Re: 2003 Ford explorer rear grinding noise
No, if the bearings are wearing, you might not hear it at all speeds or make it louder at higher speeds. I have owned three explorers, at '92, '95 and currently at 2003. The '95 had the exact same noise you are describing at 10-15 mph and I did all of the work that was required to maintain it, still ended up loosing a bearing, it went from no vibration, no loose feeling to breaking in one fail swoop. Check, or have those rear bearings checked out, they don't show much sign when getting ready to fail, and they are a sealed unit. In addition, make sure and check all of the components on the rear axle, the 03 has a fully independent rear suspension and components can fail in a very short time. Another thing to check these are famous for, the ring gears can grind pretty good, it indicates a small amount of wear, which won't cause a complete failure, but is irritating to listen to.
Another thing, do you tow with it, and if so, how much weight, they are rated for a certain amount, but even weights less than the rating can cause wear situations that cause various sounds, I think they are highly over rated by the manufacture on what they will safely tow. I would check all of the connection points on the rotating mass of the rear axles and make sure there is no significant wear in those components. Remember you have CV joints in that rear axle, just like front wheel drive cars and they need to be service, rebuilt or replaced at much shorter intervals than a straight rear axle vehicle.
Here is a listing for rebuilt axles on the '03 Explorer:
Rear Left and Right 2002 2008 Ford Lincoln and Mercury CV Drive Axle Shafts | eBay
Here is a link to a listing for a complete kit to replace both axles as well as wheel bearing and hubs:
2 Rear 02 08 Ford Lincoln Mercury CV Axle Shaft 2 Wheel Hub Bearing Assemblies | eBay
The only reason I posted the links, it shows how inexpensive it is to replace those components and have the piece of mind, it is not difficult to replace them, it takes a couple of hours. But with a grinding noise at any speed, you can be assured there is something in the rotating mass that is wearing and needs to be repaired or replaced.
Also, make sure and check the E brakes to make sure they are not dragging, common problem on them.
Another thing that I had happen to me, the rear wheel anti lock braking sensor loosened up and slipped a bit and was dragging on the ring gear, it only created a noise at slow speeds and at high speeds the pressure in the rear end held it away from the ring gear and no noise, if it happens, your ABS light may come on at low speeds and go off at higher speeds, I know, sounds odd, but it happened to me.
