Noise Diagnosis
Noises generated by the accessory drive belt are most noticeable at idle. Before replacing a belt to resolve a noise condition, inspect all of the accessory drive pulleys for alignment, glazing or excessive end play.
ACCESSORY DRIVE BELT DIAGNOSIS CHART
| CONDITION | POSSIBLE CAUSES | CORRECTION |
|---|---|---|
| RIB CHUNKING (One or more ribs has separated from belt body) | 1. Foreign objects imbedded in pulley grooves. | 1. Remove the foreign objects from pulley grooves. Replace the belt. |
| 2. Installation damage. | 2. Replace the belt. | |
| RIB OR BELT WEAR | 1. Pulley misaligned. | 1. Align pulley(s). |
| 2. Abrasive environment. | 2. Clean pulley(s). Replace the accessory drive belt if necessary. | |
| 3. Rusted pulley(s). | 3. Clean rust from the pulley(s). | |
| 4. Sharp or jagged pulley groove tips. | 4. Replace the pulley. Inspect the accessory drive belt. | |
| 5. Belt rubber deteriorated. | 5. Replace the accessory drive belt. | |
| BELT SLIPS | 1. Belt slipping because of insufficient tension. | 1. Inspect/Replace accessory drive belt tensioner if necessary. |
| 2. Belt or pulley exposed to substance that has reduced friction (belt dressing, oil, ethylene glycol). | 2. Replace the accessory drive belt and clean the pulleys. | |
| 3. Driven component bearing failure (seizure). | 3. Replace the faulty component or bearing. | |
| 4. Belt glazed or hardened from heat and excessive slippage. | 4. Replace the accessory drive belt. | |
| LONGITUDE BELT CRACKING | 1. Belt has jumped out of pulley groove | 1. Replace the accessory drive belt. |
| 2. Pulley groove tip has worn away rubber to tensile member | 2. Replace the accessory drive belt. | |
| "GROOVE JUMPING" (Belt does not maintain correct position on pulley) | 1. Incorrect belt tension. | 1. Inspect/Replace accessory drive belt tensioner if necessary. |
| 2. Pulley(s) not within design tolerance. | 2. Replace the pulley(s). | |
| 3. Foreign object(s) in the pulley grooves. | 3. Remove foreign objects from the pulley grooves. | |
| 4. Pulley misalignment | 4. Align component | |
| 5. Belt cord line is broken | 5. Replace belt | |
| BELT BROKEN (Note: Identify and correct problem before new belt is installed) | 1. Incorrect belt tension | 1. Replace Inspect/Replace accessory drive belt tensioner if necessary. |
| 2. Tensile member damaged during belt installation | 2. Replace the accessory drive belt. | |
| 3. Severe misalignment. | 3. Align The pulley(s). | |
| 4. Bracket, pulley, or bearing failure. | 4. Replace the defective component and accessory drive belt. | |
| NOISE (Objectionable squeal, squeak, or rumble is heard or felt while drive belt is in operation) | 1. Incorrect belt tension. | 1. Inspect/Replace accessory drive belt tensioner if necessary. |
| 2. Bearing noise. | 2. Locate and repair. | |
| 3. Belt misalignment. | 3. Align the accessory drive belt/pulley(s). | |
| 4. Belt to pulley mismatch. | 4. Install correct accessory dive belt. | |
| 5. Driven component induced vibration. | 5. Locate defective driven component and repair. | |
| TENSION SHEETING FABRIC FAILURE (Woven fabric on outside, circumference of belt has cracked or separated from body of belt) | 1. Tension sheeting contacting stationary object. | 1. Correct rubbing condition. |
| 2. Excessive heat causing woven fabric to age. | 2. Replace the accessory drive belt. | |
| 3. Tension sheeting splice has fractured. | 3. Replace accessory drive belt. | |
| CORD EDGE FAILURE (Tensile member exposed at edges of belt or separated from belt body) | 1. Incorrect accessory drive belt tension. | 1. Inspect/Replace accessory drive belt tensioner if necessary. |
| 2. Belt contacting stationary object. | 2. Replace accessory drive belt. | |
| 3. Pulley(s) out of tolerance. | 3. Replace the pulley. | |
| 4. Insufficient adhesion between tensile member and rubber matrix. | 4. Replace accessory drive belt. |