I posted this on a thread over on www.jeepkj.com, but I thought I'd add it here to get as many opinions as possible.

About a week ago or so I started noticing a noise coming from the rear end that seems to match my speed. I know it's not a transmission problem because it does't follow the idle, or stop when I coast in neutral. It sounds roughly like a small moped or leaf blower is behind me, and is most noticable at between about 15 and 25 mph. Per some responses on the other thread, I put it on some jack stands and manually spun the rear tires, but I couldn't really get any noise out of it, but I'm not sure if I'm spinning the tires fast enough. Some people also suggested it could be a drive shaft u-joint. I'm still open to this possibility.

However, this weekend, I took the rear diff cover off, and while I didn't see anything obvious-- chipped teeth, ground teeth, I did find a very small amount of metal filings when I ran a magnet around the bottom of the diff housing. I took some pictures of the diff. My friend didn't think that the wear pattern was 'normal', but he really wasn't sure. I also threw in a photo of the ujoint on the drive shaft because it seemed to have a tiny bit of oil around one bearing.

FYI, I've had all my services done at the dealer at regular intervals. Never missed a one.

Here are the images. Any ideas more than welcome:

A little sludgy in the bottom... not sure if this is normal.

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-=Stock, but goin' places=-

04 3.7 Sport.
Auto Trans
Yokohama Geolandar AT/S 235/70/R16
Garmin GPS on RAM Mount

Mileage Trend:

Yeah the gear pattern is not set correctly and has been scraping metal off the ring gear teeth/Time for a new R&P set and all new bearings.

U joints can be bad but still feel tight, mine felt OK at 55,000 miles but were making a noise, they were rusted solid almost!
You will always find some stuff in the bottom normal wear and tear on the diffs

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Does it have an excessive amout of backlash between the ring and pinion. Does it make like a howling noise until you let off the gas. Does it clunk when you push back on the gas?

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tjkj:



I don't know a lot about differential wear pattern, but what do you mean by 'not set correctly'? Are you talking about that adjustment screw on either side of the bearings? What would that mean, that it was wrong coming out of the factory?

JMSMN:



I don't know how to answer the 'backlash' question. As far as howling noise... this is the best I can describe it. Imagine somone behind you with a moped, or a leaf blower. But I have to emphasize the the sound isn't loud. It's subtle, and people with me don't notice it until I point it out. I wouldn't call it a 'howling noise' but someone else might. It's more of a mid-pitch growling noise. Goes up as I speed up, goes down as I slow down. There is NO clunking. All the web stuff I've read about diff noises-- a lot of them talk about clunking. The ride is as smooth as it's ever been, and there's no difference in noises when I'm turning or going straight, and definitely no clunking.



Tommud, that's what I was wondering about. It's not like I found a ton of filings. In fact, there were so few and so tiny, that I had to really run the magnet through and pick through the grease to find them. I was wondering if that was normal coming out of the factory-- especially since it appears the dealer switches my diff oil by sucking it out of the filler hole. That diff cover had never been off since factory-- I could tell.

_________________
-=Stock, but goin' places=-

04 3.7 Sport.
Auto Trans
Yokohama Geolandar AT/S 235/70/R16
Garmin GPS on RAM Mount

Mileage Trend: