The flow control valve is stuck or inoperative.

Replace the flow control valve. Refer to Power Steering Fluid Reservoir Replacement - Off Vehicle .

The pressure plate is not flat against the cam ring.

Refer to End Plate and Rotating Group Replacement .

An excessively worn cam ring

Replace the ring. Refer to End Plate and Rotating Group Replacement .

A scored pressure plate, thrust plate, or rotor

Replace the components. Refer to End Plate and Rotating Group Replacement .

The vanes are sticking in the rotor slots

Refer to End Plate and Rotating Group Replacement .

Improper installation of the vanes

Refer to End Plate and Rotating Group Replacement .

There is air in the fluid.

Locate and repair the leak.

The power steering fluid is low.

Add an adequate amount of power steering fluid. Refer to Refilling the Power Steering System .

There is damage on the hoses or the steering gear.

Replace any damaged components.