A4 1.8T losing coolant

[Barkychoc]

My wifes car (its a convertible I assume it makes no difference) with 2004 1.8T petrol engine over a period of time loses coolant to the point that the low coolant light comes on. We had it into the audi dealer last year not long after we bought it and they replaced something at the back of the engine under warranty.

All was well for a while - now its at it again, though it does last ages between top ups it is losing coolant somewhere and I'll be damned if I can see where. You can smell coolant at the front of the car when it is parked up hot and there are tell tale stains on the drive roughly corresponding to the back of the engine.

The heater also occasionally seems to have a mind of its own blowing stone cold when heat it being asked for - is this down to an airlock or something having run the coolant level too low?

All wisdom appreciated.

[00161wj]

Check the top coolant rail, thermostat housing and a plastic bung which can be seen if u look down under the intake manifold.