Suddlenly, a new fatal sounding noise from the engine room

[CVJR]

About 6 hours after my last drive (with no problem at all), I start my 928 and a loud metallic noise starts immediately. Seems to be accessory related, doesn't get any worse with engine revving. I backed out of the driveway and pulled right back in when the noise came to my attention. No warning lights on, no fluid leaks. Didn't change with A/C compressor running or not. Didn't change or get worse with turning of the steering wheel. P/S fluid level good. Please tell me if you have any ideas for diagnosing the source. Thank you.

[CVJR]

I took a short video & sound with iphone but not idea how to post it, too large to attach as a picture.

[AirtekHVAC]

Upload to you tube and post link?

Smog / air pump perhaps?

[CVJR]

928S engine noise 8/23/13 - YouTube

[AirtekHVAC]

Holy crap! Sounds like a lawn mower!

I'm thinking air pump.....or water pump ( I hope not)

[Mrmerlin]

one at a time remove the V belts then run the engine.

Also before doing the belt removal,

remove the pass side cam cover and check the timing belt tension and inspect the belt this could also be a waterpump going bad