Expensive noises?

'89 Jeep XJ (4.0, AW-4, NP-242 T-case, 3.55 axles, 350,000 miles)

Today I helped my son move an 83 Volvo with four flat tires that was sitting off pavement so he could put up a "portable garage" around it he bought from Harbor Freight.

To move the car, I used 4-low because I knew I'd need to drag it a bit sideways.

When I made a sharp right turn on the dirt road to go around to get in front of the Volvo, I heard, as did my son thirty feet away, a loud clunk from the NP-242. I straightened the front wheels, rolled slow and tried to shift out of 4-low, but the transfer case seemed to still be engaged.

I pulled the lever back into 4-low and then continued to make the forward pull to re-spot the car. Afterwards it shifted back into 2-Hi normally.

This past winter, in Full Time, it made a whirring noise loud enough to be heard over the somewhat loud exhaust, but the lubricant level is fine. In 2 wheel there's no noise. In 4-Hi there's no noises and in 4-low there's never been noises before today.

I'm suspecting the chain is worn out and needs replaced or I swap the 242 from an 92 XJ I have sitting in the yard.

Thanks!

Budd

Reply to
Budd Cochran
Loading thread data ...

Couple of observations about that "clunk" might be of some help, Budd. My MJ also has the 242 but behind an AX15 manual gearbox so we have similar systems from the tc on. First, that damned 4wd light lies like a sailor! The light is controlled by a vacuum plate position on the front axle but the actual engagement of 4wd is not complete until the slide locks the stub axle in the front end - and that does NOT accurately the lock pinion on the axle. Early on I scared the crap out of myself by yanking the tc into 4 lo then goosing the engine real quick: WHAM! - jarred my teeth so to speak. After checking things out I hadn't done any apparent damage but I found that to avoid that abrupt latch it's a real good practice to pull into 4wd and continue reasonably straight ahead for a few feet. The other thing that has caught me is the reverse problem: shift back to 2wd and the stupid light stays ON, even on gravel or sand. A number of tests has shown that unless I really have wound things up real tight the front axle actually does unlock without turning the light off. Usually, just to get rid of the light, I can get it off by shifting to 4wd (hi or lo) then down shifting (to get a higher rpm and vacuum), then swinging the steering wheel back and forth a couple of time while I shift back to 2wd.

If the clunk was a one-time event, I wouldn't worry about it too much. As for the noise in 4 hi, that's far more likely to be the cv joint in the front drive shaft than a chain. The chain typically makes more of a grinding noise (when REALLY worn) as it eats the case or, for lesser wear, you'll hear a slap as you play the gas or (for a manual) engage/release the clutch.

The clunk you heard/felt was likely the sleeve finally matching the spline teeth on the front axle. Unpleasant and it will eventually cause damage if you get a lot of it but the simple steps I used above to shift going straight and giving it time to engage before climbing on the gas and/or making sharp turns should minimize that.

Reply to
Will Honea

Watch out for the xfr case input shaft - There were various changes in the spline diameter and count in the 87-94 years depending on the tranny used. That one bit me and I had to tear down the 242 twice to get it right. There was also a change in the gear tooth cut which also bit me. The wrong one howled like a banshee!

Reply to
Will Honea

The clunk and the whirring sounds are coming from between the front seats, right over the T-case and not from the front of the XJ.

This was the first time it clunked but I was on a loose graveled street, not pavement. The whirring is anytime I'm in Full-Time 4X4 and the road is too smooth for tire noise to drown it out.

The front axle on the white 89 doesn't have the axle disconnect like my son's blue 88 had but the T-vcase has a complete disconnect of the front axle in the T-case instead.

I've heard the sound you mentioned in the blue 88 (part-time 4X4 only) before I gave it to my son and the vacuum switch on the back of the T-case failed so the front axle wouldn't disconnect dependably. I then took an aircraft grade Tele-Flex cable I had laying around and made a manual disconnect for it.

In Full-Time 4X4, the inter-axle differential, which allows driving on dry pavement in 4X4, keeps the chain from slapping as it keeps the chain under tension while driving.

Yeah, the dash light is only slightly more believable that the current federal administration. I've had it read wrong in all T-case shift positions.

I plan to pull the drivetrain from the 92 this week and I may plan on a swap in the next few days after that. Then rebuild the 89's unit and keep it for the 92's AW-4 trans.

Budd

Reply to
Budd Cochran

According to these guys it'll swap right across:

formatting link
The 92 and my 89 both have the same AW-4 automatic so it shouldn't be a problem to swap

My son's 88 has the BA10/5 manual trans and it needs a rebuild so he's looking at converting to a AX-15 trans from a JY source ... if he can find one.

Budd

Reply to
Budd Cochran

That's the swap I made - about 12 years ago. There is a junk yard outside of Oklahoma City that has nearly 20 acres of Jeeps. When I did mine, one of the owners rebuilt Jeep trannies. Whole deal, including the external hydraulic clutch parts and the needed input shaft for the transfer case plus shipping (by bus) came to about $1200. I'll see if I can find the phone number for this bunch. Last I heard, he was having trouble getting the adapter rings for the tranny -> xfr case mating to the AX15 but it would be worth a call. For me, that blasted internal clutch cylinder was worth the effort but the BA10/5 was shot anyway so it was a no brainer.

Reply to
Will Honea

shouldn't be a

external

That's basically my back doorstep. These guys? aandptruck.com

Reply to
DougW

We had a good JunkYard here in Canon City (about 3 acres of Jeeps), but they decided to crush everything and close shop.

A new yard is opening between Canon and Penrose on US-50 and 've spoke with the owner and suggested he load up on Jeep stuff since there are more Wranglers, CJ's, XJ's, MJ's, and even some full sized Jeep Cherokees and pickups than you can shake a fist at here anymore.

Budd

Reply to
Budd Cochran

I'm checking them out right now.

Thanks!

Budd

Reply to
Budd Cochran

I can't find my references right now - but they were shipping parts all over the place back when I dealt with them. Even had an 800 number where you could usually find a knowledgeable and friendly real person who spoke decent English to help you if you ran into problems. I haven't jeard much about them in recent years but then I haven't yanked that many wrenches either...

My mechanical impulses appear to be trending opposite my age these days.

Reply to
Will Honea

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.