Sierra 3500 4WD V8-6.6L DSL Turbo VIN 2 (2004)
Steps 3(continued) - 15
The numbers below refer to the steps in the diagnostic table.
2. 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 with this table.
3. The noise may be an internal engine noise. Remove the drive belt and operate the engine for a few seconds, this will verify if the chirping noise is
related to the drive belt or not. With the drive belt removed the cooling fan will not operate and the engine may overheat. Also Diagnostic Trouble
Codes (DTCs) may set when the engine is operated with the drive belt removed.
4. Inspect the drive belt for signs of pilling. Pilling is the small balls, pills or strings in the drive belt grooves caused by the accumulation of rubber
dust.
6. Misalignment of the accessory drive pulleys may be caused from improper 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 proper removal and installation procedure for that
pulley.
10. Inspection of the fasteners can eliminate the possibility that a incorrect bolt, nut, spacer, or washer was installed.
12. Inspection of the accessory drive pulleys should include inspecting for bends, dents, or other damage to the pulleys that would prevent the drive
belt from seating properly in the pulley grooves, or on the smooth surface of the pulley when the back side of the drive belt is used to drive the
pulley.
14. Replacing the drive belt when it is not damaged or there is not excessive pilling will only be a temporary repair.
