We had this clicking on our 2007 X3. Bought X3 used with 12000 miles. Took it to local dealer (Kuni in Beverton Or). It was not clicking when we brought it in, wanted to keep it over night. Next day they called and told us that BMW USA agreed to replace the head under warranty. The clicking is a well known problem. We were very happy that they agreed to repair without hassle. I had a Audi A4 that burned oil. I had to threaten th sue before Audi did the repair under warranty. My suggestion is to make your claim as soon as the problem cames up. Do it in writing and keep a record of when you hearing the clicking and under what circumstances.