humming noise - what could it be?

[cvince]

I have a strange noise that's best described as wheel bearing noise, but I have doubts it's the wheel bearings because it doesn't vary with suspension load (though it does with engine load). It's loudest at exactly 60mph, and makes the same pitch as the engine at 5th gear (but it happens in all gears).

 

When it first comes on, it's pretty quiet, but gets louder over time. Here are a few symptoms (some that contradict each other)

 

1) When hot, brakes make the same noise (or make the existing noise louder --I dont know which it is) when applied.

 

2) When the noise just starts, it's entirely ENGINE load dependent (but not suspension load --when I upset the balance of the car, the noise does not change). No load, no/low noise.

 

3) When traveling at >60mph for an extended period, the noise begins to persist even though there's no engine load. I can shift to neutral, and the noise continues.

 

4) Rear brakes seem quite hot (I don't dare touch them) after an extended highway drive. Getting an IR thermometer soon to see if I can get an actual temp.

 

The strange thing is, everything points towards rotors, but I had both rears machined, and it didn't eliminate the noise. However, if it's rotors, that doesn't explain the engine-load affecting the noise.

 

My next best guess would be driveshaft or CV shaft. I got a shitty junkyard CV shaft as a replacement because I wanted OEM, and couldn't find it anywhere. Finally found a dealership who stocks them and will pay an arm and a leg for them if this is the real culprit.

 

Anyone here experience something similar or have thoughts?

[SubOperator]

Parking brake shoes, either not hooked up correctly, worn out or not properly adjusted. How high can you raise the parking brake handle? Does the noise change if you try to raise that handle in motion (SLOWLY WHILE HOLDING THE RELEASE BUTTON DOWN) ?

[cvince]

Parking brake shoes, either not hooked up correctly, worn out or not properly adjusted. How high can you raise the parking brake handle? Does the noise change if you try to raise that handle in motion (SLOWLY WHILE HOLDING THE RELEASE BUTTON DOWN) ?

 

Thanks! I actually did this experiment. The noise doesn't seem to change with parking brake. It also has a dead spot of maybe 5 degrees. I need to raise it around 10 degrees (or 2-3 inches) before parking brakes are applied sufficiently.

 

How would this explain the engine load dependency though?

[Max Capacity]

I'm guessing input bearing in the transmission ?

[Infosecdad]

I wouldn't rule out wheel bearings just yet.

How many years/miles and original or what brand?

[cvince]

I wouldn't rule out wheel bearings just yet.

How many years/miles and original or what brand?

 

Probably got them replaced around 2012-2013, car is at 91,000mi. Had left/right replaced probably around 60 and 70 respectively. Right one was under recall.