GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2000 🢒 Express 🢒 Engine 🢒 Engine Mechanical - 4.3L 🢒 Drive Belt Chirping Diagnosis

Diagnostic Aids

The symptom may be intermittent due to moisture on the drive belts or the pulleys. It may be necessary to spray a small amount of water on the drive belt(s) in order to duplicate the customers concern. If spraying water on the drive belts duplicates the symptom, cleaning the belt pulleys may be the probable solution.

A loose or improper installation of a body component, a suspension component, or other items of the vehicle may cause the chirping noise.

Test Description

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

  1. The noise may not be engine related. This step is to verify that the engine is making the noise. If the engine is not making the noise do not proceed further with this table.

    2.

  2. The noise may be an internal engine noise. Removing the drive belt and operating the engine for a brief period will verify the noise is related to the drive belt. 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 belt removed.

    3.

  3. Inspect all drive belt pulleys for pilling. Pilling is the small balls or pills or it can be strings in the drive belt grooves from the accumulation of rubber dust.

    4.

  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 2 or 3 pulleys. If a misalign pulley is found refer to that accessory drive component for the proper installation procedure for that pulley.

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

    6.

  6. 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.

    7.

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

Step

Action

Yes

No

Notice: Do not use belt dressing on the drive belt. Belt dressing causes the breakdown of the composition of the drive belt. Failure to follow this recommendation will damage the drive belt.

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 up conditions and will subside once the vehicle reaches normal operating temperature.
    • It usually occurs on cold damp mornings.

1

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

Go to Step  2

Go to Symptoms - Drive Belt

2

Verify that there is a chirping noise.

Does the engine make the chirping noise?

Go to Step 3

Go to Diagnostic Aids

3

  1. Remove the drive belt.
  2. Operate the engine for no longer than 30-40 seconds.

Does the chirping noise still exist?

Go to Engine Noise Diagnosis

Go to Step 4

4

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

Does 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 15

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 15

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 15

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

11

Tighten any loose fasteners.

Replace any improper or missing fasteners. Refer to Fastener Tightening Specifications .

Did you complete the repair?

Go to Step 15

Go to Step 12

12

Inspect for a bent pulley.

Did you find the condition?

Go to Step 13

Go to Step 14

13

Replace the bent pulley.

Did you complete the repair?

Go to Step 15

Go to Step 14

14

Replace the drive belt. Refer to Drive Belt Replacement .

Did you complete the repair?

Go to Step 15

Go to Diagnostic Aids

15

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3