Drive Belt Squeal Diagnosis
Drive Belt Squeal Diagnosis
Diagnostic Aids
A loose or improper installation of a body or suspension component, or other item on the vehicle may cause the squealing noise.
If the noise is intermittent, verify the accessory drive components are not the problem by varying their loads, making sure they are operated to their maximum capacity. An overcharged A/C system, a power steering system with a pinched hose or incorrect fluid, or a failing generator are suggested items to inspect.
Test Description
The numbers below refer to the step numbers in the diagnostic table.
2. The noise may not be engine related. This step is to verify that the engine is making the squealing noise. If the engine is not making the noise do not proceed further with this table
3. The noise may be an internal engine noise. Remove the drive belt and operate the engine for a brief period, this will verify that the squealing noise is the drive belt or an accessory drive component. When removing the drive belt the water pump will not operate and the engine may overheat. Also DTC's may set when the engine is operating without the drive belt.
4. This test is to verify that an accessory drive component does not have a seized bearing. With the drive belt removed, test the bearings in the accessory drive components for smooth rotation. Also with the engine operating vary the load on the components in order to verify that the components are operating properly.
5. This test is to verify that the drive belt tensioner operates properly. If the drive belt tensioner is not operating properly, proper belt tension may not be achieved to keep the drive belt from slipping which could cause a squeal noise.
6. This test is to verify that the drive belt is not too long, which would prevent the drive belt tensioner from working properly. Also if an incorrect length drive belt was installed, it may not be routed properly and may be turning an accessory drive component in the wrong direction.
7. Misalignment of the pulleys may be caused from improper mounting, or incorrect installation of the accessory drive component pulley, or the pulley may be bent inward or outward from a previous repair. Check for a misaligned pulley by using a straight edge in the pulley grooves across 2 or 3 pulleys. If a misaligned pulley is found refer the appropriate procedure for replacement.
8. This test is to verify that the pulleys are the correct diameter or width. Using a known good vehicle compare the pulley sizes.
