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Top 6 Causes of Timing Belt Failure

Timing Belt & Pulley

With the help of ProTorque, We've put together a list of problems and possible causes to help you identify the reason for timing belt failure. Visually examine your timing belt drives for these top 6 failure-causing problems and it could help to prevent your drives grinding to a halt, avoiding unscheduled downtime.

1. Misalignment

Misalignment is one of the main causes of timing belt drive failure. Excessive or uneven tooth wear, belt tracking and tensile failure can all be attributed to misalignment. By checking and aligning your shafts and timing pulleys you can increase the life of your timing belts and save yourself lots of downtime.

2. Excessive load
If the timing belt teeth are shearing, excessive load is more than likely the cause. Tensile failure and even excessive tooth wear can also be caused by excessive load or shock loads, although the latter is less likely. To cure this problem you’re going to have to redesign the drive.

3. Under-tensioned Belt
Tooth skipping, also called ‘ratcheting’, is probably down to your belt being under-tensioned. Under-tensioning can also cause excessive or uneven tooth wear and excessive drive noise so use a tension gauge to set the correct tension on those timing belts!

4. Weak drive structure
If your drive is vibrating excessively or your timing belts are suffering from apparent belt stretch, you could have a weak drive structure. Try reinforcing the drive structure and you could stop the problem.

5. Damaged or worn pulleys
Damaged or worn timing pulleys will substantially reduce belt life. Worn teeth will cause belt wear and/or damage. Nicks or gouges can cut the belt. Inspect and replace pulleys that show signs of wear.

6 Debris in the timing pulley or drive
It’s the most overlooked, but debris can cause a multitude of problems for your timing belt & pulley. Dirt on the teeth can abrade the belt and oil can attack the belt materials. Use a stiff brush to clean off rust and dirt. Wipe clean of oil and grease. Debris can account for any of the above reasons for timing belt failure – so go clean those pulleys and fit a shield to that drive! 

A timing belt will eventually fail by loss of teeth in what’s considered normal wear, any other failure reason should be considered abnormal. For a full list of possible failures and the corrective action to take, consult our Timing Belt Troubleshooting Guide to check your belts & timing pulleys.