Idler pulley 320/08685 JCB JS, aftermarket

Idler pulley 320/08685 is an aftermarket part for the JCB JS excavators with the Dieselmax engine. The card also lists 320/08924. The photo shows the pulley with its bolt, washer and dust cap.

The idler pulley guides the belt and gives the pulleys enough wrap angle. A pulley with a worn bearing hums and clicks, gets hot and can finally seize, and then the belt breaks or jumps off. A smooth pulley face is needed for even belt wear. One bearing failure can stop the whole belt drive: with a broken belt the alternator stops charging, the water pump stops turning and the engine overheats quickly. So the pulley bearing is checked for noise and play at every belt change. If the pulley has play or feels rough when turned, replace it. The belt and pulleys are usually renewed together. The pulley may have a steel or plastic body, with the bearing pressed in.

Specifications

Compatibility

The part is listed for JCB JS excavators with the Dieselmax engine. The catalogue also has the genuine version of this part. Other parts are in JCB Dieselmax engine.

Fitting

After fitting, spin the pulley by hand to check that it turns freely and quietly, and inspect the belt for wear and cracks. Thread locker can be applied to the pulley bolt.