Hummer H3. Manual - part 88

DRIVE BELT VIBRATION DIAGNOSIS

Diagnostic Aids

The accessory drive components can have an affect on engine vibration. Such as 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.

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

1. Remove the drive belt(s). Refer to Drive

Belt Replacement (Without A/C) or
Drive Belt Replacement (With A/C).

2. Operate the engine for no longer than 30 to

40 seconds.

Does the rumbling noise still exist?

Go to Engine

Noise on Start-

Up, but Only

Lasting a Few

Seconds

Go to Step 4

Inspect the drive belt(s) for damage, separation, or
sections of missing ribs.
Did you find any of these conditions?

Go to Step 7

Go to Step 5

Inspect for severe pilling of more than 1/3 of the
drive belt pulley grooves.
Did you find severe pilling?

Go to Step 6

Go to Step 7

1. Clean the drive belt pulleys using a suitable

wire brush.

2. Reinstall 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 8

Go to Step 7

Install a new drive belt. Refer to Drive Belt
Replacement (Without A/C) or Drive Belt
Replacement (With A/C).
Did you complete the replacement?

Go to Step 8

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

System OK

Go to

Diagnostic Aids

2006 Hummer H3

2006 ENGINE Engine Mechanical - 3.5L (L52) - H3

2: This test is to verify that the symptom is present during diagnosing. Other vehicle
components may cause a similar symptom such as the exhaust system, or the drivetrain.

3: This test is to verify that the drive belt(s) or accessory drive components may be causing
the vibration. When removing the drive belt the water pump may not be operating and the
engine may overheat. Also DTCs may set when the engine is operating with the drive belt
removed.

4: The drive belt(s) may cause a vibration. While the drive belt(s) is removed this is the best
time to inspect the condition of the belt.

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

8: This step should only be performed if the fan is driven by the drive belt. Inspect the
engine cooling fan for bent, twisted, loose, or cracked blades. Inspect the fan clutch for
smoothness, ease of turning. Inspect for a bent fan shaft or bent mounting flange.

9: 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 smoothness
and excessive play. Compare the water pump with a known good water pump.

10: Accessory drive component brackets that are bent, cracked, or loose may put extra
strain on that accessory component causing it to vibrate.

Drive Belt Vibration Diagnosis

Step

Action

Yes

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

The vibration is engine-speed related.

The vibration may be sensitive to accessory load.

NOTE:

Refer to Belt Dressing Notice in Cautions and Notices.

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

Go to Step 2

Go to

Symptoms -

Engine

Mechanical

Verify that the vibration is engine related.
Does the engine make the vibration?

Go to Step 3

Go to

Diagnostic Aids

1. Remove the drive belt. Refer to Drive Belt

Replacement (Without A/C) or Drive
Belt Replacement (With A/C).

Go to

Diagnostic

Starting Point

2006 Hummer H3

2006 ENGINE Engine Mechanical - 3.5L (L52) - H3

DRIVE BELT FALLS OFF DIAGNOSIS

Diagnostic Aids

If the drive belt(s) repeatedly falls off the drive belt pulleys, this is because of pulley
misalignment.

2. Operate the engine for no longer than 30 to

40 seconds.

Does the engine still make the vibration?

- Vibration

Diagnosis and

Correction in

Vibration

Diagnosis and

Correction

Go to Step 4

Inspect the drive belt for wear, damage, debris
build-up and missing drive belt ribs.
Did you find any of these conditions?

Go to Step 5

Go to Step 6

Install a new drive belt. Refer to Drive Belt
Replacement (Without A/C) or Drive Belt
Replacement (With A/C).
Did you complete the replacement?

Go to Step 11

Go to Step 6

Inspect for improper, loose or missing fasteners.
Did you find any of these conditions?

Go to Step 7

Go to Step 8

1. Tighten any loose fasteners.

2. Replace improper or missing fasteners. Refer

to Fastener Tightening Specifications.

Did you complete the repair?

Go to Step 11

Go to Step 8

Inspect for damaged fan blades or bent fan clutch
shaft, if the fan is belt driven. Refer to Fan
Replacement .
Did you find and correct the condition?

Go to Step 11

Go to Step 9

Inspect for a bent water pump shaft, if the water
pump is belt driven. Refer to Water Pump
Replacement .
Did you find and correct the condition?

Go to Step 11 Go to Step 10

Inspect for bent or cracked brackets.
Did you find and correct the condition?

Go to Step 11

Go to

Diagnostic Aids

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

System OK

Go to Step 3

2006 Hummer H3

2006 ENGINE Engine Mechanical - 3.5L (L52) - H3

An extra load that is quickly applied on released by an accessory drive component may cause the
drive belt to fall off the pulleys. Verify the accessory drive components operate properly.

If the drive belt(s) is the incorrect length, the drive belt tensioner may not keep the proper tension
on the drive belt.

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

2: This inspection is to verify the condition of the drive belt. Damage may of occurred to
the drive belt when the drive belt fell off. The drive belt may of been damaged, which
caused the drive belt to fall off. Inspect the belt for cuts, tears, sections of ribs missing, or
damaged belt plys.

4: 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 misalign pulley using a
straight edge in the pulley grooves across two or three pulleys. If a misalign pulley is found
refer to that accessory drive component for the proper installation procedure of that pulley.

5: Inspecting the pulleys for being bent should include inspecting for a dent or other damage
to the pulleys that would prevent the drive belt from not seating properly in all of the pulley
grooves or on the smooth surface of a pulley when the back side of the belt is used to drive
the pulley.

6: Accessory drive component brackets that are bent or cracked will let the drive belt fall
off.

7: Inspecting of the fasteners can eliminate the possibility that a wrong bolt, nut, spacer, or
washer was installed. Missing. loose, or the wrong fasteners may cause pulley misalignment
from the bracket moving under load. Over tightening of the fasteners may cause
misalignment of the accessory component bracket.

Drive Belt Falls Off Diagnosis

Step

Action

Yes

DEFINITION: The drive belt falls off the pulleys or may not ride correctly on the pulleys.

NOTE:

Refer to Belt Dressing Notice in Cautions and Notices.

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

Go to

Symptoms -

Engine

2006 Hummer H3

2006 ENGINE Engine Mechanical - 3.5L (L52) - H3

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