Drive Belt Chirping Diagnosis
Diagnostic Aids
The chirping noise may be intermittent due to moisture on the drive belts or the accessory drive pulleys. in order to duplicate the customer concern, It may be necessary to spray a small amount of water onto the drive belts. If spraying water on the drive belts duplicates the symptom, cleaning the accessory drive pulleys may be the most probable solution.
A loose or incorrect installation of a body or suspension component, or other items on the vehicle may cause the chirping noise.
Test Description
The numbers below refer to the steps in the diagnostic table.
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The chirping 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 in this table.
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The noise may be an internal engine noise. Remove the drive belts and operate the engine for a few seconds, this will verify if the chirping noise is related to the drive belts or not. With the drive belts removed the water pump will not operate and the engine may overheat. Also diagnostic trouble codes (DTCs) may set when the engine is operated with the drive belts removed.
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Inspect the drive belts for signs of pilling. Pilling is the small balls, pills, or strings in the drive belt grooves caused by the accumulation of rubber dust.
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Misalignment of the accessory drive pulleys may be caused from incorrect mounting or incorrect installation of an accessory drive component, or the pulley may be bent inward or outward from a previous repair. Test for a misaligned pulley using a straight edge in the pulley grooves across 2 or 3 pulleys. If a misaligned pulley is found refer to that accessory drive component for the correct removal and installation procedure for that pulley.
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Inspection of the fasteners can address the possibility that a incorrect bolt, nut, spacer, or washer was installed.
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Inspection the accessory drive pulleys should include inspecting for bends, dents or other damage to the pulleys that May prevent the drive belts from seating correctly in the pulley grooves or on the smooth surface of a pulley when the back side of the drive belt is used to drive the pulley.
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Replacing the drive belts when it is not damaged or there is not above acceptable pilling will only be a temporary repair.
Step | Action | Yes | No | ||||
|---|---|---|---|---|---|---|---|
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Notice: Refer to Belt Dressing Notice in the Preface section. DEFINITION: The following items are indications of chirping:
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1 | Did you review the Symptoms - Engine Mechanical diagnostic information, and perform the necessary inspections? | Go to Step 2 | Go to Symptoms - Engine Mechanical. | ||||
2 | Verify that there is a chirping noise. Does the engine make the chirping noise? | Go to Step 3 | Go to Diagnostic Aids | ||||
3 |
Does the chirping noise still exist? | Go to Engine Noise on Start-Up, but Only Lasting a Few Seconds or Upper Engine Noise, Regardless of Engine Speed or Lower Engine Noise, Regardless of Engine Speed. | Go to Step 4 | ||||
4 | Inspect for extreme drive belt pilling exceeding 1/3 of the drive belt groove depth. Do the drive belt grooves have pilling? | Go to Step 5 | Go to Step 6 | ||||
5 | Clean the accessory drive pulleys with a suitable wire brush. Were the accessory drive pulleys cleaned? | Go to Step 14 | -- | ||||
6 | Inspect for a misaligned accessory drive pulleys. Is there a misaligned accessory drive pulleys? | Go to Step 7 | Go to Step 8 | ||||
7 | Replace and/or repair the misaligned accessory drive pulleys. Refer to Power Steering Pump Pulley Replacement. Refer to Drive Belt Idler Pulley Replacement or Drive Belt Tensioner Replacement - Accessory or Drive Belt Tensioner Replacement - Air Conditioning. Were the misaligned accessory drive pulleys replaced and/or repaired? | Go to Step 15 | -- | ||||
8 | Inspect for a bent or cracked accessory drive brackets. Did you find any bent or cracked accessory drive brackets? | Go to Step 9 | Go to Step 10 | ||||
9 | Replace the bent and/or cracked accessory drive brackets. Refer to Compressor Mounting Bracket Replacement. Refer to Generator Bracket Replacement. Was the bent and/or cracked accessory drive brackets replaced? | Go to Step 15 | -- | ||||
10 | Inspect for incorrect, loose, and/or missing fasteners. Were there any incorrect, loose, and/or missing fasteners found? | Go to Step 11 | Go to Step 12 | ||||
11 |
Were the fasteners replaced and/or tightened? | Go to Step 15 | -- | ||||
12 | Inspect for a bent accessory drive pulleys. Refer to Power Steering Pump Pulley Replacement. Refer also to Drive Belt Idler Pulley Replacement or Drive Belt Tensioner Replacement - Accessory or Drive Belt Tensioner Replacement - Air Conditioning. Was a bent accessory drive pulleys found? | Go to Step 13 | Go to Step 14 | ||||
13 | Replace the bent accessory drive pulleys. Refer to Power Steering Pump Pulley Replacement. Refer also to Drive Belt Idler Pulley Replacement or Drive Belt Tensioner Replacement - Accessory or Drive Belt Tensioner Replacement - Air Conditioning. Was the bent accessory drive pulleys replaced? | Go to Step 15 | -- | ||||
14 | Replace the drive belts. Refer to Drive Belt Replacement - Accessory or Air Conditioning Compressor Belt Replacement. Was the drive belts replaced? | Go to Step 15 | -- | ||||
15 |
Does the chirping noise still exist? | Go to Step 3 | System OK | ||||
Drive Belt Squeal Diagnosis
Diagnostic Aids
A loose or incorrect installation of the body, suspension component, or other items on the vehicle may cause the squealing noise.
