Hoping somebody can help me out. 

Just been to view a V70 D5 2007 185bhp (P2) and i was really happy with it apart from one area of concern.

When out driving, under load from about 1500rpm there was a distictive grainy/sucking noise coming from (i assume) the engine bay, but it the noise sounded like it was coming through in dials/instrument panel.

Once stationary with the bonnet up, you couldn't hear it when revving the engine, only when actually driving.

There was another V70 with identical engine on-site so we took that out for a test drive and it did not make the noise. We also took the dealer/seller out for a quick drive to show him (as he said he drives a D5 V70 as well and i wondered if it might have been normal noise), but he said he couldn't hear it, which is wierd because it's very noticeable. 

Anyone got any ideas what it could be? I liked everything else about the car and have been searching for ages. 

Cheers.