Sorry for the long post and questions but I am hoping that the little bit of history will assist in getting accurate guidance.

Through circumstances that would take too long to explain, over the weekend I was given the "opportunity " to drive my brothers 99 Bravada 2,700 miles from New Jersey to Phoenix. In preparation for the drive my brother had the vehicle serviced (oil, fluids and general once over) as well as new tires. Through 2000 miles and 8 states she drove beautifully with not a single complaint. Somewhere close to the New Mexico border I stopped to fill up and while accelerating to get back on the 40 freeway she shuddered momentarily and let off a small burst of smoke. since she continued on without issue I attributed the problem to bad gas or a miss somewhere in the ignition system. We continued on 21 miles running flawlessly when all of a sudden she lost power, revved quite high and the gauges went nuts. I quickly pulled to the side of the freeway and gave her a look over. Nothing noticeably wrong. Being precariously perched on the side of a major highway I decided to attempt to restart and limp to the off-ramp about 300 yards away. She started up but the engine ran poorly, the ABS light was on and she would not shift out of what I assume is first gear but she got me off the highway. I searched the web and found many posts attributing these exact problems to the VSS sensor on the transfer case. With a renewed sense of hope I crawled under to find a 1" hole in the transfer case (pic attached). At that point I had no choice but to tow her to civilization and rent a truck and trailer to get her home. We are home now but of course the problems persist and I have a few questions that will help me determine the right course of action. I am a relatively proficient weekend mechanic and tinkerer and have rebuilt a few cars and a ton of motorcycles but have no experience with AWD/4WD or its inner workings. My questions are:

1- Is it likely that the poor running of the engine can be attributed to the current condition of transfer case or could the breaking of the TC and the ensuing havoc have caused an issue with the engine?

2- What is the likely cause of this type of catastrophic failure of the TC? Could something have gone wrong in the engine that would possibly cause this?

3- Assuming that simply replacing the transfer case is the correct course of action , how hard is it or how long would it take for a decent weekend mechanic with righteous set of tools to complete the swap?

If you made it this far thanks again for reading through and thanks in advance if you can shed some light for me.

 

Well, at least the undercarriage is now coated! I would say that the puff of smoke was the trans fluid coming out of the vent tube, Then you drove 20 miles with it low on fluid, and it slipped. over revved the transfer case which blew up. When mine did this, I blew up the rear end and had to change the axle.
I would say that the transfer case is a symtom of another problem. Get one from a scrap yard and throw it in. the seal on the input shaft of the transfer case is the rear seal of the trans, Therefore you'll be starting off by dropping the pan and draining the trans.

 

Thanks! Yep the undercarriage is definitely coated. Please help me understand what issue this may be a symptom of. I can grab a transfer case from a local scrap yard for $200 and put it in but I certainly don't want a repeat performance. Anything I can look for?

 

It's possible that either the tcase was over filled during service or more common that the rear output seal on the trans gave out and over filled the tcase and with heat expansion it found the weak point in the tcase and that was your failure point. Check your trans fluid level my guess is you will find that it's low. Get new a new tcase and be sure to replace the output seal on the trans when you replace the tcase. I've done it more than a few times but I can do a complete r&r of my tcase in under 30 min so a couple hours in your driveway with no special tools required and you should be back up and running.

The other opposite end of the spectrum would (which the lack of trans fluid around the hole make it seem possible) be that the fluid was drained and never refilled and the heat eventually caused something to let go inside the case and blew through the case. I'd be interested in seeing the inside of the tcase if you open it up.

 

Thank you so much. I think I will give it a go. Is there a write up or particular manual that you recommend? Any tips or tricks for a first timer?

Thanks again. I truly appreciate your response.

 

Remove driveshaft at the axle and slide out of the tcase, un hook electrical wires and vacuum lines from tcase, remove 6 bolts holding tcase to trans while supporting the weight of the tcase and than slide it straight back a few inches off the output shaft in the trans and your done! Be sure to pick up a new paper gasket for between the trans and tcase as well as the output seal. I would replace the output seals on the tcase as well before installing it just for piece of mind. I would also suggest a stick of gasket adhesive just to help hold the paper gasket on the trans while you install the tcase because they can be a pain to get in place and are very easy to tear otherwise.

 

Thanks again. You have helped tremendously. I will get'er done this weekend. I'll send those pictures when I get it off. There is quite a bit of fluid spray up on the undercarriage but nothing around the hole in the transfer case and the car has not left a drop anywhere.

 

I was reminded of the 1 question that I still have while pulling the bravado off he trailer. It idles terribly. Really rough and loud. Can this be attributed to the Transfer case of is it likely the engine somehow got damaged in the process?

 

Ok guys I am hoping you can help. I got the old broken transfer case off and it sounds like a can of bolts when you shake it. Bone dry. I am now trying to get the replacement transfer case on and cant seem to get it to go back far enough to get the transfer case on the transmission spline. I have tried everything that I can think of and no matter how I turn or angle the transfer case I just cannot get it. PLEASE tell me what the trick is. I am at the end of my rope here!

 

Sorry for the late response I saw this the other day and wanted to wait till I was on my laptop to respond for my own ease lol!

What did the new case come out of?
Are you certain it is the same bolt pattern?
Have you measured the depth of the input shaft against the old case?

I have never had a problem getting either of my cases to bolt up to the transmission. Can yo post some pics of them side by side please?