If the noise is intermittent, verify that the accessory drive components, by varying their loads, are operating to their maximum capacity. An overcharged air conditioning (A/C) system, power steering system restriction, incorrect fluid, or a failing alternator are suggested items to inspect.
Test Description
The numbers below refer to the step numbers in the diagnostic table.
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The squeal 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 in this table.
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The noise may be an internal engine noise. Remove the drive belts and operate the engine for a few seconds; this will verify if the squealing noise is related to the drive belts or an accessory drive component. With the drive belts removed, the water pump will not operate and the engine may overheat. Also diagnostic trouble codes (DTCs) may set when the engine is operated with the drive belts removed.
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This test is to verify that an accessory drive component does not have a seized bearing. With the belts removed, test the bearings in the accessory drive components for smooth operation. Also, test the accessory drive components with the engine operating by varying the load on the accessory drive components to verify that the components are operating correctly.
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This test is to verify that the drive belt tensioners are operating correctly. If the drive belt tensioners are not operating correctly, correct belt tension may not be achieved to keep the drive belt from slipping, which may cause a belt squeal noise.
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This test is to verify that the drive belt is not too long, which May prevent the drive belt tensioners from operating correctly. Also, if an incorrect length drive belt was installed, it may not be routed correctly and may be turning an accessory drive component in the incorrect direction.
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Misalignment of the accessory drive pulleys may be caused from incorrect mounting or incorrect installation of an accessory drive component, or the pulley may be bent inward or outward from a previous repair. Test for a misaligned pulley using a straight edge in the pulley grooves, across 2 or 3 pulleys. If a misaligned pulley is found, refer to that accessory drive component for the correct removal and installation procedure for that pulley.
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Inspect the accessory drive pulleys to verify that they are the correct diameter or width. Using a known good vehicle, compare the pulley sizes.
Step | Action | Yes | No | ||||
|---|---|---|---|---|---|---|---|
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Notice: Refer to Belt Dressing Notice in the Preface section. DEFINITION: The following items are indications of drive belt squeal:
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1 | Did you review the Symptoms - Engine Mechanical diagnostic information, and perform the necessary inspections? | Go to Step 2 | Go to Symptoms - Engine Mechanical. | ||||
2 | Verify that there is a squealing noise. Does the engine make the squealing noise? | Go to Step 3 | Go to Diagnostic Aids | ||||
3 |
Does the squealing noise still exist? | Go to Engine Noise on Start-Up, but Only Lasting a Few Seconds or Upper Engine Noise, Regardless of Engine Speed or Lower Engine Noise, Regardless of Engine Speed. | Go to Step 4 | ||||
4 | Inspect for a seized accessory drive component bearing or a faulty accessory drive component. Did you find and correct the condition? | Go to Step 9 | Go to Step 5 | ||||
5 | Inspect the drive belt tensioner for correct operation. Refer to Drive Belt Tensioner Diagnosis. Did you find and correct the condition? | Go to Step 9 | Go to Step 6 | ||||
6 | Check the drive belt is the correct length . Did you find and correct the condition? | Go to Step 9 | Go to Step 7 | ||||
7 | Inspect for a misaligned pulleys. Did you find and correct the condition? | Go to Step 9 | Go to Step 8 | ||||
8 | Inspect for an incorrect size pulley. Did you find and correct the condition? | Go to Step 9 | -- | ||||
9 |
Does the squealing noise still exist? | -- | System OK | ||||
Drive Belt Whine Diagnosis
Diagnostic Aids
The drive belts will not cause the whine. If the whine is intermittent, verify that it is not the accessory drive components by varying their loads, making sure they are operating to their maximum capacity. An overcharged air conditioning (A/C) system, a power steering system restriction, or the incorrect fluid, or a failing alternator are suggested items to inspect.
Test Description
The numbers below refer to the steps in the diagnostic table.
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This test is to verify that the whine is being caused by the accessory drive components. Remove the drive belts and operate the engine for a few seconds, this will verify if the whining noise is related to the accessory drive component. With the drive belts removed the water pump will not operate and the engine may overheat. Also diagnostic trouble codes (DTCs) may set when the engine is operated with the drive belts removed.
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The inspection should include checking the drive belt tensioner and the drive belt idler pulley bearings. The drive belts may have to be installed and the accessory drive components operated separately by varying their loads. Refer to the suspected accessory drive component for the correct removal and installation procedure.
Step | Action | Yes | No |
|---|---|---|---|
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Notice: Refer to Belt Dressing Notice in the Preface section. DEFINITION: A high pitched continuous noise that may be caused by an accessory drive component failed bearing. | |||
1 | Did you review the Symptoms - Engine Mechanical diagnostic information, and perform the necessary inspections? | Go to Step 2 | Go to Symptoms - Engine Mechanical. |
2 | Verify that there is a whining noise. Does the engine make the whining noise? | Go to Step 3 | Go to Diagnostic Aids |
3 |
Does the whining noise still exist? | Go to Engine Noise on Start-Up, but Only Lasting a Few Seconds or Upper Engine Noise, Regardless of Engine Speed or Lower Engine Noise, Regardless of Engine Speed. | Go to Step 4 |
4 |
Did you find and correct the condition? | Go to Step 5 | -- |
5 |
Does the whining still exist? | -- | System OK |
