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Discussion Starter · #1 ·
i have found another victim of the dreaded pump rub wear. my buddy has a gmc with the duramax in, and he came in today and showed me the hole. this is the first one i have seen in person. you would think by now that gm would recall their #!&* up!!! does any one know for sure if they ever will, or any where to go to try to get them to??
 

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i have found another victim of the dreaded pump rub wear. my buddy has a gmc with the duramax in, and he came in today and showed me the hole. this is the first one i have seen in person. you would think by now that gm would recall their #!&* up!!! does any one know for sure if they ever will, or any where to go to try to get them to??
what pump rub is this? Is it LLY only? All LLY's?

Cheers
 

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I doubt they ever will. And it's not limited to any year model. My LB7 had it. Gotta love it.
 

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Does this pump rub occur on the manual transfer cases?
Yes, the tang that drives the oil pump breaks the steel clip off that protects the case then quickly rubs threw the case on all the HD trucks. Some say to add 1 extra QT of fluid and change over to syn 20wt motor oil to help with this issue.
 

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Yes, the tang that drives the oil pump breaks the steel clip off that protects the case then quickly rubs threw the case on all the HD trucks. Some say to add 1 extra QT of fluid and change over to syn 20wt motor oil to help with this issue.
I don't really think that it helps prevent the problem. The design is just a complete screw-up on GM. What the oil switch does, as I understand it, adds better lubricity to all the working parts. Dex III or IV gets pretty hot as the t-case generates a lot of heat. There are probably a few hundred threads to which is the better oil to use. I just went through a total rebulid of my t-case. I am running Mobil 1 5w30 full synthetic. My t-case is as quiet as a pop-corn fart. Tell your friend to get a hold of eric at Merchants and order a new pump from him. You can "patch" the hole with some JB Weld or do it right and get a new back half for the t-case.
 

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What about the new 07.5+ trucks? The transfer case looks different on my truck compared to my brother's '05 one ton? Maybe they addressed this issue?
 

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As far as I know, the model # of the t-case with the problem is NP263X-HD. I'm not to sure about the NP261. Maybe someone else might have some other info to add
 

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gm didn't design the case they just use them. Yes once again we're stuck fixing an inherent defect not of our own accord. Not a huge issue, but I'd rather not to have to fix my truck, but hey i drive it and eventually somethings going to break. I'm just hoping to keep it to a minimum. The way I look at it, either I fix for $250, hope it doesn't ever wear through, or trade for something else, which is a lot more than $250.
 

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NP261X HD is the manual one cause it is in my truck.
My brother Monkeys T Case is a different looking case but is manual as well.
Mabey he can post his model number. They used to make things so simple on these trucks one T case for 1500 and 2500 one tcase for 3500 and they took gear oil.
 

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I'm pretty sure that regardless of the housing, they all use the same oil pump design. Stop spending so much time worrying about it, and get out and drive.
 

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1999-06 with the NP-1 and NP-2 or shall we say the 261 and 263 transfer case are subject to the rub.

It has been seen in the 1500's with the "Auto 4WD" transfer cases as well, it is a problem handed down from New Process/New Venture the folks who made this case, and they make cases for alot of other auto manufacturers.

As for the 07-08's?? Have to get with Merchant auto.

the Oil instead of ATF is for the ATF will/can cook off, and run the case dry. some folks have seen the case dry, without a hole and wonder where it went.

Look for the article from Mike L about the t-case fluid update or something like that.

Instructions to install the pump housing are in the DIY section, look for Transfer case pump upgrade.
 

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What kind of oil cooks off int these t-cases?
 

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Discussion Starter · #15 ·
my friend got the plate to fix his transfer case. got it from kennedy diesel. only paid $50 for it. he really didnt want to spend the $250 for it, but hey i dont blame him. its in the body shop now from deer damage, so hes low on money.
 
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