Hummer H2. Manual - part 947

DIAGNOSTIC INFORMATION AND PROCEDURES

DIAGNOSTIC STARTING POINT - FRONT DRIVE AXLE

Begin the system diagnosis by reviewing the system Description and Operation. Refer to Front Drive Axle
Description and Operation . Reviewing the Description and Operation information will help you determine
the correct symptom diagnostic procedure when a malfunction exist. Reviewing the Description and Operation
information will also help you determine if the condition described by the customer is normal operation. Refer
to Symptoms - Front Drive Axle in order to identify the correct procedure for diagnosing the system and
where the procedure is located.

SYMPTOMS - FRONT DRIVE AXLE

Before beginning diagnosis, review the system description and operation in order to familiarize yourself with
the system functions. Refer to Front Drive Axle Description and Operation .

Noise Diagnosis

Any gear-driven unit produces a certain amount of noise that is normal and that conventional repairs or
adjustment cannot eliminate. Slight noise that is heard only at a certain speed or under unusual or remote
conditions is acceptable. For example, this noise tends to reach a peak at speeds from 60-100 km/h (40-60 mph)
depending upon road and load conditions, or upon gear ratio and tire size. Noise of this kind does not indicate
trouble in the axle assembly.

When an axle is suspected of being noisy, make a thorough test in order to determine whether the noise
originates in the tires, road surface, wheel bearings, engine, transmission, propeller shaft, or axle assembly.

Classifying the Symptom

Front Differential Drive Pinion Bearing Gear Yoke Washer

Front Differential Drive Pinion Bearing Gear Yoke Nut

Front Differential Carrier Oil Drain Plug Washer

Front Differential Carrier Oil Drain Plug

Front Differential Carrier Oil Fill Plug Washer

Front Differential Carrier Oil Fill Plug

Front Differential Carrier Hole Plug

Front Differential Bearing Adjuster and O-Ring Seal

Front Differential Bearing Adjuster Nut Lock

Bolt

Front Drive Axle Inner Shaft Bearing

Front Drive Axle Inner Shaft Retaining Ring

Front Drive Axle Inner Shaft

2004 Hummer H2

2004 DRIVELINE/AXLE Front Drive Axle - Hummer H2

Front Drive Axle symptoms can usually be classified into the following categories:

Leaks

Noises

Vibrations

Leak and noise related symptoms are diagnosed within the Front Drive Axle section. For vibration related
symptoms, refer to Diagnostic Starting Point - Vibration Diagnosis and Correction in Vibration Diagnosis
and Correction.

Visual/Physical Inspection

Inspect the system for loose or missing fasteners.

Inspect the system for loose or leaking components.

Inspect the system for obvious damage or conditions which may cause the symptom.

Symptoms List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom.

Front Drive Axle Noises

Noisy in Drive

Noisy When Coasting

Intermittent Noise

Constant Noise

Noisy on Turns

Front Axle Lubricant Leak Diagnosis

FRONT DRIVE AXLE NOISES

Gear Noise

Gear noise or whine is audible from 32-89 km/h (20-55 mph) under 4 driving conditions:

Drive - Acceleration or heavy pull

Road Load - Vehicle driving load or constant speed

Float - Using enough throttle to keep the vehicle from driving the engine, the vehicle slows down
gradually but the engine still pulls slightly

Coast - Throttle is closed and the vehicle is in gear

Gear noise most frequently has periods where the noise is more prominent, usually between 48-64 km/h (30-40
mph) and 80-85 km/h (50-53 mph). Gear whine is corrected by ring and pinion gear replacement or adjustment,
depending on the mileage of the gear set.

2004 Hummer H2

2004 DRIVELINE/AXLE Front Drive Axle - Hummer H2

Bearing Noise

Faulty bearings produce a rough growl or grating sound, rather than the whine typical of gear noise. Bearing
noise (hum) will pulsate at a constant vehicle speed. This indicates a bad pinion or a bad front axle side bearing.
This noise can be confused with front wheel bearing noise. Inspect and replace the bearings and the affected
components as required.

Front Wheel Bearing Noise

A rough front wheel bearing produces a noise which continues with the car coasting at low speed and the
transmission in neutral. The noise may diminish some when the brakes are gently applied. The noise may also
change when performing side-to-side maneuvers with the vehicle.

A rough and/or noisy wheel bearing can be heard by spinning the wheels by hand and listening at the hubs for
the noise. Inspect and replace the bearings and the affected components as needed.

Knock at Low Speeds

A low speed knock can be caused by a differential case side gear bore that has worn oversize. Inspect the side
gears and the differential case assembly and replace the components as necessary.

Backlash Clunk

Excessive backlash clunk under acceleration or de-acceleration can be caused by any of the following:

Worn differential pinion shaft

Worn differential pinion and/or side gear teeth

Worn thrust washers

Excessive clearance between the side gears and the axle shafts

Excessive clearance between differential side gears and the bore in the case

Excessive drive pinon and ring gear backlash

Inspect, adjust or replace the affected components as necessary.

NOISY IN DRIVE

Noisy in Drive

Checks

Action

Excessive pinion to ring
gear backlash

Adjust the pinion to ring gear backlash. Refer to Backlash Inspection and
Adjustment .

Worn pinion and ring gear Replace the pinion and the ring gear. Perform the following procedures:

Differential Carrier Assembly - Disassemble

Differential Case Assembly Disassemble

Differential Case Assembly Assemble

2004 Hummer H2

2004 DRIVELINE/AXLE Front Drive Axle - Hummer H2

NOISY WHEN COASTING

Noisy When Coasting

Pinion Bearing Cup Installation

Differential Carrier Assembly - Assemble

Worn pinion bearings

Replace the pinion bearings. Perform the following procedures:

Differential Carrier Assembly - Disassemble

Pinion Bearing Cup Installation

Differential Carrier Assembly - Assemble

Loose pinion bearings

Adjust the pinion bearings preload. Perform the following procedures:

Differential Carrier Assembly - Disassemble

Differential Carrier Assembly - Assemble

Backlash Inspection and Adjustment

Excessive pinion end play Adjust the pinion end play. Refer to Differential Carrier Assembly -

Assemble .

Worn differential bearings Replace the differential bearings. Perform the following procedures:

Differential Carrier Assembly - Disassemble

Differential Case Assembly Disassemble

Differential Case Assembly Assemble

Differential Carrier Assembly - Assemble

Loose differential
bearings

Adjust the differential bearing preload. Perform the following procedures:

Differential Carrier Assembly - Disassemble

Differential Carrier Assembly - Assemble

Excessive ring gear runout Replace the ring gear. Perform the following procedures:

Differential Carrier Assembly - Disassemble

Differential Carrier Assembly - Assemble

Low oil level

Fill the fluid level to specifications with the proper lubricant. Refer to
Lubricant Level Inspection - Front Drive Axle .

Wrong or poor grade oil

Drain and refill the system with the proper lubricant. Refer to Lubricant
Replacement - Front Drive Axle .

Checks

Action

DEFINITION: Noise is audible when slowing down and disappears when driving.
Worn pinion and ring
gear

Adjust or replace the pinion and the ring gear. Refer to Differential Carrier
Assembly - Disassemble .

Pinion and ring gear
too tight

Adjust the pinion and the ring gear backlash. Refer to Backlash Inspection and
Adjustment .

2004 Hummer H2

2004 DRIVELINE/AXLE Front Drive Axle - Hummer H2

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