How do you know if wheel bearings are bad on a grand caravan?

Answer 1

It depends on how bad they are; at first, you generally notice a whining or growling noise that seems to get louder as vehicle speed increases (though sometimes it actually fades in and out at different speeds - it might be really loud at 45 and 75, for example, but barely noticeable at 60). If it's in the front, you also often notice that the noise changes either in intensity or pitch when you turn a corner - the vehicle's weight shifts toward the wheel on the outside of the turn, so if that bearing is bad, the noise generally gets louder (in other words, if the sound gets louder during a left turn, it's probably the right bearing that's bad, and vice-versa).

Bad rear bearings can be a little harder to diagnose, they generally have less weight over them so it's not as obvious when they're "acting up", and sometimes noises from the rear wheels can resonate on the floorpan so it actually sounds like they're coming from the front. Assuming your Caravan is FWD, the easiest way to check this would be to raise the wheel off the ground and give it a spin - if it's jerky or makes a gritty, scuffing sound while turning, you probably have a bad bearing there (brake problems can also cause this, though - pull the wheel and the brake drum off and spin just the hub, if you're not sure).

It's a little more obvious when a bearing is badly worn - this will allow the wheel to "wobble" a bit while you drive, which will cause noticeable vibrations and irregular wear patterns on the tires. You can generally detect a bad bearing at this stage by raising the wheel off the ground, grabbing it at the 12:00 and 6:00 positions, and trying to rock it back and forth. If it moves much or makes a clunking noise, something is worn out (a bad ball joint, strut, or strut mount can also allow this kind of movement; it helps to have a second person do the rocking while you watch for motion, rather than going by feel. Also, a little bit of sidewall and bushing flex is normal when you do this, so you need to be able to see where the motion is actually coming from). Many suspension parts exhibit similar symptoms when they wear out, especially in the front - it's important to actually see where the "slop" is coming from before you start replacing parts.

Badly worn bearings can also create some symptoms that mimic brake problems - shudder during stopping, or a low brake pedal (this is called "pad knockback" - the wobbling wheel hub also causes the rotor to wobble, which spreads the caliper open while you drive; the next time you stop, a significant bit of pedal travel gets wasted closing this gap back up). Also, vehicles equipped with ABS or traction control systems might turn on malfunction lights on the dash - excessive play in the bearings can disrupt sensors these systems use to measure wheel speed (this doesn't always happen though - it depends on how bad the bearing is, and some vehicles are more sensitive to it than others).