| Running noises from belt |
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Tension too high: Belt whines, whistles |
Adjust tension properly |
| Tension too low: Belt knocks against covering |
| Edge wear |
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Belt not parallel to axis: Belt runs against flanged pulley |
Check drive, line up or, if necessary, replace any non-aligned pulleys, change the belt |
| Wheels axially off-centre: Timing belt cannot be properly aligned |
| Flanged pulley has flaws |
Replace idler/tensioning pulleys, change the belt |
| Bearing play in components |
| Fabric wear in the tooth root |
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Belt excessively tensioned |
Change the belt, adjust tension correctly |
| Belt is overheating |
Find out cause (e.g. check cold performance) take corrective action, change the belt |
| Timing belt pulley is worn out |
Replace timing belt pulley, change the belt |
| Unacceptable wear of tooth flanks/base separating and tooth shearing |
 |
Tension too high/too low |
Change the belt, adjust tension properly |
| Trapped foreign matter |
Remove foreign matter, check covering is seated properly, change the belt |
| Jammed timing belt pulley or tensioning pulley |
Fing out cause (e.g. defective bearing), take corrective action, change the belt |
| Teeth and fabric separating from belt body |
 |
Leaks in the engine or engine compartment |
Repair leak(s), change the belt |
| Running marks on teeth side |
 |
Foreign matter in timing belt drive |
Remove foreign matter, change the belt, check the cover is seated properly |
| Flaws in teeth of timing belt pulley caused by foreign matter or tools during fitting |
Replace timing belt pulley, change the belt, ensuring it is properly fitted |
| Timing belt damaged before/during fitting |
Change the belt, ensuring it is properly fitted |
| Cracks on back of timing belt |
 |
Ambient temperature too high/low |
Find out cause (e.g. check cold performance) corrective action, change the belt |
| Contact with foreign media |
Change the belt, check the covering is seated |
| Back idler pulley sluggish |
Replace pulley, change the belt |
| Ageing |
Change the belt |
| Timing belt snaps |
 |
Foreign matter in the drive |
Remove foreign matter/media, change the belt |
| Contact with foreign media |
Change the belt, check the covering is seated properly |
| Excessive tensioning |
Change the belt, adjust tension properly |
| Belt was crimped before/during mounting |
Change the belt and fir it correctly |
| Defective system components |
 |
Bearing play |
Replace the idler, tensioning and/or guide pulley |
| Damaged running surface |
