Hole in my Transfer Case

tlap · November 14, 2010

I just found this thread too, and it really opened my eyes. I have a 2003 1500HD and the tag on the transfer case has 246 GM on it. ID card in the glove box has a NP8, which is a NVG246 Auto Track.

I use the truck to tow my toy box, but the truck only has 57,000 miles on it.

Generally how many miles is on a truck that this problem starts to show up on?

I'm thinking that changing the case saver now might just be a cheap insurance policy.

I have watched the Truck U video and seen all the pictures and directions posted (THANKS).

My second question is, when you get the T-case out and split apart, you have to take off a snap ring in order to remove the bearing. Will the bearing just slide off the shaft? or is it a press fit?

EDIT;

I just found this link, great detailed instructions

http://www.merchant-automotive.com/tech/tcp.pdf

Edited November 14, 2010 by tlap

oakridgedriver · December 5, 2010

I have an 04 1/2 ton with the same transfer case....I noticed a year ago that the truck would "lose" drive, will going down a steep hill, similar to slipping out of gear if being a standard transmission....you could depress the accelerator, and nothing would happen. At that point, selecting 4x4 high, or auto 4x4 would then engage "power" back to the drive....

Never noticed any leaking fluid in my newly paved driveway...then one day noticed the blue drips....checked everywhere, couldn't find leaks, cleaned it all up, chalked it up to being leaking seals due to age....(345,000 kms) again, started leaking....checked through this site, found the threads concerning "pump clip rub" and behold!! There, in photos, was the EXACT same pin holes where I found mine....

I initially used some "seal-all" brand sealant, which did not work well whatsover....it did last a couple of days, but seems to get brittle once cured and exposed to the heat....although it stuck well, the fluid migrated between the seal-all and the case.

Tried jb weld, a thin application, which did work very well, for about 3 weeks.....then a small sliver of a hole poked through the patch and leaked again. Scuffed up the existing jbweld with sandpaper, and applied a heavier coating, which has not broke through and is dry 10 months later and about 18,000 kms.

Noticed a leak once again, not coming from the same spot.....

again attributed the leak to aged seals, and replaced the rear yoke seal with a $25 seal....a few days later, noticed more leaking. Replaced the rear seal again with a top line seal $50., cleaned up the yoke, applied the grease etc...noticed more leaking.

Traced the leak back to the "valley" on top of the transfer case. Thought it may be leaking through the rubber inspection plug, of which there is none available in Canada.

I cleaned the old plug, the area surrounding where it inserts and have tried using seal-all on it when replacing (didn't work), used some gasket sealer (didn't work), and most recently weld-bond (didn't work).....the plug arrives to the dealer next week from pennslyvania.

You cannot see the top of the case and have to use a mirror to view so working the area is a bit difficult. I am wondering if anyone has had experience with this issue? Could there be more pump rub leaking in the upper area? ( i have viewed all the photos above, but can't determine if the any of the other bus' or tabs extend to the upper valley of the case)

If so, does anyone have a photo of such? I cannot see any cracks, slivers or holes where fluid may be coming from so I believe it is coming from the rubber plug....can't be sure however and the plug still feels soft and flexible. Would it not be "sealed" when any of the above products were applied when I re-installed the plug, allowing time to cure?

Is there a "proper" sealant that can be used to apply to the plug when replacing? I want to rule out any leakage from that plug....also, why would or how would fluid be being forced out of that plug, as it sits on the top of the case, and it appears to be the only place where any air flow could get in/out of the case, meaning; how would pressure be built up in the transfer case to force the fluid out through the plug??? Otherwise, there would be a one way valve somewhere, to allow air in, and prevent fluid from being forced out.....

Thanks in advance for any replies or advice. I am heading out in the cold to see if I can take a close up pic and post.

tlap · December 5, 2010

My truck only has 57,000 miles on it but I decided to play it safe and install the "Riverside" kit.

Here is what I found when I split the cases.

In this shot it shows the clip has worn on the back side too.

This shot shows the plate over the pump.

This one just shows how much the tabs come up over the pump fingers.

oakridgedriver · December 5, 2010

Answered my own questions....

