ok i have a 99 2 door 4.0 AW4. i have this grinding noise that happens at all speeds. its not very loud but its always there. another thing after 30+ minutes if driving i start getting this burning smell if i have the windows open and the floor begins to get hot. i can also feel the heat just by sticking my arm out the window while sitting at a red light. it doesnt overheat or anything like that. tranny fluid is good and red and so is engine oil. what can this be? bad wheel bearings? low diff fluid? maybe t case? any help would be great

 

Where does the sound seem to come from? The front, mid, or rear? With the floor getting hot and you smelling a wonderful burning aroma I would check your transfer case fluid asap. I bought a zj from a guy last year and when I showed up he said "oh yeah, the transfer case is stuck in 4wd becasue the shift mechanism is froze". I had suspected different after driving it so I talked him down and took it home. After my 45 min drive I rolled the window down in town and thought what the heck is that smell? Pulled in the driveway and saw my t case was letting off heat like a radiant heater. NO FLUID AT ALL IN THE TRANSFER CASE!!! I was impressed it made the drive though.

 

Ok so I replaced the transfer case fluid thinking it was low. It wasn't but it was dirty anyway so I changed it. Grinding is still there. I'm beginning to think its my front differential. Could that be doing the grinding noise? Could it be low on fluid?

 

Give me a minute, I'm searching for that app so I can loosen & remove the front diff plug & stick my finger in there from over the interwebz.

 

dude, you know what he meant...

sure it could be low, sure that would cause it to grind, but the gears would fail in very short order. it probably wouldnt have lasted as long as it has. but definitely check it.

if there is a grinding noise,then something, somewhere, will either be full of metal shavings in its fluid ( tcase, trans, engine oilpan/filter, axle, whatever) or it will have obvious signs of scarring on it ( rotor, hub, ujoint, etc etc). figure out what direction the noise is coming from and start digging. you'll find it if you look hard enough.

 

If what they said isn't working, i would get the tranny checked. My tranny made a grinding noise for a while when its throwout bearing went out, now it's degraded to a constant whining noise.