Hello friends, my question is about my Citröen C5 III, 2,0 HDI Kombi Bj 2013 with only 66 tkm. The car has now lost 3 months (or longer, I only discovered it 3 months ago) cooler water. All 200 km almost 1 liter. There are no drops to be seen under the car or on the pipes. Presses show no pressure loss. I tried with CO2 leak tester, but probably because of cool weather the water does not get hot and does not circulate and therefore also no Exhaust gas in the water. Temperature indicator rises normally to the operating temperature and stays there normally. No water in the oil. No lubrication in the exhaust. One mechanic says ZKD deffekt, the other says that with a defective ZKD I could not have driven for 3 months without problems and certainly not the trip from Spain to Germany with partly 180 kmh on the highway. Start without problems. No power losses. No water in the inside of the car (defected or leak of heating). ie abnormality is dark discoloration of the balance tank (not by the cooling water of now but by the cooling water of 3 months ago when I noticed it). so I am totally desperate and irritated. Does anyone have an idea or have the same problem?