Coolant lost

[who.am.i]

Hey guys.

Have 2016,2.0tdi 110kw leon. Last week came from vacation and see low cooland warning-ok fill up cca 0.5l of water and forgot about in.
This week was car every day in use,bu yesterday had another warning-again fill up with 0.5l of water and drive from home. After 5km,warning came again-unscrew filler plug and huge buble came out and level rised.
This mornig again low coolant level-fill it up and leave car alone. Will wait untill morning,to check level again.
But there is no visible leak or driping puddle of cooland under a car.

Any ideas?

 

[SRGTD]

It could be your heater matrix is blocked - see the second post in the discussion thread at the link below. You may not have used your car’s heater in recent months if the weather in your country is warm at this time of year; if so, you wouldn’t necessarily experience lack of heating in your car’s cabin caused by a blocked heater matrix.

Heater problem coolant issue matrix ? HELP

Hi everyone just wondered of someone could help. Noticed my heater on drivers side is colder compared to passenger. On low fan speed heat better than full blast when its just cold air. I removed the bag from coolant soon as got car bit it was 4 years old at the time. Noticed coolant is getting...

www.seatcupra.net

 

[SteveGSXR600K1]

Can a blocked matrix cause a loss of coolant and not have a visible leak? I know there is a known issue with the TDi's where the EGR cooler leaks coolant, but it leaks it into the exhaust ssystem and it's burnt/boiled off. So there's no evidence of a leak.