Timing Belt: Inspection

Inspect the belt closely. If the following problems are evident, replace the belt with a new one.
1. Hardened back surface of rubber
  Back surface is glossing, non-elastic and so hard that when the nail of your finger is pressed into it, no mark is produced.
  
  Fig 1: Testing Timing Belt
  Courtesy of KIA MOTORS AMERICA, INC.
2. Cracked back surface of rubber.
  
  Fig 2: Inspecting Timing Belt For Cracks
  Courtesy of KIA MOTORS AMERICA, INC.
3. Side of belt is badly worn.
  NOTE: A belt in good condition should have clear-cut sides as if it were cut with a sharp knife.
  
  Fig 3: Inspecting Timing Belt Sides
  Courtesy of KIA MOTORS AMERICA, INC.
4. Teeth are badly worn out.
  Initial stage : Canvas on load side of the tooth flank worn (fluffy canvas fibers, rubber gone, color changed to white, and unclear canvas texture)
  
  Last stage : Canvas on the load side of the tooth flank worn down and rubber exposed (tooth width reduced).
5. Missing tooth
Fig 4: Inspecting Timing Belt Teeth
Courtesy of KIA MOTORS AMERICA, INC.
If backlash or an irregular noise is observed when rotating the pulley, replace the timing belt tensioner and idler pulley.

Fig 5: Inspecting Belt Tensionser

Courtesy of KIA MOTORS AMERICA, INC.