ACCESSORY DRIVE BELT DIAGNOSIS



When diagnosing serpentine drive belts, small cracks that run across ribbed surface of belt from rib to rib , are considered normal. These are not a reason to replace belt. However, cracks running along a rib (not across) are not normal. Any belt with cracks running along a rib must be replaced . Also replace belt if it has excessive wear, frayed cords or severe glazing.

Refer to SERPENTINE DRIVE BELT DIAGNOSIS CHART for further belt diagnosis.


SERPENTINE 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 foreign objects from pulley grooves. Replace belt.
 
2. Installation damage.
 
2. Replace belt.
 
 
RIB OR BELT WEAR
 
1. Pulley(s) misaligned.
 
1. Align pulley(s).
 
2. Abrasive environment.
 
2. Clean pulley(s). Replace belt if necessary.
 
 
3. Rusted pulley(s).
 
3. Clean rust from pulley(s).
 
 
4. Sharp or jagged pulley groove tips.
 
4. Replace pulley.
 
 
5. Rubber deteriorated.
 
5. Replace belt.
 
 
LONGITUDINAL BELT CRACKING (CRACKS BETWEEN TWO RIBS)
 
1. Belt has mistracked from pulley groove.
 
1. Replace belt.
 
2. Pulley groove tip has worn away rubber to tensile member.
 
2. Replace belt.
 
 
BELT SLIPS
 
1. Belt slipping because of insufficient tension.
 
1. Replace automatic belt tensioner.
 
2. Belt routed
 
2. Verify belt routing.
 
 
incorrectly
 
   
3. Incorrect belt.
 
3. Replace belt.
 
 
4. Belt or pulley subjected to substance (belt dressing, oil ethylene glycol) that has reduced friction.
 
4. Replace belt and clean pulleys.
 
 
5. Driven component bearing failure.
 
5. Replace faulty component bearing.
 
 
6. Belt glazed and hardened from heat and excessive slippage.
 
6. Replace belt.
 
 
“GROOVE JUMPING" (BELT DOES NOT MAINTAIN CORRECT POSITION ON PULLEY)
 
1. Belt tension either too high or too low.
 
1. Replace automatic belt tensioner.
 
2. Belt routed
 
2. Verify belt routing.
 
 
incorrectly.
 
   
3. Incorrect belt.
 
3. Replace belt.
 
 
4. Pulley(s) not within design tolerance.
 
4. Replace pulley(s).
 
 
5. Foreign object(s) in grooves.
 
5. Remove foreign objects from grooves.
 
 
6. Pulley misalignment.
 
6. Check and replace.
 
 
7. Belt cord line is broken.
 
7. Replace belt.
 
 
BELT BROKEN (NOTE: IDENTIFY AND CORRECT PROBLEM BEFORE NEW BELT IS INSTALLED)
 
1. Excessive tension.
 
1. Replace belt and automatic belt tensioner.
 
2. Incorrect belt.
 
2. Replace belt.
 
 
3. Tensile member damaged during belt installation.
 
3. Replace belt.
 
 
4. Severe misalignment.
 
4. Check and replace.
 
 
5. Bracket, pulley, or bearing failure.
 
5. Replace defective component and belt.
 
 
NOISE (OBJECTIONABLE SQUEAL, SQUEAK, OR RUMBLE IS HEARD OR FELT WHILE DRIVE BELT IS IN OPERATION)
 
1. Belt slippage.
 
1. Replace belt or automatic belt tensioner.
 
2. Bearing noise.
 
2. Locate and repair.
 
 
3. Belt misalignment.
 
3. Replace belt.
 
 
4. Belt-to-pulley mismatch.
 
4. Install correct belt.