Upon using my mirror once again to view the top of the transfer case, this time the pinhole i could not see, has grown consirably, to easily see now....

The hole has appeared in a very similar spot as the first one did, as shown in other pics above, courtesy of earlier posters.....

Of the 4 slots, 3 will succumb to the pump rub, the 4th is in a much more solid area, plenty of material/strength "fins" surrounding it. I will do a little pre-emptive application and have cleaned the area with brake cleaner, scoured lightly with sandpaper and will now apply jbweld to it, and the remaining area that does not have any perforations (yet)....hopefully that will take care of it for some time....as the first hole that appeared, I applied jbweld to it 18,000 kms ago, and it shows no sign of any further penetration. From what I can see, yes the 4 bus' will continue to receive wear, however using a sheet metal screw and a rubber washer as some posters have done should work even better, as once the screw is in place, it would provide a much more wear resistance surface then the magnesium casting housing.....I think I will try that next, if any of the repaired areas begin to leak. That seems like a far more reasonable conservation of funds then replacing an entire case housing that otherwise has nothing wrong with it.

As for the good folks at the 3 dealers I spoke with here, all deny knowing of anything like this problem whatsoever.....along with the useless braking system that g.m. installed on their trucks for a decade.....but, once I informed them I was on the g.m. forum, and saw all the people that have brought their trucks in for identical issues, they quickly appeared somewhat "sheepish".....

I will post pics after I complete the repair.

Shawn T · December 9, 2010

Wow this has been a pain in the butt trying to find this "hole". I cleaned it with brake cleaner 3 times, never to find it. But, it kept on leaking. It almost looked to me as if it was "crawling" up to the output shaft from the upper U-joint. Call me crazy, so I had a second opinion. I recently needed an alignment and asked the repair shop to clean it up and take a look. Come to find out, there is a pinhole in the yoke itself. Right in the end. The fluid is running down the spline, on the inside, and making it's way out of this hole. The centrifugal force just lamb-bastes the whole undercarraige of the truck. This is what made it so hard to diagnose. Also, my T-Case looks nothing like the ones in the photos. I asked the mechanic to run all TSB's on my VIN and the T-case hole was not one of them. It came up for the same model of truck 99-05, and some 06's but not all. A couple of questions: Did they make an updated NP Case in 06 on later year models? Has anyone heard of the yoke cap forming a hole? It's kind of ironic because a year ago, I had some warranty work done at the dealership and the mechanic said "Oh BTW you have a hole in the output shaft causing this mess underneath". I thought, no way, and found this post. So all of the while, I have been trying to locate a hole that's not there. In the end, he is putting a dab of high temp, oil resistant silicon on the inside of the yoke and replacing the output shaft seal for good measure. The hole is so small, it wont take much. I told him to add it, and let it set up overnight. This will allow it to dry, so when it splines back together the shaft spline does not "grab" the wet silicon, and the oil won't wash it away. If this doesn't work the only other fix will be replacing the yoke, I guess. Just thought I would throw this out there, to anyone that may be experiencing this issue. On the bright side, I'm not replacing the T-case, and the parts and labor only came to $136

Kroynon · December 11, 2010

Just found this thread and what an eye opener.

I have an '03 1500 HD RPO NP8 just about to roll 200,000 kms. No problems yet but I've decided to pull the case and add the Merchant Automotive kit to be safe.

For anyone else considering this, I just ordered online and they are on now for $99.

http://www.merchant-automotive.com/transfe...pgrade-kit.aspx

Edited December 11, 2010 by Kroynon

brianbram · December 17, 2010

Just found this thread and what an eye opener.
I have an '03 1500 HD RPO NP8 just about to roll 200,000 kms. No problems yet but I've decided to pull the case and add the Merchant Automotive kit to be safe.

For anyone else considering this, I just ordered online and they are on now for $99.

http://www.merchant-automotive.com/transfe...pgrade-kit.aspx

I just put the Merchant Automotive upgrade kit in my 03 Chevy 2500HD today (plow truck with 36000 miles). The clip that protects the t-case from pump rub/wear was broken but still in position. The broken tab was stuck to the magnet. I did the repair as a precaution after stumbling upon this thread also.

