Chevy & GMC Vans

My AWD Astro quickly dumped all of it's transfer case fluid the other day. Apparently the problem is a design flaw that causes this to happen pretty often. I was really surprised I never read about it here before.

There is an oil pump in the back half of the transfer case that sits in a little pocket and is run by the output shaft (news to me, I thought they all worked off of splashed oil) and the pump wears a hole through the soft magnesium case.

Here's my hole, it's about the size of a dull pencil tip.


Here's what happened when I tried to overfill the case so it wouldn't run empty as fast.



I'll be replacing my case since it ran dry for 2 or 3 days before I figured out what was wrong. It drives like new with fluid in it again but I'm sure it's days are numbered now.
Maybe somebody can benefit from this information, and if you're a better safe than sorry kind of guy you can fix your case before it's a problem. There are at least 3 products I've found that are made to combat this problem. This is the cheapest/fastest one, but all of them require you to split the case and add some parts before you wear a hole in the case.

http://www.makcotransmissionparts.com/482460.html

I haven't heard of this issue in the 136's. I have heard of many failures in the GM HD trucks with the manual shift t-cases though. Same thing...they wear a hole and puke all the oil.

Break, where do you live? I still have my awd tcase that has >60k miles on it.

I live in the Cincinnati area. I just got back home with a case out of a 98' Bravada. It's older and has more miles on it than what I want but I'm planning on using it while I look for a good deal on a better one. I would love to have one with around 60k on it.

My buddy just got cut from the Cyclones, but it's ok; he was signed right away by the Victoria SalmonKings and seems to be making an impact right away. And it's a lot closer to home for him.

I'm just assuming it wouldn't be worth it to ship the tcase; imagine it would cost a bundle.

A very good friend of mine films all the Salmon Kings games and creates promotional video's for them. He also covers all of the pro and semi-pro sports in Victoria and some sports in Vancouver.
He is just making a promotional video for the Salmon Kings.
He sends them out to his friends for a preview, here's a peak.
http://www.youtube.com/watch?v=z9BUPAC_VQI

ahhh shit Salmon Kings!!! My french canadian cousin Olivier Filion played for the Salmon Kings the last few seasons! He's now in Kansas City, MO with the Mavericks...

Love me some EHCL ...

Killer video.... Perfect music for hockey... sounds like Canadian Chesser Rock for sure.... Don't get me wrong my years living in Bellingham created a soft spot in my heart for cheese rock... i love it

Sounds like your TC case has same design flaw as the NP246 Auto trac cases in the fullsizes that had "pump rub" from '98 on up to about '04. As you've found they do have some fixes, you can actually try to fix your's even though it has the whole alreayd, it is possibly to plug hole and put in the repair plates. I've got a 246 apart on my bench inspecting before I install into my Tahoe as someone put wrong fluid in my Autotrac case and it's on way out. Lucky, I don't have pump rub in new one, my case had a clip holding pump tight from factory. Your AWD is probably similar to the Autotrac as it has clutches inside like a tranny so it needs a pump to move the fluid through it unlike older ones that got by on splashed fluid.
Here's a couple pics of mine torn apart, pretty easy to take apart. Last pic shows clip and where hole occurs...I got lucky on this one.
Oh, sorry about the Cincy thing...I live here too. I can help you if you want o try to repair yours.

Great pics Blazer. I've read that the clip failing is what causes the pump to wear holes in the case but I've never actually seen what the clip looks like. I know one of the fixes is an updated clip from GM.

The models 136, 146, 246, 261, 261HD, 263HD, 263XHD, and 261XHD transfer cases are all susceptible to pump rub.

I'm going to hang onto my old case but I don't think I'll be using it again. It's not showing any signs of being damaged in any way but it had to be hard on it running low and eventually out of oil. I've read online where a lot of guys JB weld the holes (as many as 3 on one case) and fill them back up with fluid but I would rather just buy a used case for $100 and hope it's a good one.

Found a video that shows exactly what happens to these transfer cases and one of the fixes. The part they use is $100.
http://www.youtube.com/watch?v=Nj5ZS8wOmNk