I had a 2008 X5 3.0 engine with the problem.

It would happen in the morning for about 3 to 5 minutes.

Used my cell phone and recorded the sound.

Dealer listened to the sound. (They won't begin any procedure without some cause.)

At that time (about a year ago) the procedure was to bleed first.

The problem re-occurred, took another recording back and the head was replaced.

Problem resolved.

( The current procedure is to bleed then replace the lifters - not the complete head.)

That is the way mine went.

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Current - 2010 X5 35d
Retired - 2008 X5 3.0
Retired - 2007 X5 3.0
Retired - 2006 325 3.0