Maybe someone has heard this before and can help me diagnose a noise I'm getting.

Truck: 2001 Dak 4.7 SLT quad cab 4x4 with LSD

I recently put new tires on it, and started getting a noise that would have sworn was just loud tires, but no, it's not, and I can't figure out what it is.

I know it's not the tires because the pitch of the noise is consistent no matter what surface I'm driving on (gravel, dirt, blacktop, concrete)

It's a very consistent, almost smooth howling noise. No change when the truck shifts, which leads me to believe it's not the tranny.

I start hearing it at about 10mph, and it increases in pitch as the truck accelerates - very consistent with speed. No change in pitch when braking or turning.

Basically, you'd swear it was just loud tires until you realize that it's not.

I just changed the rear diff and xfer case fluids. That made no difference. (both were in very good condition after about 50k mi since the last change).

It's not rythmic at all, the way a wheel bearing would be. It's a very smooth noise, but I sort of feel like I can feel it in the accelerator pedal (shallow, fast vibration), especially when going slow (the same way the tread of a really aggressive tire might feel, except that the tires are just plain Bridgestone Duelers).

Does anyone have any knowledge of this noise or can you think of anything else I can lube or try? This noise is reallly annoying. Especially at 70mph. And I do regular road trips of over 250 miles.

Oh... when I have all the windows open, and drive along side a jersey wall, I don't notice the sound echoing back at me at any speed, and it's just as loud with the windows all rolled up as it is with them down. So I'm almost thinking drive shaft since it's burried under the middle of the truck. Is there anything I can do in there?

Thanks!!!

 

Did you check to see if the fan belt is too tight? Easy to look at and fix incase it is.

 

No, I haven't. Would noise from the fan belt follow the tire speed? It seems like it would follow engine speed or remain constant.

 

Is the noise a dull sound or is it a high pitched? is it a screech or a rubbing sound?

 

It starts fairly low, but not really low, then gets higher pitched as the truck speeds up. Not high pitched the way squeaky bearings sound though. When I'm going about 70, it's almost the sound of a truck horn in the distance.

I really hate to take this thing to a dealer and spend $100 just for them to look at it and probably have no idea what's causing it. But if they could put it on a lift and run it, it might make it easier to locate the noise.

 

jack up your truck, get a pry bar under the tires and lift to check your wheel bearings. start with looking at the obvious. grab the drive shafts and shake them. check everything for play. some things (gear backlash) are permitted play, others (wheel bearing play) arent. must be tight.

 

I would bet on it being a hub bearing. I sort of had the same noise as well at first but it slowly became worse and eventually started howling on turns. Your bearing is in the early stages of going bad. My two cents worth... Good luck

 

Sounds like the tell tale sign of a wheel bearing starting to go. it may be tight still, but give it time, it'll loosen up.

 

Thanks. Well, it's not the sound I've heard from the wheel bearings going bad in other vehicles, so I'll check that out. It would make sense.