1991 GMC Forward Control 5.7 K, Standard, SM465/M20FACTORY OEM SERVICE PROCEDURE

Power Steering Pump: Overhaul: Reassembly

  1. Lubricate all "O" rings, seals, pump ring, rotor and vanes with power steering fluid. Using Seal Installer (J-7728), install new shaft seal.
  2. Install dowel pins and all "O" rings. Install drive shaft and thrust plate. Install rotor over shaft splines, with counterbore toward drive shaft end of housing.
  3. Install new rotor retaining ring. Ensure ring is seated in groove. Install vanes with rounded edges toward pump ring. Install pump ring and pressure plate. Install "O" ring, flow control valve, and spring.
  4. Install pressure plate spring, end plate, and retaining ring. Install seals and reservoir. Install union, "O" ring, and reservoir retaining bolts.


  1. Lubricate all "O" rings, seals, pump ring, rotor and vanes with power steering fluid.
    CAUTION: Install pump ring with identification marks facing toward thrust plate end of housing. Thrust plate must be installed so indentations in thrust plate align with bolt holes of housing, and thrust plate engages with pump ring dowel pins.
  2. Install sleeve and dowel pin. Install pressure plate spring and "O" ring. Install pressure plate with dowel pin hole aligned with that of the housing. Install dowel pins.
  3. Install vanes with rounded edges toward pump ring. Install rotor with counterbore toward drive shaft end of housing. Install pump ring with identification marks facing toward thrust plate end of housing. Install "O" ring and thrust plate.
  4. Place pump assembly in arbor press. Compress thrust plate and install retaining ring so opening of ring is centered with bolt hole of housing.
  5. Using a socket, install drive shaft seal in housing until seal bottoms. Install bearing on drive shaft. Install drive shaft in housing. Rotate drive shaft during installation to align with rotor serrations.
  6. Install snap ring. Ensure beveled edge seats properly. Install spring, flow control valve, and "O" rings. Install return tube or reservoir with new "O" ring.
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Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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