hi all... - The Unofficial BMW M5 Messageboard (m5board.com)

BANKROBBER · 1st February 2009, 23:49

....got a small problem,well not really a problem i hope!
when i startup the m5 in the mornings,after a few minutes i get a 'howling' noise.this stays on untill i blip the throttle.
now i dont get howling but an awefull 'farting' type noise!!
it sounds like a leaf has been sucked into the small airbox/filter thing under the header tank.
i took that box off and looked at the filter,all ok and with it off the car still made the same noise.
it doesnt sound like its coming from the main airbox but from under the engine.i am a little confused as to where/what this is!....anyone?

ROB

gavinp · 2nd February 2009, 00:33

Could it be that you have noticed the air pump is working a little harder during this cold snap we are experiencing as the engine settings detect more cold start required ?

BANKROBBER · 2nd February 2009, 00:37

....i think its all as should be....just sounds like a leaf or some kinda valve fluttering.just need to know what bits are connected to each other regards air pump etc...
cant find bits on reall oem

ROB

///Manuel · 2nd February 2009, 03:38

I agree with the air pump comment or the lack of vacuum to the pump forcing it vent outside.
I'm not exactly sure how all of the mechanics work on the pump but it sounds like some problem around there.
It could also be some vacuum line leaking somewhere.
You could pull the air pump relay out and see if the noise is still there.
Maybe it's possible for you to pop the hood and try to locate the noise.
It would be helpful to see a video and hear for ourselves.
Keep us informed.

Steve Mac · 2nd February 2009, 21:09

Not the Viscous coupling locked on??