When diagnosing serpentine accessory drive belts, small cracks that run across the ribbed surface of the belt from rib to rib (1), are considered normal. These are not a reason to replace the belt. However, cracks running along a rib (not across) (2) are not normal. Any belt with cracks running along a rib must be replaced. Also replace the belt if it has excessive wear, frayed cords or severe glazing.Refer to the ACCESSORY DRIVE BELT DIAGNOSIS CHART for further belt 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. CONDITIONPOSSIBLE CAUSESCORRECTIONRIB CHUNKING (One or more ribs has separated from belt body)1. Foreign objects imbedded in pulley grooves.1. Remove foreign objects from pulley grooves. Replace belt.2. Installation damage2. Replace beltRIB OR BELT WEAR1. Pulley misaligned1. Align pulley(s)2. Abrasive environment2. Clean pulley(s). Replace belt if necessary3. Rusted pulley(s)3. Clean rust from pulley(s)4. Sharp or jagged pulley groove tips4. Replace pulley. Inspect belt.5. Belt rubber deteriorated5. Replace beltBELT SLIPS1. Belt slipping because of insufficient tension1. Adjust tension (2.5L)2. Belt or pulley exposed to substance that has reduced friction (belt dressing, oil, ethylene glycol)2. Replace belt and clean pulleys3. Driven component bearing failure (seizure)3. Replace faulty component or bearing4. Belt glazed or hardened from heat and excessive slippage4. Replace belt.LONGITUDAL BELT CRACKING1. Belt has mistracked from pulley groove1. Replace belt2. Pulley groove tip has worn away rubber to tensile member2. Replace belt"GROOVE JUMPING" (Belt does not maintain correct position on pulley)1. Belt tension either too low or too high1. Replace accessory drive belt tensioner (Refer to 7 - COOLING/ACCESSORY DRIVE/BELT TENSIONERS - REMOVAL)2. Pulley(s) not within design tolerance2. Replace pulley(s)3. Foreign object(s) in grooves3. Remove foreign objects from grooves4. Pulley misalignment4. Align component5. Belt cordline is broken5. Replace beltBELT BROKEN (Note: Identify and correct problem before new belt is installed)1. Excessive tension1. Replace belt and adjust tension to specification2. Tensile member damaged during belt installation2. Replace belt3. Severe misalignment3. Align pulley(s)4. Bracket, pulley, or bearing failure4. Replace defective component and beltNOISE (Objectionable squeal, squeak, or rumble is heard or felt while drive belt is in operation)1. Belt slippage1. Replace accessory drive belt tensioner (Refer to 7 - COOLING/ACCESSORY DRIVE/BELT TENSIONERS - REMOVAL)2. Bearing noise2. Locate and repair3. Belt misalignment3. Align belt/pulley(s)4. Belt to pulley mismatch4. Install correct belt5. Driven component induced vibration5. Locate defective driven component and repair6. System resonant frequency induced vibration6. Vary belt tension within specifications.TENSION SHEETING FABRIC FAILURE (Woven fabric on outside, circumference of belt has cracked or separated from body of belt)1. Tension sheeting contacting stationary object1. Correct rubbing condition2. Excessive heat causing woven fabric to age2. Replace belt3. Tension sheeting splice has fractured3. Replace beltCORD EDGE FAILURE(Tensile member exposed at edges of belt or separated from belt body)1. Excessive tension1. Replace accessory drive belt tensioner (Refer to 7 - COOLING/ACCESSORY DRIVE/BELT TENSIONERS - REMOVAL)2. Belt contacting stationary object2. Replace belt3. Pulley(s) out of tolerance3. Replace pulley4. Insufficient adhesion between tensile member and rubber matrix4. Replace belt and adjust tension to specifications