2011 BMW X5 35i engine knocking at 2000 rpm only 66k miles on car
 

This is my first and last BMW I ever buy, in only 5000 miles of ownership is just one thing after another. This sound started about 2 weeks ago but I just noticed it was that bad. But when idling and bringing the rams to 2000-2500 it is clearly a knocking sound. Engine hasn't been starved of oil and oil change was done about a month ago. No check engine light, engine otherwise is smooth, no hesitation, no power loss, accelerates strong.

Let me add that there is no white smoke, no oil leaks, check the seals around engine all clear.

It does that knocking after engine is warm, if I rev to 2000 rpm with engine cold it does not makes the knocking sound.

What you guys think this is?

https://www.youtube.com/watch?v=KO_upc4Op10

Then I saw this part today kind of vibrating, is this normal, I didn't have anyone to rev the car to see if it was coming from that part.

https://www.youtube.com/watch?v=KO_upc4Op10

Is it a CPO by any chance?

No CPO )-:

I'd start with something simple: check that all spark plugs are torqued...

+2, however, did this issue start overnight? If so, then start with the basics. When I first read the post, I assumed it may have been misfires.

I would also start with making sure all spark plugs are tightened.

The belt tensioner is unlikely to cause a noise like that.

It does not sound like a spark plug issues.....

I agree with your second video:
https://www.youtube.com/watch?v=t5XUbeCVbCc

I think your serpentine belt tensioner is bad and needs to be replaced.
Is anything else loose on the belt assembly?

Damn, that sounds like a rod knock...

Not sure if that's a rod knock; it sounds duller in frequency. A rod knock sounds more metallic in nature. Also, a rod knock will be much more pronounced under sharp engine accelerations. Stab and let off the throttle quickly, and listen for it. Have you revved the engine higher than 2500 RPMs; like up near 4-5000?? Does the noise increase, subside, or stay the same? Is there roughness/vibration in the engine while its running?

Nothing else is loose, bringing it to get fixed on Friday. At least the belt tensioner kit is not expensive only $150.