ABiT1

So I have a 2000 Cherokee that's making a humming/grinding sound like this. It happens on acceleration or deceleration, with the brakes on or off and the only time it doesn't is when the wheels aren't turning. It's not obnoxious it's almost like road noise.
Does anyone know what this could be or where I could start looking?
The wheel bearings are good and doesn't seem like the differential bearings since it happens all the time. Could it be the gears being worn? It has about 180,000 miles on it.

It sounds just like this.

ABiT1

I saw this.
http://www.hotrod.com/articles/how-t...oisy-rear-end/

Maybe it just needs new shims? Does anyone know I would check that?

zjhomme

2000 xj with ife?and sounds like a v6?

zjhomme

oh,gas tanks in the wrong place as well.liberty maybe?

ABiT1

Not sure what the video is from. Found it on youtube and was exactly what mine sounds like.

OldTires

U joints, maybe on the drive shaft maybe.

Jeepin'_Aint_EZ

Is it speed related? Like, does the noise get faster/slower with acceleration/deceleration?

ABiT1

Yeah it slows down when the speed does or speeds up with it.

The only other thing I can think of is maybe something in the transfer case? The u-joints are good on both ends but you can twist the front drive shaft more than the rear.

moparado

I could be wrong but sounds to me like more of a thumping noise than a humming, grinding noise from the video.

Sounds like something is worn out of round. U-joints, bearings maybe even brakes binding would be my first guess. Sure it isn't out a round tires?

I special ordered my 2000 XJ from the factory and since day one the rear diff. whined mainly on de-celeration. Of course the dealer chalked it off with some BS.
Had it professionally rebuilt at 300K and all is quiet now.

ABiT1

Maybe but don't think so, once your going its like humming but coming to a stop it has a metal sound to it. Just had the tires balanced and rotated too.

This is my list to check:
wheel out of round
wheel bearings
brakes
ebrake
carrier bearings
carrier bolts/bracket
pinion bearings
pinion bolt tightness
u-joints
and if none of those the transfer case

Am I missing anything?

300K on the Cherokee? Nice. I'm hoping for that.

moparado

If the front U-joints are or about to go out, they make noise mainly when turning unless they're totally shot. Are you 100% sure you're not hearing tire noise. Don't take much for an oddly worn tire to make road noise.

Re-listened to the video and i here a groaning noise with a thumping cadence.
You might want to pop the cover off the front differential and check for missing or worn teeth on the ring and pinion gears. While you're at it check better yet replace the axle bearings.
If nothing else you'll have a fresh differential lube and eliminating all that as the root cause.

OldTires

OP made the thread confusing by linking to a noise video from a different vehicle that has sound issues like he is experiencing.

Back on topic, diagnosing differential noise requires getting the Jeep up to speed and then listening for the noise when you step on the accelerator (load) and not (no load). Since you stated is happens all the time, it would not be the pinion bearings.

So I would focus on U joints, wheel bearings, and finally carrier bearings. Check your diff fluids too. But before you do all that, look around for something rubbing, something bent in the undercarriage that would cause the noise. Sometimes it is something really stupid and simple.

Good luck.

ABiT1

No the video sound is the same as I'm getting. I'm sure it's a different car but that rhythmic sound is the same.

Starting to think it's just an old jeep but going to run through everything again just in case.

Thanks for for all the help

ABiT1

No but pretty sure. Mostly because when you get below 20 mph it has a metallic sound to it and also had the tires rotated and sound is still coming from the same rear drivers side.

Then also it has a rhythm to it that's slower than the wheels are turning if that makes sense. Almost like what's making the sound makes one rotation and the wheel turns twice.

Alex Yanez

I heard two noises apart from normal car sounds. One was a high pitched sound like a bird chirp. If that’s what your talking about it my bad your break pad hard wear is missing on one or both sides. I was hearing that exact sound last week and I figured out that’s what was causing it.