I was reading this thread and I didn't understand why/how a vaccum pump looked like the one shown in the pictures (posted above). It must be oil separator.

I replaced the oil separator on my '06 530i (N52).
Oil separator [on N52] is attached on the back of intake manifold.

 

LOL, if that's what it is cool, the mechanic that fixed it spoke no english, so to him it was a vacuum pump. The name didn't matter much to me, if it's the oil separator, thanks for the correction. What matters to me is the car is running flawlessly now.

 

Did you have a photo of that hose or general area in which you were referring to? i looked underneath the car engine bay area couldn't find the oil separator.

 

The oil separator is located under the intake manifold on the driver's side. The hose that I was told commonly cracks (or the fitting cracks) is at the bottom of the separator.

 

Part labeled #4 is the hose Pjinca is referring to.
If you are going to replace that hose, I'd recommend you to go ahead and replace the other hose (labeled #3, that attaches the oil separator to the valve cover) and the oil separator itself.

I have replaced the oil separator and all related hoses on my '06 530i in January as a preventive maintenance while I was replacing the starter.

 

vacuum pump a ?
your car has CCV failure and secondary air pump failure dude

 

Yes this is a common problem on the M54 engines. Actually I've never had to address it personally but I read about it heavily 4 years or so ago. you can call it CCV/oil separator etc.