when i did mine i simply made sure i had no bubbles and that the reservoir is topped off. Then i turned the steering wheel from lock to lock until i got no air bubbles in the reservoir. Although the first time i disconnected the PS lines from the pump i removed the pressure line and did not replace the o-ring and kept getting air in the lines. So if he has topped off the reservoir and still finds air in the system i would definitely check all connections on the pump to make sure you are not getting air in the lines.