GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Isuzu 🢒 2000 🢒 S/T Isuzu - 2WD 🢒 Driveline/Axle 🢒 Rear Drive Axle 🢒 Rear Axle Noise Diagnosis

Many noises that may seem to be coming from the rear axle, are actually from other sources such as:

    • The tires
    • The wheel bearings
    • The engine and/or the transmission
    • The exhaust system
    • The body
    • The road surface

Another source of noise is the rear axle differential. The rear axle differential gears, like any other mechanical device, are not absolutely quiet and should be accepted as being commercially quiet unless some abnormal noise is present. To assist in determining the different types of rear axle noise, refer to Rear Axle Noise .

A thorough and careful check should be made in order to determine the source of the noise before disassembling the rear axle.

Step

Action

Yes

No

Important: After the noise has been determined as being in the axle, establish the type of noise in order to help in making any necessary repairs.

1
  1. Road test the vehicle to verify the complaint.

    2. Select a level and smooth road surface to perform the test.

  2. Drive the vehicle long enough to thoroughly warm-up the rear axle lubricant.

    3. Note the vehicle speed and engine RPM where the noise occurs.

Does the condition exist and is repeatable?

Go to Step 2

System OK

2
  1. Raise the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  2. Inspect the vehicle for the following:
    3. • Proper rear axle lubricant level. Refer to Lubricant Level Check .
    • Metal-to-metal contact between the suspension bushings and the springs and/or frame

Do any of the above conditions exist?

Go to Step 3

Go to Step 4

3

Adjust, repair or replace components as necessary.

Is the repair complete?

Go to Step 17

--

4
  1. Inflate the tires to their maximum pressure listed on the sidewall of the tire.
  2. Drive the vehicle at the same speed and on the same level and smooth road.

    3. Note as to if the noise has changed.

  3. Accelerate the vehicle from 32 km/h (20 mph) to 48 km/h (30 mph).

    4. Note as to if the noise is present.

  4. Allow the vehicle to coast from 48 km/h (30 mph) to 32 km/h (20 mph).

    5. Note as to if the noise is present.

  5. Accelerate and decelerate the vehicle quickly between 32 km/h (20 mph) and 48 km/h (30 mph).

    6. Note as to if the noise is present and has not changed with each acceleration/de-acceleration.

  6. Adjust the tires to their normal pressure. Refer to Tire Inflation Pressure Specifications in Maintenance and Lubrication.
  7. Drive the vehicle over different road surfaces (smooth pavement, dirt road (not gravel), concrete, etc.).

    8. Note as to if the noise has changed and/or disappeared and reappeared while driving over the different road surfaces.

Was the noise present and/or changed from the original noise for each situation?

Go to Step 5

Go to Step 6

5

The noise may be caused by the tires. Determine the cause of the noise and correct as necessary.

Was a repair made?

Go to Step 17

Go to Step 6

6
  1. Drive the vehicle at a constant speed and on the same level and smooth road where the noise occurred.
  2. Lightly apply the brakes while maintaining vehicle speed.

Has the noise diminished or stopped?

Go to Step 7

Go to Step 8

7

The noise may be caused by the front wheel bearings. Inspect the front wheel bearings and repair or replace as necessary.

Was a repair made?

Go to Step 17

Go to Step 8

8
  1. Drive the vehicle at a constant speed and on the same level and smooth road where the noise occurred.

    2. Note the engine RPM where the noise occurred.

  2. Shift the transmission to the next lower gear while maintaining vehicle speed.

Did the noise increase when the engine RPM increased?

Go to Step 9

Go to Step 10

9

The noise may be caused by the engine and/or transmission. Inspect and correct as necessary.

Was an adjustment or repair performed?

Go to Step 17

Go to Step 10

10
  1. Stop the vehicle.
  2. Apply the park brake.
  3. Place the transmission in NEUTRAL.
  4. Increase the engine RPM to where the noise occurred.

Is the noise present at the same engine RPM as before?

Go to Step 11

Go to Step 12

11
  1. The noise may be cause by the following:
    2. • The exhaust system
    • Other engine or transmission conditions
  2. Inspect the exhaust system, the engine and the transmission and correct as necessary.

Was an adjustment or repair performed?

Go to Step 17

Go to Step 12

12
  1. Drive the vehicle on a level and smooth road.
  2. Determine if the noise occurs under any of the following conditions:
    3. • In drive
    • When coasting
    • On turns
    • Constant
    • Intermittent

Does the rear axle make noise while in drive?

Go to Noisy in Drive

Go to Step 13

13

Does the rear axle make noise when coasting?

Go to Noisy When Coasting

Go to Step 14

14

Does the rear axle make noise while turning?

Go to Noisy on Turns

Go to Step 15

15

Does the rear axle make a constant noise?

Go to Constant Noise

Go to Step 16

16

Does the rear axle make an intermittent noise?

Go to Intermittent Noise

System OK

17

Verify proper system operation.

Is the noise still present?

Go to Step 1

System OK