'95 XJ - growl from front right in 4wd

[dauntless89]

Alright, so just before my daily driver pickup took a dump I got my XJ back on the road to drive while I fixed the pickup. It was my wife's DD and then sat in the driveway with a bad motor for several months. New motor, test drove it in 2wd, all was good.

snowed two nights ago so I used 4wd to get onto the highway, then turned it off while accelerating to 65 mph. Noticed a whirring growly noise coming from the front right wheel area, kept going for several miles, and then there was a bang and a shudder and it stopped whirring. Thought I hit a bump in the road at first and that jarring motion helped ease the hub or CAD out of engagement. It's been sitting awhile, whatever. Drove the remaining 30 miles to work, then was in and out of 4wd on the way back. Noticed the whirring when it was in 4wd, but it wasn't there when I'd go back to 2.

This morning, same drill getting onto the highway. whirring after going back into 2wd then another bang/shudder (but in a different place where I know there is no bump on the road) and it quit making noise. Again I was in and out of 4wd coming home. Whirring in 4wd, but not in 2. The last time I engaged it, and went back into 2wd, the whirring stayed.

Haven't had a chance to check anything in the hub area yet. This is a 95 so it doesn't actually have the CAD. Brakes are new so it's probably not them. It was the wife's daily driver so who knows how long it's been doing this. Do these XJs have factory auto-locking hubs or does the front drivetrain just not have any disconnect?

 

[BusaDave9]

I am thinking bad U joint.
The XJ doesn't have hubs you can unlock.
The problem is worst when in 4WD. When in 2WD the axle shafts are still turning but not under power.
You can check the U joint without removing the tire or anything else
If you don't see anything wrong with the u joint put in 4WD. Jack up the front right tire. Try rotating the tire. You should be able to see if the free play is the U joint. Also push back and forth on the tire to see if the hub is bad. Try to lift and lower the tire to see if the ball joints are bad.
If it's the hub check out this link:Hub Replacement

If it's the U joint that same link should help because you have to remove the hub before you get the axle shaft out. Then replace the U joint.

Keep us posted. I still think its the U joint.

 

[mtnwhlr]

They do have a vac switch on the left side of the axle that locks it in 4WD. BusaDave may be right I would check the U-joints.

 

[BusaDave9]

The way that vacuum disconnect works is the outer ends of the axle shafts still rotate (along with the u joints)
Since there is no locking hubs the u joints always rotate.

 

[dauntless89]

I am thinking bad U joint.
The XJ doesn't have hubs you can unlock.
The problem is worst when in 4WD. When in 2WD the axle shafts are still turning but not under power.
You can check the U joint without removing the tire or anything else
If you don't see anything wrong with the u joint put in 4WD. Jack up the front right tire. Try rotating the tire. You should be able to see if the free play is the U joint. Also push back and forth on the tire to see if the hub is bad. Try to lift and lower the tire to see if the ball joints are bad.
If it's the hub check out this link:Hub Replacement

If it's the U joint that same link should help because you have to remove the hub before you get the axle shaft out. Then replace the U joint.

Keep us posted. I still think its the U joint.

That was my guess too. I'm so used to the closed knuckles on my '69 CJ I forgot these modern ones are open-knuckle. Totally spaced the part where you can visually inspect them without tearing it apart. But yeah, that's how much time I've had to check this until tomorrow morning.

But I drove it again today and no irregular function except the growl while in 4wd. took it a short distance on the highway, shifting into 2 just after pulling out onto the roadway. gave the whirring until I stopped at a gas station. Then when I started moving again it wasn't there. When it was growling or whirring, the sound got louder as I steered right and when steering left, it hit a spot where it almost completely went away, then with more left steering input it came back.

They do have a vac switch on the left side of the axle that locks it in 4WD. BusaDave may be right I would check the U-joints.

This one doesn't. They stopped doing that on the XJs after the 1991 model year. That's what I thought it was at first since i remembered seeing it on my buddy's YJ, where that design was retained a bit longer, and it's located right where the sound seems to be coming from. Since it can't be the "center axle disconnect" as it's called, next suspect in line is the u-joint. Next after that is bearings.

it's 10 degrees and very dark outside, and there are two broken vehicles between the XJ and my heated garage. I think this inspection thing is an adventure for tomorrow...

 

[dauntless89]

Bad news-

U-joints looked okay. Saw evidence on the front left knuckle of an oil leak. Went for the front diff plug, and dark grey powder fell the the ground when the plug came out. Finger in, bone dry.

Put a quart and a half of new gear oil in, drove it around the block in and out of 4wd. Sound is still the same.

At this point, best case scenario is the differential bearings. Permanent damage to the gears is also highly probable by now. Even though most of the miles on the front diff have been without a load (in 2wd) that lack of lubrication is bound to have taken a toll.

After my truck is done, I was planning to put a 3" lift and my CJ's old 31x10.50s on this XJ. Looks like I will also be pulling the diff cover and dealing with whatever fun lies waiting for me in there.

I have to drive it about 50 miles round trip this evening, most of it highway. Hopefully it'll throw all the new oil around enough to at least quiet it down. Now I know it's the differential making all that noise, it's well past the point of no return, though the oil (and knowing I need to check it) should stop most any further accelerated wear.

 

[dauntless89]

Quieted down a little bit, but something's permanently damaged. Likely the ring & pinion or the pinion bearing since the whine is at a faster rate than the axle-shafts would be.