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.