Ok i just bought my jeep about a week ago its a 2000 xj sport it was stock and at that point and time it had a low growling noise at speeds above 35. i put a 3inch Rc lift and 31's and now when im coasting at about 40 and i let off the gas i can hear a growl/grinding noise, and if i hit the gas again it will make the same noise, its rather loud its like a 1 second growl and then just stops. so i pulled it in on a lift got in it and did about 40mph and it made the noise it it was coming from the outlet on the transfer case. 167k on the jeep. Has any one had this issue?

 

i only hear my tires roar and my engine sounded like a diesel so i cant tell you if thats normal or not, but id definatly look into that...

 

And it got worse when you lifted it..which makes sense you pulled the slip yoke out farther with the lift.

I have no idea, mine does make those noises..and Im only guessing off of what you told us..so I dont know, thats my guess..maybe someone else can help you out? you had that problem before.

 

I would say replace your rear-drive shaft U-Joints and check the fluid level in your T-Case and Trans. Do you have a manual or auto trans? Have you tried reproducing the sound and as soon as you hear it, place the trans into neutral? Any difference? What t-case do you have? NP 231 or 242? Are you sure your t-case is disengaged and working properly?? I would however start with u-joints and mabey even a t-case drop kit. Good Luck!!

 

check and change t-case fluid and check u-joints like stated above, also check rear diff fluid and change if needed.

 

If all else fails turn up the radio till something blows up.

 

its a aw4 tranny 231 case i have checked the ujoints and there is no play but some one stated that lifting the jeep pulled the yoke so now it really has me pointing to the Tcase. looks like its time for SYE kit . i love when stuff breaks. once i do find out what it is ill let you all know. i can make it make the noise anytime i tap the gas or let off it makes the noise.

 

I'm still betting on the slip yoke ..

 

It is the SYE. I had the same problem in my 94 and I rebuilt my 8.25 twice because of it. I was pissed when the shop I took it to after the second time told me it was a bent axle tube.
It's the vibes on the rear end. I'm having the same issue in my 97 I just finished putting a lift on.
SYE should be at the top of the list.
Good Luck!!
Sigsandjeeps