Inspection of the Drive Belt
sb mm 01.03.002
- Inspect the belt for glazing. See Fig., Ref. A. Glazing is indicated by shiny sidewalls, and is caused by friction created when a loose belt slips in the pulleys. It can also be caused by oil or grease contamination on the pulleys.
- Check the belt for ply separation. See Fig., Ref. B. Oil, grease, or belt dressing can cause the belt to fall apart in layers. Repair any oil or coolant leaks that are affecting the belts before replacing the drive belts. Do not use belt dressing on any belt. 3.
- Check the belt for a jagged or streaked sidewall. See Fig., Ref. C. Jagged
or streaked sidewalls are the result of foreign objects, such as sand
or gravel in the pulley, or a rough pulley surface.
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Glazing
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Separating Layers
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Streaked Sidewalls
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Tensile Break
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Uneven Ribs
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Cracks
Fig. 1, Drive Belt Replacement Conditions
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- Check for tensile breaks (breaks in the cord body). See Fig., Ref. D. Cuts in a belt are usually caused by foreign objects in the pulley, or by prying or forcing the belt during removal or installation. 5.
- Check for uneven ribs on serpentine (poly-V) belts. See Fig., Ref. E. Foreign objects in the pulley will erode the undercord ribs, causing the belt to lose its gripping power.
- Check the drive belts for cracks. See Fig., Ref. F. Small irregular cracks are usually the signs of an old belt.
- Visually inspect the pulleys for excessive play or wobble. Excessive play or wobble indicates a failure of the pulley bearing. Check for belt squealing or squeaking. Replace the bearings as necessary.
- Inspect all pulleys for foreign objects, oil, or grease in the grooves.
Note: If it is difficult to distinguish the location of a supposed bearing noise, obtain a stethoscope and place it on the component being checked, not the pulley, to isolate the area from outside interference.
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