Symptom | Possible Sources | Action |
Accessory drive belt noise | * Accessory drive system - Vehicles with accessory drive belt tensioner | * CHECK the system with the engine running and the accessory drive belt removed (only run the engine for a very short period). If a noise is apparent, the cause is not the accessory drive system. If a noise is not apparent, the cause is the accessory drive system. CHECK where the noise is coming from. Use a stethoscope or other listening device to determine the source of the noise. INSTALL new components as necessary. TEST the system for normal operation. |
* Accessory drive system - Vehicles without accessory drive belt tensioner | * Use a stethoscope or other listening device to determine the source of the noise. INSTALL new components as necessary. TEST the system for normal operation. |
* Accessory drive belt incorrectly installed. | * CHECK the accessory drive belt is correctly installed in the pulley grooves. INSTALL a new accessory drive belt as necessary. REFER to: Accessory Drive Belt (303-05 Accessory Drive, Removal and Installation). TEST the system for normal operation. |
* Pulley(s). | * CHECK the pulley(s) for damage, freedom of rotation, stone entrapment and alignment. INSTALL new components as necessary. TEST the system for normal operation. |
* Lubricant or other contamination. | * CHECK the accessory drive belt for contamination or damage. RECTIFY the source of the leak and INSTALL a new accessory drive belt. REFER to: Accessory Drive Belt (303-05 Accessory Drive, Removal and Installation). TEST the system for normal operation. |
NOTE:Squeal is defined as a continuous shriek, most noticeable when the engine is being accelerated or with electrical load. Accessory drive belt squeal | * Accessory drive belt tensioner worn, damaged or contaminated with oil. | * CHECK the accessory drive belt tensioner for correct operation, damage or contamination. REFER to the Accessory Drive Belt Tensioner Component Test in this procedure. INSTALL a new accessory drive belt tensioner as necessary. TEST the system for normal operation. |
NOTE:Whine is defined as a continuous noise at the same frequency, generally associated with plastic pulleys. Accessory drive belt whine | * Poor surface finish on accessory drive belt idler pulley flat surface(s). | * REMOVE the accessory drive belt. REFER to: Accessory Drive Belt (303-05 Accessory Drive, Removal and Installation). INSPECT the idler pulley(s) for surface finish. INSTALL a new idler pulley(s) as necessary. TEST the system for normal operation. |
* Accessory drive belt idler pulley bearing failure. | * REMOVE the accessory drive belt. REFER to: Accessory Drive Belt (303-05 Accessory Drive, Removal and Installation). INSPECT the idler pulley(s) for smooth rotation. INSTALL a new idler pulley(s) as necessary. TEST the system for normal operation. |
NOTE:Chirp is defined as a twittering noise, often intermittent Accessory drive belt chirp | * Pulley misalignment (usually evident at idle). | * CHECK that the accessory drive belt is running centrally on the flat pulleys. TEST the system for normal operation. * CHECK the pulleys for excessive end float and bent flanges. * With the engine running at idle, use a stethoscope to identify the source of the noise. INSTALL new components as necessary. TEST the system for normal operation. |
NOTE:Rattle is defined as a metallic knocking noise Accessory drive belt rattle | * Accessory drive belt tensioner hitting the end stops. | * CHECK the accessory drive belt tensioner for correct operation or damage. REFER to the Accessory Drive Belt Tensioner Component Test in this procedure. INSTALL a new accessory drive belt tensioner as necessary. TEST the system for normal operation. |
* Loose components or hardware. | * CHECK the components or hardware for correct installation and tighten as necessary. TEST the system for normal operation. |
Accessory drive belt fraying | * Accessory drive belt. * Pulley(s). | * CHECK the extent of the fraying by referring to the illustrations shown in the Visual Inspection section. Only INSTALL a new belt if the fraying is within the criteria quoted in the Visual Inspection section. TEST the system for normal operation. * CHECK the pulley(s) for damage, freedom of rotation and alignment. INSTALL new components as necessary. TEST the system for normal operation. |