Drive Belt Falls Off Diagnosis
Drive Belt Falls Off Diagnosis
Diagnostic Aids
If the drive belt repeatedly falls off the accessory drive belt pulleys, this may be caused by a pulley misalignment.
An extra load that is quickly applied or released by an accessory drive component may cause the drive belt to fall off. Verify that the accessory drive components are operating properly.
If the drive belt is the incorrect length, the drive belt tensioner may not maintain the proper tension on the drive belt.
Test Description
The numbers below refer to the steps in the diagnostic table.
2. This inspection is to verify the condition of the drive belt. Damage may of occurred to the drive belt when the drive belt fell off. Inspect the drive belt for cuts, tears, sections of ribs missing, or damaged belt ply's.
4. 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 of that pulley.
5. 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 a pulley when the back side of the drive belt is used to drive the pulley.
6. Accessory drive component brackets that are bent or cracked will also cause the drive belt to fall off.
7. Inspection of the fasteners can eliminate the possibility that a incorrect bolt, nut, spacer, or washer was installed. Missing, loose, or incorrect fasteners may cause pulley misalignment from the accessory drive brackets moving under load. Over tightening the fasteners may cause misalignment of the accessory component brackets.
