Strange noises on my E53 4.8is

[Junkycosmos]

Wonder if the sound on left could be coming from the vacuum pump that is driven from the cam right under oil cap?

Remove your air scoop to intake filter box. Follow the vacuum line from your brake booster 1/2" line across front of engine to this pump
(http://www.amazon.com/Power-Brake-Bo.../dp/B00AC58R6W)

There is a small vacuum "test nipple" on the front side of the pump. Know my pump (new few k miles ago) makes a sound that matches rpm of motor. Maybe try pulling the test nipple and see if the sound from the vacuum pump matches exact timing of what you hear from from the oil cap.

IF it is the pump they are easy to change but do change the oil pressure sensor while you have it off, common leaker and easy to reach with pump off.

[bmwktm]

another update... clicking sound on the left definitely IS vacuum pump just like Junkycosmos said. I had a small leak from that area so i got an eBay o-ring set of 2 and sensor below the pump (since it can be changed only with the pump removed so i just did that also). AND how do i know 100% clicking sound on the left (actually on the right if you are looking from inside) is created by the vacuum pump??? ive just started the car without it! it was such a nice sound with no extra clicking... ive just covered the hole where it was and started it for a minute... and when everything was back in the place i had the same clicking back. oil leaks stopped and finally we have the answer what is that fakin clicking sound on BMWs. and that is not only on N62... it is on all engines (including diesels) having this type of vacuum pump. and this pump is on cars with valvetronic because that technology was introduced to remove vacuum from the intake (fuel efficiency). and since brake booster needs vacuum bmw installed this clicking vacuum pump on bank 1. Mystery solved... i wonder why no one else wrote that on the webz because i have been searching an answer for many months....