Power Steering Pump Rattle

[shnthms1]

I replaced my power steering pump the other day and the light stayed on the dash and the steering was still stiff. I haven’t coded the pump yet so I presume this is why. However today, I turned my car on and the pump was rattling quite loud but the steering felt light again (heavier when I was turning from a slow speed/stationary but considerably lighter than before). I’ve just tried to bleed the system again but no bubbles have come out of the pump so I’m quite unsure where this rattling is coming from. Any help??