I've recently started having problems with my 156 1.8TS overheating. I generally use a local mechanic who I trust and can afford rather than the local Alfa dealership, but we are struggling to find the cause for the problem. I'm not a mechanic but am hoping we can find a solution without resorting to using the dealership! The water level in the expansion tank is fine, as is the oil level when checking the dipstick. When the car reaches the 'normal' running temperature between 70-90, the gauge drops down again before rising, leading me to think the thermostat is opening. I can moderate the heat by turning the heater on and the pipe leading into the expansion tank gets warm, which makes me think the water pump is working. When the car reaches extreme temperatures (it reached approx. 110 when I first realised the problem) the radiator fan is not kicking in. Also the OBD (engine management) light was on for a short period after we recently changed the cambelt, but the light went off after a week (is this related?). These clues point towards it being something sensor or OBD related...? Anyone any ideas what we should try next? I've also had suggestions that it could be an air-lock, does this sound feasible and how would I go about releasing one??