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 | ||||
