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For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2005 🢒 Grand Prix 🢒 Vehicle Control Systems 🢒 Vehicle DTC Information 🢒 Drive Belt Squeal Diagnosis

Diagnostic Aids

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

If the squeal 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 generator are suggested items to inspect.

Test Description

The numbers below refer to the steps in the diagnostic table.

  1. 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

    2.

  2. The squeal 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, DTCs may set when the engine is operated with the drive belts removed.

    3.

  3. This test is to verify that an accessory drive components 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 is operating properly.

    4.

  4. This test is to verify that the drive belts tensioners are not operating properly. If the drive belt tensioners are not operating properly, proper belt tension may not be achieved to keep the drive belts from slipping which could cause a squealing noise.

    5.

  5. This test is to verify that the drive belts is not too long, which would prevent the drive belt tensioners from operating properly. Also if the incorrect length drive belts was installed, it may not be routed correctly and may be turning an accessory drive component in the incorrect direction.

    6.

  6. Misalignment of the accessory drive pulleys may be caused from improper mounting or incorrect installation of a 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 two or three pulleys. If a misaligned pulley is found, refer to that accessory drive component for the proper removal and installation procedure for that pulley.

    7.

  7. Inspect the accessory drive pulleys to verify that they are the correct diameter or width. Using a known good vehicle, compare the accessory drive pulleys.

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 drive belt squeal:

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

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 squeal noise?

Go to Step 3

Go to Diagnostic Aids

3

  1. Remove the drive belts. Refer to Drive Belt Replacement - Accessory .
  2. Operate the engine for no longer than 30-40 seconds.

Does the squealing noise still exist?

Go to Engine Noise on Start-Up, but Only Lasting a Few Seconds

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 proper operation. Refer to Drive Belt Excessive Wear Diagnosis .

Did you find and correct the condition?

Go to Step 9

Go to Step 6

6

Check for the correct length drive belts.

Did you find and correct the condition?

Go to Step 9

Go to Step 7

7

Inspect for a misaligned pulley.

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

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9
  1. Install the drive belts. Refer to Drive Belt Replacement - Accessory .
  2. Clear any codes.
  3. Run the engine in order to verify the repair.

Does the squealing noise still exist?

--

System OK