Drive Belt Falls Off and Excessive Wear Diagnosis
Drive Belt Falls Off and Excessive Wear Diagnosis
Drive Belt Falls Off Diagnosis
Diagnostic Aids
If the drive belts repeatedly fall off the accessory drive pulleys, this may be caused by pulley misalignment.
If the drive belts repeatedly fall off the accessory drive pulleys, this may be caused by pulley misalignment.
If the drive belts are the incorrect length, the drive belt tensioners may not maintain the correct tension on the drive belts.
Test Description
The numbers below refer to the steps in the diagnostic table.
2. This inspection is to verify the condition of the drive belts. Damage may have occurred to the drive belts when the drive belts fell off the pulley. Inspect the drive belts for cuts, tears, sections of ribs missing, or damaged belt plies.
4. 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 of that pulley.
5. Inspection of the accessory drive pulleys should include inspecting for bends, dents or other damage that May prevent the drive belt from seating correctly in the pulley grooves or on the smooth surface of a pulley when the back side of the drive belts are used to drive the pulley.
6. Accessory drive component brackets that are bent or cracked will also cause the drive belts to fall off.
7. Inspection of the fasteners can address the possibility that an 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.
Drive Belt Excessive Wear Diagnosis
Diagnostic Aids
Above acceptable wear on a drive belt is usually caused by incorrect installation or the wrong drive belts for the application.
Minor misalignment of the drive belt pulleys will not cause above acceptable wear, but will probably cause the drive belts to make a noise or to fall off the pulleys.
Major misalignment of the drive belt pulleys will cause above acceptable wear and may also make the drive belts fall off the pulleys.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. The inspection is to verify that the drive belts are correctly installed over all of the drive belt pulleys. Wear on the drive belts may be caused by misalignment the drive belts by one groove on a pulley.
3. The installation of a drive belt that is to wide or to narrow will cause wear on the drive belts. The drive belt ribs should match all of the grooves on the pulleys.
4. This inspection is to verify the drive belts is not contacting any parts of the engine or body while the engine is operating. There should be sufficient clearance when the drive belt accessory drive components load varies. The drive belts should not come in contact with an engine or a body component when snapping the throttle.
