Transfer Case Questions

[99Sierra2500]

I think I overheated my TC, it is a 246 NP8 in a 99 Sierra 2500. Appears to be working for now. I have seen them for $200 used on fb marketplace, AZ has a Zumbrota for like $1500 or so, and a GM Reman is like $2300, though I have not called the AC Delco place to confim that, could be more. Getting to be an old man, so even buying the used, and throwing it in there, something I would have done 30 years ago, is not always that exciting of an idea anymore. Thoughts?

 

[ORVietVet]

I think I overheated my TC, it is a 246 NP8 in a 99 Sierra 2500. Appears to be working for now. I have seen them for $200 used on fb marketplace, AZ has a Zumbrota for like $1500 or so, and a GM Reman is like $2300, though I have not called the AC Delco place to confim that, could be more. Getting to be an old man, so even buying the used, and throwing it in there, something I would have done 30 years ago, is not always that exciting of an idea anymore. Thoughts?

Welcome to the forum from Oregon. Glad you are here.

As a veteran of the shops for 40+ years, the first thing I am going to ask is, "What makes you think that you overheated the transfer case? What was it doing that made you think that and what is it now not doing that makes you think it is "working for now". What is the fluid level and what does a sample look like? Good looking fluid should look blue. Auto-Trak II. If you want, drain and refill with whatever your owner's manual fluid says and see if the fluid change eases your concerns, what ever those are. Takes no more than 2 quarts.

Now, to address the age concerns. I am 72 and still work in my driveway, all the time. I got some "Inguinal Hernia" concerns from my VA doctor the other day. I am now limited on the amount of lifting I can do. I did an oil change for a neighbor yesterday, on her 2017 Cherokee. She also wanted a tire rotation. I had to turn that down because there is the moment when you lift the tire and wheel weight off the studs and also when you are lining up and stab the wheel back on the studs, and at those times you are supporting all the weight at the ends of your arms and your "core" is handling all that. If I needed to do a transfer case R&R, I would be getting some help from a couple youngsters and guide them thru the process of turning the case just right to ease out of there. They usually work cheap......pizza and beer.

 

[99Sierra2500]

Thanks for the welcome.

It was making a vibration, soaked the case, felt around for pump rub, didn't find any holes, still might be there, it's rebuilt. Drained the fluid was dark red brown, my fault for being lazy, put auto trak 2 in it, and it doesn't vibrate as much, tires have some road noise so can't exactly tell, seems a little quieter. I used to be a mechanic, had my own shop.

 

[ORVietVet]

Sounds like someone put auto transmission fluid in it before. Been long enough that I cannot remember but there are some videos at you tube that can point you in the direction of the usual rub spots to look for.

My favorite is Eric at South Main Auto and others are Hoovies Garage and Watch Wes Work....

 

[ORVietVet]

If you respond and I don't answer back quickly, I am just busy doing some "Honey Do's" for my girl.

 

[99Sierra2500]

It does look like they put atf in it, to give them credit, some of that says it is good as auto trak. Should have done it myself though. I think it boiled out of the vent, as I can't hook a fingernail where it would rub through, no fresh fluid there, nothing dripping either, except now the drain plug has a weep of course, doesn't really drip on the garage floor. I work the rig, tow 10k dump trailer or auto hauler, take it out 4 bying. Going up a muddy hill is where I might have done it, smelled like burnt atf coming home, thought I had fried the trans, didn't get back under there with a power washer for a while to check it out.

I hurt my back, never really gets better, esp now with arthritis setting in. Takes a lot of strength out of me. Don't have a lift anymore either which makes everything harder.

Thinking of going with the zumbrota when I have the gumption to do it.

 

[ORVietVet]

I don't have a lift here either. To tell you the truth, I only miss it about 5% of the time I am out in my driveway. My girl got me some "Performance Tool" roll out mats, kind of like a 4'x8' yoga mat and I can stack them if needed. Soft to lay on and can set jack stands on them and use a floor jack on them and all fluids do not harm them. I also use a 2" thick kneel down pad when needed. I have helped at my friend's shop before and standing long enough, especially if twisting and reaching for something, my back starts to hurt and I have to walk away and sit down for a bit. The mats are actually better for me.

