Power Steering Pump GMC Vandura I

DESCRIPTION

The Saginaw vane type power steering pump can be identified by the "ham can" shape of the fluid reservoir. Internally, rectangular pumping vanes carried by a shaft driven rotor move fluid from intake to pressure cavities of cam ring.

As rotor begins to rotate, centrifugal force throws vanes against inside surface of cam ring to pick up residual oil, which is then forced into high pressure area. As more oil is picked up by the vanes, oil is forced into the cavities of the thrust plate and through the 2 cross-over holes in the cam ring and pressure plate (which empty into high pressure area between pressure plate and housing end plate).

Filling high pressure area causes oil to flow under vanes in slots of rotor, forcing vanes to follow inside oval surface of cam ring. As vanes rotate to small area of cam 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 appropriate POWER STEERING GENERAL SERVICING article in the STEERING section below.

1. POWER STEERING GENERAL SERVICING (for all Chrysler models)
2. POWER STEERING GENERAL SERVICING (for all Ford models)
3. «POWER STEERING GENERAL SERVICING»(/gmc/vandura/i-1970-1996/remont/manual-power-steering/#power-steering-general-servicing) (for all General Motors models)
4. POWER STEERING GENERAL SERVICING (for all Jeep models)

Loosen pump adjusting bolt (or nut) and pump mounting bolts, then withdraw pump drive belt. Disconnect pressure and return hoses from pump and cap ends to prevent loss of fluid and entry of dirt.

Remove bolts attaching pump mounting bracket to engine, and withdraw pump, pulley and mounting bracket as an assembly. To install, reverse removal procedure and bleed hydraulic system.

OVERHAUL

Scheme 11

Scheme 12

1. DO NOT use a hammer to remove pulley. Drain pump reservoir, clean exterior of unit and remove mounting bracket(s). Using a puller, withdraw pulley from shaft. (Scheme 11) (Scheme 11): Using Puller to Remove Pump Pulley DO NOT use hammer to remove pulley.
2. Clamp pump (with shaft pointing downward) in a soft jawed vise, making sure vise grips pump at square boss and shaft housing. Remove pressure line union and "O" ring seal. Remove reservoir retaining studs.
3. Tap against filler tube with plastic hammer to loosen reservoir on pump body. Remove reservoir from body, then withdraw and discard "O" ring seals.
4. Using a 1/8" diameter punch, tap end plate retaining ring around until one end of ring is near hole in pump body. Insert punch in hole far enough to disengage ring from groove in pump bore, then use a screwdriver and pry ring out of body. (Scheme 12) (Scheme 12): Removing Retaining Ring for Pump End Plate Tap end plate with a soft-faced hammer to break it loose from housing.
5. Tap end plate with a soft faced hammer to break it loose; the spring, located under the end plate, should push plate up. Remove spring. Remove pump from vise.
6. Place pump in inverted position on flat surface, and tap end of drive shaft with soft-faced hammer to loosen pressure plate, rotor, and thrust plate assembly from body.
7. Lift pump body off rotor assembly (flow control valve and spring should also slide out of bore). Remove and discard end plate and pressure plate "O" rings. Pry drive shaft oil seal from body using a screwdriver.
8. Inspect seal bore in housing for burrs, nicks, or score marks that would allow oil to by-pass outer seal surface. Lift pressure plate and cam ring from rotor, then remove rotor vanes.
9. Clamp drive shaft in soft-jawed vise, with rotor and thrust plate facing up, and remove rotor lock ring from shaft. Use care not to nick shaft or rotor. Slide rotor and thrust plate off shaft, and remove shaft from vise.

Cleaning & Inspection

1. Clean all pump components (except drive shaft seal) in clean solvent and blow dry. Inspect flow control valve assembly for wear, scoring, burrs or other damage.
2. Check all machined surfaces of body for scratches or burrs which might allow leaks. Mating surfaces on "O" rings require special attention. Inspect pump body drive shaft bushing for excessive wear.
3. If replacement is required, replace pump body and bushing as an assembly. Inspect end cover for nicks and burrs on surface for "O" ring, then polish with a fine oil stone if necessary.
4. Inspect rotor ring for roughness or irregularities. Use a small oil stone to correct minor irregularities and replace ring if outside cam surface is badly worn or scored. Check thrust plate and pressure plate for scoring and wear.
5. To remove light scoring, carefully lap with crocus cloth until surface is smooth and flat. Clean surface thoroughly. Check fit of vanes in rotor to ensure that they slide freely but fit snugly into slots.
6. If vanes are excessively loose in slots, the rotor and/or vanes require replacement. Scoring on rotor may be removed by careful aping using crocus cloth, and then cleaning thoroughly.

Reassembly

1. Lubricate all "O" rings and seal areas with power steering fluid. On Jeep models, use petroleum jelly to lubricate "O" rings. Place pump body on a flat surface. Drive a new shaft seal in until it bottoms on shoulder in bore.
2. Lubricate seal with power steering fluid, then clamp body in vise with shaft pointing downward. Install end plate and pressure plate "O" rings in groove on body. Install body to reservoir "O" rings and install on pump body.
3. With drive shaft clamped, splinted end up, in a soft-jawed vise, install thrust plate on shaft with smooth, ported side up. Slide rotor over splines with counter bore of rotor facing down.
4. Install rotor lock ring making sure it is seated in groove. Install two dowel pins in holes in pump cavity. Carefully insert drive shaft, rotor, and thrust plate assembly in pump cavity, indexing location holes with dowel pins. NOTE: Always use a new full diameter locking ring.
5. Slide cam ring over rotor and onto dowel pins, with arrow on ring facing toward rear of housing. Install vanes in rotor slots with radius edge facing out towards cam ring inner surface. Position pressure plate on dowel pins with circular spring depression toward the rear of housing.
6. Place a 1 1/4" socket in groove of pressure plate, and seat entire assembly on "O" ring in pump cavity by pressing down on socket with both thumbs. Place spring in groove in pressure plate and position end cover lip edge up over spring.
7. Press end cover down below retaining ring groove with thumb or arbor press. Install retaining ring, making sure ring is seated in groove. Care should be taken to prevent cocking end cover in bore or distorting assembly.
8. Using a punch, tap retaining ring ends around in groove until opening is opposite flow control valve bore. This is necessary for maximum retention of retaining ring.
9. Install new reservoir "O" ring, mounting stud "O" rings, and flow control valve "O" ring on pump body, then carefully position reservoir on pump body. Align mounting stud holes until studs can be started in threads.
10. Using a soft-faced hammer, tap reservoir down on pump and install flow control valve spring and valve assembly slotted end up. Install new "O" ring seal on pressure hose fitting, making sure it is installed on the UPPER groove. CAUTION: It is possible to install pressure hose "O" ring in lower groove. This will restrict relief outlet orifice.
11. Install pressure hose fitting and tighten mounting studs. Tighten hose fitting and rear mounting studs. Remove pump assembly from vise and install mounting bracket and drive pulley.

Pressing Pump Pulley into Position DO NOT hammer pulley on shaft. Scheme 13

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

See also:
• TROUBLE SHOOTING - BASIC PROCEDURES
• POWER STEERING GENERAL SERVICING