GM Service Manual Online
For 1990-2009 cars only

    Caution: Refer to General Repair Instructions in the Preface section.


    Object Number: 1957138  Size: SH
  1. Clean all parts in a suitable cleaning fluid and dry.
  2. Inspect the power steering pump drive shaft (2) for:
  3. • Scoring, pitting or bush pick-up on the pump housing bush surface (1).
    • Worn or damaged splines (5).
    • Scoring, pitting or bush pick-up on the rear end plate bush surface (4).
    • Excessive wear on the seal track (3).

    Object Number: 1957141  Size: SH
  4. Inspect the pump rotor (4) for:
  5. • Scoring on the thrust surfaces (1).
    • Worn or damaged splines (2).
    • Damage to the vane channels (3) that may cause the vanes to stick.
  6. Inspect the vanes (5) for:
  7. • Excessive wear on the contact surface (7).
    • Wear on the thrust faces of the vane (6).
    • Make sure the vanes move freely in the vane channels (3).

    Object Number: 1957150  Size: SH
  8. Inspect the thrust plate (1) for wear and any scoring marks (2).

  9. Object Number: 1957144  Size: SH

    Important: A high polish is always present on the surface of the power steering pump ring as a result of normal wear. Do not confuse this with abnormal wear.

  10. Inspect the power steering pump ring (1) for excessive wear and scouring on the inner surface (3) and the side faces (3).

  11. Object Number: 1957147  Size: SH
  12. Inspect the rear end plate (1) for:
  13. • Excessive wear, signs of bush material pick-up or pitting of the rear end plate bush (3).
    • Scouring and excessive wear on the thrust face (2).

    Object Number: 1957148  Size: SH
  14. Inspect the power steering pump housing (3) for:
  15. • Excessive wear, signs of bush material pick-up or pitting of the power steering pump housing bush (1).
    • Blockages in the power steering pump housing bush lubrication passage (2).

    Object Number: 1957152  Size: SH
  16. Inspect the high pressure outlet fitting for:
  17. • Damage to the threads (2).
    • Restrictions in the outlet orifice (1).
  18. Inspect the droop flow control valve for:
  19. • Burrs and foreign material on the shaft and piston plunger.
    • Blocked filer screen, which is located in the base of the valve assembly.
    • Insert the valve assembly into the pump housing and make sure the valve is free to move in the housing bore. If sticking is observed, check for foreign material and burrs on the inside the housing.