Step 1:Purging air from a hydraulic air bottle jacks is similar to the small trolley jacks. Start by loosening the release valve, and pumping the handle a few times. Step 2:Then, tip the bottle jack over so that the oil fill plug is facing upwards, and the unit is level. Step 3:Push the oil fill plug sideways with a flat screwdriver to allow the air to escape, be careful not to damage the plug....