Humming/Droning noise mistaken for road noise at first

I just noticed a humming/droning sound in my 2008 tacoma 2WD TRD sport. i first thought it was road noise and then realized it wasnt. I have done some looking on internet and talked to my son about it and we think maybe bad hub bearing or bad tires. (I am in need of new tires in the very near future.) truck has 105K, it has no mods, there is no noticeable vibration and no extra sounds when turning left or right and no wiggle in the tires (as hub bearing might indicate.) there are no other performance issues. Just this "humming" ... or droning (?) sound...... sound is maintained as long a speed is maintained either by cruise control or having foot on gas, but if cruise is released or foot removed from gas pedal....like a gradual slow without applying brakes, the sound seems to go away (which makes me fear it's an engine issue) ..... I am not sure how long it’s been going on as most of my driving is short distance and slower speeds. I noticed it for first time the other day when i was on freeway for a 2-hr drive. Any ideas? At the very least, some ideas/suggestions to take with me to the garage. Thanks!

 

There was an issue some had with the wind hitting the suspension. There are holes which act as a flute.

 

a few months back I had a droning sound, I attributed it to the tires, had 60K on slightly aggressive tires (Falkon Wildpeaks). I replaced the tires and noise was still there. Turned out to be my left front wheel bearing. my 2007 access cab had about 230K miles on it then.
If you can, jack it up and spin the wheel, if it is a bearing, the growling sound is usually obvious. also, while off the ground, rock the tire with hands at 12 and 6 o'clock and/or 3 and 9. you'll hear a clunk and feel some play.
I ordered both front hub assemblies and changed them out. Not to tough to do, hub assembly comes with the bearing and you don't have to press the bearing out and in. only costs a few $$$ more than the bearing alone.
check youtube for a video.

 

Does it drone and resonate through the whole cabin?

Rear wheel bearing. Mine was passenger side.
Search my threads to read my saga...

 

That doesn’t sound like an engine problem. That sounds like a drivetrain problem.

A whine under load (acceleration) can be a symptom of a failing differential. I’m not saying it is, but it fits what you described.


I’d take it to a reputable shop for diagnosing. Sounds are very hard to diagnose over the internet.

 

I don’t know if it can be heard through the whole cabin - I am pretty much the only one in it 99% of the time. But when I lean forward toward the firewall, it seems to be coming from the engine area. At about 90K I had a thorough check of driving and towing components because I was getting ready to haul about 4K lbs. about 1800 miles. (My truck does have the tow package on it.) They recommended a flush/drain of diff with new put in. That was 2-1/2+ years ago. Didn’t have any issues with my tow, she performed like a champ. It’s making me a little anxious not being able to properly diagnose my issue right now. Patience as it relates to my truck isnt readily available.

 

If you can, you can check your front wheel bearings when you lift the front end. With the front end supported on jacks, position yourself facing the wheel as if you were going to pull the tire off. If you grab the tire at the 3 & 9 o'clock position and push/pull like you're trying to turn the vehicle. If the tire has a bit of play, it 'may' be your wheel bearing or your steering control arms. If you grab the tire at the 6 & 12 o'clock position and push/pull, play here could be your UCA/LCA. With your vehicle still in the air, spin the wheel. If it sounds gritty or like metal rubbing metal that could also be indication of your wheel bearing going out or your brakes rubbing. There shouldn't be deflection on the tire when you try to forcibly try to push/pull on the tire. With over 100k miles on the vehicle, your bushings are reaching their life span. It'll be faster to replace with new, it'll be cheaper to rebuild. Front end noises can be a pain to narrow down. Another thing you might try if you trust the road you're driving on by removing the skid plates. They may be rubbing on things that they shouldn't and doing a quick road test with them off might help you narrow down but please don't leave the skid plates off. A busted oil pan or transmission pan would put you up shit creek pretty quick. Also, an aside, your needle bearing might be going out. If the noise is primarily on the drivers side and you have a 4wd, that might be your problem too. You can check that by putting your vehicle in 4hi while driving. If the sound goes away that may be your culprit. If you do replace it, a lot of members go for the East Coast Gear Supply needle bearing replacement. Best of luck.

-J

 

From what you are saying, it sounds to me it is the transmission, is this a manual or auto? My guess it is auto. If the sounds and/or vibration is present only under constant acceleration and it is a auto transmission, an easy way to tell is when it is humming/droning keep you foot on the gas pedal and apply some brake with you left foot. Does it go away for a few seconds? Another way is to down shift manually into 4th, but with the increase of RPMs it's hard to really be sure.
Most, if not all newer transmissions have beefy clutch plates instead of torque converters. The clutch plates pulse together at part throttle during cruising speeds to decrease RPMs and save fuel. The plates become damaged do to breakdown of the friction modifiers in the fluid or wear do to heavy use. By tapping the brakes or down shifting, the ECU locks in the clutch.

