panicp

Hi all,

2008 E60 520d

Coming back from work tonight, I noticed a slight drop in power followed by a sudden onset high pitched noise under the bonnet which rose and fell with the revs.

When I opened the bonnet, it was really hard to locate - I really couldn't see what was making the noise.

No lights or warnings have come on and the car seems to drive fine.

Any ideas most welcome.

Incidentally, I'm in Perth, Australia - can anyone recommend a trusty garage to go to?

Thanks for your help.

Dave.

DavidF

Alternator bearing, water pump bearing, power steering pump, or belt idler/tensioner pulleys. Best way to isolate the source is with an automotive stethoscope (cheap at FLAPS). My bet is one of the idler/tensioner pulleys.

acuteperformance

My guess would also be Idler/tensioner pulley. As they wear out they can create noises as well as more friction which can account for a slight loss in power. These tend to gradually go bad, instead of a noise and loss of power all at once. A local indy shop would be a good place to get a more accurate diagnosis.

panicp

Great. Thanks for your help guys.