So I've tried to search around and I've gotten a few ideas, but nothing really exactly fits the scenario I've got. I have a 2001 4.0L XJ Sport with 183,000 miles, automatic transmission, Chrysler 8.25" rear end, and NP231 TC, and as soon as I put it into gear (any gear R, D, 2, 3) it starts to make a 'whirring' sound. The sound is as loud as the engine sound (maybe a little louder) and it increases in pitch as the RPM increase (even if it's just from the compressor on the A/C kicking on). As soon as I put it in 'N' it goes away.


I have recently installed about 3" OME lift, could something be wrong with the TC or driveline angles?


If this helps anyone here's a youtube video of the sound, I switch back and forth from N to D a few times so you can notice when it starts up:



The sound is a very 'gear-like' whirring, it isn't a whistle or anything like that, it definitely sounds mechanical.

Thanks for your help!

How are your transmission fluid? Brown and burnt? Filled to correct levels? Is it slipping and lurching between gears?

Sounds a little like the AC/compressor cycling...

Well, it does increase in pitch when the AC Compressor cycles on (I turned it on toward the end of the video since that would increase RPM slightly while in gear without driving over my phone).

Transmission fluid is a little brownish, it doesn't smell bad or anything. I'm leaning toward something on the motor side of the transmission, but there's no way I'm going to be able to do any work on a transmission. I guess I'll just have to take it somewhere to get it looked at. I was just curious if it sounded like 100% transmission. I know a good transmission shop, but I didn't see any reason to take it there if it was something else.