Parts supplier NTN-SNR has issued some important advice on tensioner fitment and in particular why mechanics should always replace the retaining bolts when replacing the damper.

The NTN-SNR technical team point out that during the original assembly or replacement of a damper, high tightening torques are applied to the retaining bolts. Some applications require secondary tightening angles to be applied once the torque settings have been reached. Once the retaining bolts are tightened correctly they have reached the elastic limits. The bolts lengthen or deform according to the manufacturers specifications, once stretched and deformed the bolts cannot be used again. If a stretched or deformed bolt is refitted there is a high risk of it not tightening correctly or snapping.

NTN-SNR say that not replacing the used bolts means a technician runs a high risk of an accessory system failure and in some cases this may result in serious engine damage.