I wonder if anyone could help me my 1.8 petrol has developed an overheating problem .Its basically boilng over the exspansion chamber but the guage reads normal.If i watch the engine idle as the engine gets hot the level in the chamber rises until it almost gets to the top at this piont the top rad hose is quite hard and if you give the engine a little rev the rad gets hot,then the fans come in and the water level drops.Then you go for a drive and if all goes wrong,the temp guage stays at about half way for about 5 minutes then suddenly rises to 3/4 and you can hear the tank boiling over,lift the bonnet and you will find top rad hose red hot and hard exspansion bottle empty and the rad cold with the fans running.Have just changed the thermostat ,have bled the system at the 2 bleed points and checked the cylinder head airvalve (ok). I know it may be the head gasket but I cant see how that could cause this problem any suggestion would be most welcome
