Timing Components: Testing and Inspection

INSPECTION OF TIMING BELTS





The timing belts must be checked closely. Should the following defects be evident, replace the belt with a new one, Replace every 60,000 miles.
(1) Hardened back surface rubber, glossy, non-elastic, and so hard that no mark is produced even when scratched by a fingernail.





(2) Cracked back surface rubber.
(3) Cracked or separated canvas.
(4) Cracked tooth bottom.
(5) Cracked side.





(6) Abnormal wear on side.

NOTE: Normal belt should have clear-cut sides as if cut by a sharp knife.





(7) Abnormal wear on teeth.
Initial stage:
Canvas on load side tooth flank worn (fluffy canvas fibers, rubber gone and color changed to white, and unclear canvas texture).
Final stage:
Canvas on load side tooth flank worn down and rubber exposed (tooth width reduced).

(8) Missing tooth.

TENSIONER PULLEY AND IDLER PULLEY





(1) Turn the pulleys to check for possible binding, excessive play, and unusual noise. Replace the pulley if any of these defects is evident.
(2) Replace if there is a grease leak.

AUTO TENSIONER





(1) Check the auto tensioner for possible leaks and replace as necessary.
(2) Check the rod end for wear or damage and replace as necessary.





(3) Measure the rod protrusion. It it is out of specification, replace the auto tensioner.

Standard value: 12 mm (0.47 in.).





(4) Using a vise with soft jaws push in the auto tensioner rod. If the rod can be easily retracted, replace the auto tensioner. You should feel a fair amount of resistance when pushing the rod in.

Caution:
1. Clamp the auto tensioner in the vise so it maintains a level position.





2. If the plug at the bottom of the auto tensioner protrudes, surround it with a plain washer as illustrated to prevent the plug from being in direct contact with the vise.