Weird humming noise please help!!!

I’m just about to give up and take it to a mechanic shop, 05 PRERUNNER rear wheel drive, humming noise going 30+ mph. Gets louder as I speed up, gets quieter as I slow down, like an airplane lifting off or landing. Just had all the differential bearings redone thinking it was that but it’s not. Wheel bearings seem fine and the sounds always there.

 

How about the u joints?

 

Do I check them by just rocking the driveshaft back and forth? Or slightly rotating it back and forth ?

 

It is best to remove the shaft , sometimes a U joint will get tight and dry. You can't tell doing the rocking test if it is siezed, Pulling the shaft lets you flex the joint to see if it binds.

 

Gotcha. I can’t hear any vibrating or thumping when I first put it into or out of gear, could it be anything else? The carrier bearing would typically squeal on Tacoma’s.

 

Mileage? What tires are you running and how old are they? When’s the last time you replaced u joints or carrier bearing? Do you have a lift, what is it, and is your opinion angle properly set? Lots of things it could be. Good luck.

 

This has got to be a wheel bearing. Does it get quiet when going around a corner on the highway? Could be a left corner, or a right, depending on which side your wheel bearing has worn out.

 

Wheel bearings likely not fine. Jack up the truck and spin each tire on its own.

 

No the noise is always there whether I’m turning left or right, all tires spun just fine with no noises, and no play. Brand new tires didn’t change the noise as well. No lift all stock. 110k miles, haven’t changed the carrier bearing and the ujoints.

 

I really think it's a wheel bearing still. They usually wear out around 75-90k miles. I have 178k miles on my 2010 and had that same noise. Both front wheel bearings were shot. Carrier bearing and u joints are still original and fine. I'm lifted and still don't have carrier bearing issues.

 

Yep I just checked the wheel bearings they seem completely fine with no noise at all. Tires turn smooth with ease.

 

Have you greased the driveshafts?

 

Its not just noise you're looking for when spinning the wheels. Spin each front wheel while holding the knuckle with one hand. You're feeling for a roughness coming through the knuckle. A good bearing will be completely smooth and whisper quiet. Any roughness felt through your hand is a bad wheel bearing. Compare side to side. If one side feels rough and the other side feels smooth the rougher side is the bad bearing