1999 Chevy Tahoe PS Gear or pump?

Tiny
BPUTNAM
  • MEMBER
  • 1999 CHEVROLET TAHOE
  • V8
  • 4WD
  • AUTOMATIC
  • 21,100 MILES
I recently replaced the power steering gear on my tahoe; at the same time I replaced the pitman arm and power steering hoses. After draining and refilling the pump with fresh fluid I tried to bleed the air from the system by first removing the coil wire and turning the engine over while turning the steering wheel back and forth, then did the same with the engine running, making sure to keep the pump full. At first the steering was easy, then it started to get more difficult to turn the wheel. On the test drive I noticed that the wheel is difficult to turn (maybe only 50% power steering) and that there is more play in the steering wheel than there was before changing the gear (wheel freely rotates 20-25 degrees back & forth). Does it sound like the stiffness is because there is still air in the system? How can I determine whether the PS pump has failed? Any way to adjust the free play out of the wheel or do I need to go through the trouble of getting and swapping out another rebuilt gear?
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Sunday, June 20th, 2010 AT 10:55 AM

3 Replies

Tiny
MERLIN2021
  • EXPERT
HYDRAULIC SYSTEM BLEEDING 1. Fill reservoir to correct level. Allow fluid to settle for no less than 2 minutes. Start engine and run for 30-60 seconds, then turn off. Check fluid level and add fluid (as necessary). Repeat procedure until fluid level in reservoir remains constant. 2. Raise and support vehicle with both front wheels off ground. Start engine. Turn wheels right and left, lightly contacting stops. Check fluid level and add fluid (as necessary). 3. Lower vehicle. Turn wheels right and left, slowly from lock to lock. Turn off engine. Check fluid level and add fluid (as necessary). If fluid is foamy, allow vehicle to sit for a few minutes and repeat bleeding procedure.
WORM BEARING PRELOAD 1. Remove steering gear from vehicle and mount in vise before performing preload adjustments. See STEERING GEAR under REMOVAL & INSTALLATION. Remove worm bearing adjuster lock nut. See Fig. 1 . Using spanner wrench, turn adjuster plug clockwise until plug is seated in housing. Torque should be about 20 ft. lbs. (27 N.m). 2. Index mark housing even with one hole in adjuster plug. See Fig. 13 . Measure back 1/2" counterclockwise from first index mark. Mark housing with second index mark. Rotate adjuster plug back counterclockwise until hole in adjuster plug aligns with second index mark on housing. Install and tighten adjuster plug lock nut. Ensure adjuster plug remains in position. Fig. 13: Measuring Worm Bearing Preload Courtesy of GENERAL MOTORS CORP. OVER-CENTER PRELOAD 1. With worm bearing preload adjusted, rotate stub shaft slowly from stop to stop while counting total number of turns. With stub shaft positioned at either stop, rotate stub shaft back 2/3 total number of turns counted. Stub shaft should be back to exact center position. Flat on stub shaft should be facing upward and parallel to side cover and master spline on pitman shaft should be aligned with adjuster screw. 2. Turn pitman shaft adjuster screw counterclockwise until extended, then back off one full turn. Place INCH-lb. torque wrench in vertical position on end of stub shaft. Measure gear over- center torque by rotating torque wrench attached to stub shaft in a 90-degree arc, 45 degrees on each side of center. See Fig. 14 . Record highest degree of arc on each side of center. Record highest reading. 3. Turn adjuster screw in until torque required to rotate stub shaft is 6-10 INCH lbs. (.6-1.1 N.m) greater than reading in step 2 . Continue adjustment until over-center reading is within specification. See LASH ADJUSTMENT PRELOAD table. Tighten adjuster screw lock nut when reading is obtained.
NOTE: Adjust worm bearing preload before performing over-center preload adjustment.


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Or go to an alignment shop and pay to have the box adjusted on the vehicle...
Last resort, grab another rebuilt.
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Sunday, June 20th, 2010 AT 11:44 AM
Tiny
BPUTNAM
  • MEMBER
I just went out to make sure the PS fluid wasn't foaming in the pump and noticed the same thing I did this morning. When I first start the engine and rotate the wheel back and forth it feels normal for the first couple of cycles and then gets tighter and tighter the more I cycle it. What could be causing this?
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Sunday, June 20th, 2010 AT 12:20 PM
Tiny
MERLIN2021
  • EXPERT
If you replaced the other box for wear out, did you flush the old fluid out of the pump? I would check to see if anything is loose on the box on the top at the adjusting screws, the sector shaft may be moving out of position.
Pressure testing will tell if the pump is the problem, or the rebuilt box.
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Sunday, June 20th, 2010 AT 2:41 PM

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