A4 S-line Power steering noise/ judder / vibration when turning.

[Jonniwizz]

Hi please can someone point me in the right direction as to what to try next? I've been getting steering wheel judder/ vibration when turning at slow speed round corners or reversing off the drive and also from standstill doing a 3 point turn. Under the bonnet the vibrations seem to be coming from the return hose from the steering rack to the cooler pipe, like there is a low flow or blockage or something fighting against the system. I changed this hose and then the steering rack for a reconditioned one and bled air out for hours...no change. I then went on to change the power steering pump, resovoir and rubber return hose from cooler, both the top and bottom control arms on both sides of the front suspension, the top shocker mounts, track rod ends, new belt and anternator clutch pulley, flushed with brand new pentosin fluid and even bypassed the cooler pipe to eliminate any possible blockage in that.... no change! Please can someone come up with more feasible ideas to try, I really don't want to get rid of this car as it is brilliant to drive, just really embarrassing when turning! TIA

[Jonniwizz]

I have now put a smaller serpentine belt on to bypass the air con pulley. The pulley seemed to be quite noisey and the air con needs re gassing anyway so I thought this would eliminate the air con being the issue. Still same, so that eliminates this pulley being the problem. Please can anybody help with any more suggestions? Getting a bit fed up with it now.