without fluid the rack will function the same way as a manual rack but will require much more force. you will need to keep it lubricated by either looping the lines or setting each side up on a resivoir. if its not lubricated the rack will eventually bind up.
personally i would be more worried about putting all that stress on the torsion rod/bar. this bar twists and is what controls the valves for fluid flow. when you are putting all that extra effort into low speed turning it could go from elastic to plastic deformation and possibly break after time.
All power assisted racks will function normally as a manual rack as a safety feature if the power assist where to fail, but they are in no way designed to take prolonged exposure to driving with no assist.
Originally Posted by PowerFocer
That's incorrect. The rack requires the fluid to function as per design. Just because there is no high pressure assist or way of replacing the fluid (i.e. the pump) doesn't mean it isn't a hydraulic system. A brake system with no booster is still a hydraulic system.
^^ Fluid is not required for the rack to function, you are looking at the system in the wrong way. its a mechanical system that has a hydraulic assist.