GM Full-Size Trucks 1980-1987 Repair Guide

Power Steering Gear

Print

GENERAL DESCRIPTION



The steering gear is of the recirculating ball type. This gear provides for ease of handling by transmitting forces from the wormshaft to the pitman shaft through the use of ball bearings.


WARNING
Use only an approved power steering lubricant in the pump. Never use brake fluid in the power steering pump, or damage may occur.

Hydraulic System Checks

See Figure 1

Click image to see an enlarged view

Fig. Fig. 1: Checking power steering pressures

The following procedure outlines methods to identify and isolate power steering hydraulic circuit difficulties. The test provides means of determining whether power steering system hydraulic parts are actually faulty. This test will result in readings indicating faulty hydraulic operation, and will help to identify the faulty component.

Before performing hydraulic circuit test, carefully check belt tension, fluid level and condition of driving pulley.

Engine must be at normal operating temperature. Inflate front tires to correct pressure. All tests are made with engine idling. Check idle adjustment and, if necessary, adjust engine idle speed to correct specifications and proceed as follows:

  1. With engine NOT running disconnect pressure hose from pump and install Tool J-5176 using a spare pressure hose between gauge and pump. The gauge must be between shut-off valve and the pump. Open shut-off valve.
  2.  
  3. Remove filler cap from pump reservoir and check fluid level. Fill pump reservoir to full mark on dipstick. Start engine and, momentarily holding steering wheel against stop, check connections at Tool J-5176 for leakage.
  4.  
  5. Bleed system as outlined under Maintenance and Adjustments.
  6.  
  7. Insert thermometer (Tool J-5421) in reservoir filler opening. Move steering wheel from stop to stop several times until thermometer indicates that hydraulic fluid in reservoir has reached temperature of 150 degrees to 170 F.
  8.  


WARNING
To prevent scrubbing flat spots on tires, do not turn steering wheel more than five times without rolling vehicle to change tire-to-floor contact area.

  1. Start engine and check fluid level adding any fluid if required. When engine is at normal operating temperature, the initial pressure read on the gauge (valve open) should be in the 80-125 psi range. Should this pressure be in excess of 200 psi, check the hoses for restrictions and the poppet valve for proper assembly.
  2.  
  3. Close gate valve fully 3 times. Record the highest pressure attained each time.
    1. If the pressures recorded are within the listed specification and the range of readings are within 50 psi, the pump is functioning within specification.
    2.  
    3. If the pressures recorded are high, but do not repeat with 50 psi, the flow controlling valve is sticking. Remove the valve, clean it and remove any burrs using crocus cloth or fine hone. If the system contains some dirt, flush it. If it is exceptionally dirty, both the pump and the gear must be completely disassembled, cleaned, flushed and reassembled before further usage.
    4.  
    5. If the pressures recorded are constant, but more than 100 psi below the low listed specification, replace the flow control valve and recheck. If the pressures are still low, replace the rotating group in the pump.
    6.  

  4.  
  5. If the pump checks within specifications, leave the valve open and turn (or have turned) the steering wheel into both corners. Record the highest pressures and compare with the maximum pump pressures recorded. If this pressure cannot be built in either (or one) side of the gear, the gear is leaking internally and must be disassembled and repaired.
  6.  
  7. Shut off engine, remove testing gauge, spare hose, reconnect pressure hose, check fluid level and/or make needed repairs.
  8.  

ADJUSTMENTS



Adjustment of the steering gear in the vehicle is not recommended because of the difficulty encountered in adjusting the worm thrust bearing preload and the confusing effects of the hydraulic fluid in the gear. Since a gear adjustment is made only as a correction and not as a periodic adjustment, it is better to take the extra time and make the adjustment correctly the first time.

Since a handling stability complaint can be caused by improperly adjusted worm bearings a well as an improper gear over-center adjustment, it is necessary that the steering gear assembly be removed from the vehicle and both thrust bearing and over-center preload be checked and corrected as necessary. An in-vehicle check of the steering gear will not pinpoint a thrust bearing looseness.

Before any adjustments are made to the steering gear attempt to correct complaints of loose or hard steering, or other wheel disturbances, a careful check should be made of front end alignment, shock absorbers, wheel balance and tire pressure for possible steering system problems.

Steering Gear High Point Centering
  1. Set front wheels in straight ahead position. This can be checked by driving vehicle a short distance on a flat surface to determine steering wheel position at which vehicle follows a straight path.
  2.  
  3. With front wheels set straight ahead, check position of mark on wormshaft designating steering gear high point. This mark should be at the top side of the shaft at 12 o'clock position and lined up with the mark in the coupling lower clamp.
  4.  
  5. On the C series, if the gear has been moved off high point when setting wheel in straight ahead position, loosen the adjusting sleeve clamps on both left and right hand tie rods. Then turn both sleeves an equal number of turns in the same direction to bring gear back on high point. Turning the sleeves an unequal number of turns or in different directions will disturb the toe-in setting of the wheels.
  6.  
  7. On K series, if the gear has been moved off high point when setting wheels in straight ahead position, loosen the adjusting sleeve clamps on the connecting rod. Then turn sleeve to bring gear back on high point.
  8.  
  9. Readjust toe-in, if necessary.
  10.  
  11. Be sure to properly orient sleeves and clamps, when fastening and tightening clamps to proper specifications.
  12.  

PUMP BELT TENSION ADJUSTMENT



See Figure 2

Click image to see an enlarged view

Fig. Fig. 2: Checking belt tension with J-23600

  1. Loosen pivot bolt and pump brace adjusting nuts.
  2.  


WARNING
Do not move pump by prying against reservoir or by pulling on filler neck, or damage to the pump could occur.

  1. Move pump, with belt in place until belt is tensioned to specifications as indicated by Tool J-23600.
  2.  
  3. Tighten pump brace adjusting nut. Then tighten pivot bolt nut.
  4.  

FLUID LEVEL ADJUSTMENT



  1. Check oil level in the reservoir by checking the dipstick when oil is at operating temperature. On models equipped with remote reservoir, the oil level should be maintained approximately 1 /2-1 in. from top with wheels in full left turn position.
  2.  
  3. Fill, if necessary, to proper level with GM Power Steering Fluid or equivalent.
  4.  


WARNING
Never use brake fluid in the power steering pump, or damage may occur.

 
label.common.footer.alt.autozoneLogo