POWER STEERING PUMP
1988 Jeep Cherokee
Jeep Power Steering Pumps - Saginaw Vane-Type
Cherokee, Comanche, Grand Wagoneer, Pickup, Wagoneer, Wrangler
Saginaw vane-type power steering pump can be identified by "ham-shaped" fluid reservoir can. Rectangular pumping vanes carried by a shaft driven rotor move fluid from intake to pressure cavities of cam ring.
Centrifugal force throws vanes against inside surface of cam 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 cam 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 vanes in slots of rotor. This forces 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.
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
POWER STEERING PUMP
Removal & Installation
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.
pump bracket-to-engine bolts. Remove pump, pulley
and mounting bracket as an assembly. To install, reverse removal
procedure. Bleed system.
CAUTION: When clamping pump in vise, be careful not to exert
excessive force on front hub or pump. DO NOT use hammer to remove pulley.
1) Drain pump reservoir. Clean exterior of unit. Remove mounting bracket(s). Using a puller, withdraw pulley from shaft. See Fig. 1.
Fig. 1: Removing Pump Pulley
pump, with shaft pointing down and at the square
boss of the shaft housing, into a soft-jawed vise. Remove pressure
line union and "O" ring. Remove reservoir retaining studs.
against filler tube with plastic hammer to loosen
reservoir on pump body. Remove reservoir from body. Remove and discard
1/8" punch, tap end plate retaining
until end of ring is near hole in pump body. Inserting punch in hole,
disengage ring from groove in pump bore. Using a screwdriver, pry ring
from body. See Fig. 2.
Fig. 2: Removing Pump End Plate Retaining Ring
plate with a soft-faced hammer to loosen. Spring
tension should push plate up. Remove spring. Remove pump from vise.
Invert pump and place on flat surface. Using soft-faced
hammer, tap end of drive shaft to loosen pressure plate, rotor, and thrust plate assembly from body.
pump body off rotor assembly. Flow control valve and
spring should slide out of bore. Remove and discard end plate and
pressure plate "O" rings.
screwdriver, pry drive shaft oil seal from body.
Lift pressure plate and cam ring from rotor. Remove rotor vanes.
drive shaft in soft-jawed vise, with rotor and
thrust plate facing up. Remove rotor lock ring from shaft. Use care
not to nick shaft or rotor. Slide rotor and thrust plate off shaft.
Remove shaft from vise.
CLEANING & INSPECTION
pump components (except drive shaft seal) in
clean solvent. Blow dry. Inspect flow control valve assembly for wear,
scoring, burrs or other damage. Inspect seal bore for burrs, nicks, or
score marks that would allow oil to by-pass outer seal surface.
all machined surfaces of body for scratches or burrs
which might allow leaks. Check "O" ring mating surfaces. Inspect pump
body drive shaft bushing for excessive wear.
replacement is required, replace pump body and bushing
as an assembly. Inspect end cover "O" ring mating surface for nicks
and burrs. Polish with oil stone (if necessary).
rotor ring for roughness or irregularities. Use
oil stone to correct minor irregularities. Replace ring if outside cam
surface is worn or scored. Check thrust plate and pressure plate for
scoring and wear.
light scoring, lap with crocus cloth until
surface is smooth and flat. Clean thoroughly. Check that vanes slide
freely but fit snugly into slots.
are loose in slots, replace rotor and/or vanes.
Scoring on rotor may be removed by lapping with crocus cloth. Clean
all "O" rings, seals and seal
power steering fluid. On Jeeps, lubricate "O" rings with petroleum
jelly. With pump on flat surface, drive new shaft seal in until it
bottoms on bore shoulder.
body in vise with shaft pointing down. Install end
plate and pressure plate "O" rings on body. Install body to reservoir
"O" rings. Install on pump body.
shaft, splined end up, in soft-jawed vise. Install
thrust plate on shaft with smooth, ported side up. Slide rotor,
counter bore down, over splines.
new rotor lock ring. Ensure ring is seated in
groove. Install 2 dowel pins into holes in pump cavity. Insert drive
shaft, rotor, and thrust plate assembly into pump cavity. Align
locating holes with dowel pins.
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 facing
rear of housing.
a 1 1/4" socket in groove of pressure
down on socket with both thumbs to seat assembly on "O" ring in pump
cavity. Place spring in groove in pressure plate. Place end cover lip
edge over spring.
thumb or arbor press, press end cover down below
retaining ring groove. Seat retaining ring in groove. Take care to
prevent cocking end cover in bore or distorting assembly.
punch, tap retaining ring ends around in groove
until opening is opposite flow control valve bore. This ensures
maximum retention of retaining ring.
new "O" rings to reservoir,
mounting studs, and
flow control valve. Place reservoir on pump body. Align mounting stud
holes. Install studs.
a soft-faced hammer, tap reservoir down on pump.
Install flow control valve spring and valve assembly slotted end up.
Install new "O" ring on pressure hose fitting uppermost groove.
CAUTION: DO NOT install pressure hose "O" ring in lower groove. This will restrict relief outlet orifice.
pressure hose fitting. Tighten mounting studs.
Tighten hose fitting. Remove pump from vise. Install mounting bracket
3: Exploded View of Power Steering Pump
Fig. 4: Exploded View of Control Valve Assembly
Fig. 5: Installing Pump Pulley
TORQUE SPECIFICATIONS TABLE
Application Ft. Lbs. (N.m)
Gear End Hose Fittings 20 (27)
Pump End Hose Fittings 20 (27)
Bracket Bolts 35 (48)