Common Timing Pulley and Timing Belt Problems

Common Timing Belt and Timing Pulley Issues and Corrections 

Components fail when you least expect them to. Because of complexity in drive systems, it can be difficult to pinpoint where to begin to look for the problem and how to correct it. Some common issues with timing belts and timing pulleys along with their causes and corrections are listed below.

Problem: Snapped timing belt

Causes:

• Obstruction/objects in drive
• Remove obstruction and assess for damage; replace belt if necessary
• Fluid contamination
• Check for leaks in drive, clean components, replace belt
• Tension too high
• Replace belt, adjust to correct tensioning
• Crimp in belt when fitting
• Replace belt and fit correctly

Problem: Wear on belt edges

Causes:

• Belt running along flange
• Fix misalignment, replace belt if necessary
• Play in component bearings
• Replace idler/tensioner pulley, Replace belt

Problem: Wear in tooth root and reinforcements

Causes:

• Tension too high
• Replace belt, adjust to correct tensioning
• Worn timing pulley
• Replace pulley

Problem: Wear and/or cracks in tooth flank, broken off teeth

Causes:

• Tension too high/low
• Replace belt, adjust to correct tensioning
• Obstructions/objects in drive
• Remove obstructions, change affected components
• Seized timing pulley or tensioner
• Find and correct problem, replace belt

Problem: Belt teeth and reinforcements separated from belt body

Causes:

• Fluids caused chemical effect on compounds in the belt
• Find and fix source of fluids, clean timing pulleys, replace belt

Problem: Indentations on tooth side of belt

Causes:

• Obstructions/objects in drive
• Remove obstructions, check drive for damage, replace belt
• Imperfections on pulley cased by tools when installing/fitting belt
• Replace pulley, replace belt
• Damaged belt prior to handling
• Replace belt

Problem: Belt teeth broken off sporadically

Causes:

• Tooth profiles of belt and pulley don't match
• Install matching profiles

Problem: Back of belt cracked

Causes:

• Ambient temperature too high/low
• Fix temperature, replace belt

• Fluid contamination
• Fix leak, clean drive, replace belt

• Back of belt overheated from seized idler
• Change idler and belt, ensure proper rotation of idler

• Lifetime of belt over
• Replace belt

Problem: Other damage to back of belt

• Reverse idler seized, plastic contact surface melted
• Change idler and belt, ensure proper idler rotation

• Contact with obstruction/object, incorrect position of scews/washers/brackets
• Replace bearings and belts, ensure no object can obstruct the operation of the running belt

Problem: Operating noise

Causes:

• Tension too high - squeal
• Adjust to correct tensioning

• Tension too low - belt striking guard
• Adjust to correct tensioning

• Worn/defective pulleys
• Replace worn/defective pulleys and replace belt

• Misaligned pulleys
• Ensure proper alignment, replace belt