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.