Volvo v70 steering noise
 

Hi all.
i wonder if anyone can help me seeing as my local dealership seems uninterested to assist me with a recent noise I discovered on my 2008 V70 2.4d

when I gently turn the steering wheel left or right either while the car is moving or stationary, there is a hissing noise coming from where the steering column meets the floor.
if I give it full lock and hold it the noise goes away.
it sounds like air escaping from a small hole or similar.

it's not very loud, but if I put my head down by the pedals, it's very obvious. The dealership did A recent fluid flush but there was no noise present immediately after (about 4 months ago)

I would be grateful for any suggestions !