Looking for some help on tracking down my slow leak. 2015 VRS petrol with DSG, had the waterpump changed about a year ago so that was the first place I looked when I noticed the coolant going down - nothing. I have been under the car, cant see any coolant or any dry deposits etc. I swear I can sometimes smell coolant like it is burning off somewhere but that could be in my head. Recent oil change was fine, no mayonnaise etc.

 

The leak is only small, only a few mm on the coolant bottle every 2-3k kms but as it is a sealed system it has to be going somewhere?

 

Any ideas on where to look guys?

 

Thanks in advance.

Have you tried to check all the potential leaking points when the engine is cold? Admittedly, some times the leak is so weak that it does not happen when the system is not under pressure. I have a similar experience but with a different car which the thermostat housing was not properly sealed and had a very slow leak like one tiny drop every several minutes. What you could do is following all the cooling pipes (which you could find them in the workshop manual) and inspect the pipes and the connection points. But, I guess the bottom line would be doing a compression test.

Many threads on this subject, with all engine types, but there doesn't seem to be any definite answer.