power steering pump

so i installed a new P/S pump and lines on my XJ last weekend and i noticed that when i drive around there is a really high pitched whistle when the pump builds up pressure (i.e. turning the wheel). but when i stop and am idling or just not steering at all the whistle goes away. its not the sound like the pump is low and i know its not because i checked the fluid multiple times. I also took my time and bled the system and made sure all the air was out. it drives fine down the road, just has the whistle. Is the whistle normal? like some sort of a pressure release built into it?

Might be the belt sliping, tey to tighten a bit more and see if that helps.

also, make sure you didn't kink of pinch any of the lines. that could cause a squeal.

did you bleed the steering system after install?
could be the pump cavitating air.