now see that coolant IS BEING FORCED THE coolant tank eventually. But it's also not returning back to the coolant tank at times. And I STILL HEAR THE gurgling behind the middle vents, like water is sloshing around in a half empty bottle. And as I mentioned above. My heaters a still giving out hot air. It's quite hot at 22° c and it gets hotter as I turn the dial to higher temperature.

Someone mentioned that it could be a thermostat issue. But I don't know how that makes sense or what does a thermostat actually do? Someone said that it's either sticking open or closed.

Personally my mechanic said that I need a pressure test done to check for leaks. However last time 5 years ago, when I had the heater matrix issue. The pressure test came back normal.

 

[nd-photo.nl]

Thermostat regulates the temperature, it opens a valve at a preset temperature, so that coolant is able to run through the radiator. When it cools down to much, the thermostat closes again, so the radiator is taken out of the loop. And it opens again when the coolant reaches a certain temp (etc cycle continues).

- If the thermostat sticks in open position, the coolant never gets to operating temperature as there is too much cooling going on. You will notice higher fuel consumption, as the ECU will compensate for this low temperature by running richer
- If the thermostat sticks in closed position, it will force out the coolant. The coolant gets hotter and the pressure rises in the coolant circuit. As the coolant cap has a mechanical spring set at a certain pressure, it will open and the coolant will be pushed out. Thats why it also important to replace the coolant cap every now and then, in the end its a mechanical part.

 

[SuperV8]

If it is your thermostat causing an over-heat and so expelling coolant out the header tank - you should be able to see this in live data/diagnostics on an OBD reader, I would also presume is would flag a dash warning light? If you monitor coolant temperature you can check this, my coolant temps for example quickly ramp up to around 90, and then stay very close to 90 as the thermostat blends the cooler radiator circuit with the hot engine circuit, its not an open/closed valve, it should be constantly modulating.

Maybe you have a weak expansion tank cap (as mentioned by nd-photo.nl) - mine was weak letting go at something like 1/2 the specified pressure/bar, easy to test, by connecting a bicycle pump with gauge to your tank and blanking off the ports. Cheap to get a new one.

As I mentioned, I would also test your coolant for combustion gasses/CO2, you can get a cheap kit, under £20. It tests for CO2 in your coolant - to rule out headgasket/cracked cylinder head/block, which could also over pressurise your coolant.

If you are loosing coolant probably good to do a coolant pressure test, however not always conclusive - i.e. you might only have a 'leak' when hot - so a cold pressure test wouldn't show anything. I got a vevor coolant pressure tester for something like £25. Easy to test yourself.

 

[YKFR]

If it is your thermostat causing an over-heat and so expelling coolant out the header tank - you should be able to see this in live data/diagnostics on an OBD reader, I would also presume is would flag a dash warning light? If you monitor coolant temperature you can check this, my coolant temps for example quickly ramp up to around 90, and then stay very close to 90 as the thermostat blends the cooler radiator circuit with the hot engine circuit, its not an open/closed valve, it should be constantly modulating.

Maybe you have a weak expansion tank cap (as mentioned by nd-photo.nl) - mine was weak letting go at something like 1/2 the specified pressure/bar, easy to test, by connecting a bicycle pump with gauge to your tank and blanking off the ports. Cheap to get a new one.

As I mentioned, I would also test your coolant for combustion gasses/CO2, you can get a cheap kit, under £20. It tests for CO2 in your coolant - to rule out headgasket/cracked cylinder head/block, which could also over pressurise your coolant.

If you are loosing coolant probably good to do a coolant pressure test, however not always conclusive - i.e. you might only have a 'leak' when hot - so a cold pressure test wouldn't show anything. I got a vevor coolant pressure tester for something like £25. Easy to test yourself.

Hi,

Thank you so much for continued replies with ideas on what my issues could be.

Okay so let me just sum it up as I feel like I have seen a pattern.

- There is water sloshing noise behind the middle vents/dash
- My coolant is being lost as pressure is building up and it's being forced out of the expansion tank
- Coolant is also not being sent back to expansion tank properly at times (I think this is the case because when I undo the expansion tank cap the coolant comes rushing back and fills past the minimum line)
- I have replaced the expansion tank cap
- My heating in the car is very warm on highest temp, and there isn't really a temperature difference between the left side and right side of the car
- The coolant loss/drop is very sporadic (irregular)
- Sometimes the coolant will be lost/dropped while I travel to work 17 miles away (motorway journey) or sometimes it will hold levels for like 7 days and then lose coolant

The last time coolant was being forced out the expansion tank was when I bought the car and it turned out to be a blocked heater matrix because of the silica bag bursting inside the expansion tank. And my car's heaters weren't really all that warm/hot

When I got the issues fixed I didn't buy a new expansion tank with a silica bag.

With this information can anyone suggest where fingers might point towards? Or if anyone has come across a thread with similar issues as myself?

Can you please link me both combustion test and pressure test kit? And let me know how easy is it to run both test your self? I have asked around for the tests at garages and the prices are insanely high!!!

Thanks! Any help will be greatly appreciated!!!

 

[YKFR]

Thermostat regulates the temperature, it opens a valve at a preset temperature, so that coolant is able to run through the radiator. When it cools down to much, the thermostat closes again, so the radiator is taken out of the loop. And it opens again when the coolant reaches a certain temp (etc cycle continues).

- If the thermostat sticks in open position, the coolant never gets to operating temperature as there is too much cooling going on. You will notice higher fuel consumption, as the ECU will compensate for this low temperature by running richer
- If the thermostat sticks in closed position, it will force out the coolant. The coolant gets hotter and the pressure rises in the coolant circuit. As the coolant cap has a mechanical spring set at a certain pressure, it will open and the coolant will be pushed out. Thats why it also important to replace the coolant cap every now and then, in the end its a mechanical part.

