horrific popping noise

i just bought an 87 XJ (wagoneer) and when it is in "hi lock" "4wd" and "lo lock" it makes a horrific popping noise from the rear half of the jeep... i would like to say it is coming from the diff but i can not tell...

i rolled down the window, and watched the drivers rear tire, and it seems to be skidding when i make a hard left turn in conjunction with the pops, and the whole vehicle shking somewhat violently.

any ideas???

All I have to say is you aren't doing this on dry pavement right???

well yeah, i just bought it. and so i just noticed it, and came here for advice

Do yourself a favor and DON'T repeat. That horrific noise you hear is your transfer case chain tweaking. The NP 321 transfer case is used ONLY on ground that gives: snow, ice, sand, mud. You can get away with it on firm pavement in a dead straight line, but when you turn your wheels, the outer wheels must travel longer distance than the inner wheels. The part-time/full-time 4WD NP 242 transfer case is desinged to deal with this, so it can be used on dry, firm pavement.

Yep, hope you didn't ruin anything before you get to see how capable your 4x4 is. The 231 is a strong case but use it when you go wheelin. Has no business being used on the street. Obvoiusly you haven't had a four wheel drive before, no worries, just take it to the woods and try it out. The cherokee,even stock is a great wheeler... Have fun.. Good Luck

well actually i have had a 4x4 before, i drove an 88 suburban for 3 years, and never had anything like that happen before, so it freaked me out. i didnt htink anything like that would happen... i was afraid there was something wrong with my spider gears. thanks for the headds up. this is however my first jeep, so i will be more carefull. thank you

ok, so this is normal. i do remember my burban bouncing a little on pavement when i turned full lock in 4x4, but it wasnt this insane. well one less thing for me to worry about then

otto said:

Do yourself a favor and DON'T repeat. That horrific noise you hear is your transfer case chain tweaking. The NP 321 transfer case is used ONLY on ground that gives: snow, ice, sand, mud. You can get away with it on firm pavement in a dead straight line, but when you turn your wheels, the outer wheels must travel longer distance than the inner wheels. The part-time/full-time 4WD NP 242 transfer case is desinged to deal with this, so it can be used on dry, firm pavement.

Click to expand...

haha...
well today i swapped out my track bar, and while i was under there i looked at a few things...
it seems that it has been jumped at least once, becaust the tranny cooler lines right above the UCA are pinched flat, and the pan has a big nic in the edge of it. no biggie i only paid 350 for it so i am not complaining...

however on the t-case ID tag it reads "242 AMC" under the model heading...

the shift positions on the 4wd lever are: 2wd-2loc-4wd-N-lo loc
so is this the part time, or is it a full time case???
i tested it on some loose gravel, and in 2wd only the rears spin, and in 4wd front and back have at it.
it still popped a few times, but nothing like on the pavement.

now my question is this... if this is a full time case, why does it pop like crazy on the pavement??? or is it even full time???

thanks guys

Well let me just take a stab at this one...

It could be the chain in the transfer case slipping. I had an '89 with the 242 and it popped like mad in any 4wd mode. The chain was stretched and skipping off the teeth of the gears.

If that's the case, replace the chain before it eats thru the bottom of the case.

Or.....

I would say your front u-joints may be shot as well. Given that the vehicle is 19 years old and has "been jumped at least once" I would guess it hasn't had an easy life.

Get the front end up on jack stands and check for play in the axle u-joints. The popping is most likely the joints letting you know they are about to come apart, and take the ears off the axle shafts as well.

Good luck

Rich