Coolant loss

Just leaving this here incase somebody does a search

For over 2 years My BKD engined A3 had intermittent coolant loss ... sometimes it’d go months without needing a top up to expansion tank then i’d have to top up once or twice then ...nothing for months there was no obvious sign of a leak. then about two weeks ago I started to top up every few days. The car was starting and running fine, no overheating, no gunk around the oil filler cap no steam from exhaust usually associated with water mixing with oil (blown head gasket porous cylinder head, etc)
i did a thorough inspection and found traces of water trickling onto the top side of the gearbox. Online investigation pointed to a possible water flange leak.
I booked the car in for pressure testing and they confirmed coolant was indeed seeping from the water flange.
Replacement flange and all seems well again

pictures to follow

Edit

water trickling onto gearbox..


flange highlighted in red ...


new flange in place...

Coolant flange GSF call it ...