Hi,

I have heard from multiple people that it could be the thermostat. My car is 12 years old and I assume A LOT of things are wearing out FAST under the hood.

How would I check if the thermostat is messed up????

I'm just sick and tired of this coolant issue right about now! :''''(

 

[SuperV8]

Hi,

I have heard from multiple people that it could be the thermostat. My car is 12 years old and I assume A LOT of things are wearing out FAST under the hood.

How would I check if the thermostat is messed up????

I'm just sick and tired of this coolant issue right about now! :''''(

As I mentioned:

If it is your thermostat causing an over-heat and so expelling coolant out the header tank - you should be able to see this in live data/diagnostics on an OBD reader, I would also presume is would flag a dash warning light? If you monitor coolant temperature you can check this, my coolant temps for example quickly ramp up to around 90, and then stay very close to 90 as the thermostat blends the cooler radiator circuit with the hot engine circuit, its not an open/closed valve, it should be constantly modulating.

 

[SuperV8]

Hi,

Thank you so much for continued replies with ideas on what my issues could be.

Okay so let me just sum it up as I feel like I have seen a pattern.

- There is water sloshing noise behind the middle vents/dash
- My coolant is being lost as pressure is building up and it's being forced out of the expansion tank
- Coolant is also not being sent back to expansion tank properly at times (I think this is the case because when I undo the expansion tank cap the coolant comes rushing back and fills past the minimum line)
- I have replaced the expansion tank cap
- My heating in the car is very warm on highest temp, and there isn't really a temperature difference between the left side and right side of the car
- The coolant loss/drop is very sporadic (irregular)
- Sometimes the coolant will be lost/dropped while I travel to work 17 miles away (motorway journey) or sometimes it will hold levels for like 7 days and then lose coolant

The last time coolant was being forced out the expansion tank was when I bought the car and it turned out to be a blocked heater matrix because of the silica bag bursting inside the expansion tank. And my car's heaters weren't really all that warm/hot

When I got the issues fixed I didn't buy a new expansion tank with a silica bag.

With this information can anyone suggest where fingers might point towards? Or if anyone has come across a thread with similar issues as myself?

Can you please link me both combustion test and pressure test kit? And let me know how easy is it to run both test your self? I have asked around for the tests at garages and the prices are insanely high!!!

Thanks! Any help will be greatly appreciated!!!

Search for "VEVOR 14 Pcs Radiator Pressure Tester Coolant" I have this, good quality kit with metal pump for around £25. Simple to use, just screw the correct adapter on to your tank - and pressurise with the pump and wait for 30mins, see if it drops.

I don't have a "COMBUSTION LEAK KIT - DIESEL HEAD GASKET & BLOCK" but looks like this: Again, simple to use and around £35. Plenty on youtube videos on using one.

There are many one way valves in the cooling system, if you check from the previous thread I shared - one of these failed open which caused issues. Rather tricky to fault find though as probably involves removing each hose and physically checking!

 

[Tester01]

Check charge air cooler.

Common issue where coolant leaks into there

 

[James_R]

Check charge air cooler.

Common issue where coolant leaks into there

+1

 

[Compo1]

Used a endoscope to look in my charge cooler, but if not available, its pretty easy to temporally bypass. If your issues go it would then look like the charge cooler.

 

[Compo1]

I am thinking what if it is the main water pump that is not pumping the coolant properly through the car?? But I do not know how to get that tested.

Testing the main coolant pump and its electronic shroud is pretty easy. Get the car up to temp i mean really up to temp not just 90 on the gauge.

Get the bonnet up and have someone keep the revs at a stable 2000rpm, look at the thin return pipe going back into the coolant tank. If your not seeing flow into the tank then you may a impeller and the shroud sticking issues. The shroud would usually fail open though. But impellers do come loose on the shaft.

I will say if either of the above were true id expect some over heating issues.

Gurgling behind the dash seems more like an air lock issue. If this was my car the first thing is do would be a coolant flush and id refill the coolant via vacuum filling. Its the only way for the home mechanic to ensure the system is filled without introducing air.

 

[YKFR]

If it is your thermostat causing an over-heat and so expelling coolant out the header tank - you should be able to see this in live data/diagnostics on an OBD reader, I would also presume is would flag a dash warning light? If you monitor coolant temperature you can check this, my coolant temps for example quickly ramp up to around 90, and then stay very close to 90 as the thermostat blends the cooler radiator circuit with the hot engine circuit, its not an open/closed valve, it should be constantly modulating.

Maybe you have a weak expansion tank cap (as mentioned by nd-photo.nl) - mine was weak letting go at something like 1/2 the specified pressure/bar, easy to test, by connecting a bicycle pump with gauge to your tank and blanking off the ports. Cheap to get a new one.

As I mentioned, I would also test your coolant for combustion gasses/CO2, you can get a cheap kit, under £20. It tests for CO2 in your coolant - to rule out headgasket/cracked cylinder head/block, which could also over pressurise your coolant.

If you are loosing coolant probably good to do a coolant pressure test, however not always conclusive - i.e. you might only have a 'leak' when hot - so a cold pressure test wouldn't show anything. I got a vevor coolant pressure tester for something like £25. Easy to test yourself.

Hi,

I connected an OBD reader yesterday and had the car get to temp and 90° was reached pretty soon. After that it didn't fall below or go too high.

I went and selected live data information for coolant or water related things as there was no actual option for thermostat. Please see images attached.

Do you (or anyone) think (s) that this live information data shows thermostat to be working? Or if it still could be somehow not functional properly?

Also I have bought a pressure testing kit. Will be using it as soon as it arrives.