Bad Bearing

I have a slight whirring sound on acceleration that I started noticing lately. It's pretty low, but I have very good hearing for a 47 year old.

My first thought is bad Bearing, seems to be coming from the back, any other ideas?

 

You need to do more investigation.

A "slight whirring sound" could be almost anything.

 

Agree with this. It's quite unusual for rear WB to fail versus the more common front WBs. I would suspect the noise would be related more to driveshaft components.

 

If it's louder under acceleration (under load) then it might be a pinion gear

But check the driveshaft carrier bearing too

 

Jack it up and turn the wheel by hand, should be smooth with no grinding. I just finished doing my first Tacoma rear wheel bearing on my 06(230k) and it was a real pain. See thread: https://www.tacomaworld.com/threads/2nd-gen-rear-axle-bearing-diy.246760/
On mine, a shop had replaced the bearing but forgot the rear axle bearing washer which (probably) ended up in premature failure.
Also my tire was starting to wear out on the inside. You might check that.

 

Check the universal joints also.

 

When I got my 2013 used, it was already droning. My wife thought it was coming from the front, and it did sound like it, but I always use my ChassisEar because I have found more than half the time, it's NOT the bearing it sounds like from inside the cabin.

Ended up being the right rear. Water had infiltrated into the race. The stud bolts that hold the bearing to the backing plate were so rusted I couldn't even pound it out with a 9x rivet gun. I had to actually cut through the bearing casing through the bolts at a low point with a grinder/cutoff wheel to get the bearing out of the backing plate.

Got the bearing tool from the fleabay seller that developed/made the cheap version (compared to the factory tool) that there are a lot of Chinese knockoffs of now - I already have a 20 ton press.

If it is the rear bearing, and you do it yourself, replace the axle shaft seal AND the big o-ring, don't re-use the spacer (it gets galled in the removal process) - but the washer is reusable if in good shape (I just bought new since it's cheap anyway - be careful of the orientation, as it is slightly conical in shape and has to face a particular direction that I can't remember right now).

 

Figured it out, it's the air conditioning.