The history:
I have a 98 ford explorer 156k miles. V6 automatic AWD w/ 4WD. I recently took it in for a rebuild on the transmission due to 3rd gear slippage. When I picked it up (after business hours) the dashboard lit up like a christmas tree with code lights about 4wd & OD. It drove fine and I needed the vehicle so I took it and called the mechanic the next day. He advised me if they did something wrong they would fix it but he would have to run the codes to know what was going on. He told me if it drove fine it was ok to take my time about coming in. Since it was an hour drive (and time off work) I waited till the following week. They ran the codes and determined that they had forgot to "plug my 4wd in" and it was throwing every code possible for that system. Lol...

The problem:
During the week I drove it I noticed a distinct grinding / chunking noise when I punched the gas hard at any speed in any gear. It happens about 85% of the time and is sometimes light noise and sometimes very bad.
I knew previously that I had bad ball joints so I figured it was that issue making a grinding noise based on the truck rocking back when I gassed it hard.
After about 2 weeks of hearing the grinding occasionally, it gets to bothering me so I go get the ball joints fixed. New ball joints and it still grinds... Now Im really worried it the transmission so I go back to the transmission mechanic yesterday (another half day off work and hour drive) and he test drives it. Tells me it is the transfer case going bad. Also tells me it wasnt like that when I picked it up because they 'test drive' every car after the work is complete (but somehow didnt notice the flashing codes on this test drive).

The question:
Is it possible while rebuilding the transmission or installing it, that they damaged the transfer case?
Are these systems connected directly to one another?
Is it possible that my 4WD being unplugged for a week or so of driving could have caused an issue in the transfer case?
Is it possible that if the 4WD was 'unplugged' the AWD may have also been disengaged and as a result caused an issue in the transfer case?
Is it likely that its just normal wear on two closely related systems and I should just suck it up and get it fixed?

any advice would be greatly appreciated.
thnx!

 

I have heard transfer case chains make a noise similar to your description when they get loose and rub the case on hard acceleration, but usually at even higher mileage than yours. Regardless of the cause you are probably wasting your time pointing fingers and arguing over it. If it is indeed the T/C they are tough and I doubt that their mistake caused any dammage.<O</O