rhythmic humming above 55mph

I'm stumped on this one, I started hearing this rhythmic humming in 2009 Taco about a month ago and I cannot pinpoint the problem. I searched the board and tried a few suggestions.

So far I've visually inspected the tires, rims and all look fine and have no excessive play, rotated the tires, spun all the wheels and the bearings aren't grinding, greased the driveshaft and even drove around on 4WD to see if that changed anything. Nothing.

I set up an appointment with a local shop but is there something else I should be looking at?

 

Are you lifted? Any vibration or just the hum?

 

So hard to diagnose this stuff from a forum.. but what tires are you on and how long have you had them? They could be worn to the point that they are starting to increase road noise. Since you didn't mention any other issues, that's my first thought, especially if they're AT or MT tread.

Also could have lost a splash shield or something that helps prevent road noise getting into the cabin or even possible bad/old/low fluid somewhere or a dragging brake. So may possibilities.

 

You have to physically feel the knuckle while spinning the tires to diagnose the front wheel bearing on these trucks. If you have play, it BAD. Really BAD.
The rear bearings are even worse to diagnose.

At least that’s been the case for me.

 

no lift or vibration

just EOM 2017 rims and 1.25" spacers

 

standard Bridgestone Duelers, probably pushing 40k miles with lots of tread left and no visual cupping or uneven wear

I did add an updated aluminum skid plate but that was months ago before the sounds began, so frustrating

 

I had one hand on the front strut and rear shock when I turned them and them and there was zero vibration.

The only thing was kinda weird is when rotating the rears, either direction, the drive shaft when wiggle a little bit but not engage (had entire rear end jacked up)

 

How many miles on the current wheel bearings?. You can hear them long before you can feel them. If the sound gets worse with speed and reduces by high speed cornering in only one direction, likely a wheel bearing.

 

I'm also starting to get something like this in my 2009 Sport. Mine happens around 62 MPH. No vibration, just a resonance or hum. No issues going slower or faster. 4WD or not makes no difference. Truck has 127,000 miles, wheel bearings are original as is the belt tensioner. Tires are year old Michelin LTX that are in perfect condition. I am not too worried about this... yet. But it can be annoying. I'll follow this thread to see what the collective comes up with.

 

I'd bet front wheel bearings, especially if you're over 100k miles. If they're bad enough you can audibly hear them grinding when spinning by hand, you're waayyy past bad...like about to fall apart.
Did you check for play, 12 & 6 o'clock position? It doesn't take much play for them to be bad. Sounds like you're mostly stock setup, so it's probably the 1.25" spacers that are making your bearings wear.

 

my 09 has 146,000 miles so assuming a bad bearing would make sense. there is just zero indications that I can tell which bearing it might be.

there was no play at 12 & 6 or 3 & 9. yeah mostly stock except the spacers.

I'm going to change the serp belt this weekend before I take to shop next week as it's original anyway just to rule that out

 

You aren’t telling me anything.
I drove on a dad bearing for a year “just to find out for sure” what bearing it was.
Like I said earlier, neither one had play you could feel.

It finally got bad enough on turns I figured it out.
When turning, it will get “worse”. What ever way you turn, and it gets louder. It’s usually the opposite bearing that is bad. For instance, turning right get louder, it’s the left bearing. At least it was for me.

 

LOL... only way to be sure and really get your money's worth is to wait for the wheel to fall off. ;-)

 

Yeah, the serpentine belt has nothing to do with it...

Checking 3 & 9 play tells you if you need ball joints or not.

Like @TnShooter said & my experience as well, the 12 & 6 o'clock play was hardly noticeable. The rhythmic humming alone at 55+ tells you it's bad. Change BOTH fronts and I'd bet the noise will disappear. I've replaced mine 2 times & it's sounding like I'm due for my 3rd set of fronts. I have yet to have issue with the rear.

Only other possibility I would consider is the needle bearing that is usually replaced/upgraded with the ECGS bushing. BUT since you say no vibrations, I'm still shoving all in on front wheel bearings.

 

Check the roadforce on your tires.
Replace the wheel bearings if they’re due
Throw spacers in trash where they belong
Rebuild the brake calipers

 

What’s worse is after doing the one, I decided to just go ahead and do the other.
So in the end, I’d been better off just doing them both at the same time. Which is what I’d suggest most people do if they can afford it.

 

Also, just to cover all bases, did you make any changes to the audio system recently? I know alternator whine can be an issue that might be more present at different speeds. Just one more thing to rule out if you are unable to find it in the drivetrain or wheel hardware.

 

I changed my left front wheel bearing today. there was no play, just a humming noise that started a month ago at highway speeds. Prior to changing I diagnosed it was the left front because loading up the bearing via a high speed sweeping right hand corner significantly reduced the noise whereas turning the opposite direction did not. When I got the hub off and spun it by hand it was clear that the bearing was notched, dry and failed. I had one go out about 50k miles ago on the passenger side and it behaved the same. The post repair highway road test resulted in no more humming, droning failed bearing noise.

 

From my experience if it sounds like your truck has mt tires(and you dont) its most likely a bearing.

 

So, what bearings are you guys getting? I may go ahead and replace mine this summer since they are getting there, if not already bad. I am going to avoid the whole go to a shop with a press thing and just get the assemblies. Looks like we can get the OEM Toyota parts for about $150 apiece, at least from my local dealer using the Toyota parts gateway. I see others like Torq brand for half that, but I am reluctant to go there. I also watched a video of some guys doing a bearing only swap without a press. Lots of hammering and prying... LOL. I am gonna pass on that.