I realize this type of problem is hard to describe/diagnose but what the heck, maybe someone knows why. :(

I've got an 05 WRX wagon (no mods) with about 17k miles. At exactly 64 mph it makes a consistent humming noise, medium to high pitch.

It doesn't matter if I'm accelerating or decelerating it makes that sound. As soon as I accelerate past 64 it goes away. And when I decelerate it hums briefly until about 63 mph then it goes away.

Most of the time when it happens I'm on the expressway and the road is flat.

It doesn't seem to affect handling or performance (that I can tell) just annoying. I thought maybe it was a wheel bearing but the service manager disagrees. He told me they took it for a spin and didn't hear nothing -go figure.


Any thoughts?

Could be a tire/wheel inflation/defect/imbalance problem. Can you tell if the sound is coming from the front or back, left or right? Make sure all your tires are properly inflated, with fronts the same and rears the same. Check the treads for any signs of uneven wear. Also, you've rotated your tires 2 or 3 times by now, right?

There is a thread on this topic in the Warranty section...
http://forums.nasioc.com/forums/showthread.php?t=569754