After months of this problem it's finally time to ask for help. 98 xj 4.0 aw4 30/35 6.5 long arm with sye front shaft in the rear 33x10.5 bfg mud terrains. My jeep randomly roars out of its mind. Sometimes it's immediate an sometimes I'm ten miles down the road before it starts. When it's not doing it everything is smooth an quiet. Then it will sound like I'm running buckshots an it has a little vibration in it. It feels as if the jeep is bogged down slightly an u have to give it a little extra gas. I used to feel like it was coming from the front end but now it seems to be everywhere. I have opened the diffs an changed the fluids. Checked the ring gears. Rear diff looked really good an the front only had a small piece of one tooth missing an very little metal on the magnet. Pinion bearings seemed tight too. Moved on to the u joints. Found one u joint with a little slack in my front shaft. Replaced it an everything is the same. I was having some braking issues so the brakes got looked at next. I took the front brakes off expecting them to be trashed an I was surprised. The pads an rotors barely looked warn even tho I have had the jeep a year an a half an never changed them. So I changed the pads out anyways an moved to the rear. I knew the shoes were shot for awhile, this was my main braking issue. I took the drums off an sure enough the shoes are shot. New shoes, hardware kit, an drums. Button everything back up an I still have the same problem with roaring. It stops better now but still leaves something to be desired. I'm definitely going disk brakes in the rear when I swap axles. Next I checked the front wheel bearings. Everything seemed to be tight there. I'm running out of options to check. This happens at high an low speeds an doesn't seemed to be effected by being on or off the accelerator although it is better when coasting. Like I said it started out as being very noticeably in the front end an now after 6-7 months seems like its coming from everywhere. It will sound like the front sometimes an the rear others an then both. It happens atleast 50% of the time I'm driving the jeep. Makes it feel sluggish an weighted down. Transfercase is full an has good fluid. Same with the tranny an it had a transcooler added a few months ago. Anybody have any thoughts? I'm to the point of just wanting something to break so I can know what it is an fix it but it never happens that way does it.

 

I have that same problem but it's usually when I first step into the shower in the morning....

Back to serious...The only thing I can think of is the clutch fan or the auxillary fan. My 98 roared when i was negotiating to buy it. I found the bearings in the Aux fan were shot and the seller replaced the fan. I got used to the roaring of the clutch fan on hot days but this is probably not your problem, although if it had bad bearings, it could be making noise like you describe. Probably not much help here, but you gotta start somewhere.

 

No thoughts on this?