GM Service Manual Online
For 1990-2009 cars only
Table 1: Drive Belt Chirping
Table 2: Drive Belt Squeal
Table 3: Drive Belt Whine
Table 4: Drive Belt Rumbling
Table 5: Drive Belt Vibration
Table 6: Drive Belt Falls Off
Table 7: Excessive Drive Belt Wear

Definitions

The following are symptomatic noises of the drive belt system:

Chirping

The following items are indications of chirping:

    • A high pitched noise that is usually heard once per revolution of a pulley or a belt.
    • It is most common on cold, damp mornings.
    • Verify this condition by squirting water onto the belt. The noise will momentarily stop.

Squeal

The following items are indications of squeal:

    • A loud screeching noise that is caused by a slipping belt (this is unusual for a belt with multiple ribs).
    • The noise occurs when a heavy load is applied to the belt, such as an air conditioning compressor engagement, snapping the throttle, or slipping on a seized pulley.

Whine

A high pitched continuous noise that may be caused by a failed bearing.

Faint Cycle Rumbling

A low frequency noise heard once per revolution of the drive belt.

Pilling

The following items are indications of pilling:

    • The random accumulation of rubber dust in the bottom of the multi-ribbed belt grooves.
    • A small amount of pilling is normal.
    • Operation of the drive belt system will not be effected unless the buildup exceeds one third (1/3) of the belt groove depth.

Multiple-ribbed type drive belts wear evenly with their pulleys. Unusual wear indicates a correction is needed. The following diagnostic tables will aid in diagnosing drive belt system conditions.

Drive Belt Chirping

Step

Action

Value(s)

Yes

No

DEFINITION: A high pitched noise ususally heard once per revolution of a pulley or belt. It is usually heard at idle and is most common on cold damp mornings. Squirting water on a chirping belt will usually cause the noise to momentarily go away.

1

Check for misalignment of the pulleys.

Are any of the pulleys misaligned?

--

Go to Step 2

Go to Step 3

2

Replace any misaligned pulleys.

Is the chirp still present?

--

Go to Step 3

System OK

3

Check for bent or cracked brackets.

Are there any bent or cracked brackets?

--

Go to Step 4

Go to Step 5

4

Replace any bent or cracked brackets.

Is the chirp still present?

--

Go to Step 5

System OK

5

Check for any loose or missing fasteners.

Are there any loose or missing fasteners?

--

Go to Step 6

Go to Step 7

6

Tighten any loose fasteners and properly install any missing fasteners. Refer to Fastener Tightening Specifications .

Is the chirp still present?

--

Go to Step 7

System OK

7

Check for a bent pulley flange.

Is the pulley flange bent?

--

Go to Step 8

Go to Step 9

8

Replace the pulley flange.

Is the chirp still present?

--

Go to Step 9

System OK

9

Check for severe pilling, exceeding 1/3 of the belt groove depth.

Is there severe pilling?

--

Go to Step 10

--

10

Replace the accessory drive belt. Refer to Drive Belt Replacement .

Is the chirp still present?

--

--

System OK

Drive Belt Squeal

Step

Action

Value(s)

Yes

No

1

Check for a misaligned pulley.

Is there a pulley misaligned?

 

Go to Step 3

Go to Step 2

2

Check for incorrect belt length, refer to Drive Belt Tensioner Diagnosis .

Is the belt length correct?

 

Go to Step 4

Go to Step 3

3

Repair or install new parts as necessary.

Is the repair complete?

 

System OK

 

4

Check for a malfunctioning drive belt tensioner, refer to Drive Belt Tensioner Diagnosis .

Is the tensioner malfunctioning?

 

Go to Step 3

Go to Step 5

5

Check for correct pulley size.

Are the pulleys the correct size?

 

Go to Step 6

Go to Step 3

6

Check for siezed bearings.

Is there a siezed bearing?

 

Go to Step 3

System OK

Drive Belt Whine

Step

Action

Value

Yes

No

1

Check for a worn accessory component bearing.

Is a bearing making the noise?

--

Go to Step 2

System OK

2

Install new parts as necessary

Is the repair complete?

--

System OK

--

Drive Belt Rumbling

Step

Action

Value(s)

Yes

No

1

Check for severe pilling.

Is there severe pilling of more than 1/3 of the rib depth?

