DIAGNOSIS HELP: TJ Rear - Bump & Grind
Let me start by saying, I'm handy and can fumble my way around repairs via a Chilton/Haynes manual, but I'm not a mechanic, so please -- go easy on me.
I have a used (125k) TJ, 5 spd, that I've owned for all of four months. I have limited (and likely bogus) info on previous owners via the lot that I got it from; for what little it's worth, the CarFax I ran came up clean. No real mechanical issues to date outside of a lingering whine when pressing in the clutch, as if something was slowly rolling to a stop, but no problems or resistance to gear shifts ... I've been guessing it's the throw-out bearing going bad.
So today, a cold morning, I get in, head out, and halfway up a moderate hill in our subdivision (but moderate RPMs), I hear a loud "clunk" from underneath the body, followed by rhythmic grinding that sounds like it's coming from the back end.
* The pattern of it is roughly a slow "cuh-cuh-CLACK, cuh-cuh-CLACK" that parallels the speed.
* Other than the terrible noise (that goes right through the frame and into the pit of my soul), it drives/accelerates/rides "normally".
* Engaging 4wd hi/low, clutch in/out, forward vs. reverse -- none of it makes any difference.
* However, turning to the point where the body leans (esp. to the left) quiets it up briefly.
My suspicion: The rear differential just died, and if I open it, I'll find the metal-shaving equivalent of used coffee grounds. Lovely.
Worth noting: A quick inspection of the rear diff. revealed some grease-pencil writing on it (so prob. replaced/rebuilt recently?) and while the lube level was low, I was more disturbed by the brown-sludge appearance of it.
Before I throw any money at this problem, any thoughts, suggestions or been-there-myself insights? Thanks!