If I was you, I would open up that drain hole on the transfer case and reach thru the fill hole and spray with the spray tip in as many directions as you can, using brake clean. That stuff dissolves. Use as many cans as you can and clean it out as best you can and watch what flows out. When done, walk away for 1-2 hours and let dry. Then fill with the blue Auto Trak II and see what happens.

 

[ORVietVet]

I also encourage you to go to the Forums page and at the top is Introduction. Introduce yourself and since you had a shop, tell some stories and what you may specialize in, if anything. What other vehicles you have and where the hell do you live.

Plus, post pics of the vehicle(s). Thanks

 

[99Sierra2500]

That is a good idea with the brake clean, maybe find out if the case is actually leaking. Thanks.

I can put some stuff up in introduction.

 

[stutaeng]

My 04 project suburban 2500 has the same transfer case and it was filled with red ATF fluid as well. When I bought it the 4x4 didn't work but it was the shift encoder reductor wheel. I fixed that and it seems to work now.

A few months ago I replaced the fluid and that's when I discovered it had ATF. No chunks or debris were in the old fluid, so I refilled it with blue fluid and sent it.

Welcome from Texas BTW!

 

[99Sierra2500]

Thanks!

Nothing was wrong when I drained it earlier, no metal, etc.. The fluid was burned, very dark, and smelled. I checked it again today, case still wet, gut feeling is something is wrong. Seems to work fine, no noise though, goes into 4x4.

 

[ORVietVet]

Thanks!

Nothing was wrong when I drained it earlier, no metal, etc.. The fluid was burned, very dark, and smelled. I checked it again today, case still wet, gut feeling is something is wrong. Seems to work fine, no noise though, goes into 4x4.

So, you completely cleaned the case when added the new fluid and then drove it and the case was wet? Where was it wet?

 

[99Sierra2500]

Just power washed the underside to get the mud off. It is fluid filmed on the underside as well. Looks like the foward output shaft housing is wet, running down the actuator, from up top somewhere. Parts of the case are still clean though. Very well could be a trashed case, won't know until I drop it.

 

[ORVietVet]

Need to power wash the entire thing. Let dry completely. Drive it 5-10 miles only and then crawl under and look. OR....get some florescent dye and add to the fluid and drive and look with a blacklight. Either way, wash and dry it first.

 

[99Sierra2500]

Miss having a parts washer. It was cleaned off wiped it down, have driven it a good bit, couple hundred miles. Suppose I'll know if it goes low on fluid, starts making noise.

 

[ORVietVet]

Miss having a parts washer. It was cleaned off wiped it down, have driven it a good bit, couple hundred miles. Suppose I'll know if it goes low on fluid, starts making noise.

Ok then. If you cleaned it all up and need to find a leak, by the time you drive 200 miles the fluid can leak out and the air flow under the truck will blow that fluid around and then the source of the leak is almost impossible to find. Adding the dye can help pinpoint the leaks, even is blown around.

 

[99Sierra2500]

Dye is good. I'll know too when I pull it, because the leak will clean the spot. No way getting around that. This is the way these TC's go too, get wet, and then frag, I can get a little more time putting fluid in it.

 

[99Sierra2500]

Sounds like everyone likes the zumbrota though, unless other suggestions?

 

[stutaeng]

How much is the zumbrota?

A few weeks ago I messaged Kodiak to ask how much a rebuild for NP246 and they said $950, including a core return. That seemed like a good price for me.


Edit: that guy that owns and operates Kodiak Truck apparently is very reputable on transmissions, transfer cases, axles, etc.


And it would be helpful if I actually posted a link so you know what I was talking about. Sorry...

Chevy GMC NP246 Auto Trac Transfer Case | Kodiak Truck

Chevy GMC NP246 Auto Trac Transfer Case is available at Kodiak Truck Transfer Case & Differential Repair and North Prairie, Wisconsin.

kodiaktruck.com

 

[99Sierra2500]

How much is the zumbrota?

A few weeks ago I messaged Kodiak to ask how much a rebuild for NP246 and they said $950, including a core return. That seemed like a good price for me.

Zumbrota is around $1500 w/actuator, GM is I think I was quoted around $2300; both w/o core charges. Kodiak for $900 is really good. The actuator is around $200 as far as I know.