Noises a wheel bearing makes when going bad?

[pet575]

The front driver side bearing on my 2004 went out a few years ago. Started as a quiet hum and then turned into a loud moan, but only at certain speeds. Eventually made the noise anytime over 30MPH.

Now, I've got a new noise that sounds like excessive tire noise coming from the rear of the cabin. Just got brand new tires a few months ago, so I know it is not tire wear. To go along with this, I've got a little shaking in the seats and am just now starting to get a whiny sound on tight u-turns. Just recently, a feeling like there is a bump in the tire has started to come on at speeds of about 5-10 MPH.

I suspect it is my driver rear wheel bearing, but it doesn't sound anything like the previous one did when it was going out. Am I missing the target here? Are we possibly talking about the U-Joint or a problem in the rear end instead? Rear axles look to be intact.

 

[pet575]

Just to be clear, I've had the rear pinion issue addressed once on this vehicle so I know what that sound is. This is not the same sound.

 

[imp]

These vehicles CAN be placed on jackstands, supporting the suspension points appropriately, not by the frame, wheels removed, and run in Drive to pinpoint noise location and/or source. If a non-AWD the transfer case must be placed in "4X4 HIGH" to avoid the bias clutch from engaing/disengaging rapidly, which disallows running the driveline.

Sound crazy? I have done it successfully with my '04, but do not recommend the process to anyone not pretty well-seasoned in Auto Mechanics. imp

Edit: BTW, if this is done, it is amazing how much normal running noise is generated by the driveline, even if no wholesale noise source is present, such as a bad wheel bearing, considering at the same time how quiet these Explorers are when cruising down the highway!

 

[pet575]

Starting to become a little concerned that I might be missing the target on this one. Can anyone describe what the sound of a rear end/rear differential going out would be? Again, I've had the pinion ring issue fixed and I'm aware of what that noise is and that it only happened when I would accelerate and then went away when coasting.

This noise is always there over about 40MPH. I can be doing 70MPH and put it in neutral and coast and it will do it. A little louder at 70 v. 40MPH, though.

 

[imp]

Starting to become a little concerned that I might be missing the target on this one. Can anyone describe what the sound of a rear end/rear differential going out would be? Again, I've had the pinion ring issue fixed and I'm aware of what that noise is and that it only happened when I would accelerate and then went away when coasting.

This noise is always there over about 40MPH. I can be doing 70MPH and put it in neutral and coast and it will do it. A little louder at 70 v. 40MPH, though.

Noise originating from within the differential housing, if from gears, is a hum or whine, like singing, and it can result from misalignment of the gears due to bearing issues. In other words, if the gears lose precise alignment, they make noise. This condition is fairly rare, since in order for bearings supporting either the pinion gear, or the differential case itself to get bad enough to allow misalignment, they themselves would have already forced the vehicle into the shop. Whether alignment-caused, or scored, pitted, cracked, or otherwise damaged gear teeth almost always have a different sound pitch between drive and coast conditions.

Pinion bearings gone bad make sounds unlike a singing whine, more like a high-pitched grumbling, and continue at all speeds and nboth under drive or coast conditions. This may be the issue in your case.

The surest low-cost diagnosis would come from a stethoscope listen directly to the differential case with the driveshaft spinning. imp

 

[RickM]

My one rear bearing made a very distinct grinding sound...about as subtle as finger nails on a chalk board.

 

[pet575]

As a follow-up, I guess I should add (and should have included it from the beginning-sorry) that I know I have a bad bearing for sure on this vehicle. I have the low-speed THUMPTHUMPTHUMP at about 10 MPH that seems to be getting worse, the hum at about 15-20MPH, AND I have the grinding noise when making tight turns in my parking garage.

Some days I'm convinced it is from my rear passenger wheel, other days it sounds like drivers side. Shoot, some days it sounds like FRONT drivers side. I need to have someone else drive the vehicle so I can sit in the back seat and move around a bit. For all I know, I could have more than one gone bad.

This noise from the rear end is definitely not a singing whine or much of a whine at all. I'd call it more of a hum, sounding more like tire noise when you get a rock stuck in your tread or when you have a low tire. It is constant and much more of a low frequency sound than the whine I had when the pinion ring issue got taken care of.

Looks like it is time to become a passenger and then put her up on jack stands and take a closer look at all wheels.

I'll post up an update when I finally have the time to get to all of this.

 

[matt0248]

The rear wheel bearings are usually cheaper to replace that the differential bearings. start with those. Besides, if they haven't been replaced yet they are bound to go bad.