Mitsubishi 380. Manual - part 851

POWER STEERING

37-2

POWER STEERING OIL PUMP 
ASSEMBLY . . . . . . . . . . . . . . . . . . . .

37-43

REMOVAL AND INSTALLATION   . . . . . . . 

37-43

INSPECTION  . . . . . . . . . . . . . . . . . . . . . . . 

37-44

POWER STEERING HOSES  . . . . . . .

37-45

REMOVAL AND INSTALLATION  . . . . . . . . 

37-45

SPECIFICATIONS  . . . . . . . . . . . . . . .

37-49

FASTENER TIGHTENING SPECIFICATIONS

37-49

GENERAL SPECIFICATIONS  . . . . . . . . . . 

37-50

SERVICE SPECIFICATIONS  . . . . . . . . . . . 

37-51

LUBRICANTS  . . . . . . . . . . . . . . . . . . . . . . . 

37-51

SEALANT  . . . . . . . . . . . . . . . . . . . . . . . . . . 

37-52

GENERAL DESCRIPTION

POWER STEERING

37-3

GENERAL DESCRIPTION

M1372000100360

Power steering has been adopted in all vehicles to 
make the steering system easier to handle.

• A 4-spoke steering wheel is used. 

• A steering column has a shock absorbing mecha-

nism and a tilt steering mechanism.

• A rack and pinion steering gear is used.

• An oil pump responsive to engine RPM is used, 

to enhance steering stability at high speeds.

• The separate plastic resin oil reservoir is used to 

reduce weight and to make the fluid level check-
ing easier. 

POWER STEERING DIAGNOSIS

INTRODUCTION TO POWER STEERING DIAGNOSIS

M1372008500209

Hydraulic power steering is used for all vehicles. 
Faults in the power steering can include excessive 
play of the steering wheel, difficult steering wheel 
operation, noise, vibration, and oil leaks, etc. Possi-
ble causes of these faults can include defects in the 
gear box, oil pump or steering linkage.

POWER STEERING DIAGNOSIS TROUBLESHOOTING STRATEGY

M1372007300202

Use these steps to plan your diagnostic strategy. If 
you follow them thoroughly, you will be sure that you 
have exhausted most of the possible ways to find a 
power steering fault.
1. Gather information from the customer.

2. Verify that the condition described by the 

customer exists.

3. Find the malfunction by following the Symptom 

Chart.

4. Verify malfunction is eliminated.

SYMPTOM CHART

M1372007600225

SYMPTOM

INSPECTION 
PROCEDURE

REFERENCE PAGE

Excessive play of steering wheel

1

P.37-4

Difficult steering wheel operation (insufficient power assist)

2

P.37-4

Rattling noise

3

P.37-6

Shrill noise

4

P.37-7

Squealing noise

5

P.37-7

Hissing noise

6

P.37-8

Droning noise

7

P.37-8

Squeaking noise

8

P.37-9

Vibration

9

P.37-10

Oil leakage from hose connection

10

P.37-11

Oil leakage from hose assembly

11

P.37-11

Oil leakage from oil reservoir

12

P.37-11

Oil leakage from oil pump

13

P.37-12

Oil leakage from steering gear

14

P.37-12

POWER STEERING DIAGNOSIS

POWER STEERING

37-4

SYMPTOM PROCEDURES

INSPECTION PROCEDURE 1: Excessive Play of Steering Wheel

DIAGNOSIS

STEP 1. Check for looseness at the steering shaft coupling 
section and at the steering wheel linkage.

Q: Is there any looseness?

YES : Repair or replace the part. And then go to Step 3.
NO :  Go to Step 2.

STEP 2. Check the steering wheel free play.
(1) With the engine running (hydraulic operation), set the front 

wheels straight ahead.

(2) Slightly move the steering wheel in both directions, and 

measure the play on the steering wheel circumference 
before the wheels start to move.

Limit: 30 mm (1.2 inch)

(3) If the free play exceeds the limit, set the steering wheel 

straight ahead with the engine stopped. Apply 
approximately 5 N (1.1 pound) to the steering 
circumference and check the play.

Standard value (steering wheel play with engine 
stopped): 10 mm (0.4 inch) or less

Q: Does the play exceed the standard value?

YES : Remove the steering gear box (refer to 

P.37-30

) and 

check the total pinion torque (refer to 

P.37-38

). And 

then go to Step 3.

NO :  Go to Step 3.

STEP 3. Check the steering wheel play.
Verify that the steering wheel play is not excessive.

Q: Is the steering wheel play excessive?

YES : Repeat from Step 1.
NO :  The procedure is complete.

INSPECTION PROCEDURE 2: Difficult Steering Wheel Operation (Insufficient Power Assist)

DIAGNOSIS

STEP 1. Check the drive belt for damage.

Q: Is the drive belt damaged?

YES : Replace the drive belt. And then go to Step 9.
NO :  Go to Step 2.

ACX01122AB

POWER STEERING DIAGNOSIS

POWER STEERING

37-5

STEP 2. Check the power steering oil pump drive belt 
tension.
Refer to GROUP 00, Maintenance Service 

− Drive Belts 

P.00-39

.

Q: Is the power steering oil pump drive belt tension within 

the standard value?
YES : Go to Step 3.
NO :  Adjust the tension (refer to GROUP 00, Maintenance 

Service 

− Drive Belts 

P.00-39

). And then go to Step 9.

STEP 3. Check the fluid level.
(1)  Park the vehicle on a flat, level surface, and then start the 

engine.

(2) Turn the steering wheel several times to raise the 

temperature of the fluid to approximately 50 

− 60°C (122 − 

140

°F).

(3)  With the engine running, turn the wheel all the way to the 

left and right several times.

(4) Check the fluid in the oil reservoir for foaming or milkiness. 

Check the difference of the fluid level when the engine is 
stopped, and while it is running.

Q: Is the check result OK?

YES : Go to Step 4.
NO :  Bleed the air (refer to 

P.37-18

). And then go to Step 9.

STEP 4. Check each hose for crushing or twisting.

Q: Is any hose crushed or twisted?

YES : Repair or replace the hose. And then go to Step 9.
NO :  Go to Step 5.

STEP 5. Check for oil leaks.

Q: Are there oil leaks?

YES : Find the cause of the oil leakage and repair it. And 

then go to Step 9.

NO :  Go to Step 6.

STEP 6. Check the wheel alignment (camber and caster).
Refer to GROUP 33, On-vehicle Service 

− Front Wheel Align-

ment Check and Adjustment 

P.33-6

.

Q: Is the wheel alignment incorrect?

YES : Adjust wheel alignment. And then go to Step 9.
NO :  Go to Step 7.

ACX01131

WHILE ENGINE

RUNNING

WHILE ENGINE

STOPPED

AB

FLUID FLUCTUATION