A timing belt idler is a small pulley that helps route and stabilize the timing belt in its correct position. Depending on the size and length of the belt and engine, there can be one or more idler pulleys.
Symptoms of Wear or Failure
- Grinding or roaring type noise from inside the timing cover
- Belt may "jump time" (skipping a tooth or more, usually on the cam gear). This results in a loss of synchronization and engine performance.
- Trouble codes from the camshaft or crankshaft sensors, causing Check Engine Light to illuminate
- Slapping or scraping noises from engine
Related Repair Advice
- It is often recommended that you replace the idler(s) along with items like the water pump, front engine seals, drive belts, and tensioner any time the timing belt is replaced