| Diagnosis and Testing Inspection and Verification - Verify the customer's concern by operating the engine to duplicate the condition.
- Inspect to determine if any of the following mechanical concerns apply:
Visual Inspection Chart | Mechanical | - Drive belt cracking/chunking/wear
- Drive belt noise or squeal
- Pulley misalignment or excessive pulley runout
| - Inspect for drive belt cracking/chunking/wear.
- If the concerns remain after inspection, determine the symptoms. GO to Symptom Chart.
Under severe operating conditions (high temperature, low humidity), drive belt rib cracking can occur at less than 96,000 km (60,000 miles). Drive belt rib cracking (cracks across grooves): - is not a reason for concern.
- has no detrimental effect on drive belt performance.
Cracks parallel to grooves are acceptable. The drive belt is still perfectly functional until rib chunking occurs. Drive belt chunking is where the rubber material actually chunks out between the cracks. Install a new drive belt if chunking occurs. Vee-Ribbed Serpentine Drive Belt with Cracks Across Backing Vee-Ribbed Serpentine Drive Belt with Chunks of Rib Missing Symptom Chart Symptom Chart | Symptom | Possible Sources | Action | | Drive belt cracking | * Drive belt. | * System OK. | | Drive belt chunking | * Drive belt. | * | | Drive belt noise or squeal | * Drive belt. * Pulley(s). | * DETERMINE what area of the pulley(s) the noise is coming from, then CHECK that area with a straightedge and LOOK for the accessory pulley(s) to be out of position in the fore or aft direction, or at an angle to the straightedge. | | Drive belt does not hold tension | * Drive belt cracking or damaged. | * INSPECT the drive belt for cracking parallel with and through to the backing. INSTALL a new drive belt if necessary. | | * Drive belt tensioners worn or damaged. | * CHECK the drive belt tensioner for damage and correct operation. REFER to the Component Test in this section. INSTALL a new drive belt tensioner if necessary. | | Drive belt squeal or chirp | * Incorrect drive belt installed. | * CHECK the drive belt for correct part application. | | * Lubricant or other contamination on the drive belt. | * CHECK the drive belt for oil, coolant, power steering fluid, brake fluid or other contamination. REMOVE the drive belt and WASH with detergent and water. If the drive belt cannot be cleaned or is damaged (softened) by contamination, INSTALL a new drive belt. | | * Drive belt pulleys not aligned correctly, damaged or not rotating freely. | * CHECK the pulleys for correct alignment, devices and pulleys for correct freedom of rotation and damage. REPAIR the pulleys and devices as necessary. | Component Test Drive Belt — Misalignment CAUTION:Incorrect drive belt installation will cause excessive drive belt wear and may cause the drive belt to come off the drive pulleys. NOTE:Original equipment drive belts are made of a special cord construction and are subjected to special testing before they are approved for use. New non-standard drive belts may track differently or incorrectly. If a new drive belt tracks incorrectly, install a new original equipment drive belt to avoid performance failure or loss of drive belt. With the engine running, check drive belt tracking (the position of the drive belt on one of the grooveless pulleys, idlers or drive belt tensioner. If the edge of the drive belt rides beyond the edge of the pulley, noise and premature wear may result). If a drive belt tracking condition exists, visually check the drive belt tensioner for damage, especially the mounting pad surface. If the drive belt tensioner is not installed correctly with the locating pins in the locating holes, the mounting surface pad will be out of position. This will result in abnormal drive belt tension and chirp and squeal noises. If the above procedures do not correct the drive belt noise, install a new drive belt. However, the drive belt noise may return (with mileage) if one of the above conditions still exists uncorrected. - With engine running, visually observe the grooves in the pulleys (not the pulley flanges) for excessive wobble. Install new components as necessary.
- Check all accessories, mounting brackets and drive belt tensioner, for any interference that would prevent the component from mounting correctly. Correct any interference condition and recheck belt tracking.
- Tighten all accessories, mounting brackets and drive belt tensioner retaining hardware to specification. Recheck drive belt tracking.
Belt Tensioner The automatic drive belt tensioner can be checked as follows: - With the engine running, observe the drive belt tensioner movement. The drive belt tensioner should move (respond) when the A/C clutch cycles or when the engine is accelerated rapidly. If the drive belt tensioner movement is constant without A/C clutch cycling or acceleration, a pulley or shaft is probably bent or a pulley is out of round. In rare cases, excessive drive belt rideout (uneven depth of grooves in drive belt) can cause excessive drive belt tensioner movement. This condition can be checked by removing the suspect drive belt and installing a known good original equipment drive belt and repeating the observation.
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