Got a Disco Td5 that makes a noise from the PAS pump. Fitted new pump and water pump as well as new belt and idler or belt tensioning bearing. Blead system and noise went away. Noise is back each time after running for about 10 minutes at idle. The PAS works realy well but makes a noise even without touching the steering wheel. Have cleaned the tank, this has the strainer in the bottom, have checked out all lines and no faults, holes or perished rubbers. Noise still comes back as though no ATF after 10 minutes. Any one have any ideas? have the CD's and the manuals but nothing as such is covered in any books or software versions.