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So... Mechanic tells me...

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Old Jan 9, 2011 | 01:59 AM
  #1  
makingaZJ's Avatar
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From: Georgia
Year: 1997
Model: Grand Cherokee
Engine: 4.0 L6
Default So... Mechanic tells me...

My rear gears/diff are shot...

i went in for a allignment....

my rear end has always made a "roaring" sound.

ive been driving it like that for 2 YEARS!

i replaced my rear wheel bearings to make sure it wasn't that...

and i cleaned out and replaced the fluid in my rear diff.

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
(no signs of wear, tear, metal shavings... NOTHING!)

could it be something to do with the driveshaft???

(the driveshaft IS greased...)

So is this something i should be worried about???

the truck runs EXTREAMLY STRONG.

any thoughts/support/ideas would be great!

thanks guys

-Nate
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Old Jan 9, 2011 | 02:37 AM
  #2  
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From: some small town oregon
Year: 1989
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i would tell the mechanic to **** off... but thats cause im one too lol
its prob fine he just wanted more work to make up for the holidays...
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Old Jan 9, 2011 | 04:10 AM
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From: Manlius, east of Syracuse, NY
Year: 2000 XJ Sport & WJ Laredo
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Engine: 4.0L
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When you had the rear cover off the dif, did you happen to see the wear pattern in the ring and pinion? If it's smooth and full faced, I wouldn't worry too much about it. Grab hold of the driveshaft and see if there is any backlash. there should be a tiny bit, but a lot would be causing your whine.
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Old Jan 9, 2011 | 04:19 AM
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Most roaring noises are from a worn gearset. It's not like its going to self destruct so as long as you don't mind the noise why spend the money to get it fixed? I have trucks at work that have had gear noise for 3 years now, and they have not gotten any worse.
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Old Jan 9, 2011 | 04:28 AM
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From: Manlius, east of Syracuse, NY
Year: 2000 XJ Sport & WJ Laredo
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Well said, sems.
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Old Jan 9, 2011 | 02:35 PM
  #6  
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From: Oroville, CA
Year: 1995
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Engine: 4.0 with all of the noise and clatter
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It could be a bad pinion bearing, but I would drive it until it dies.
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Old Jan 9, 2011 | 03:09 PM
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From: Kentucky
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If the pinion depth is jus a little off it will whine..
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Old Jan 9, 2011 | 03:11 PM
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What axle do you have?
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Old Jan 9, 2011 | 03:31 PM
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Year: 1999
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Looks like you're on 31's? Boom, I just found the source of your roar. First time is free, but it'll cost you next go around.
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Old Jan 9, 2011 | 04:59 PM
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Care to enlighten us as to why 31's are the source of his problem?
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Old Jan 9, 2011 | 05:29 PM
  #11  
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From: Manlius, east of Syracuse, NY
Year: 2000 XJ Sport & WJ Laredo
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Originally Posted by 91XJLINK
If the pinion depth is jus a little off it will whine..
Case in point. I had the pinion seal replaced by an incompetent mechanic that resulted in total destruction of the pinion bearings, ring,and pinion. When he fixed it, (because he was liable) he installed a new gearset which he didn't set the depth right. It whines but after 8,000 miles I'm going to drive it until it dies. It actually seems to be getting quieter, or maybe I'm going deaf to it.

You win a few, lose a few, drink a few beers, and go home alone quite often.

Last edited by dave1123; Jan 9, 2011 at 05:32 PM.
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Old Jan 9, 2011 | 05:39 PM
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Originally Posted by FrankZ
Care to enlighten us as to why 31's are the source of his problem?
Problem? I didn't say problem, just that they were the source of his roar!
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Old Jan 9, 2011 | 07:05 PM
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Originally Posted by FrankZ
What axle do you have?
the axle is stock, as well as my gear set.
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Old Jan 9, 2011 | 07:07 PM
  #14  
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Originally Posted by 4Doors
Looks like you're on 31's? Boom, I just found the source of your roar. First time is free, but it'll cost you next go around.
31's don't roar THAT bad bud...

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Old Jan 9, 2011 | 08:01 PM
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Originally Posted by makingaZJ
the axle is stock, as well as my gear set.
There's more than 1 stock axle for your rig.
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