Hey fellow XJ drivers; haven’t been on in a while because mine has been healthy, but no longer....

1995 Jeep Cherokee SE 4x4, 4.0L Auto Trans, NP231 Txfr case, approximately 170k miles. At least a year ago, I noticed if driving ON-road in 4wd HI, I have a growling noise during acceleration or deceleration that seems to be coming from the transfer case. If I’m just maintaining speed, it’s very slight.. The growl in deceleration is not quite as loud as during acceleration. I can’t find any play in the front driveshaft, axles, or at the output shaft of the case going toward the front end. I did change the txfr case fluid, but the old fluid looked good. Used O’reilley’s DexIII / Mercon. I also get the growl when I accelerate in 4wd LOW, but the stress of acceleration is brief, so the growl is brief, but it’s still there.

I get no noise accelerating or decelerating in 2wd, so I know it’s the txfr case or something in the front end. I have not changed the front differential oil in the front end, but it’s not low and does not appear to be contaminated. I did put a new hub and axle shaft u-joint on the right front about two years ago. Left front hub and u-joint are original.

I’m afraid I may have an internal bearing In the txfr case failing, and I don’t know if I’m up to that level of repair. Anything else I should check for? I keep eyeballing that double u-joint on the front driveshaft, but there is no play I can feel in it. I realize u-joints don’t always have play.....at first...

Thanks in advance to all.

 

Possible it's the transmission mount allowing the exhaust pipe to rub on the crossmember?

 

I don’t think so. Acceleration & deceleration would torque the motor in opposite directions. I would guess an exhaust pipe rub would happen in both 2wd and 4wd if that was the issue. This noise is only in 4wd, and there’s a slight bit of gear whine in the deceleration. It does happen when torque is applied.

 

Years ago, my moms 95 had a growl coming from what she assumed was the transfer case. Which it was. it was low on fluid and the chain was slack. New fluid and chain and it was quiet again. That was her fix, anyway.

 

I was just thinking of the obvious, but low on fluid is a good point. You may have a bearing going. If it is, it's probably the front output shaft bearing behind the yoke. That's the one that takes most of the off center forces on a short shaft.

 

I think I’ll drop the front driveshaft next weekend and see if the growl persists with no “load” on the front output shaft of the TXFR case. I can also more carefully evaluate the condition of the front output shaft bearing.

 

I did drop the front driveshaft this past weekend. It had nothing loose enough to be the source of the problem, although it did have the double Cardan ball seal all shelled out.

I drove the rig with the front driveshaft out and accelerated a few times with the TXFR case engaged and disengaged. The rumble / growl wasn’t nearly as noticeable without the driveshaft connecting the case to the front axle, but you could still hear and feel some rumble from the case. I put the driveshaft back in and the problem returned to the same as it was before I started.

I’m fairly sure I have a bearing in the case that’s getting loose, and it almost has to be the section of the case connected to the front axle since there is no rumble or growl while accelerating in 2wd. I suppose it could also be the drive chain getting a little floppy, or a combination of the drive chain and one of the bearings on the front output shaft.

While the drive shaft was out, I got a hold of the front output shaft and tried to Shake it to see if the bearing on it was loose. The shaft had a very tiny bit of play, probably no more than a very few thousands, but generally seemed ok. My fear is that it is the bearing on the back end of the front output shaft, the one that presses in to a blind hole inside the T-case. That would require splitting the case to replace and a specialty puller to get the bearing out.

I’ve looked around to see if anyone has changed out a front output shaft front bearing while the case is in the jeep. The bearing does have a retaining ring holding it in place so I thought it might come out without having to drive it out of the housing from behind. Anyone know if that front bearing on the front end of the front output shaft can be removed and replaced with the T-case in the jeep?

 

I think it can, but you'll have to remove the seal and hook a puller into the ball cage. Something like a small slide hammer with a hook on the end.

 

Well,I tried 5w-30 motor oil as lube in the TC and it was a minor improvement, but not a fix. I’m guessing chain and rear bearing on the front output shaft, probably both. Since the straight through side is quiet, and the TC has always been serviced, it also seems like a normal wear issue & not an induced failure. I may try to drop it and rebuild, but that will take time I don’t have yet (retiring in August!).

Any “most likely” part failure or could it be about anything? Since it’s on the 4wd side only, it seems the trouble has sort of isolated itself to that side, but I’m not sure of that.

Thanks in advance for any advice.

 

Well, I’m still trying to find my growl / rumble while accelerating or decelerating in 4WD. I did replace all u joints in my front driveshaft after I ordered a new driveshaft fro a Amazon (JC Whitney), and it was so out of balance of vibrated the whole Jeep at any speed over 30 MPH. (Sent it back). When I got the inner U joint out of the Cardan joint on the end of the driveshaft that bolts up to the transfer case, it had a dry cap. Now I have a good front driveshaft, but that didn’t solve anything. I jacked up the whole rig today and ran it with the wheels off the ground, but that didn’t t really reveal anything.

While the Jeep was up off the ground, I turned the driveshafts with the TC in gear and out of gear. I still didn’t find anything definite. I did discover a little slack in the slip yoke of the rear driveshaft. Check out the attached and see if that seems too loose. Keep in mind I have no issues when in 2WD, just in 4WD, but I’m fixing anything I find as I go.

 

Haven’t been able to get the video to attach. I’ve gone through the process about a dozen times.

.....and finally success. Kept doing the same thing over and over. It finally worked. Insanity paid off this time....

And yes, those are dirt dobber mud tubes on the under side of the floorboard. The Jeep often sits idle durning the week.

 

Input from all those that seem to have some knowledge is “loose chain”. I’ve heard that from about 1/2 dozen people. I found a used NP 231 for $100. I’m going to grab it and try to rebuild it so mine won’t be down while I’m feeling my way along....