I posted a similar question before. When I cold start my new 09 civic, I hear a ‘whirr’ at all rpms from the engine. I took it to a different dealer than I bought it from and they said it’s normal and that the auto-belt tensioner ‘moves’. Well, when I drive a while and get home, the ‘whirr’ is gone. So whenever this engine warms up, the sound goes away. What is it?- timing chain tensioner or auto-belt tensioner?? And what is an auto belt tensioner anyways?? - Always had a RWD vehicle. Thanks.
A tensioner is basically a wheel on a spring to provide tension for the belt. Test drive another car of the same model and see if it is normal. Tensioners are not that expensive, but for a new car I would try and get it replaced under warranty.