Trouble with my KJ

[Robert OB 33/48]

Hello folks,

Now I do need some advice. As I am not a mechanic, so I dont know the details.
Since yesterday I noticed a strange sound coming from my drive train.
When in 4wd, high, partime, fulltime or low gear, there is the noice as if something skips gear tooths.
A friend of mine who is fairly into Overlanding from South Africa, said it could be the transfer case.
So today I checked the transfer case about leakage or such. nothing found.
Secondly when the front wheels are up in the air I can rotate them frealy when in 4wd.
But I cant turn the drive shaft towards the front diff. from the transfer case.

Questions are.
First of all, what do you think can it be.
second, shoud I be able to turn the wheels when in 4wd? And I cant turn the driveshaft?

Can you help me out?

Many thanks from Robert

 

[El-Dracho]

I hope you are at home with the rig and not standing somewhere?

I am not the Jeep expert. This parttime and fulltime always confuses me. But if you have a noise like that in the drivetrain and it's nothing loose or knocked out (shaft, universal joints, etc.) what you have certainly already checked, then it could be a diff or transfercase problem. I would drain the oils and see what they look like. Good luck!

 

[Autism Family Travels]

Sounds like the transfer case. Does it make the noise in 2wd? 4 low? My buddies chain was stretched in his TJ, sounds like what you are describing.

 

[smritte]

Noises can be deceiving, even to the trained ear. Right off the top of my head I can think of several things that sound like you describe. Turning the wheels isn't what you wanted to do. Turning the driveshafts is. Even though they didn't turn, is not much of an indication. Crunching when you turn is something else.

If you actually broke a gear or wore it down enough to skip a tooth with a chain. You will have metal in the oil. If I hear a noise I cant pin down, I have something called chassis ears I use. if your determined to track down the noise, pull both driveshafts one at a time (starting with the front) and see if the noise is still there. If not, its not the T-case or transmission. When i test drive something for noise I need to know if its 2wd, 4wd or both. Accelerating, decelerating, coasting in drive, reverse and neutral. Everything is a puzzle piece and you try to see where it doesn't make noise. Those you eliminate and look at what you have left. A binding CV driveshaft will sound exactly like a broken transfercase if you don't know the difference in the sound.

Unless someone who actually knows the different noises, hears it and narrows down the location, your just going to be throwing parts at it.
Having gears break is not common unless your driving it hard. Gears having issues over time is not. When you do your diff services, transfercase, trans services you would have seen metal flakes from the wear.

 

[Robert OB 33/48]

Thank you.

I can drive in 2wd without noices and other problems.
I did loads of teststing today and will do some more tomorrow. But for now it looks like I see some movement in the front driveshaft cv joint just behind the front diff.
So tomorrow once more I will lift the car and will try to move the driveshaft to find play in the CV joint.
Hopefully it is that part.

 

[El-Dracho]

Thank you.

I can drive in 2wd without noices and other problems.
I did loads of teststing today and will do some more tomorrow. But for now it looks like I see some movement in the front driveshaft cv joint just behind the front diff.
So tomorrow once more I will lift the car and will try to move the driveshaft to find play in the CV joint.
Hopefully it is that part.

Good luck then! Fingers crossed, that it is only a worn out cv joint!

 

[Autism Family Travels]

Thank you.

I can drive in 2wd without noices and other problems.
I did loads of teststing today and will do some more tomorrow. But for now it looks like I see some movement in the front driveshaft cv joint just behind the front diff.
So tomorrow once more I will lift the car and will try to move the driveshaft to find play in the CV joint.
Hopefully it is that part.

Check your side and rear axles too.

 

[LostWoods]

Secondly when the front wheels are up in the air I can rotate them frealy when in 4wd.
But I cant turn the drive shaft towards the front diff. from the transfer case.

Totally normal spinning just one tire. If you do both in the same direction (or hold one static), they should not move or they should spin the driveshaft if it can move freely. This is normal differential operation.

Big question is if the noise is actually skipping teeth or if it's more a popping noise. A failed CV will make popping noises under load and I believe the KJ has 6 of them up front (both driveshaft joints and all axle joints).

Checking for grinding gears is pretty easy though - just drain the differential and transfer case and look for shiny bits. Just pull the fill plug before the drain because nothing is worse than being unable to remove it after you drain the fluids. It's just drain, plug, and fill with the correct fluid until it comes out the fill hole on those so it's about as simple as changing your oil.

 

[smritte]

Big question is if the noise is actually skipping teeth or if it's more a popping noise

This right here is the biggest issue with noise diagnostics. To some of us the difference between a thump and a rattle is obvious. Add in the fact that noise can transmit through things making it sound like its coming from somewhere else. You can get 3 different noises from a CV drive shaft alone. One of them sounds like a chipped diff tooth. Broken motor and trans mounts to some are obvious. I had a car where the customer put drive axles in because his "expert" friend told him they were broken. What he really needed was motor mounts.
My only hope is that its something obvious.

BTW. if you have an issue with the CV ball, it will bind slightly when you bend it. You most likely wont get it to make noise by hand.