Flexible pulleys – inspection methods

28 Dec 2022

The pulley should be inspected every 60,000 km or whenever the V-belt is replaced. The NTN-SNR specialists explain the easiest way to check the pulley.

When the engine is cool and switched off, create a mark on the wheel. The mark should drown from outer edge of the wheel to the hub.

Then start the engine and switch on all functions using the V-belt drive (power steering, turning the steering wheel, alternator, switching on electrical equipment, compressor, switching on AC).

Switch off the engine and check the mark on the pulley. The mark should return to its original position. If this is not the case, replace the wheel because the flexible insert is not performing its function.


  • Swelling of the flexible ring, e.g., due to exposure to oil
  • Cracks or furrows in the elastic ring
  • Deformation of the flexible ring
  • Cracks on the hub or outer (guide) wheel
  • Dismemberment of wheel segments
  • Presence of pieces of the elastic part of the wheel on the belt

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