00-2 SERVICE INFORMATION TROUBLE SHOOTING Steering System PROBLEM POSSIBLE CAUSE CORRECTION Objectionable “Hiss” Noisy relief valve. There is some noise in all power steering systems. One of the most common is a hissing sound most evident at standstill parking. Hiss is a high frequency noise simi- lar to that experienced while slowly closing a water tap. The noise is present in every valve and results from high velocity fluid passing valve orifice edges. There is no relationship between this noise and perfor- mance of the steering. “Hiss” may be expected when the steering wheel is at end of travel of when slowly turning at stand still.
Do not replace the valve unless “hiss” is extremely objectionable. A replacement valve will also exhibit slight noise and is not always a cure. Rattle or Chuckle Noise in the Steering Gear 1. Gear housing loose on frame. 2. Steering linkage looseness. 3. Pressure house touching other parts of the truck. 4. Loose pitman shaft over center adjust- ment. A slight rattle may occur on turns because of increased clearance off the “high point.” This is normal and clear- ance must not be reduced below speci- fied limits to eliminate this slight rattle. 5. Loose pitman arm. 1. Check gear mounting. Torque the bolts to specifications. 2. Check linkage pivot points for wear. Re- place if necessary. 3.
Adjust the hose position. Do not bend tubing by hand. 4. Adjust. 5. Torque the pitman arm nut. Groan Noise in the Steering Pump 1. Low oil level. 2. Air in the oil. Poor pressure house con- nection. 1. Fill the reservoir to the proper level. 2. Torque the connector. Bleed the system. Rattle or Knock Noise in the Steering Pump Loose pump gear nut. Torque the nut. Rattle Noise in the Steering Pump 1. Vanes not installed properly. 2. Vanes sticking in the rotor slots. 1. Install properly. 2. Repair or replace. Switch Noise in the Steering Pump Defective flow control valve. Replace or repair. Whine Noise in the Steering Pump Pump shaft bearing scored. Replace the housing and shaft.
Flush and bleed the system. Growl Noise in the Steering Pump Excessive back pressure in houses or the steering gear caused by restriction. Locate the restriction and correct. Replace the part if necessary. Growl Noise in the Steering Pump (Par- ticularly Noticeable at Standstill Parking) 1. Scored pressure plates, thrust plate or rotor. 2. Extreme wear of the cam ring. 1. Replace the parts and flush the system. 2. Replace the parts.