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 glossed, non-elastic and so hard that when the nail of your finger is pressed into it, no mark is produced.
  
  Fig 1: Checking Belt Surface With Finger Nail
  Courtesy of HYUNDAI MOTOR CO.
2. Cracked back surface of rubber.
  
  Fig 2: Identifying Cracked Belt
  Courtesy of HYUNDAI MOTOR CO.
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: Identifying Separating Or Rounded Belt
  Courtesy of HYUNDAI MOTOR CO.
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: Checking Timing Belt
  Courtesy of HYUNDAI MOTOR CO.
If backlash or an irregular noise is observed when rotating the pulley, replace the timing belt tensioner and idler pulley.

Fig 5: Checking Timing Belt Tensioner
Courtesy of HYUNDAI MOTOR CO.