Hello, today I have a problem again. The vehicle of my daughter an Opel Agila 1.0, built in 2002, ran 160000 km now again a cooling water loss. The vehicle was already with water loss in a free workshop. The workshop master was a longtime master in an Opel workshop. After my knowledge a defective cylinder head seal was replaced. After about 2 weeks again no cooling water was in the compensation tank. Then a defective seal on the AGR was found as a source of error. This was renewed and now after a further 2 weeks the compensation tank was empty again from the cooling system. Now I drove once by car to the workshop. Now I was told that at that time not the cylinder head seal but the seal from the side cover was renewed. Together with the workshop master I have now filled the compensation tank with warm engine up to the edge with water. Then I the engine runs at an increased speed and then again and again small air bubbles rose. In my opinion this indicates perfectly a defective cylinder head seal. The workshop master is not convinced of my diagnosis yet and wants to do further test. Who can tell me something about it now? Is the head seal defective or not, or is the cause possibly entirely elsewhere? Thanks Helmut