Inspection of the Belt and Pulley

4700 mm 01.02.001
Worn or loose drive belts may cause engine overheating or loss of alternator power. Replace the drive belt if any conditions described in Fig. are found. To inspect a belt, gently twist it to view the belt sidewalls and bottom.

  1. Abrasion

  2. Chunk-out

  3. Improper Install

  4. Cracking

  5. Pilling

  6. Uneven Rib Wear

  7. Misalignment

  8. Gravel Penetration

Fig. 1, Damaged Belts

  1. Inspect the belt contact surfaces for chips, flaking, cracks, discoloration, and other damage. See Fig..

    2. Important: For EPDM rubber drive belts, do not rely on cracking as an indicator of belt wear. EPDM rubber drive belts resist cracking better than neoprene belts. A better indicator of wear on EPDM belts is material loss.

  2. For EPDM belts, check the belt for material loss, which causes the belt to seat further down in the pulley and to ride directly on the pulley tips. See Fig..

    1. New Belt

    2. Worn Belt

    3. Material loss results in belt riding directly on pulley tips.

    Fig. 2, EPDM Belt Wear

  3. 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.

    4. Note: If it is difficult to distinguish the location of a supposed bearing noise, place a stethoscope on the component being checked, not the pulley, to isolate the area from outside interference.

  4. Inspect all pulleys for foreign objects, oil, or grease in the grooves.
Note:
Parent topic: Engine Belt Inspection
Document Number: 0000120089
Manual Publication Date: 2024-05-23
Topic Publication Date: 2024-10-31