Seat alhambra tdi , lossing water , refill every other day , pressure test carried out , expansion bottle , was replaced as , air release sound was comming , did pressure test , after fitting now showed no loss of pressure , after one one day , same problem , loss of water , changed thermostat , still have same problem loss of water . Their is no sign of water leak , looked usual places , looked under footwell , passenger side , no wet carpet or water leak. I have put head gasket sealer , still loss of water , water is clear and clean when I look in the expansion tank any advice