Hole in my Transfer Case

LSVLance · September 4, 2010

Here's the new rear case with the new oil pump housing from Merchant Automotive sitting in it.

Here you can see the much better design the new housing is, it spread the load out across the notches in the case.

I got the T-case back in the truck today. Only about 3 hours total working on it. Not that bad of a job at all. And it made the trip home with no weird noise, leaks or rubs. The worst part of the job was snaking the front drive shaft out and back in to the front of the T-Case. Might have been easier if I dropped the exhaust or at least took the O2 sensor out...but it will fit. You just have to hold it just right.

Not sure how a shop gets 6.2 hours for this job when I did it in 3, guess they build a bit extra time in. IF anyone is nervous about taking it on themselves, it's really not that big of a deal for anyone with a good set of tools and decent mechanical knowledge. Thanks for all the help I garnered from here on this.

Lance

ColoradoSkiCountry · September 4, 2010

jl856 · September 9, 2010

Here's the new rear case with the new oil pump housing from Merchant Automotive sitting in it.

Here you can see the much better design the new housing is, it spread the load out across the notches in the case.

I got the T-case back in the truck today. Only about 3 hours total working on it. Not that bad of a job at all. And it made the trip home with no weird noise, leaks or rubs. The worst part of the job was snaking the front drive shaft out and back in to the front of the T-Case. Might have been easier if I dropped the exhaust or at least took the O2 sensor out...but it will fit. You just have to hold it just right.

Not sure how a shop gets 6.2 hours for this job when I did it in 3, guess they build a bit extra time in. IF anyone is nervous about taking it on themselves, it's really not that big of a deal for anyone with a good set of tools and decent mechanical knowledge. Thanks for all the help I garnered from here on this.

Lance

Can you give a step by step how you got the case out of the truck. Do you need a transmission jack? How much does the case weigh. Any help appreciated.

Jeff

LSVLance · September 9, 2010

It wasn't nearly as bad as I thought it would be. The case itself weighs about 90 pounds or so.

Here are pretty much the steps I took to get the transfer case out.

Drain fluid from Transfer case

Remove rear drive shaft.

Remove front drive shaft

Remove Transmission cross member (requires supporting the back of the transmission up with something)

Disconnect the 3 or 4 electrical connections to the T-case

Disconnected the transmission shift cable from the trans (might not be necessary but I didn't want anything to hang up on it)

At this point the 6 bolts holding the T-Case to the transmission are all that is holding it in

When you loosen those up, you will get a little bit of trans fluid spilling out, but it won't be much

To remove the T-Case, I had the truck on a lift and a friend of mine held it while I took the last bolt out, we then together lifted it up, moved it towards the back to get it off of the transmission, then tilted the front of it down and lowered it out of the truck. It's probably easier to do with your hands than a trans jack because it's pretty light and needs to be moved around just right to get around everything.

Re-installation is just a reversal of the above. The only difficulty I had was with the front drive shaft, the exhaust pipe, O2 sensor and front differential make it a pretty tight fit to slide the drive shaft forward enough to get the other end out of the T-Case. I almost had to drop the exhaust but it has just enough room to fit.

Hope that helps some...

sidth · September 12, 2010

Does anybody have any idea what the original oil pump housing is made of material wise??

sonjaab · September 12, 2010

That part of the case where it gets the rub hole is magnesium.

The rest is aluminum. IIRC.............

sidth · September 16, 2010

That part of the case where it gets the rub hole is magnesium.
The rest is aluminum. IIRC.............

Ok thanks.

Shawn T · September 16, 2010

I am at a total loss. I can see the oil spray pattern, and it is directly around the yoke on the output shaft. The only place there is fresh oil. There is spatter everywhere, but it looks like just that spatter. The oil spotting on my garage floor is directly under the yoke also, not one spot under the case, and it is parked in the exact same spot every time. I know this because it barely fits in my garage. My transfer case is a NP1 and from what I can tell on the outside is the "bumps" where the ring keys on the inside, there is no hole, in the bottom. I can't see the top. Could I just have a bad output shaft seal? Am I wishful thinking and the hole is really tiny and I can't see it somewhere on top of the case? WTF?

LSVLance · September 16, 2010

Clean everything underneath there up with brake clean and rags...get the back half of the T-Case really clean and dry. Then drive the truck just a short way, wit won't take long and the oil will show.

I had my truck on a lift and just putting it in gear and then stopping it right away was enough to see where the oil was spitting out of the tiny hole in the case. It didn't' spit much when in gear and "moving" but as soon as the brakes were applied oil puked right out the hole.

You won't be able to tell for sure until you clean everything up real good first.

