Babbabooey

2009 A6 coolant level keeps dropping. Neither my mechanic nor Audi dealership can find a leak. Water pump was replaced right before I bought it. Had it for a week before coolant level dropped. Initial diagnosis was air or burbing. Sometimes it's days at same level, then it will drop an inch or two suddenly. Keeps happening. No indication of dried pink gunk anywhere. Thoughts?

raj99

Could be the actual cap, the reservoir tank (micro-fractures)...but there's definitely a leak somewhere. My guess is that a new cap will fix it, since these things have been known to have issues from time to time.