There is excessive back pressure in the hoses or the steering gear caused by restriction

Locate and repair the restriction. Refer to Power Steering System Test .

The power steering gear inlet (pressure) hose is touching other parts of the vehicle.

Check and adjust for proper mounting and clearance.

Refer to Power Steering Pressure Pipe/Hose Replacement .

There is scoring on the pressure plates, thrust plates, or rotor

Replace the power steering pump. Refer to Power Steering Pump Replacement .

There is an excessively worn cam ring

Replace the power steering pump. Refer to Power Steering Pump Replacement .