USMCJeeper

I have 99 Jeep xj with 174000. I change the fluids regularly and have noticed a loud whirring, whining type noise that begins at 25 mph and increases as the speed goes up. When I slow down the noise doesn't go away until below 7mph. I recently changed my front diff fluid and tcase fluid less than 10k miles ago. I also put the jeep into full time 4wd today on the drive home. I have the 242 so it is ok for on road use. However when it was in 4wd the whirring turned into whining and became much louder. I am looking for suggestions as to what some issues could be or a definite answer would be awesome. Also the noise gets louder as I give it gas and subsides a bit when I let off the skinny. I haven't checked the fluids but I was planning on that tomorrow.

JB

The jeep is 4.0l, Aw4 and np242 with D30 in front and D35 in rear
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freegdr

check the fluids, did u use the proper fluid for the tc change

cameraman7d

I have a 98 cherokee limited... I jacked it up and set it on jack stands man the noise was loud then... used a stethoscope and listened to the T-case, front diff and rear diff... noise was definitely coming from the rear diff... I called a friend who has a transmission shop... he advised me the carrier bearings in the last 4-5 years of production of the cherokees go out... mine has 184000 on it so im guessing this is the problem... very soon im gonna replace them and see if my problem disappears... if anyone else has words of wisdom please voice it...

Thanks, Adam

USMCJeeper

checking fluids tomorrow, I know that the fluids were proper. I know it is the front since I just redid the rear. btw the noise goes away when it is jacked up off the ground, only under load does the noise occur.