maintenance ISUZU TF SERIES 2004 Repair Manual

POWER-ASSISTED STEERING SYSTEM 3B-1

STEERING
POWER-ASSISTED STEERING SYSTEM
TABLE OF CONTENTS
PAGE
General Description ......................................................................................................... 3B – 4
Power Steering System Test ........................................................................................... 3B – 7
Maintenance ..................................................................................................................... 3B – 8
Fluid Level ........................................................................................................................ 3B – 8
Bleeding The Power Steering System............................................................................ 3B – 8
Bleeding Procedure ......................................................................................................... 3B – 8
Flushing The Power Steering System ............................................................................ 3B – 8
Steering Wheel Free Play Inspection ............................................................................. 3B – 9
Front End Alignment Inspection and Adjustment ......................................................... 3B – 9
Special Tools .................................................................................................................... 3B – 10
Power Steering Unit ......................................................................................................... 3B – 11
Power Steering Unit and Associated Parts ............................................................... 3B – 11
Removal ....................................................................................................................... 3B – 11
Installation ................................................................................................................... 3B – 12
Power Steering Unit Disassembled View .................................................................. 3B – 13
Disassembly ................................................................................................................ 3B – 13
Inspection and Repair ................................................................................................. 3B – 13
Reassembly ................................................................................................................. 3B – 14
Main Data and Specifications ..................................................................................... 3B – 14
Special Tools ............................................................................................................... 3B – 15
Power Steering Pump and Associated Parts (4JH1-TC, 4JA1-TC, 4JA1-L) ............ 3B – 16
Removal ....................................................................................................................... 3B – 16
Installation ................................................................................................................... 3B – 16
Power Steering Pump Disassembled View .............................................................. 3B – 17
Disassembly ................................................................................................................ 3B – 18
Inspection and Repair ................................................................................................. 3B – 18
Reassembly ................................................................................................................. 3B – 19
Main Data and Specifications ..................................................................................... 3B – 19

3B-8 POWER-ASSISTED STEERING SYSTEM

6. Fully close the shutoff valve. Record the highest
pressures.


If the pressure recorded is within 9300-9800 kPa
(95-100 kg/cm
2/1350-1420 psi), the pump is
functioning within its specifications.


If the pressure recorded is higher than 9800 kPa
(100 kg/cm
2/1420 psi), the valve in the pump is
defective.


If the pressure recorded is lower than 9300 kPa (95
kg/cm
2/1350 psi), the valve or the rotating group in
the pump is defective.
7. If the pump pressures are within specifications,
leave the valve open and turn (or have someone
else turn) the steering wheel fully in both directions.
Record the highest pressures and compare with the
maximum pump pressure recorded in step 6. If this
pressure cannot be built in either side of the powe
r
steering unit, the power steering unit is leaking
internally and must be replaced.
8. Shut the engine off, remove the testing gauge.
9. Reconnect the pressure hose, check the fluid level
and make the needed repairs.
10. If the problem still exists, the steering and fron
t
suspension must be thoroughly examined.

Maintenance
The hydraulic system should be kept clean and fluid
level in the reservoir should be checked at regula
r
intervals and fluid added when required. Refer to
Recommended Fluids and Lubricants in General
Information section for the type of fluid to be used and
the intervals for filling.
If the system contains some dirt, flush it as described in
this section. If it is exceptionally dirty, the pump must be
completely disassembled before further usage. (The
steering unit cannot be disassembled.)
All tubes, hoses, and fittings should be inspected for
leakage at regular intervals. Fittings must be tight. Make
sure the clips, clamps and supporting tubes and hoses
are in place and properly secured.
Power steering hoses and lines must not be twisted,
kinked or tightly bent. Air in the system will cause
spongy action and noisy operation. When a hose is
disconnected or when fluid is lost, for any reason, the
system must be bled after refilling. Refer to Bleeding the
Power Steering System in this section.


Inspect belt for tightness.


Inspect pulley for looseness or damage. The pulle
y
should not wobble with the engine running.


Inspect hoses so they are not touching any othe
r
parts of the vehicle.


Inspect fluid level and fill to the proper level.

Fluid Level
1. Run the engine until the power steering fluid
reaches normal operating temperature, about 55
C (130
F), then shut the engine off.
2. Check the level of fluid in the reservoir.
3. If the fluid level is low, add power steering fluid as
specified in General Information to the proper level
and install the receiver cap.
4. When checking the fluid level after the steering
system has been serviced, air must be bled from
the system. Refer to Bleeding the Power Steering
System in this section.

Bleeding The Power Steering System
When a power steering pump or unit has been installed,
or an oil line has been disconnected, the air that has
entered the system must be bled out before the vehicle
is operated. If air is allowed to remain in the powe
r
steering fluid system, noisy and unsatisfactory operation
of the system may result.

Bleeding Procedure
When bleeding the system, and any time fluid is added
to the power steering system, be sure to use only powe
r
steering fluid as specified in General Information.
1. Fill the pump fluid reservoir to the proper level and
let the fluid settle for at least two minutes.
2. Start the engine and let it run for a few seconds. Do
not turn the steering wheel. Then turn the engine
off.
3. Add fluid if necessary.
4. Repeat the above procedure until the fluid level
remains constant after running the engine.
5. Raise and support the front end of the vehicle so
that the wheels are off the ground.
6. Start the engine. Slowly turn the steering wheel right
and left, lightly contacting the wheel stops.
7. Add power steering fluid if necessary.
8. Lower the vehicle, set the steering wheel at the
straight forward position after turning it to its full
steer positions 2 or 3 times, and stop the engine.
9. Check the fluid level and refill as required.
10. If the fluid is extremely foamy, allow the vehicle to
set a few minutes, then repeat the above procedure.

Flushing The Power Steering System
1. Raise and support the front end of the vehicle off
the ground until the wheels are free to turn.
2. Remove the fluid return line at the pump inlet
connector and plug the connector port on the pump.
Position the line toward a large container to catch
the draining fluid.
3. While running the engine at idle, fill the reservoi
r
with new power steering fluid. Turn the steering
wheel in both directions. Do not contact or hold the
steering wheel to the wheel stops. This will cause
the pump to go to pressure relief mode, which ma
y
cause a sudden fluid overflow at the reservoir.

3E-6 WHEELS AND TIRES

SERVICING
Servicing refers to general maintenance procedures to be performed by qualified service personnel.





WHEEL NUT TORQUES
Wheel Nut Torque kgf
m(lb
ft/N
m)
12.0  1.0 (86.8  7.2 / 117.7  9.8)




TIRE ROTATION
For of radial tires, interchange the front and the rear wheels on
the same side as shown in the figure.




If one-sided tire wear appears on radial tires, rotate the wheels
as shown in the figure.

Note:
After rotation, adjust the front and rear tire pressure and be sure to check wheel nut tightness.