Thought I'd add to this very important thread.

Just went out to Merchant Automotive in Holland, MI yesterday to get my transfer case upgraded. I've had a slow leak on the top of the case for a while. I haul commercially with mine and put about 8k miles a month on it. I haven't been sleeping well as of late worrying about this whole issue. Turned out my leak was just from the rubber plug that locates a certain snap-ring. 76k on my '05 Duramax 1-ton and fortunately it had no damage yet from the pump. They installed their upgraded part and I'm back on the road with a HUGE load off my mind. :cool:

Eric Merchant is the owner of the shop. Very sharp, very good guy. He designed the upgraded part himself and his shop is the only place you can buy it. Once he had my case apart he showed me exactly what the problem is and how his part fixes it. I asked him how likely it was that mine would have started to wear, had I not fixed it and he said it's almost impossible to predict. Maybe tomorrow, mabe 6 months from now, who knows. Unfortunately, you won't know for sure until you have a hole in the case and like Smitty said, you will have a VERY short time to discover it before it kicks all the fluid out and runs the case dry.

These guys at Merchant sell at LEAST 5 of these parts a week and have replaced about 50-60 damaged cases just at their shop alone in the last 9 months or so. This certainly isn't a fluke deal and I would highly recommend getting this taken care of, if this case design is on your vehicle. I've learned that GM has used cases with this design on everything from AWD Astro vans to 1-ton trucks, since about 1998. :eek: The new style '08 trucks have a different case, but it is unknown whether they still have the same flawed internal design.

One of my neighbours is a senior tech with a GMC dealership, his specialty has been 4wd systems for a long time, he said that this transfer case issue seems to not be a problem with southern based vehicles though he was aware of it, he had not seen it.

Now that I've finally seen how the case operates and what the actual problem is, I wouldn't think that the warmer climate would make any difference. :( Maybe if the majority of your miles are highway miles and you can keep the stop and go driving to a minimum, that MIGHT help? I only say that because that's the case with my truck and at 76k I had no damage. Then again, I've heard of people with only 20-30k miles and already having it fail. I don't know. :(

I was under the impression that the problem occured in vehicles with high amounts of 4wd use, such as you get where it snows. I dont know though

Whoops, misunderstood you there! :o

It unfortunately has nothing to do with 4-wheel drive use, that's the real ***** of it all. The problem is in the upper portion of the case, so if you're driving it, it's working it.

From what I learned yesterday, the part in question is a thin plate about 6 inches or so in diameter, that basically is just a guide to keep the output shaft of the transfer case and the surrounding gears and chains and what-not, located in the correct position, as it is a completely floating assembly. The plate has I think four ears on it, which fit into matching spaces in the case housing. That's what holds it all in place. In one of the spaces there's a thin little wear clip that one of the ears kind of rides on. Since the whole assembly is moving and floating, the clip basically keeps the plate from touching the case housing.

The problem is, the factory plate is very thin and the ears have sharp edges on them. What seems to happen is the one ear will rub the clip enough to actually break it. Once the clip is gone, the ears have nothing to ride on except the actual case housng itself. So every time you are on and off the gas, the assembly is sort of moving back and forth and that plate is tapping into the case housing, now in all four spots. There just happens to be one that is a little thinner than the others on the passenger side, which is where the hole is typically showing up.

The aftermarket plate has wider ears on it which fit into the spaces on the case much better and the edges are rounded smooth, so the friction I guess is much less on the clip.

Check out the previous links in this thread from dieselplace.com. There's a lot of info and some pictures about this there. Hope this helps. :cool:

thanks for the info, I am going to print this stuff out and go see my neighbour again:drink:

Update on my end,I have fixed 3 different trucks since posting this thread,2were melted down,one was just dripping and hadn't ran out of oil yet. The problem has nothing to do with 4wd use or snow,its the oil pump ears rubbing thru the outer case once the support clip falls apart. The oil pump is rocking back and forth everytime the vehicles rear driveshaft speeds up and slows down,it turns no more or less when in 4wd. One small dealer I buy parts from has never seen one failed,a bigger dealer I buy from says they have seen "a few". This happens though after 80-90 thousand miles so it won't neccesarily be taken to the dealer as it wouldn't be under warranty,Smitty

New Venture Gear is now owned by Magna International, the Canadian Co. It used to be part of DCX.

Hopefully they will redesign the part.

Here are the applications this case is in.


http://www.drivetrain.com/transfercasesparts.html

Wannabe

Is this problem only on HD 2500 or what?? I just bought a new 2007 1500 Z71. Should I look into this problem?

HayJay,
How much does the upgrade cost? My 02 has 92k and im getting nervous. My transfer case has always been noisy when in 4 wheel drive. The noise seems to go away while accelerating or decelerating but holding at a constant speed the transfer case is very noisy. Anyone else have this problem.