NP242-worn chain or linkage out of adjustment after lift?

Yesterday I took my XJ out to play for the first time since lifting my jeep 2.25".

Since buying the jeep a year ago (10k kilometres ago), I have frequently used 4hi/full-time alot with no abnormal noise, and 4lo several times with no abnormal noise either.
Long story short, I have used 4hi/full-time on several occasions in the last month with zero problems. I have not used 4lo for around 3 months.

Yesterday I put it in 4lo and did a little wheeling-almost immediately I noticed that when under load, I was getting a bad popping/clacking noise-exactly what I would imagine a stretched chain or poorly adjusted linkage to sound like. I turned around around 400m into the trail, went back down to the logging road. I fiddled around with it in 4hi, climbing a bank at high RPM's to see if I could get the t-case to pop again while under load..no noise, nothing unusual.
Tried climbing the same bank in 4lo, and while I was able to climb the bank I was getting the same popping/clacking noise. Shifted back to 2wd and headed home. On my drive home, no noise at all.

Now, I'm pretty new to diagnosing t-case issues..so I need a little insight. Can the popping/skipping noise be attributed to the recent lift? In searching, I read that when the linkage goes out of adjustment, 4lo is the first to suffer.
Any advice? I'm going to drain the T-case fluid and check it for metal particles. Last time I checked the fluid it looked in good shape, but I have never drained it, only checked level.

1990 XJ/D30 non-disco/D35/NP242/AW4 with around 110k miles.

If it's in low range the extra torque could cause a stretched chain to slip. It would be more like banging and pretty loud. The chain can become stretched if used in part time on surfaces with good traction (street). If you didn't drop the transfer case with the lift then the adjustment shouldn't have changed.

Have you added larger tires? My 31's catch the inside edge of the fender flares when the wheels are turned just right. They make a pretty loud popping sound. Just need a little trimming on the inside of the flare.

hmm, I have never personally run it in part time on the road, only in full-time in the snow. This was a fairly loud popping, more like a bad u-joint except it was present when going straight, not only when turning. Sounds like a stretched chain to me, but I'll still drain the fluid and check for metal then re-adjust the linkage, just in case it got screwed up at some point.

psybud said:

Have you added larger tires? My 31's catch the inside edge of the fender flares when the wheels are turned just right. They make a pretty loud popping sound. Just need a little trimming on the inside of the flare.

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nope, still running the same LT235 AT's as when I had it stock.

clunk said:

hmm, I have never personally run it in part time on the road, only in full-time in the snow. This was a fairly loud popping, more like a bad u-joint except it was present when going straight, not only when turning. Sounds like a stretched chain to me, but I'll still drain the fluid and check for metal then re-adjust the linkage, just in case it got screwed up at some point.

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Does it do it under light throttle straight ahead or heavier throttle?

lighter throttle, the I was just idling up the trail I was climbing at around 1500rpm, not really giving it much gas.

It was fine before the lift and nothing else was done to it before the problem was noticed?

MJR said:

It was fine before the lift and nothing else was done to it before the problem was noticed?

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nope, just did the lift and replaced the shocks. Is it possible the sound I was hearing was just a worn u-joint on the front driveshaft?

clunk said:

nope, just did the lift and replaced the shocks. Is it possible the sound I was hearing was just a worn u-joint on the front driveshaft?

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Don't know but you can take it out and look at it, maybe drive it in low without it in there and see what it does. Not eliminating the t-case yet but it seems wierd to just start. I know the rear driveshaft yoke can bind when unloaded with only a 3" lift but your problem sounds wierd. Get under it and see if anything is loose or if the trans mount has collapsed causing the exhaust pipe to hit the crossmember.

just had a look under there, drained the fluid. Fluid came out red, smells clean. Reached into drain hole and felt around, no metal shavings. Currently straining the fluid through a clean rag, I'll report what I find in a few minutes. Everything looks tight under there..

Move the driveshaft by hand to see if theres any movement in driveshaft ujoints or axle ujoints, never had a stretched chain before cant help you there

strained fluid, found what I think (to me) are normal signs of wear. A tiny amount of very very fine metal, not shavings, more like the consistency of baking flour, probably around the amount to fill a pinhead. I would assume that on an 18 year old truck, a little wear is normal but maybe I'm wrong? Checked u-joints for any play, nothing major. The rear pinion is pointed down quite a bit, but the noise I hear is more from the transfer case area.

Interesting. There is a magnet in the bottom of the t-case that metal would stick to but if the chain is slipping it wouldn't necessarily have metal in there. Try pull the front shaft and driving it in low.

MJR said:

Interesting. There is a magnet in the bottom of the t-case that metal would stick to but if the chain is slipping it wouldn't necessarily have metal in there. Try pull the front shaft and driving it in low.

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I don't have my torque wrench around to tighten the caps back to spec.

Tight but not too tight. It doesn't carry any weight so just tight enough not to leak or fall out.

took it for a little wheel up a steep trail behind my house, purposefully ran it at a variety of RPM's to see if I could get it to make the noise--no dice.

The only difference between yesterday and today is that the trail I tried today had much better traction, they had solid traction the whole way up. Yesterday, the trail had a layer of clay and the tires would spin/catch/spin/catch a bit, at steady RPM. It seems that this was when I was getting the popping/skipping type noise.
Is this just a worn u-joint at the driveshaft? Am I panicking for nothing?

clunk said:

took it for a little wheel up a steep trail behind my house, purposefully ran it at a variety of RPM's to see if I could get it to make the noise--no dice.

The only difference between yesterday and today is that the trail I tried today had much better traction, they had solid traction the whole way up. Yesterday, the trail had a layer of clay and the tires would spin/catch/spin/catch a bit, at steady RPM. It seems that this was when I was getting the popping/skipping type noise.
Is this just a worn u-joint at the driveshaft? Am I panicking for nothing?

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Man I'd look at the motor and trans mounts.

If your chain was strecthed it would pop on hard surfacees as well. Front u joint on axle? moter mount ie fan hiding shroud. angry sparrows on drive shaft when it loads up and unloads or maybe slip yoke on front driveshaft seizing up.

Hey XJ, I am having the same problem, did you figure out what was causing your problem? I'm going to check my t-case linkage and adjustment. I also intend to check for coins in the shifter. Found a few already.