So I have a 2002 s60 with 130000 miles and now if i turn sharp to the left while applying power I get a vibration that is felt through the steering wheel and floor. Also today in a fit of anger in a large parkng lot I wiped the stearing left to right while gassing it up and it got pissed. It did the noise and vibration like before but now it also has a power stearing wine like when the pump is dry. The car sat while we went inside and when we came back to go home all was good (no power wine).
Is there a pressure relief valve in the rack?

 

I would check the fluid level maybe also there is some air in the system, ive read you need to turn the wheel lock to lock 10 times to remove air from the system

i just changed the power steering fluid in my S60 today, i was getting a whining noise on cold starts that would go away after 30 seconds, i havent had a chance to see if the problem is gone now, but the old fluid was a kinda brownish red color and the new fluid is green

i used a hand bulb type siphoner (10 bux at a parts store) and siphoned everything from the resevoir
then started the engine for 2 seconds to try and drain the rack and syphone some more
then dumped in the new stuff and did the lock to lock 10 times
checked level and did lock to lock again.
let the car warm up for a while then made sure it was on the HOT mark

Not sure if i did it right but it is working after a bit of whining to get the new fluid through. I couldnt find any way to remove the upper hose on the resevoir as someone else suggested. anyway i hope my problem is solved (ill find out tomorrow) and hope this info helps you

i think its called chf pentosin 202, i got it from partsgeek.com for like $17.. not sure what else to use, the original stuff is a different color? no idea what you could top it off with, I dont like going to the stealership for anything.. its always long drive through heavy traffic

if all else fails you might need a new PS pump which is like $70 i think