I'm with Chuck, it's air. Further, as air burps out, you will need to add fluid to the reservoir. When we replace a rack, we turn the wheel back and forth multiple times on the lift, to dispel the air. Sometimes the air bubbles are defiant. When this is the case, I drive to a little culdesac, bout a quarter mile from the shop, and on that dead end, I go around and around and around to the right, and then around and around and around to the left. Often wonder what the people in the house on that corner think about the bizarre woman who has so many Volvos.

Chris