@javacontour
Update:
We lifted the car and put it on jack stands and considering the unibody design, specific and limited number of jack points, not being a real mechanic, using only one floor jack, etc. it was a little bit of fun.
I verified the noise was coming from the part that sits right behind the rear diff.
Eric from the South Main Auto Repair/Channel calls it viscous coupler. Refer to the video in post #2 by
@ctechbob and later by
@javacontour. Dealer called it 4WD Coupler.
We have 4 or 5 dealers within 15-40 miles. I called my only favorite dealer and the first thing the service dept guy told me was not to spend that kind of money on it ... He said the part should be about $1400 (he didn't do a computer check) and the repair cost would be $2500-$4000 depending on what's wrong ...
Eric (South Main Auto Channel) said $1400-1500 for the part but I think his video is 6 years old. i.e. the price could be even higher now.
now that we confirmed the source of the noise, I went back and carefully watched the video without interruption and paid attention ...
1- The car in the video is AWD and mine if 4WD. But I think it's the same problem even though the noise that Eric is describing (that the customer is experiencing) is different that mine ... It's the same part and location and the diff between awd and some 4wd can be somewhat foggy these day. So the odds are that it's the same part that is failing.
2-
Eric said in the video, "if I can do it, so can you". Wrong! lol
That guy is pretty resourceful and knowledgeable. I enjoyed watching that video. I'm sure he was talking to real mechanics or at least a half mechanic with lots of tools.
I seriously doubt any "city mechanic" would be willing to do the job. I'll have to ask them to watch the video and then try to repair (assuming it's the same problem), order parts, car sitting in their busy "city" shop for a few days ... It will be cheaper to buy the part at that point. As I mentioned before, all the shops I contacted, referred me to the dealer. Maybe I should find a small city or shop like someone suggested (backwoods shop?).
3- another big thing that reconfirmed my initial thinking (post #1) at the end of the video, Eric was going to give the car back to the owner (while waiting for parts) with the coupler and drive shaft removed. He said that she can drive it in 2WD for a few days ... Not sure if they experienced any issues (e.g. any engine lights, etc.) or not. I am going to read the comments in that video just in case ... But that's what my original intention was. Something quick and cheap to keep the car as a 2WD. We have an AWD and 2 other 4WD cars including my Tundra so I don't mind losing the 4WD option on this car. Maybe we can just remove the rear diff (not the coupler) main gear from the housing (pumpkin) and seal it back . Not sure how difficult that is. As long as 4wd is not engaged or no slip is detected, the coupler and rear diff and the drive shaft are free spinning via the rear tires and removing the rear diff gear should stop the rotation. If slip is detected once in a while, the coupler and xfr case will engage momentarily and will make a little noise. I'm just thinking out loud ...
Removing parts and making it a 2WD is still on my list.
If I can find a reliable part and keep it all under $2000 is an option but I like the idea of removing parts for under $500 and making it a 2WD if my research shows that besides losing the 4WD, there will be no other safety implications. I
Ayways, I need to do more research and decide.
Thanks everyone (including Eric at South Main Auto Channel) for all the help and info!