I have a high mileage 405, 1.9TD. Recently, I noticed steam coming from the offside front of the car, although the temperature guage read normal. I had been driving for around 20 mins on a dual carriageway when I hit slow moving traffic and noticed the steam after a few minutes. I called out the AA, who diagnosed a stuck thermostat. However, I have now replaced it but still have the problem. After driving the car and then stopping the engine, I can see a slight amount of water bubbling out of the radiator cap. As it runs down the expation bottle, it hits the hot radiator and then steams off. I think that this was the cause of the original steam I noticed in the traffic jam. Additionally, after the engine has cooled, there is still some (but not much) pressure in the cooling system and, upon removing the radiator cap, a small amount of water is occasionally lost on releasing the pressure. Why would I be losing water through the radiator cap? It is not a great amount-about 1 pint a week (300miles). Could it be the head gasket? My car has otherwise had 224k trouble free miles!