I have a 2008 galaxy 1.8 tdci. Coolant level keeps fluctuating. When cold and filled no apparent leaks. When run coolant level drops about an inch/inch and a half and remains there. Temperature gauge reads ok at 90 and no problems with performance or fuel consumption. Have been to 2 different mechanics and replaced expansion tank and cap twice. problem persists. Neither of them seems to think there is a problem although one did say that 21 psi was high as most other cars run caps at about 14 psi. If hot and undo the cap (slowly) releases pressure and levels return to normal. Thermostat has been replaced and seems ok. have seen this in other cars in fleet and they all seem to do a similar thing. I have read all the other posts regarding similar problems on older models but could not find anything recent. Unfortunately cannot even get a manual at the moment. Any ideas? Thanks.