--

Go to Step 2

System OK

2

Clean the drive belt pulleys.

Are the drive belt pulleys clean?

--

Go to Step 3

Go to Step 2

3

Install a new accessory drive belt.

Is the repair complete?

--

System OK

--

Drive Belt Vibration

Step

Action

Value(s)

Yes

No

1

Check for loose or missing fasteners.

Are there loose or missing fasteners?

--

Go to Step 2

Go to Step 3

2

Re-tighten or replace as necessary.

Is the repair complete?

--

System OK

--

3

Check for damaged fan blades.

Are there damaged fan blades?

--

Go to Step 4

Go to Step 5

4

Replace as necessary.

Refer to Fan Replacement in Engine Cooling.

Is the replacement complete?

--

System OK

--

5

Check for a bent fan clutch or coolant pump shaft.

Is the fan clutch or coolant pump shaft bent?

--

Go to Step 6

Go to Step 7

6

Replace as necessary.

Refer to Fan Clutch Replacement in Engine Cooling.

Is the repair complete?

--

System OK

--

7

Check for bent or cracked brackets.

Are there bent or cracked brackets?

--

Go to Step 8

System OK

8

Replace the brackets as necessary.

Is the repair complete?

--

System OK

--

Drive Belt Falls Off

Step

Action

Value(s)

Yes

No

1

Check for a misaligned or a bent pulley.

Are the pulleys misaligned?

--

Go to Step 2

Go to Step 3

2

Replace any misaligned or bent pulleys.

Does the drive belt continue to fall off?

--

Go to Step 3

System OK

3

Check for a bent or a cracked bracket.

Are any of the brackets bent or cracked?

--

Go to Step 4

Go to Step 5

4

Replace the damaged brackets.

Does the drive belt continue to fall off?

--

Go to Step 5

System OK

5

Check for loose or missing fasteners.

Are there any loose or missing fasteners?

--

Go to Step 6

Go to Step 7

6

Replace any missing fasteners and tighten to specifications. Refer to Fastener Tightening Specifications .

Does the drive belt continue to fall off?

--

Go to Step 7

System OK

7

Check for a misaligned power steering pump pulley.

Is the power steering pump pulley misaligned?

--

Go to Step 8

Go to Step 9

8

Realign or replace the power steering pump pulley. Refer to Power Steering Pump Replacement in Power Steering.

Does the drive belt continue to fall off?

--

Go to Step 9

System OK

9

Check for a damaged drive belt.

Is the drive belt damaged?

--

Go to Step 10

Go to Step 11

10

Replace the drive belt. Refer to Drive Belt Replacement .

Does the drive belt continue to fall off?

--

Go to Step 11

System OK

11

Check for a malfunctioning drive belt tensioner.

Is the drive belt tensioner malfunctioning?

--

Go to Step 12

Go to Step 13

12

Replace the drive belt tensioner.

Does the drive belt continue to fall off?

--

Go to Step 13

System OK

13

Check for worn idler or tensioner pulley bearings.

Are the idler or tensioner pulley bearings worn?

--

Go to Step 14

--

14

Replace the worn bearings.

Does the drive belt continue to fall off?

--

--

System OK

Excessive Drive Belt Wear

Step

Action

Value(s)

Yes

No

1

Check to see if the ribs in the drive belt do not match the grooves in the pulley.

Do the ribs in the drive belt match the grooves in the pulley?

--

--

Go to Step 2

2

Replace the drive belt.

Refer to Drive Belt Replacement .

Is there still excessive wear in either outside groove of the drive belt?

--

--

System OK

General Instructions

The following graphics illustrate the correct way to route the drive belt over the pulleys, and some examples of incorrect belt placement.


    Object Number: 172992  Size: SH
  1. Observe the drive belt correctly installed on the pulley.
  2. Each groove on the drive belt rests inside a matching groove in the pulley.


    Object Number: 172989  Size: SH
  3. When installing a new drive belt, observe the indicator on the tensioner.
  4. A new drive belt should fall inside this range.


    Object Number: 172991  Size: SH
  5. When installing a used drive belt, observe the indicator on the tensioner.
  6. A used drive belt should fall inside this range.


    Object Number: 172993  Size: SH
  7. Observe these incorrectly installed drive belts:
  8. Avoid mis-positioning the belt by one or more grooves.