Another Rear Noise Question....Sorry

[jonboyb]

My father in law had a mint 2003 Mountaineer 4.0 2wd with 120k he was looking to unload so I bought it for a spare vehicle. Original owner, minor issue (power windows) that whacking doors solved, and been driving it daily since....lol. Anyways, it has a minor roar like AT tires from maybe 20-60 mph which points to rear gear mesh (have not changed to 75-140 yet) but code 45 axle (3.55 open diff). Anyways, everyone calls the mesh noise a whine.....this is definitely a roar like rough tires.....wah wah wah, etc. I swear it sounds like front left too....bit dang near impossible to tell once up to speed enough to hear. Hanging out the window doesn't work from wind noise by the time it starts being audible. Opinions if I'm headed down the right path with rear gear mesh noise or should I lean front bearing? Wheels spin smooth and silent other than slight brake drag. It's confirmed not the tires too FWIW....needed tires anyways and swap changed nothing. Thsnks

 

[jonboyb]

And to give an idea on volume, fans at speed 2 actively drowns the noise....it's really not bad.

 

[Joe in NY]

if it is a WHA WHA WHA WHA and changes with turning that is bad wheel bearing(s)

if it is a ROAAAAAAAAAARRRRRRRRRRRRRRRRRRRR that is the rear diff.

 

[jonboyb]

Definitely wah wah like off road tires, but no audible difference turning. Forgot to mention....ABS light is on steady ....and has been for years according to FIL. Could definitely point to bearing too, but diagnostics costs as much as the hub so I'd love to figure it out. Not sure diagnostics would actually say which corner anyways would it.....just speed sensor failure in general correct???

 

[Joe in NY]

A bad wheel bearing runs hot and also has bits flying around in it. Both will wipe out a speed sensor. Jack the car up and spin the wheel by hand as fast as you can, should be silent. Also, grab it firmly and try to wobble it. Bad bearings will have play.

 

[jonboyb]

I put it in the air checking front bearings as soon as I got home from buying it. Bearing was my first thought. Both fronts free wheel with just a hair of noise from brake pads with zero wiggle. I wonder if I need to turn my attention to a rear wheel bearing? Think I might be able to drive it a while then hit each hub with a laser thermometer and possibly see a high temp outlier to determine a potential bad bearing location. The no change in noise when turning the steering wheel and hands on inspection of the front kinda makes me shy away from thinking it's a front bearing. That's why I was kinda thinking it could be the gear mesh noise.

 

[Joe in NY]

Yes check the rears

 

[07gtman]

at about 35 mph switch lanes kind of quick and listen for the noise to go away...if you go left and the noise goes away its a left side bearing..you will be taking the weight off the wheels in question..i just had the same issue.i thought it was the rear end howling. it was not that at all, but instead 3out of 4 of my wheel bearing were bad and i lifted the truck and tried to wiggle the tires and they were solid no movement at all. put new bearings in and not a sound ...

 

[jonboyb]

It was long overdue for rear diff fluid swap, my father in law never changed it, and fluid looked great. Absolutely no visable particulate in fluid or when strained, no metal bits in bottom, and the magnet only had a thin film of particulate "sludge". Rubbed sludge through my fingers and every once and a while I'd see a tiny metallic spec or 2, but overall very pleased with the 120k mile (75-90) oil. Friend owns a tire shop so gonna let him drive it tomorrow and see if his trained ears can zero in on a corner. He has on-car high speed balancing capability too....I wonder if he can spin them up and hear it???? I've never had an on-car balance done.....but don't see why using the roller couldn't be used to find a bad bearing correct? The vehicle is sitting full-weight when those methods are used right?

 

[Joe in NY]

if it is the 3.73 limited slip did you add the additional friction modifier ?

 

[jonboyb]

Nah, it's in original post. Just a 3.55 open

 

[fordysenior]

Definitely wah wah like off road tires, but no audible difference turning. Forgot to mention....ABS light is on steady ....and has been for years according to FIL. Could definitely point to bearing too, but diagnostics costs as much as the hub so I'd love to figure it out. Not sure diagnostics would actually say which corner anyways would it.....just speed sensor failure in general correct???

I had my ABS light go on, I did the diagnostic and it pointed right to the left front wheel bearing/ABS system. The hub assembly gets replaced, both problems solved. I downloaded Forscan and got a connector from Amazon.com at approx. $18. Or you can go to different parts shops and some of them will check it for free.

 

[jonboyb]

The on-car balancing machine worked great. Zeroed in on the left rear bearing making the noise and also front left very slightly. They went ahead a pulled ABS codes......of course right rear where the bearing is fine....lol. I thought it only had a single speed sensor on the pumpkin back there for some reason....but i guess not.

 

[imp]

The on-car balancing machine worked great. Zeroed in on the left rear bearing making the noise and also front left very slightly. They went ahead a pulled ABS codes......of course right rear where the bearing is fine....lol. I thought it only had a single speed sensor on the pumpkin back there for some reason....but i guess not.

@jonboyb
Vehicles WITH Advance Trac (Ford calls it "IVD") system had wheel speed sensors on both rear wheels. WITHOUT IVD, only one in the center-section. imp