Basically:

• I have a 2006 H3--I replaced its shift fork in the transfer case 3 years ago, because the H3 wouldn't even make 90 degree turns in slow speeds. This worked!
• Recently: Some unrelated problem caused damage to the front drive shaft and so I had to remove the front drive shaft until a new one could be ordered. It drove fine as a 2wd vehicle without the front drive shaft.
• The new front drive shaft was put on--The Hummer suddenly won't turn again. The mechanic who put on the front drive shaft claims it needs a new front differential.
• Another mechanic said he opened the transfer case and it was WELDED into 4 hi-lock (which makes no sense to me) and thus suggested a new transfer case.

So which should I buy: a new transfer case or a new front differential...or something else!?

 

I would not buy either until I knew which one was needed. You should be able to inspect the front diff yourself pretty easily. I guess there is always the chance that both items are damaged, but I doubt it.

 

Thank you- I just don't even have basic car knowledge enough to look at the front differential and determine whether or not it's damaged...or to even find it

 

What do you think of the mechanic saying that it is "welded into 4-hi lock"- does that even make sense??

 

So you changed the shift fork a while ago, and it drove normal for a time until the front drive shaft was damaged?

If the transfer case gears had, for some insane reason, been welded into 4hi lock, it would not have driven normal for any amount of time after that. In 4hi lock you would have noticed substantial binding/tire skipping when turning on pavement. I rarely would suggest this, but you might consider taking it to a dealership. At the very least they'll have mechanics on hand that have seen a few hummers.

Good luck, let us know what happens.

Edit: the "not turning" symptom you are talking about seems to me to be pointing to the transfer case more than the front diff. If the transfer case is stuck in 4hi lock, youll get binding when trying to turn on pavement. I highly doubt it, but perhaps when you had the shift fork replaced they put another plastic one in that has since failed again...? If I'm not mistaken they switched to a metal shift fork in 2007 or 2008, and any repairs since then use the metal fork. But maybe someone had an old plastic one laying around and threw it in your truck...?

 

Thank you for your response! To clarify, the turning problem happened immediately upon replacement of the front drive shaft; I thought this was odd.

I did specify when I replaced the shift fork a few years ago that it had to be a metal one, but sure, they could have duped me...

Also thank you for your suggestion to go to a dealership; I will see what they can do. Hopefully it won't cost me an insane amount!

 

it sounds like you need to look at the fluid in both the of them. One of them got hot and burned up the fluid and has caused some issues. or your driveshaft was installed properly and damaged something. I know a couple of people had the same issue, and had the differential gears all replaced and that fixed the issue.

 

That's very interesting! Thank you!!

 

Sounds like the tcase. The Tcase actuator actually. Try shifting from 4hi lock to 4hi several times then low lock and back to 4hi unlocked. Drive in reverse 10-15 feet. Sometimes the actuator can get stuck if the drive shaft to the front is out for a while.

 

Thank you for your insight! It had been driven for a long while without the front drive shaft until I could find someone to put a new one on. Ok so this is bizarre- I definitely have tried driving forwards and backwards and trying to shift by pressing the buttons. Then yesterday, I just pressed the 4 hi lock and then 4 hi one time....and suddenly the hummer is out of 4 hi lock!!! (It has been stuck there for months and I really did try all the tricks before seeking help).... I guess I can cancel my apt.....rides like a dream again.