Engine sound : higher pitch? (now with sound clip)

M

Montjeu

Member
I have the N52, a 2007 2.5 Si in fact, owned for two years. We get very used to how our p & j sounds don't we, and today I noticed a higher pitched 'whirr', over the top of the throaty straight six seemingly, but not all the time. Anyone experienced this already? Hopefully it's not a prelude to a big problem. I made a video sound clip, sorry quality is not great!

https://www.dropbox.com/sc/g2kxwc3oz3j77eu/O5tbtQ48Ak
 
Smartbear: Could be, I don't know what that sounds like!

ben g: I first noticed it gently revving in neutral, circa 2500 rpm, warming the engine a little from cold.
 
I have a "whirr" coming from my 3.0si I can replicate in neutral and in 1st, 2nd and 3rd gears though its most noticeable in 1st and 2nd, it climbs with engine revs.

I have taken it to BMW a number of times and there technicians either refuse to hear it or they say its normal. Ive given up trying, though I might try a different BMW dealer to see if I get any joy.

The only way I can describe the sound is a bit like the noise that reverse gear makes. My gut feel is that it is something to do with a bearing on the tensioner pulleys or something. Either way its not really got any worse over the past year.

I would love to hear another 3.0Si to see if it is normal.
 
Could it be an air leak sound?

When the rubber boot on the DISA valve split on my zed there was a noticible higher pitched whoosh sound when accelerating.
 
That's pretty weird. Exhaust blowing? Or is that solely engine noise? Could be a cracked manifold perhaps? Does it get louder as you rev higher (5k rpm)?
 
Pretty sure it's not the exhaust. I'm going to take her for a run in the morning and test it out a bit.

Worth pointing out that at idle it sounds perfectly normal.
 
Did you get to the bottom of this noise? Mine has always made a similar noise but not got any worse.

Ben G. Would that make a difference/ cause the noise?
 
I'm taking her to my favourite garage on Friday as it happens to do some investigation and tune if required.

100% there's a tone change. The deep throat is overlaid by a whiney whistle when revving, it's hard to describe. Not a tapping or nasty sound, more of a whistle or air escaping. Gets worse towards the red line.

The phone video doesn't capture sound very well and it's not clear in the clip.
 
Update, they couldn't find anything wrong. Advised to monitor and if it exacerbates bring back (as obviously only I knew the exact engine note beforehand). But some peace of mind. Not a wasted trip, got a couple of odd jobs done, CDV deleted and transport mode deleted as well.
 
Very odd a new sound developed after running for two years. Coincidentally I did decide to refuel with V Power around the same time.
 
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