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I need HELP! Wheel hum and it doesn't seem to be the bearings!

I have a 99 tahoe 4x4. It has 220000 miles. I had a wheel hum that got loud when I went faster and the pitch changed with speed. It doesn’t seem to matter if I swerve left or right. I took it to a dealer and was told I needed bearings, both wheels. I bought the wheel hub assembly and changed them out. I figured it is just better to change the whole assembly. Well, I still have the hum and it seems to be getting worse. I’ve watched many you tube videos and talked on many blogs. No one seems to be able to help.
I don’t know if the u-joint would do that or if it could be a shaft thing. I can not tell what needs to be fixed but can usually fix them when I know what it is. I don’t know if there is a transfer case problem either? Just wanting to throw a lot of suggestions out there so nothing gets over looked. I am poor and really don’t want to pay a dealer another $180 to tell me another thing that isn’t broke!
I know the shaft spins when I turn the wheel. I assume the lock for 4x4 would be in the transfer case?
I really need help with this. It seems to be getting worse and I don’t want to do any damage. I don’t get paid for another week and have to drive 50 miles a day.
Thanks ahead of time,
Jagg1300

I don’t know specifics for your car, but I have a 70’s Ford 4x4 truck. That symptom certainly does sound like faulty wheel bearings, sorry replacing them didn’t fix it for you. About the only thing I can suggest is to make sure the fluid level is full on the differential and transfer case. Low fluid in those spots can cause a sort of whining noise which varies in pitch as speed increases. What I notice when my U-joint wears out is a clunking noise when starting and stopping. But a mechanic could easily tell you if you have a U-joint problem or not, just by doing a visual inspection, checking the drive shaft free play.

If it’s not wheel bearings, I’d check for one or more tires begining to have a tread separation or cupping in the tread. BTDT.

@Jagg1300, So you changed the front hubs?

Are you sure the rear bearings aren’t the noisey ones?

Did the shop specifically tell you that the front bearings were noisey?

I might ask what kind of tires are on there and whether there are any tire tread oddities such as Mc McAnick referred to.

Just wondering about an aggressive tread pattern, feather edging, cupping, and so on seeing as how this is a 4X4.

@ok4450 & MG McAnick - The tires have been on the vehicle for a few years and never made noise in the past. Snow tires but not real aggressive. I’ll be at a tire store to have that checked in the morning.
@db4690 I am not sure about the rear bearing. The noise seems to be in the front but I guess I can be fooled. I’ll have to check the rear. The dealer told me I needed both bearings changed, I assumed the front but will have to double check to see if the paper work says front. Hell, if it is the rear, that would be something.

@Jagg1300, I have some advice for you.

First of all, I’ll assume you have power windows, and that they’re working.

Drive until you hear the noise.
Then lower and raise your windows one at a time until you’ve isolated which corner the noise is coming from. I’ve used this method many times.
Hopefully this’ll help narrow it down.
Post back if this didn’t make any sense.

Is there any change in the sound if you put the truck into 4WD? You have a rear differential, a front differential, and a transfer case and all can get noisy when gears get worn down. Once a gear wears below the hardened area they can deteriorate quickly, then things start to fly apart causing more severe damage.

I’m not sure for your truck where and how the front wheels are engaged when you go in to 4WD. It is possible that your front differential and some part of the transfer case are spinning even when you are in 2WD.

I want to thank you all for the info. I took the advice of having my tires rotated. I have snow tires on the vehicle and they have 10000 miles on them. They were not rotated and I found out that the fronts wore unevenly and were “jumping” a little due to cupping and the uneven wear. This was causing the hum after the bearings were changed. Maybe even before but the dealer wanted the work? Just glad I changed them myself and saved hundreds!
I feel a little like a fool because I allowed the air pressure to get low (which helped wear the tires sooner), and didn’t check this first. A very simple rule and fix that could have cost me lots by having others due the work. I preach tire pressure checks monthly but didn’t listen to myself!

@Jagg1300, the cupping would lead me to believe you might have worn shocks.
Cupping could also be caused by rims that need to be balanced.