Speed dependent humming
 

2004 AT with 209000 miles. For the last month I have been hearing a low pitch SPEED dependent whine. It has no relation at all to engine rpm (I have coasted in neutral with no change in the sound). It comes on at about 25 mph and gets progressively louder as speed climbs. The sound quality does not change with turning right or left so I am less suspicious about a failing wheel bearing. Underhood inspection shows AT fluid and motor oil are at full levels and fluid is clean (ATF drained x1 about 10k miles ago and I do a single drain/fill cycle every 15 K miles). No unusual sound from the drive belt. Water pump, tensioner, and alternator have all been replaced within the last two years. Underbody inspection reveals a mild leak of the transmission case gasket but there are no drips in my garage and ATF level is normal as stated above. CV joints are clean though there is a small amount of fluid seepage where the axles join the transmission case. The transmission shifts smoothly. Brake calipers are not binding. Fuel mileage has dipped maybe 1-2 mpg for the last 6 months but I have been attributing this to more stop and go driving and winter fuel mix.

Any experienced opinion on the source of the sound? I have read that internal transmission case failures can start with this kind of sound, but I am not having any shifting issues.

Assuming it's not tire cupping, it sounds like an axle issue. That said, I haven't experienced that, and am only repeating what I 've read here (more than once), but that's my guess. Hopefully those among us here who have had axles go bad can chime in.

^ Wrong. Axle shafts don't really whine or hum when going bad.

OP just because you don't hear it turning left and right doesn't mean it's not the actual wheel bearing. Where does the sound come from exactly?

Thanks for the responses. Since my original post, the sound has gotten significantly louder. It's hard to localize exactly, but it definitely emanates from beneath the front of the car. I began to notice a slight vibration in the steering wheel at highway speeds so I put the car back up on stands and did some more aggressive rocking of the wheels and there is now a slight but definite degree of play in the driver's side front wheel when I hold at 12 and 6. I think this clinches the diagnosis of a bad wheel bearing. I called the dealership and they quoted $830 to replace it and another $120 for an alignment.

The job is not too hard- I did a bearing replacement on my 2002 Odyssey - but it is tedious and 13 year old bolts and other knuckle parts are probably pretty corroded and I will likely tear the ball joint covers when I do the removal. A new OE bearing is about $75 and I also had to replace the speed sensor to the tune of $110 when I did the Odyssey. I may just have them do the work.

So I finally completed the bearing swap today. Took awhile to get the knuckle out to the machine shop to have the old bearing pressed out and a new one pressed in. Everything is bolted back up and I lowered the car down and took it for a spin......

The noise persists :ugh: :what: :whyme:

After I got back I jacked it up and rocked the wheels again. Both sides are nice and tight with no play at all. Sigh...maybe I replaced the wrong side or perhaps both needed to be replaced. Now I notice the sound seems to be louder when I turn left, so maybe it's the right front bearing after all.

Well, the third time was the charm. I replaced both front bearings with no change in the sound. I then changed the passenger rear bearing and voila! the sound is gone. It's frustrating since the sound is so low pitched it is very hard to localize the source of the sound.

Might as well change the driver rear the next time I swap my winter wheels. The car rode noticeably smoother after each bearing change.

2013 TL Humming above 25mph
 

Thanks for this post KBH, i am having a similar issue with my 2013 TL FWD (165K). Similar experience and very hard to pinpoint the main source of the sound. I feel like it is louder in the cabin and have a hard time hearing it with the windows down. I may have to find a local shop who can do this repair. Not looking forward to a $2,500 repair. Do you think it makes sense to replace all four bearings at once or just do one at a time to try to isolate?

Suggest raising the wheels and rotate wheels by hand while feeling the center axle nut or wheel lug on rear wheels. A bearing causing noise will generate a different vibration that is detectable. A helper may be needed.

good luck

Drag
 

I recently replaced all of the rotors and put new ceramic pads on and when turned the pistons in on the rear calipers I sprayed them heavily with PB blaster. They went in but not without some force, also the caliper bolts/pins that allow the caliper to travel when depressing the brakes were are little stuck as well, so I used more pb blaster on them to work them loose. Idk if this is what you ran into when replacing your rears but maybe they are sticking causing your issue.

That brown sludge is suspect, almost looks like oil/water mixture?

Thanks jmig, it has been raining and I think the sludge is a mix of pad dust and rain. There wasn't any sign of oil or brake fluid present. I ordered the hub and bearing and will try to install it this weekend (weather permitting). I will try to post an update after I get it installed and have driven it a bit. Hoping this resolves the issue.

Hub Removal
 

Update -
So the How to replace 4G hub and bearing is not exactly correct. The rear hub is retained by four rear bolts that hold the assembly in place not by a center retaining nut.
I ran into an issue by ordering a Detroit Axle Hub assembly that was a fit for my TL. Unfortunately, the image on Amazon showed dust covers on the assembly but the part that arrived did not have dust covers and i feel like this unit will fail pretty quickly so i ordered a new hub and bearing from acura. Turned a pretty quick repair into a much longer one but oh well, live and learn.


https://cimg2.ibsrv.net/gimg/acurazi...133c0be661.jpg
Old (OEM) and New (Detroit Auto) Hub Rear View
https://cimg9.ibsrv.net/gimg/acurazi...b923064a84.jpg
old (OEM) and new (Detroit Axle) hub front view

How to Hub and Bearing