I have a 2004 v70.After I have been driving my car for 15+/- minutes - the power steering starts to make whirring sound obviously when moving my steering wheel. I have taken it to a local trusted mechnic but tono solution - He has replaced the power steering unit twice and it still has the same issue - changed the fluid, etc - everything - Have you ever heard of such a thing? Any suggestions? HELP!

 

Sometimes the fluid bottle breaks inside and makes the noise like that.
If you remove the lid and look in there with a flashlight where the small hose attaches to the bottle.
Look and see if the black tube is still attached. If you see a little copper nipple then it needs a new bottle.