Hello, I have a growling/grinding/humming noise that seems to be coming from the front end of my '92 XJ. The noise begins to present it's self at 55mph while accelerating, and is in full effect by 60mph. From 60mph the noise gets worse as vehicle speed increases (again while accelerating) and seems to have little relation to engine speed but does get worse with increased engine load (moderate to aggressive acceleration). When engine load is released (at the described speeds) the noise seems to be less consistent but more sporadic.
Putting the vehicle into "4HI" causes the noise to be more subdued under the conditions described above, but it remains eriely present.

The noise began once the vehicle was aligned after replacing all of the tie rod ends (along with their respective adjustment sleeves), the track bar, and the upper control arm bushings (at the axle).

I apologize for the long-wordy write up but I want to give as much info as I can. Also I posted this in the "Modified Cherokee Tech" area because my XJ has an aftermarket lift but if this is out of place, please let me know so that I know where to post concerns like this next time.

Thank you to all,
-Angel

The vehicle is a '92 XJ with: 4.0L engine, AW4 transmission, NP242 tranfer case, Dana 30 front axle (stock), Chrysler 8.25" rear axle (stock, no LSD or locker, 3.55 ratio), stock front and rear drive shafts, brand new Rough Country 3" suspension lift, new front and rear sway bar bushings/links, all new tie rod ends(with their respective adjustment sleeves), new track bar, new upper control arm bushings (at the axle), new Rough Country steering stabilizer.

All of the parts listed as "new" have been purchased new and installed within 6months/6,000mi of current date and vehicle mileage. There are more new parts but I will list them as they become relevant.

 

Wheel bearing?

 

Like Wauto said, look at the hub bearings at the steering knuckle.

Also check the front differential, could be the pinion bearings or the carrier bearings. Though the change in sound with load would indicate pinion. But look for the simple things first. Check the fluid level (should be topped off). Get under it (while engine is off and parked in a safe place) and wiggle the drive shaft at the yoke. There should be no side to side movement.

For the wheel hub bearing check, you are going to have to lift the front, take off the tires, and rotate, wiggle and inspect the wheel hubs. They should turn by hand, no wiggle side to side. If you feel grinding, well then that may be it.

But look for other things, something rubbing somewhere that could make that noise. Don't just assume the more expensive things. Try the small stuff first.

 

When doing an alignment, changing caster also changes the pinion angle. Incorrect pinion angle can cause what you describe due to the u-joints being out of phase, this also puts additional strain-stress on the pinion bearing and it's distress can be a growling sound.
Front pinion/yoke should be in line with driveshaft.

 

Both of the wheel bearings along with the axle shafts are new. I will check the fluid level and the pinion play this weekend as you suggested.

Much appreciated,
-Angel

 

I did notice that the caster was way out of spec. when the alignment was performed, but I was told it shouldnt be an issue because both sides were equally out. I'll have to get that taken care of soon.

Thank you,
-Angel

 

That's funny, "equally out" I hope so, otherwise you will have serious issues.

Problem is, when a lifted jeep goes to a regular tire/alignment shop, the technician is not specifically familiar with lifted rigs and their special requirements.
The special requirement is to have the correct pinion angle. If the tech dialed in a normal seven-eight degrees of caster, that will cause the pinion to point too low on an XJ lifted 3"

Changing caster rotates the axle, which affects the driveline (pinion angle in relation to driveshaft).
Have a look yourself, kneel down behind the front driver tire and 'sight' the relation of driveshaft and the pinion/yoke that exits the front differential. They should appear to be in-line.

 

Bent dust cover?

 

Quoting first post, "The noise began once the vehicle was aligned "

 

Update: I just "shook down" the front drive-shaft(D.S.) and I found that the U-joint that connects the D.S. to the front axle has significant play.

Can this sort of play cause the noise I've described?

Also, I noticed that the front pinion/yoke is not completely in line with the D.S. but seems to be pointing too far down, as SteveMongr suggested.

Thank you
- Angel