Hummer H3. Manual — part 285

16: Misalignment of the pulleys may be caused from improper mounting of the accessory
drive component, incorrect installation of the accessory drive component pulley or the
pulley bent inward or outward from a previous repair. Test for a misaligned pulley using a
straight edge in the pulley grooves across two or three pulleys. If a misaligned pulley is
found refer to that accessory drive component for the proper installation procedure for that
pulley.

17: This test is to verify that the pulleys are the correct diameter or width. Using a known
good vehicle compare the pulley sizes.

19: Replacing the drive belt when it is not damaged or there is not excessive pilling will
only be a temporary repair.

Drive Belt Chirping, Squeal and Whine Diagnosis

Step

Action

Yes

No

DEFINITION: The following items are indications of chirping:

A high pitched noise that is heard once per revolution of the drive belt or a pulley.

Chirping may occur on cold damp start-ups and will subside once the vehicle reaches
normal operating temp.

DEFINITION: The following items are indications of drive belt squeal:

A loud screeching noise that is caused by a slipping drive belt. This is unusual for a
drive belt with multiple ribs.

The noise occurs when a heavy load is applied to the drive belt, such as an air
conditioning compressor engagement snapping the throttle or slipping on a seized
pulley or a faulty accessory drive component.

DEFINITION: The following items are indications of drive belt whine:

A high pitched continuous noise.

The noise may be caused by an accessory drive component failed bearing.

NOTE:

Refer to Belt Dressing Notice .

1

Did you review the Drive Belt Symptom
operation and perform the necessary
inspections?

Go to Step 2

Go to
Symptoms -
Engine
Mechanical

Verify that there is a chirping, squeal or

2007 Hummer H3

2007 ENGINE Engine Mechanical - 3.7L - H3

2

whine noise.
Does the engine make the chirping squeal
or whine noise?

Go to Step 3

Go to Diagnostic
Aids

3

1. Remove the drive belt.

If the engine has multiple drive
belts, remove the belts one at a time
and perform the test below each
time a belt is removed.

2. Operate the engine for no longer

than 30-40 seconds.

3. Repeat this test if necessary by

removing the remaining belt(s).

Does the chirping, squeal or whine noise
still exist?

Go to
Symptoms -
Engine
Mechanical

Go to Step 4

4

If diagnosing a chirping noise, inspect for
severe pilling exceeding 1/3 of the belt
groove depth.
If diagnosing a squeal or whine noise,
proceed to step 13.
Do the belt grooves have pilling?

Go to Step 5

Go to Step 6

5

Clean the drive belt pulleys with a
suitable wire brush.
Did you complete the repair?

Go to Step 20

Go to Step 6

6

Inspect for misalignment of the pulleys.
Are any of the pulleys misaligned?

Go to Step 7

Go to Step 8

7

Replace or repair any misaligned pulleys.
Did you complete the repair?

Go to Step 20

Go to Step 8

8

Inspect for bent or cracked brackets.
Did you find any bent or cracked
brackets?

Go to Step 9

Go to Step 10

9

Replace any bent or cracked brackets.
Did you complete the repair?

Go to Step 20

Go to Step 10

10

Inspect for improper, loose or missing
fasteners.
Did you find the condition?

Go to Step 11

Go to Step 12

2007 Hummer H3

2007 ENGINE Engine Mechanical - 3.7L - H3

11

1. Tighten any loose fasteners. Refer to

Fastener Tightening
Specifications.

2. Replace any improper or missing

fasteners.

Did you complete the repair?

NOTE:

Refer to Fastener Notice .

Go to Step 20

Go to Step 12

12

Inspect for a bent pulley.
Did you find the condition?

Go to Step 18

Go to Step 19

13

Inspect for an accessory drive component
seized bearing or a faulty accessory drive
component.
Did you find and correct the condition?
If diagnosing a whine noise and the
condition still exist, proceed to
Diagnostic Aids.

Go to Step 20

Go to Step 14

14

Test the drive belt tensioner for proper
operation. Refer to Drive Belt
Tensioner Diagnosis.
Did you find and correct the condition?

Go to Step 20

Go to Step 15

15

Inspect for the correct drive belt length.
Did you find and correct the condition?

Go to Step 20

Go to Step 16

16

Inspect for misalignment of a pulley.
Did you find and correct the condition?

Go to Step 20

Go to Step 17

17

Inspect for the correct pulley size.
Did you find and correct the condition?

Go to Step 20

Go to Diagnostic
Aids

18

Replace the bent pulley.
Did you complete the repair?

Go to Step 20

Go to Step 19

19

Replace the drive belt. Refer to Drive
Belt Replacement (Without A/C) or
Drive Belt Replacement (With A/C).
Did you complete the repair?

Go to Step 20

Go to Diagnostic
Aids

20

Operate the system in order to verify the
repair.
Did you correct the condition?

System OK

Go to Step 3

2007 Hummer H3

2007 ENGINE Engine Mechanical - 3.7L - H3

DRIVE BELT RUMBLING AND VIBRATION DIAGNOSIS

Diagnostic Aids

The accessory drive components can have an affect on engine vibration. Vibration from the
engine operating may cause a body component or another part of the vehicle to make rumbling
noise. Vibration can be caused by, but not limited to the A/C system over charged, the power
steering system restricted or the incorrect fluid or an extra load on the generator. To help identify
an intermittent or an improper condition, vary the loads on the accessory drive components.

The drive belt may have a rumbling condition that can not be seen or felt. Sometimes replacing
the drive belt may be the only repair for the symptom.

If replacing the drive belt, completing the diagnostic table and the noise is only heard when the
drive belts are installed, there might be an accessory drive component with a failure. Varying the
load on the different accessory drive components may aid in identifying which component is
causing the rumbling noise.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

2: This test is to verify that the symptom is present during diagnosing. Other vehicle
components may cause a similar symptom.

3: This test is to verify that one of the drive belts is causing the rumbling noise or vibration.
Rumbling noise may be confused with an internal engine noise due to the similarity in the
description. Remove only one drive belt at a time if the vehicle has multiple drive belts.
When removing the drive belts the water pump may not be operating and the engine may
overheat. Also DTCs may set when the engine is operating with the drive belts removed.

4: Inspecting the drive belts is to ensure that they are not causing the noise. Small cracks
across the ribs of the drive belt will not cause the noise. Belt separation is identified by the
plys of the belt separating and may be seen at the edge of the belt our felt as a lump in the
belt.

5: Small amounts of pilling is normal condition and acceptable. When the pilling is severe
the drive belt does not have a smooth surface for proper operation.

9: Inspecting of the fasteners can eliminate the possibility that the wrong bolt, nut, spacer or
washer was installed.

11: This step should only be performed if the water pump is driven by the drive belt. Inspect
the water pump shaft for being bent. Also inspect the water pump bearings for smooth
operation and excessive play. Compare the water pump with a known good water pump.

2007 Hummer H3

2007 ENGINE Engine Mechanical - 3.7L - H3