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Power Steering Pump GMC Magnavan G3500

Manual & Power Steering 2 illustrations ~979 words

DESCRIPTION

Two different types of Saginaw vane-type power steering pumps are used. The Model P pump is mounted inside the reservoir. The Model TC pump is mounted below the reservoir. On both models, the vanes are driven by a rotor and moves fluid from the intake to the pressure cavities of pump ring.

Centrifugal force moves vanes against inside surface of pump ring to pick up residual oil. As more oil is picked up, it is forced into cavities of thrust plate, into 2 cross-over holes in pump ring and pressure plate and into a high pressure area between pressure plate and housing end plate.

Filling the high pressure area causes oil to flow under the vanes in slots of the rotor. This forces vanes to follow inside oval surface of pump ring. As vanes rotate to small area of pump ring, oil is forced out from between vanes.

TROUBLE SHOOTING

Refer to TROUBLE SHOOTING - BASIC PROCEDURES article in the GENERAL TROUBLE SHOOTING section.

LUBRICATION & TESTING

See POWER STEERING GENERAL SERVICING article in the STEERING section.

Removal & Installation

  1. Loosen pump adjusting bolt (or nut) and pump mounting bolts. Remove pump drive belt. Disconnect pressure and return hoses from pump. Cap ends to prevent loss of fluid or contamination.
  2. Using Puller (J-29785-A), remove pulley from shaft. Remove bracket-to-engine bolts. Remove pump and mounting bracket as an assembly. To install, reverse removal procedure. Use Pulley Installer (J-25033-B) to install pulley. Fill and bleed system. See «POWER STEERING GENERAL SERVICING»(/gmc/magnavan-g3500/1985-1993/remont/manual-power-steering/#power-steering-general-servicing) article in the STEERING section.

Scheme 2

Scheme 2
Scheme 2

Scheme 3

Scheme 3
Scheme 3

Disassembly (Model P)

  1. Drain pump reservoir. Clean exterior of unit. Using Puller (J-29785-A) remove pulley from shaft if not previously removed.
  2. Remove pressure line union and "O" ring. Remove reservoir retaining bolts. Remove reservoir and "O" rings from housing.
  3. Using punch and screwdriver, remove end plate retaining ring. Remove end plate and pressure plate spring. (Scheme 2)
  4. Remove "O" ring, flow control valve and spring. Using soft-faced hammer, tap end of drive shaft to loosen pressure plate. Remove pressure plate, pump ring, vanes, retaining ring, rotor, and thrust plate assembly from body.
  5. Remove drive shaft. Using a screwdriver, pry drive shaft oil seal from housing. Remove dowel pins and seals.

Cleaning & Inspection

  1. Clean all pump components in solvent. Blow dry. Inspect flow control valve assembly for wear, scoring, burrs or other damage. Inspect seal bore for burrs, nicks, or score marks.
  2. Inspect machined surfaces of body for scratches or burrs. Check "O" ring mating surfaces. Inspect drive shaft for excessive wear.
  3. Inspect pump ring for roughness. Check thrust plate and pressure plate for scoring and wear. Ensure vanes slide freely but fit snugly into slots. If vanes are loose in slots, replace rotor and/or vanes.

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.

Disassembly (Model TC)

  1. Clamp front hub in soft-jawed vise. Pry tab outward and remove reservoir clips (if equipped). (Scheme 3) Remove reservoir or return tube and "O" ring. Using Puller (J-29785-A) remove pulley from shaft if not previously removed.
  2. Remove fitting, "O" ring, flow control valve and spring. Note location of beveled side of snap ring. Remove snap ring, drive shaft and bearing. (Scheme 3) Using screwdriver, remove drive shaft seal from housing. Remove retaining ring by inserting punch into access hole and disengage retaining ring.
  3. Using a brass drift, tap on thrust plate and remove. Remove "O" ring, pump ring, rotor and vanes. Remove dowel pins, pressure plate, "O" ring and pressure plate spring. Remove "O" ring, dowel pin and sleeve.
  1. Clean all pump components in solvent. Blow dry. Inspect flow control valve assembly for wear, scoring, burrs or other damage. Inspect seal bore for burrs, nicks, or score marks.
  2. Inspect machined surfaces of body for scratches or burrs. Check "O" ring mating surfaces. Inspect drive shaft for wear.
  3. Inspect pump ring for roughness. Check thrust plate and pressure plate for scoring and wear. Ensure vanes slide freely but fit snugly into slots. If vanes are loose in slots, replace rotor and/or vanes.
  1. Lubricate all "O" rings, seals, pump ring, rotor and vanes with power steering fluid.
  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. CAUTION: Pump ring must be installed 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.
  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 properly seats. Install spring, flow control valve and "O" rings. Install return tube or reservoir with new "O" ring.

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