doorman4444

I just bought my first XJ-
97 SE 4.0L 6 4WD 99,000 Miles
I suspect it is a Chrysler rear end but I dont know, the transfer case is a NP 231

It is making a howl at the sweet spot between accelerating and decelerating. I have seen this in other trucks as being a u-joint problem.
The u-joints seem tight, no play at all. It almost sounds like exhaust burbuling like a PCV problem.

How much play is normal for the diff? I can rotate it 5 or 10 degrees back and forth before the gears mesh.

2nd question, what changes were in the "Towing Package" and how can I tell if I have it?

Thanks in advance for the help.

00xj-classic

towing package would have a hitch of some srot and a transmission cooler mounted infront of the radiator..

firstime00XJ

I don't understand what you mean by 'the sweet spot', is that a certain speed or what? Rotating the wheels 5-10 degrees before you have movement of the gears sounds like a normal LSD to me...but I'm new to RWD vehicles and 4wd vehicles. I would check wheel bearings first, check for movement.

doorman4444

By sweet spot I mean just coasting, before it starts to deccelarate.
The 5 to 10 degrees play is at the diff yoke, not the wheel.

ol"blue

Sorry but I think your diff bearings are either going or gone.
And Welcome to CF!
Dan

xjrev10

yep exactly what i was thinking. thats alot of play.

zr2toxj

I have read that a pinion bearing will howl on deceleration.

JeepFreeze

OP, I don't know how hard you drive your jeep but I bought my first XJ 3 years ago. I couldn't test drive it before buying it because I got it on ebay with a bad engine. Anyway, after the engine was replaced and I finally drove it, it made a slight howling sound from the rear and had a vibration similar to a bad u-joint. I put it on the lift and found that the pinion was pretty loose. I'm not sure if I had any rotational play like the 5 to 10 degress your talking about but when I grabbed the yoke I had a good amount of side to side play between the pinion shaft and the bearings. At that time I figured I'd have to rebuilt or replace the rear soon. That was 3 years ago and it's still doing fine. The pinion seal leaks a touch but I've only added oil twice in 35,000 miles. I don't drive my jeep very hard so if it was me I'd run it for awhile and see if it gets worse. Thats just me though and I don't go on any long trips. Mine is a 2000 with an 8.25 FWIW.

G

mcssls

pinion can howl on acceleration or deceleration. Depends on if it's too tight or loose. Go to a transmission shop, have them test drive it and they will tell you.