Humming/buzzing sound traced to Extension Box?

2012 SUBARU IMPREZA
150,000 MILES • 2.0L • 4 CYL • 4WD • AUTOMATIC
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ARTEMISPLATZ
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Recently I noticed a new humming/buzzing sound occurring only when the car is moving and audible at low speed. (This happened very shortly after a service which included new brakes, but I think that's a coincidence-It doesn't sound like any brake noise I've ever heard).

My mechanic test drove the car and put it on lift to try trace the noise. He determined it was likely a "rubbing sound" coming from the extension box in the transmission and referred me to a transmission shop to further investigate. He said it's not urgent.

My questions are:
1. Any ideas of what this might be?
2. Is it reasonable to just wait and see if it gets worse before doing anything further?
3. If it does need an expensive transmission repair, how would I determine if it's worth it?

Thanks for reading my question!
Sep 28, 2024 at 4:38 AM
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STRAILER
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Does the noise change when you hit the brakes? "Rubbing sounds" can come from the backing plate of the brake system. Can you please shoot a quick video with your phone so I can hear the noise? That way I can tell for sure what's going on. Also, if the brake caliper is loose it will make sounds as well, if the mechanic did not tighten the bolts, they could have fallen out which is common. Here is what you want to look for, use a flashing for the inspection. Check out the images (below). Please let us know what happens.
Sep 28, 2024 at 11:45 AM
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ARTEMISPLATZ
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Thanks for your reply. The noise doesn't seem to change when I hit the brakes. I'll get a recording as you suggested.
Oct 2, 2024 at 3:27 AM
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STRAILER
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When you say serviced did they change the transmission fluid? If so the incorrect fluid will make the transmission have noises.

Fluid Types


CVT Fluid

Type .................... SUBARU CVT Oil for Lineartronic
Capacities


CVT Fluid (CVTF)

Capacity .................... 12.6 - 13.1 qt (11.93 - 12.43L)

This car has the CVT transmission which the main drive band goes out on internally. Can you tell if the fluid is burnt? If so I would change the fluid out, here is how. Check out the images (below). Please upload videos in your response of any problems so we can see what to help you with.
Oct 2, 2024 at 11:02 AM