Doing an 05 GMC 2500HD (plow truck w/77000 miles) tomorrow. Also as a precaution. The Merchant part is a good quality fix.

Good luck!

jcwaddell · January 31, 2011

Just to add to the statistics:

My 2005 Silverado 1500 Z71 was just diagnosed with a hole. It has about 115,000 miles, I don't use 4wd very often - just every now and then in the winter when there is snow on the ground, and it doesn't tow more than a small trailer with an atv or mower a few times a year.

Mine has the push-button auto 4wd controls.

Edited January 31, 2011 by utexalum

RaddHazzard · January 31, 2011

Thats a bummer. I have a similar truck and have not heard of this problem on the 1500s transfer case. Most cases are HDs.

Riverjet502 · February 1, 2011

Just curious guys what model of transfer case seems to be the most problematic with this issue?

oiksy05 · March 24, 2011

Hi all, just wondering if there is any noise associated with this issue? I have a 2001 2500HD with the 6.0 and just over 75K. I have an almost squeaking noise that is rotational and changes speed with driveline speed. when driving is sounds like it is coming from just behind me (right where the t-case is) I topped off the t-case (only 1/2 quart low) and it still makes the noise. I haven't cleaned up the case or found any holes yet. No play in the driveline either. The yoke at the end of the cone of the t-case is wet with fluid as well.

m_livingston61 · March 24, 2011

Just replaced my 263HD transfer case on my 03 2500 HD. I bought a rebuilt one from Anahiem Gear for $1250 with a 1 year warrenty. It was pretty easy to swap out. The guys at Anahiem Gear were well aware of the issue and said the rebuild has the upgraded pump and the rear housing was changed. I will see how it does. My OEM case started leaking around 140,000 miles and the hole developed on the bottom side. It was run dry and had a constant grinding noise, that why I just replaced it. Hope this helps and hope my story helps someone else.

Sir Dan · March 24, 2011

Hi all, just wondering if there is any noise associated with this issue? I have a 2001 2500HD with the 6.0 and just over 75K. I have an almost squeaking noise that is rotational and changes speed with driveline speed. when driving is sounds like it is coming from just behind me (right where the t-case is) I topped off the t-case (only 1/2 quart low) and it still makes the noise. I haven't cleaned up the case or found any holes yet. No play in the driveline either. The yoke at the end of the cone of the t-case is wet with fluid as well.

oiksy05-

Your U-joints likely need to be replaced. Just because there is no play doesn't mean they are OK. Very typical for them to squeak when going bad. Easy and cheap fix...cheers!

Edited March 24, 2011 by Sir Dan

SmithKC · July 6, 2011

My earlier post about the leak at my transfer case has been diagnosed as a small hole....

Newest member of the club reporting in...

1998 1500 going on 240,000 miles, and one afternoon there's the hole, as advertised in this excellent forum. A couple of questions, after reading thoroughly:

1. Can anyone report success after pinhole breaks through with using the Merchant Auto Upgrade Kit but NOT replacing the transfer case half cover (i.e., JB weld in combo with the MA kit)? I know Merchant recommends a new case cover half, but wondered if it's possible to successfully patch, instead.

2. Can I trust an outer JB weld temporary patch for 2,000 to 5,000 miles, assuming I thoroughly scuffed, cleaned and let it cure sufficiently?

3. As others did, I only discovered the leak once the T-Case was groaning; probably put 150 miles on it with little to no fluid remaining. With fluid restored, it now runs quiet, but if I did damage, any guess as how the damage will show itself going forward? (i.e., catastrophic failure, or just increasing noise?)

Thanks again to all who helped a newcomer to pinpoint this apparently very old problem.

stglide07 · July 7, 2011

MountaineerTom I just had to have my truck towed in for the exact same thing. Only thing is that my mother had borrowed my truck to take a trip it started leakin when she was gone. I gues I got lucky cause the transfer case didnt go out untill she was about 10 miles from home. When I took it to the shop, my bubby (my mechanic) looked under it and knew istantly what the problem was just from seeing the oil all over everything under the truck.

If this problem has been going on for this long on so many different models when will Chevy finally recall