GM Pump Rub in Transfer Case

[Sturgeon-Phish]

GM transfer cases 261 and 263 are prone to a condition known as Pump Rub. It is where the pump used to circulate the fluid in the transfer case wiggles back and forth wearing a hole in the transfer case, allowing fluid to leak out and if not caught the loss of fluid will destroy the transfer case.
Know of this condition I installed a modification to prevent the pump rub, but I was too late and had a hole in my transfer case not knowing it. I still had plenty of fluid so the damage was limited to the case housing.
I am currently in the process of replacing the damaged transfer case housing with the pump rub mod to prevent damage in the future.

My point is to frequently check the fluid level in your transfer case, and at the first sign of leakage if you see any, perform the pump bub fix.
Jim

[kw_00]

Thanks!

[Bigfoot_affair]

kw/00 wrote:
Quick question since we are on topic, does the newer 2007.5 and up have the same issue? Just curios, I have looked on my 09 and have not seen any evidence of it. It only has about 73k on it now.
Thanks

NO

[RCMAN46]

kw/00 wrote:
Quick question since we are on topic, does the newer 2007.5 and up have the same issue? Just curios, I have looked on my 09 and have not seen any evidence of it. It only has about 73k on it now.
Thanks

No problem with 2007.5 and up. Different transfer case.

[jesseannie]

Had the same problem in my 2000 Silverado. I had a complete transmission overhaul with upgraded parts to renew and correct the problem. The trannie guy who did my work said the thing that bothers him the most is that it is a defect that GM has known about for years and won't remedy so it continues today.
jesseannie

[kw_00]

Quick question since we are on topic, does the newer 2007.5 and up have the same issue? Just curios, I have looked on my 09 and have not seen any evidence of it. It only has about 73k on it now.
Thanks

[minnow]

Here is a video explaining the Merchant Automotive replacement kit.

My 04' 2500HD is a proud owner of this kit.


Video

[BurbMan]

Thanks guys!

[RCMAN46]

The pump turns with the output shaft. Thus it is in service both 2 wheel and 4 wheel.

The pump is a lubrication pump to supply fluid to the upper section of the transfer case that is below the fluid level.

[partsman01]

[Iraqvet05]

Here are some pics, BurbMan

[BurbMan]

Any pics on where to look for a hole in the housing? Am I correct that when running in 2WD the only thing spinning in the transfer case is the input shaft? So for failure to occur due to lack of lube you would need to be running in 4WD?

Edumacate me here.

[Double_Haul]

You can find aftermarket rear transfer cases here
www.transfercases.com. In Oakland, CA
They come with all the gaskets needed. These cases are built with harder aluminum so you don't need the adapter kits.
Pump rub was news to me until I noticed some case oil dripping. The "pump" is held by clips that eventually break then the pump rubs on the soft transfer case wall and wears a hole. This is not a "might happen" thing it is a "when will it happen" thing. Damage occurs when you loose enough fluid to damage the unit. Since the hole is usually above the fluid line it only leaks when operating so you don't get a big puddle when you park. I would suggest getting getting it done now or inspect the case regularly for any fluid on the outside of the rear case.

[Swampman597]

Mote wrote:

1oldtruck wrote:
http://www.merchant-automotive.com

They have complete cases, kits to fix the problem on your case or just the tail housing.

X2 on the Merchant kit.

[BenK]

There TWO potential issues with these NP transfer cases...

One is that the snap ring for the tail housing shaft doesn't hole it well enough
and allows the shaft to move rearwards. A clamp on collar is that fix. I've seen
kits with new snap ring, but the collar is the best, IMHO

Other is this topic and is with the impeller/pump on the shaft. The first NP's
relied on the chain to drag lube 'up there' and a must was to run in 4x4 every
once a while...like once a month

This pump problem has two types of fix-it-kits. One is a metal plate to increase
the Xfr-Case wall thickness. Those kits are in the under $10 buck range. The
better fix is with a ADDITIONAL disc in the pump/impeller stack and comes with
a stack of gaskets too

Many DIY'ers just epoxy the hole and seems to a be holding from the years I've
read about that one