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gsarmed 01-17-2012 06:22 PM

Whining sound on decel?
Hi guys. I have a 2009 5.7 limited with quadradrive. 45k miles. When I lift off the gas and coast down from 60 mph I hear a whining sound coming from the middle/rear of vehicle that gets lower in pitch as the speed goes down. Has anyone else experienced this? Love the GC!

Any help is apprecieted.


SvenskaJeepGuy 01-17-2012 07:01 PM

Re: Whining sound on decel?
rear differential, have you changed the fluid lately? did you use friction modifier?

Boomer914 01-18-2012 08:08 AM

Re: Whining sound on decel?
actually normally on decel its the FRONT diff. You'll hear the rear diff on power. most likely bearings in the diff. by the way mine are bad in the rear and at 60 or about ON POWER it whines.:D

dr.lee.baugh 01-18-2012 10:05 AM

Re: Whining sound on decel?
If fluid levels are good, I would guess rear differential, front pinion bearing (though it could be many other things as well, noises like that are hard to isolate!)

As an overly general rule, a whine on coast can be a worn/out of spec front pinion bearing and a whine under load is a worn/out of spec rear pinion bearing OR pinion OR gears OR carrier bearings. No way to really tell without opening it up...

Some suggest tightening the pinion nut slightly to compensate for any abnormal wear...up to you, it's a cheap solution if it works, but if you OVER tighten your future will be one with a lot less cash!

The optimal (but costly) solution, since the nut uses a crush sleeve to ensure proper preloading on the bearings, is to disassemble the differential, replace any worn bearings, and then set everything back to factory spec.

Let us know how it goes!

gsarmed 01-18-2012 06:45 PM

Re: Whining sound on decel?
Thanks for the feedbck guys One question: this thing only has 45k miles on it. It seems crazy that a drivetrain component like the front/rear diff would fail . I do not doubt the diagnosis, but is this a normal occurence? It has never been abused and driven on the highway 95% of the time. Just a common failure mode?


dr.lee.baugh 01-19-2012 09:35 AM

Re: Whining sound on decel?
Remember, we can only suggest what could be wrong over the internet - I certainly wouldn't consider any of these opinions a diagnosis!

That being said, it all depends on the specifics of the vehicle. I wouldn't say differential noises are common on these Jeeps, but they certainly aren't unheard of at that mileage.

The axles have a relatively short service interval (every 15,000 miles in most conditions) so if it has been missed once or twice it is conceivable that could result in premature failure.

When was the last time you changed the diff fluid? It certainly wouldn't hurt to start there and have a look at the gears (at least on the rear...front service is performed through a drain plug) while the cover is off. You may luck out and that is all that it requires.

SvenskaJeepGuy 01-19-2012 12:49 PM

Re: Whining sound on decel?
45k is three service intervals for the differentials so if you have never serviced it.......... you could definately have damaged it

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