79broncojosh

hey guys i have a 99 xj with the dana rearend and it has 162,000 miles on it now and 235-75-15 AT tires. I took it on a 4 hour round trip yesterday to indianapolis and by the time i got back to town the rear axle or something in the back of the truck was making a loud whining kind of humming sound.

Where would be the first place to look?

Just FYI i just replaced every drop of fluid in everything accept the t-case friday in anticipation of the trip and it needed it anyway. I just got the truck and the last guy just drove it into the ground and now im starting to get it back in good working order.

huntingman2706217

diff fluid... just cause you stuck some in dont mean its still there! may as well check that transfer fluid and jack up the back end and rock the wheels and tires top to bottom... if theres play then the wheel bearing may be shot... also make sure its not your fuel pump about to go... sometimes when the guts get hot in the motor they start whining really bad...

TrekkerJmm

X2 on re-checking the fluid. I have a 94 and had the same "Whining" hum and it turned out the be an axle/wheel bearing...Tj

MasterShakeXJ

do you feel it or only hear it? cuz if you can feel it it might be ds ujoints. might also want to check your lugnuts and tire pressure. your exhaust can also contribute to this, i know mine does, thought it was a driveline vibe but turned out to be my exhaust rattling and making noise.

79broncojosh

When im driving down the road with the cruise on it is just a constant wwwhheeeeerrr sound and it will go away for a second when i let off the gas then come back when the motor starts to drag. U joints were just changed.
The back axle has a little lash to it but not much, if you crawl under with it in nuetral and moved drive shaft back and forth it has about a quarter inch movement as i rotate it back and forth.
Also when i got the truck it had two different size tires on the back axle, it doesnt have limited slip (atleast it doesnt work) so would that have done anything?
P.s. all tires are the same know, and all fluids are still full

jeeploversaudi

I am a newbie but my jeep had that when i just bought it and it ended up being the differential and my back left ball bearing. Both of which were messed up. Hope it helps

JLS