Car: Mazda 6 2009 2.0 DE diesel.

My car started make a reverse like sound (Which turns into a more high pitched sound at higher rpms, the noise is on all the time, even in neutral standing still albeit not very noisy) that seemed to come from the serpentine belt, one has already been ordered however now I've noticed that the engine had a crackling sound to it, almost as if you were dropping sand or corn into the engine. It only start at 2.750rpm or more (estimate) and there's nothing at lower rpms. The engine still had power and everything seems to work fine. Doing this test I only tried in neutral standing still, I don't dare it to drive yet. I've checked oil, it's at full. The sound seems to be coming from the right middle somewhere. Very close to the vacuum pump for the brakes. Albeit not too sure on that.

Any ideas what it could be? Thanks!

1 Answer 1


When car is cold, remove aux belt. Start car and rev to 2750rpm and see if noise resumes-likely to be a loose pulley due to bearing failure, which could be causing the whine as well.

  • Thanks for the comment. It turned out to be a bad generator bearing that made the whine noise. The dealer couldn't figure out what the crackling sound was, but he was not concerned as it wasn't too audible and unable to be heard while driving. Dec 28, 2018 at 10:05

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