Hi All

Pretty much out of ideas with a problem I have with my van. There was a power steering pipe that was leaking so I replaced it. That's when it all started. Everything seems fine for a few miles than steering become very difficult to turn. After a while it suddenly frees up then it happens again. I tried draining and refilling fluid, dispelled all air locks but no different. So, replaced pump. No different. Has to be rack I thought. Replaced rack! No different. So what now? I'm sure you guy will have the answer. Thank you!

Just to add that the belt on pump is 100k original but seems tight. The pump does get hot but its right next to engine. I dont think the fluid gets too hot but not entirely sure. I used the fluid recommended by Halford but have been unable to find details on the correct fluid elsewhere.
Barry