* Misaligned pulleys: This is the most common cause. Even a slight misalignment of one or more pulleys can cause the belt to ride off center and rub. This can be due to:
* Bent pulley: A bent pulley will be visibly out of alignment.
* Worn pulley bearings: A worn bearing can allow the pulley to wobble, leading to misalignment.
* Pulley mounting bolts loose or broken: Check that all pulley mounting bolts are tight.
* Damaged or warped pulley bracket: The bracket that holds the pulleys might be bent or damaged.
* Worn or damaged belt: A belt that's worn, cracked, or glazed will be more likely to slip and ride off center. Even a slightly too-small belt can cause this.
* Incorrect belt routing: Make absolutely sure the belt is routed correctly. Consult your owner's manual or a repair manual for the correct routing diagram. A single mistake in routing can cause significant problems.
* Idler pulley issues: Idler pulleys guide the belt. If they are worn, seized, or misaligned, they can cause tracking problems. The idler pulley's bearing could be the problem here.
* Tensioner pulley problems: The tensioner pulley is responsible for applying the correct amount of tension to the belt. If it's faulty (worn bearings, sticking, or incorrectly adjusted), the belt tension and tracking will be affected.
* Interference: Something might be interfering with the belt's path, such as debris, a loose wire, or a damaged component near the belt.
Troubleshooting Steps:
1. Visual Inspection: Carefully examine the entire serpentine belt system. Look for any bent, damaged, or loose pulleys, worn bearings, cracks in the belt, or anything that's interfering with the belt's path. Check all pulley and bracket mounting bolts for tightness.
2. Belt Routing: Verify the belt is routed correctly according to the diagram in your owner's manual or a repair manual.
3. Pulley Rotation: Spin each pulley by hand and check for any wobble or roughness indicating a worn bearing. Listen for unusual noises.
4. Tensioner Check: Check the operation of the tensioner pulley. It should move smoothly and apply the correct tension to the belt.
5. Belt Tension: If you can access it, verify that the belt tension is correct using a belt tension gauge or by following the manufacturer’s specifications. Too loose and the belt will slip.
If you find any of the above problems, address them before replacing the belt. Replacing the belt without fixing the underlying issue will likely just lead to the same problem recurring. If you're not comfortable performing these checks and repairs yourself, take your vehicle to a qualified mechanic.