Shawn T · September 17, 2010

OK, I will clean it up and have a look. I'll probably need to snake my camera over the top, or get a mirror to see it. I'm dreading the inevitable. So I guess I can buy the new pump retainer ring. Do they sell the new rear housing for a reasonable price too. I am probably asking questions that have already been answered but I'm still trying to diagnose it. My case looks different that the pictures. Maybe just because it's not on the ground.

Hemipede · September 28, 2010

I'm going to go ahead and post these pictures in case it helps anyone else decide to go ahead and fix this before it wears through...

Okay, here we go...

Hole the Transfer case came out of

Back half of the case removed

Only parts removed from the Transfer case

The oil pump housing sitting in the back half of the case

Look how sharp the edges of it are

The spring clip (bandaid fix) New Process put in the cases to keep the oil pump from rubbing through the case

The part of the clip that broke off

That is the loose part that was stuck to the magnet in the bottom of the case.

Better picture of the hole wore through the case

Where one of the other cogs of the oil pump was also wearing through the case.

If you have a truck with a NP or NV transfer case and it has many miles on it at all, I'd highly suggest putting the Merchant Automotive $175 fix in it BEFORE it wears through and you chance destroying a $1500-2000 transfer case.

It really isn't that big of a job and it's cheap insurance.

Hopefully I'll get mine back together and back in the truck this afternoon after my new parts get here.

Does anyone have any pics of a NP 149 being reassembled? I'm rebuilding mine and I've reached the point where I've put the chain back in but I can't figure out where the carrier retaining ring goes. Help, anybody?

peculiarmike · September 29, 2010

Add my 2001 Silverado 2500HD 4X4 with V8100 & Allison, 187000 mi., to the list. I tow a 26 ft. RV trailer, 20 ft. Champion bass boat, 17 ft. Tracker bass boat and a couple utility trailers with it off & on.

While installing a new set of shocks my mechanic noted the underside of the truck was coated with some sort of fluid. He traced it to the transfer case and guess what? There was a hole in the rear portion of the case. And not much fluid left in the case.

Not a cheap repair.

And another little item - I had two Chevrolet dealers nearby, one 6 miles north, one 6 miles south. Both are no longer in business because GM closed them down. Both were viable dealers, though not huge, and had been in business a long time. Now I have to drive 45 minutes to an hour, depending on traffic, to get to a GM dealer.

BUT, there IS a Ford dealer 6 miles south. And the former Chevrolet dealer 6 miles north is now a Chrysler dealer. Hmmmmmmmmmmmmm..........................

Wish I'd kept my '93 GMC K1500. I sold it at 300000 miles and bought this little sweetheart. It still looked & ran good and I still see it around. I put 2 alternators and 2 power steering hoses on that truck while I had it. And washed it once in a while.

tim73 · November 4, 2010

I just finished mine today. The little clip on the transfer case was actually in one piece. But the clip itself had worn through the case and since it allowed the pump to move the other fingers, that dont have clips(Cheap design), had eaten into the case too. I held up the case with a flashlight on the backside...and you could see the hole really good. Anyway, seeing as i couldnt afford a $300 new rear case right now. I elected to JB Weld the inside and outside, and install the $50 stamped "case saver".

The job itself is a bit aggrivating, just make sure you have some good lock ring pliers. I got some from oreilleys, made in the USA even, but they didnt quite open up wide enough. Sears has a good set though. Plus, a good idea to mark which side the speed sensors go on. Guy at the transmission shop said it matters(I chit chatted with him a few weeks ago), I marked mine so I dont know this from 1st hand experience. Also, when you go to put the two halves back together...you kinda need three hands. One to hold open the snap ring...and two to lower the case, while making sure the shifter shaft aligns properly and trying not to smear the RTV sealant too much.

So far so good. I did opt to replace the rear shaft seal

SVGA1 · November 8, 2010

Hello all,

New guy here and I have read all the post in this thread...very good info here!

I too have the hole in my transfer case, 2004 GMC 2500HD with 168000 on her. Problem here is I noticed the problem way too late me thinks. When I drained the fluid I got very little out of it...less than an ounce I would say. The hole showed up in the winter and I never noticed the leak! he fluid was very thick and silvery in color. I really hope that replacing the rear half, chain, and pump will fix it? Or am I better off buying a reman for $1500+ ?

At the moment I believe the chain is now broke as when I first noticed a problem the chain was stretching and slipping over the gears...at least that's what it felt like. I took it to a transmission place and he took it for a test drive...now the 4WD does not work at all. I can hear the motor moving but there is no indication that the front axles are under power now.