Not very loud, kind of humming noise. I installed jacks under rear axle and was running engine, in drive.
I was listening by stethoscope (with very long rod). In drive (wheels spinning)it was making low pitch sound (not knocking or rattling), but no noise in park (that was stupid to check, nothing is turning in TC, when transmission is in park)
I should probably try in TC neutral.
Transmission(AT) did not make noise.
Slip yoke eliminator was installed 2 years ago. Did installer screw up?
Also big bolt of housing is leaking.
Fluid was fine.
Any ideas for additional diagnosing?
Did anybody try heavier oil in TC? 4x4 works fine.
Thanks.

 

The noise you're describing is of no concern I believe. TC's will humm while running. Try putting a bottle of Instant Quiet in the TC (see pic). I put a bottle in mine at last ATF change and it seemed to quiet it down. It's kind of hard to find. I had to swallow my pride and go to autozone to get it.

 

Thanks, Ken! I feel better.

 

The black color concerns me. The transfer case is supposed to have ATF in it (red). Either you have oil in it, or the ATF is so burned up that it is now black.

I would double check that before you do anything.

 

You can see red drop next to bolt head.

 

Those plugs don't looknthey have been turned in a while, pop the top one out and check the color and smell of the fluid. Not saying this is the cause but if you haven't checked and it's low it might be.

 

If you do manage to get those nasty plugs out I recommend tossing them in your parts box and install these plugs. Makes changing fluid much easier.



Here's a pic of the equipment I used/use to remove the old internal wrenching plugs (10 MM hex/socket) and the tools I use to service the TC.



Your hex plugs look like they've been in there for awhile but you say a Slip Yoke Eliminator was installed 2 years ago so can I assume the fluid was changed then. It's probably a good time to change your fluid now anyway since you're worried about the noise it's making.

 

That bolt/plug in the rear output shaft bearing retainer looks like a mod. I've never seen one before (not to say they don't exist). I wonder if there was a problem removing the refill plug (top plug) to service the TC fluid, and when the SYE was installed, the retainer was modified then inorder to service the TC. Novel idea.

As far as it's leaking; You may want to remove that bolt/plug and see if there's a gasket under it, or simply see if it's tight.