np1 transfer case

goatboy0067 · January 21, 2013

i have a 2001 chevy 2500hd with an np1 transfer case i was looking around to see what others were using for fluid and i found alot of different answers more importantly i found that this trans has a oil pump rub issue. how many miles were on before it starts and how can i tell if mine has been fixed? there is not a leak from the transfer case that i can tell but the trans has to be turning forthe pump to be working and the case is full. also any input on fluid would be nice. i was going to use the allison approved mobil delvac synthetic atf.

Prokopchuk_9 · January 21, 2013

Is this a duramax? If so it's a 263 hxd transfer case. If its not leaking it will, you would know if it had a hole. From the transfer case back would be smeared in tranny fluid. It's not a matter of "if" it will rub a hole thru, it's when. Go on merchant automotive's website search for the 263hxd pump rub kit. Well worth the $$$$$

goatboy0067 · January 22, 2013

i have an 8.1 the code in the glove box is np1 just not familiar with this doing research. trying to figure out if my transfer case had been fixed already or not. if not ill be doing that soon. also how many miles is it taking to wear through i have 141000 on mine as far as i know. i read there are 4 different variations of this case. any helpful info would help thanks.

Prokopchuk_9 · January 22, 2013

i have an 8.1 the code in the glove box is np1 just not familiar with this doing research. trying to figure out if my transfer case had been fixed already or not. if not ill be doing that soon. also how many miles is it taking to wear through i have 141000 on mine as far as i know. i read there are 4 different variations of this case. any helpful info would help thanks.

That's because it's the wrong code you're lookin at the gassers have a 263hd t-case the diesels are slightly different have a 263xhd t-case. I believe the splines are the same, only difference is where it mounts on the crossmember. We used one out of a gasser once in my buddies duramax, had to fab up a bracket to make it work.

Anyways the only way of knowing is physically leaking oil or dropping it and splitting it to find out. Personally if its not leakin I wouldn't screw with it, if its working fine no weird noises just leave it. You have to split it to find out if it has it anyways, so you may as well just leave it if its fine!! Like my dad always tells me "don't fix it if it ain't broke"

I don't know why gm never made a tsb on this issue, instead they left it for 5 years almost knowing it was an issue. The kit from merchant automotive is good. Here's a vid I found bud

goatboy0067 · January 22, 2013

thanks for the info i found a thread on here "hole in transfer case" ranging over 6 years starting in 06-11. im going to do a little more inspecting on my case. i wish they had an inspection camera that would fit inside.

Prokopchuk_9 · January 22, 2013

No man it's like 2001-2007 classic style. Gmt-900 the problem was resolved..

goatboy0067 · January 22, 2013

i know the tread was from 06-11 the problems are from 01-07 so this is an on going problem that keeps getting drug up again and again. seems the best fix is the Merchant autos plate. i guess im going to pull it apart after i get the kit to see if mine has been done i have 141000 miles and im guessing it has been fixed or replaced.

Prokopchuk_9 · January 22, 2013

The pump rub issue was corrected in 07's and up. Trust me, after 07.5's te transfer case will eat thru rear output seals but pump rub was fixed man. 100% sure.

goatboy0067 · January 22, 2013

i have an 01 so how do i find out if this problem has been resolved in my transfer case without tearing it apart?

Prokopchuk_9 · January 22, 2013

You won't, unless you wanna split it. Man if its not leakin oil. Just leave it alone. Worry about it then or pull it apart inspect. It's not worth taking it apart without Doing a rebuild either IMO

goatboy0067 · January 22, 2013

i would rather tear it apart now when work is slow than when im in the middle of a job and have to rent a truck and have this one rebuilt. from what im told if it hasent been fixed it will leak.

plumbob98 · January 22, 2013

You're correct Eric. I'm a firm believer in prevention; especially when this is a know problem and WILL eventually rub a hole through the case and leave you stranded somewhere!!! If it hasn't shown up yet, it will.

Prokopchuk_9 · January 22, 2013

It won't leave you stranded, it will start a VERY slow leak. Just a pin hole.

goatboy0067 · January 22, 2013

even a pin hole wont take to long to drain 2 quarts. better to get it fixed before i ruin the case by putting a hole in it though.

Prokopchuk_9 · January 23, 2013

I hat two trucks with this issue, it's not something that happens fast. I just kept an eye on them. Soon as I noticed sweating I fixed it. But that's just me, you're probly right just doin it now would be best. If you wanted to split the case. It's an all day event pretty much.