front end whirring. Is it Diff or Tcase

[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

 

[UsmcJeeper]

Also I have no noise when the car is not under load. ie I jacked it up on stands and did not hear anything.

 

[tireburner1975]

When you are driving say 40mph, swerve back and forth (like you are changing lanes abruptly) see if it gets louder with the weight transfer, if it does its a good indication its a wheel bearing. Kind of sounds like a wheel bearing to me, but you should be able to hear a wheel bearing unloaded if ran up to about 40mph.

 

[UsmcJeeper]

it is definitely not a wheel bearing. Just replaced that and it quieted down a bit but it is still there and hasn't faded but gotten worse.

 

[tireburner1975]

I'd have to hear it but sounds like a Differential bearing noise, and/or gear wear noise.

 

[UsmcJeeper]

I am thinking gear wear. Or diff wear. Both of which I hope it isn't but I am looking at switching gears to 4.10s so if it isn't going to fail then I will probably save up and just replace the whole thing.

Plus im sure you will have some time to hear it this weekend.

 

[tireburner1975]

Yeah, I'll take a listen at it. You convoying with us down there saturday morning?

 

[UsmcJeeper]

Not sure I think eric and I are going down friday. I believe we will be there mid day or so and get our area set up for everyone. I will be bring jack and stands, plus cooler for food and what not. gonna be fully loaded up

 

[tireburner1975]

Sounds good, be there some times early saturday. I doubt I'll bring much more than the fire wood I got and little stuff.

 

[getstucksome]

have you taken off your front driveshaft to see if the noise goes away?

 

[UsmcJeeper]

I am putting on my SYE tomorrow so I will pull the front DS tomorrow to test it out.

 

[UsmcJeeper]

Solved, Front end vibes caused by tc drop. All gone now