If you think that is what's going on, have the fluid flushed and change, do it religiously every 30k (sooner if you tow a lot). It most likely won't fix it, but it'll stop more damaged from being done at an accelerated rate. I'd keep running it until you can feel it slipping, and who know when that'll be.

 

Thank you all for the input. Right now she is sitting quietly in the garage while I visit family out of town. Next week I will be talking and working with a mechanic about her issue and working through the process of elimination. Keep any suggestions coming and I will let you know what the final diagnosis and fix is when I find out.

 

Sounds like this could be from gear meshing.

Have you checked or changed the fluid in the rear differential?
Have you checked the U-joints?
Have the wheel (all 4) bearings checked.

Based on my experience, this "sound" could be coming from gears changing from a load condition to an unload condition. I'd take a look at the fluid in the rear diff as a first step.

Wheel bearings will "growl" when the wheel is spinning, won't matter if accelerating or not.

U-joints typically will make a "clunk" when slowing or stopping.

 

Ok....allow me to try to explain load vs unload condition.

Load....drive train (U-joints) will load during acceleration or deceleration. The load reverses direction.

Unload... drive train will unload while coasting. Yes, there is some load, but the load is significantly smaller compared to accel or decel.

Gears will have the same type of conditions.

 

Do you think this applies when the sound completely goes away when there is no pressure at all on the gas pedal - foot completely removed … cruise control not being used so I start to slow down…

Finally drug myself out to check bearing with a simple jack up and wobble test. Came across some sounds that seem not too good to me. Keep in mind, I’m kinda new at this and in my later years of life, I am interested in learning more about the workings of my truck, especially since I now live in an area where I have yet to find a trustworthy mechanic. The Toyota dealership here in town SUCKS big time and the one I do trust is a 2-hr drive away. I LOVE my truck and am planning to adventure a lot in her while I still can and I now have the time to do so.

 

How old is your muffler

 

it’s the muffler that was on it when I bought it in 2016 … 65K miles ago. I am assuming it is the original (2008 model.)

 

Sometimes droning can come from mufflers

 

UPDATE: hub/bearings fine on all wheels, rear diff fluid level & fluid condition good.

Now convinced it has something to do with or is associated with acceleration because when speed is not being maintained via accelerator or cruise control, there is absolutely no humming/droning. (If cruise control is not being used and foot is not on accelerator, there is no sound.)

Going to pursue a road diagnostics with 2 different mechanics next week. [heavy sigh…]

 

Never even thought about that! Checked out underside as much as I could when I was under it and didnt notice anything out of place, but will take another look specifically at muffler and pipes.

 

Try out what I said earlier if you haven't already. My truck does exactly what you are saying and it is 100% the transmission. There are forums on here that go in to detail about our clutch style torque converters and why they start humming/droning/vibrating. If it's the transmission clutch causing the noise, it will stop immediately when you tap the brakes while maintaining throttle. It could be any one of the possible solutions brought up here, but it's so easy to check this. Could save you a lot of headache.

 

Oh my thank you so much for keeping up with my dilema! I just spent some time out in garage checking basically over things just for the sake of the process of elimination. In my conversation with a mechanic i know personally, I told him I am convinced it is associated with the acceleration as it connects/works with the transmission. I will copy your suggestions and forward to him. thanks again. Will keep progress updated!

 

UPDATE: thinking the problem is the torque converter clutch, as mentioned by @mywhitetoyota. Other than the various testing to provide confirmation of something or its elimination as a suspect, I have done quite a bit of searching and reading on the subject. Frequent mentions of stalling and/or shuttering/shaking (similar to a manual clutch when you need to downshift) I have had none of this. There was also mention of poor gas mileage - which coincidentally on that trip I was on when I first noticed the sound, I used almost 2x as much fuel as usual! And, there was mention of “throwing a code.” I have not had that either - and to be honest, I dont know if my truck throws codes on its own or if you have to have a diagnostic done to get a code. I dont think the TF looks bad or worn - which I wouldn't expect to see anyway since it was just changed about 15K miles ago. And level is good. So now it’s on to researching a fix and time with mechanic friend for education about this so when/if I have to deal with a facility to fix this, I will be better prepared to not be taken advantage of. (Mechanic friend isnt sure yet if he could do what is required to fix it) Thank you all for all your insight, suggestions, experience, and most of all, thank you for the education! I consider it invaluable and am grateful! ❤️ I am open anything else you all may have to say about the matter, and I will keep you posted of the progress.
2008 Tacoma Sport, automatic, 2WD, 105K mi, 4 dr, Prerunner All stock