2013 CX-9 Loud droning noise from behind at highway speed

[ftp19601960]

There is loud droning noise from behind if I drive with sufficient speed. I tried to manually rotate rear wheels and I did not find any play or grinding within rear differential. If it is the differential it can be only from the drive shaft input gear I guess. Any ideas?

 

[roundle1979]

How many miles on your tires? Maybe they are cupped/worn?

I had a BMW with factory staggered wheels. it loved to 'cup' the rear tires after 15K miles. They made a hell of a lot of noise (like a roaring type sound, almost as bad a shot wheel bearing).

 

[ftp19601960]

Tires have wear indicator at 60%. This comes from the rear regardless of tire swap.

 

[truckster]

Possible loose exhaust?

 

[ftp19601960]

I thought about that. But there is no noise at stop with high RPM. It's very speed dependent , not RPM. I will try to change both rear hubs just in case.

 

[klaatutrout]

I believe I had this same issue on our 2010 CX-9 (~100k). We ended up having to replace the rear hubs.

At idle and at lower speeds, there was no sound, but once I hit between 35-40, it would appear and continue until I went below that threshold.

 

[mazdacx9017]

 

[mazdacx9017]

The noise from my video was taken when it was really cold outside. I experience similar noise when accelerating at 35MPH or so.

@@klaatutrout,

@ftp19601960​

is your noise similar at all? My Mazda dealer looked at the car 2 times and were not able to replicate or figure out the nature of the noise

 

[Bronco Boy]

View attachment 307196

Sounds like an exhaust shield vibrating; check them all. There is one right behind the rear axle where the exhaust Y's, and on mine, the clamps were all gone. Two hose clamps later and she was good to go.

 

[klaatutrout]

@@klaatutrout,

​

is your noise similar at all? My Mazda dealer looked at the car 2 times and were not able to replicate or figure out the nature of the noise

Mine only made noise once it got over 30 - 40 mph; sitting still it sounded normal.

 

[mazdacx9017]

@klaatutrout, Thank you!

@ftp19601960 thank you!

I failed to mention that I had my transmission, transfer case replaced with new parts (by the mazda dealer) and some rear differential work done. Based on their feedback they do not think any of that causes the noise. Often though dealers do not put back the parts properly back.

I wonder if they just did not get the parts put back together properly. Any thoughts on what could be loose besides the exhaust? The dealer does not put enough effort to reproduce the noise and I need to research possible issues.

I will definitely ask them to check on the exhaust shield as the car is still with the mazda dealer