Np 263 Transfer Case

memsic · March 24, 2010

I have a NP 263 in my 2002 2500hd silverado...ive rear built the transfer case once already and it seems like everytime that i pull a heavy trailer or put a load on my truck that the transfer case will pump all the fluid out of the case...Any suggestions before i go rippin it apart again????????????????

RaddHazzard · March 24, 2010

Do you have the dreaded rub hole from the pump? Is that why you rebuilt once?

gmtech4 · March 24, 2010

you're making no sense ,what does "pump it out"mean ????

what did you put in it to call it a rebuild?

BrockwayMT · March 25, 2010

Load should have no effect on any leak. Where does it leak?

memsic · March 25, 2010

It pumps all the fluid out the blow by tube, no i didnt have the rub threw pump...i through a u joint and snapped it off the tranny, so i decided it would to a good idea to go through it

BrockwayMT · March 25, 2010

So it pushes the oil out through the vent (I believe it's up on the firewall)? I find it very unusual for the oil to be pushed that high. Have you checked your transmission fluid level? Is the transfercase overfull? If there is too much fluid in the transfercase it's coming from the transmission.

memsic · March 25, 2010

the vent hose goes from the top of the transfer case to the frame rail...its rufflys 18inch hose..but the first time this happened i was pulling a trailer with a s-10 pickup on it and it pumped the fluid out and painted everything transfer case back in fluid. The trans a transfer dont share the same fluid so i dont believe that would be the cause for this, ive tryed ATF and the GM transfer case fluid and still this happens. Im starting to wonder if there is a malfunction in the transfer case pump???? have you ever even heard of this happening?

BrockwayMT · March 25, 2010

I know they don't share the same fluid. But if you use a single lip input seal where you should have a double lip you will have fluid moving between the two.

That vent hose should be up at the top of the bell housing. The picture below shows a Borg transfercase from a H2 but the idea is the same.

BrockwayMT · March 25, 2010

Here's the vent hose on an NV261. The vent should terminate about a foot above the transfercase. The hose needs to be downhill so the condensate will run back downhill into the transfercase.

gmtech4 · March 26, 2010

find the vent for the tranny,it is either by itself or in with the t -case ,an overheated or overfilled tranny will puke tranny oil,the t-case may have dextron as well,if NON AUTO,the t-case seal as said before can fail and let tranns oil in and way overfills the t-case .,the t case vent terminates at the engine/bellhousing mount bolt,upper passenger bolt

the pump inside only as said lubs the shafts and bushings and planetary gear set .

please stop assuming ,the vent for the tranny comes out just above and behind the NSBU switch and it is a hose and will cover the t -case if it pukes out there ,

get it looked at by a tech fast before you grenade something and leave shrapnel on the road lol

ok?

class dismissed

I was a tranny guy for a few years,I've taken a few out ,lol (( a few million!!!!))

i have never ever seen a t -case puke out oil

memsic · March 26, 2010

well considering that it has been to a GM tech already and a few other places and EVERYONE that has a looked at it has determined that it is coming out of the vent..it was proven by running with the hose off..im also a mechanic too not some average joe

So you must not have to much experience dont get cocky with your class dismissed bullshit

BrockwayMT...thanks for your help