Jeep Cherokee (XJ): Power steering

Description and operation

STEERING SYSTEM

DESCRIPTION

The power steering system has a hydraulic pump.

The pump is a constant flow rate and displacement, vane-type pump. The pump on the 4.0L engine has a reservoir mounted to it (Fig. 1). The 2.5L engine has a remote mounted reservoir.

The steering gear (Fig. 1) used is a recirculating ball type gear with 14:1 gear ratio. A tilt and non-tilt column provide steering input.

NOTE: Right hand drive (RHD) and left hand drive (LHD) service procedures and torque specifications for steering linkage, gear and column are the same.

The power steering pump procedures are different.

Refer to appropriate service procedures regarding each component in the system.

OPERATION

The steering gear acts as a rolling thread between the worm shaft and the rack piston. Power assist is provided by the hydraulic pump. When the steering wheel is turned the worm shaft turns which moves the rack piston. The rack piston movement turns the pitman shaft which is connected to the steering linkage by the pitman arm.

Fig. 1 Power Steering Gear & Pump - 4.0L
Fig. 1 Power Steering Gear & Pump - 4.0L

1 - 4.0 L PUMP
2 - RETURN HOSE
3 - STEERING GEAR
4 - PRESSURE HOSE
5 - RESERVOIR

Diagnosis and testing

POWER STEERING SYSTEM DIAGNOSIS CHARTS

STEERING NOISE

There is some noise in all power steering systems. One of the most common is a hissing sound evident at a standstill parking. Or when the steering wheel is at the end of it's travel. Hiss is a high frequency noise similar to that of a water tap being closed slowly. The noise is present in all valves that have a high velocity fluid passing through an orifice. There is no relationship between this noise and steering performance.

CONDITION

POSSIBLE CAUSES

CORRECTION

OBJECTIONAL HISS OR WHISTLE
  1. Steering intermediate shaft to dash panel seal.
  2.  Noisy valve in power steering gear.
  1.  Check and repair seal at dash panel.
  2.  Replace steering gear
RATTLE OR CLUNK
  1. Gear mounting bolts loose.
  2.  Loose or damaged suspension components/track bar.
  3.  Loose or damaged steering linkage.
  4.  Internal gear noise.
  5.  Pressure hose in contact with other components.
  1.   Tighten bolts to specification.
  2.  Inspect and repair suspension.
  3. Inspect and repair steering linkage.
  4. Replace gear.
  5.  Reposition hose.
CHIRP OR SQUEAL
  1. Loose belt.
  1. Adjust or replace.
WHINE OR GROWL
  1. Low fluid level.
  2.  Pressure hose in contact with other components.
  3.  Internal pump noise.
  4.  Air in the system.
  1.  Fill to proper level.
  2.  Reposition hose.
  3. Replace pump.
  4.  Perform pump initial operation.
SUCKING AIR SOUND
  1. Loose return line clamp.
  2.  O-ring missing or damaged on hose fitting.
  3.  Low fluid level.
  4.  Air leak between pump and reservoir.
  1.  Replace clamp.
  2.  Replace o-ring.
  3. Fill to proper level.
  4. Repair as necessary.
SCRUBBING OR KNOCKING
  1. Wrong tire size.
  2.  Wrong gear.
  1.   Verify tire size.
  2.  Verify gear.
DIFFICULT TO TURN WHEEL STICKS OR BINDS
  1. Low fluid level.
  2.  Tire pressure.
  3.  Steering component.
  4.  Loose belt.
  5.  Low pump pressure.
  6.  Column shaft coupler binding.
  7.  Steering gear worn or out of adjustment.
  8.  Ball joints binding.
  1.  Fill to proper level.
  2.  Adjust tire pressure.
  3.  Inspect and lube.
  4.  Adjust or replace.
  5.  Pressure test and replace if necessary.
  6.  Replace coupler.
  7.  Repair or replace gear.
  8.  Inspect and repair as necessary.

INSUFFICIENT ASSIST OR POOR RETURN TO CENTER

CONDITION

POSSIBLE CAUSE

CORRECTION

HARD TURNING OR MOMENTARY INCREASE IN TURNING EFFORT
  1. Tire pressure.
  2.  Low fluid level.
  3.  Loose belt.
  4.  Lack of lubrication.
  5.  Low pump pressure.
  6.  Internal gear leak.
  1.  Adjust tire pressure.
  2.  Fill to proper level.
  3.  Adjust or replace.
  4.  Inspect and lubricate steering and suspension compnents.
  5. Pressure test and repair as necessary.
  6. Pressure and flow test, and repair as necessary.
STEERING WHEEL DOES NOT WANT TO RETURN TO CENTER POSITION
  1. Tire pressure.
  2.  Wheel alignment.
  3.  Lack of lubrication.
  4.  High friction in steering gear.
  5.  Ball joints binding.
  1.  Adjust tire pressure.
  2.  Align front end.
  3.  Inspect and lubricate steering and suspension compnents.
  4.  Test and adjust as necessary.
  5.  Inspect and repair as necessary

Some roads will cause a vehicle to drift, due to the crown in the road.

LOOSE STEERING AND VEHICLE LEADS/DRIFTS

CONDITION

POSSIBLE CAUSE

CORRECTION

EXCESSIVE PLAY IN STEERING WHEEL
  1. Worn or loose suspension or steering components.
  2.  Worn or loose wheel bearings.
  3.  Steering gear mounting.
  4.  Gear out of adjustment.
  5.  Worn or loose steering coupler.
  1.  Repair as necessary.
  2.  Repair as necessary.
  3. Tighten gear mounting bolts to specification.
  4. Adjust gear to specification.
  5. Repair as necessary.
VEHICLE PULLS TO ONE SIDE DURING BRAKING
  1. Tire Pressure.
  2.  Air in brake hydrauliics system.
  3.  Worn brake components.
  1.  Adjust tire pressure.
  2. Bleed brake system.
  3. Repair as necessary.
VEHICLE LEADS OR DRIFTS FROM STRAIGHT AHEAD DIRECTION ON UNCROWNED ROAD.
  1. Tire pressure.
  2.  Radial tire lead.
  3.  Brakes dragging.
  4.  Wheel alignment.
  5.  Weak or broken spring.
  6.  Loose or worn steering/ suspension components.
  7.  Cross caster out of spec.
  1.  Adjust tire pressure.
  2. Cross front tires.
  3.  Repair as necessary.
  4.  Align vehicle.
  5.  Replace spring.
  6.  Repair as necessary.
  7.  Adjust or replace axle as necessary.

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