I don't like this noise...

[D is for DENALI]

On the freeway doing 82, and then the truck starts to make this growly wirrrrrr noise... i slow down and the noise matches perfectly with my movement... After more listening I counted out wheel hubs, assumed it was coming from the driveshaft somewhere. So i bought 2 quarts of transfer case fluid and went to my buddies house with the truck lift.. we drain the transfer case fluid and as he pulls the FILL plug, dark reddish purple fluid comes flying out of it... way more than a quarts worth... he goes "holy shit dude!!!" And jumps out of the way. we pull the drain and its not blue fluid. at all..its a Dark red purple color. Super dark.

I said, " is that tranny fluid? Why on earth would it be red? " so he shows me how it's all married and all the bearings involved and what could have happened..

We put in new auto Trac fluid and closed that up.. filled up the transmission to full, it was almost 2 quarts low. the noise is obviously still there after doing this work.. could it be the diff..

He showed me the inside of transfer case with this flexible light camera deal he has, and said the transfer case needs to be rebuilt after looking at the gears and checking chain tension just from age(almost 195k)..

But when we lowered it down to about 13 inches, I hopped in and started it up and put it in gear.. he had his creeper and we both confirmed that the noise isn't coming from the transfer case and from the front of the transmission somewhere... or possibly the diff.. unfortunately he had to leave and do a mobile service and we couldn't check the front diff...

But I would like expert thoughts on what the hell I got myself into here..

I don't go above 50 now, and drive with my hazards on...ugh..


Why was my trans fluid low, transfer high, reddish not blue... he said that if one bearing went the other one on the other side is going too... but if it's way up front could it be the front diff... we didnt check, and im going to check the level tomorrow morning after this Coors banquet hangover im volunteering myself into wears off...lolz

Im hoping it's not liquid graphite when I check it, but I guess it would be better for that than the trans or case... the fluid swap has me scratching my head still...

Diff kits with timken bearings are 175, transfer case rebuild kits are 350ish?, but if some bearing in the tranny I think my 12k warranty has been passed...

These are the type of days I want to sell it and buy a AWD limited Sienna and just call it a day... I drank 3 beers typing this so take it for what it's worth... lolz

 

[OR VietVet]

There is a seal between the transmission and the transfer case. Sounds like it is leaking badly and now you have the two fluids mixing and causing problems/noises with the two units.

 

[rockola1971]

Start here, first. https://www.webmd.com/drugs/2/drug-9824/xanax-oral/details

 

[D is for DENALI]

That is what he was saying but was losing me with all the specific names of the parts...

Thanks for the input, that was the short version of what I heard... lol

And hold the xanax....

 

[OR VietVet]

When the fluids mix like that you can have damage to the trans and the transaxle because of the fluid contamination and then hydraulics and lubrication problems occur. Think of how fast parts are moving inside each of those components.

 

[mals]

I found the same thing when I went to service my transfer case fluid a few months ago. I opened the fill port to make sure it would come out before I drained the case. About a quart of cherry red fluid came out. I didn't have the luxury of having it up on a lift, so I had to quickly scramble while I was on my back to unexpectedly get the drain pan into position.

As others have said, after some research I found out that the seal on the shaft between the transmission tail and the transfer case can fail, and allow transmission fluid into the transfer case. In my case it was not a major issue since both my transmission and transfer case take Dex III ATF. I've just been keeping an closer eye on my trans fluid level since then, and luckily if it is still leaking it is very slow. Eventually something else will fail and I will tackle it as part of a larger project.

 

[zraffz]

Is it a whining noise almost like a "old school" roots supercharger? (This would be a common torque converter sound)
A whirring could be pump/converter/front differential related.

Do you notice any difference in how the transmission shifts?

 

[D is for DENALI]

It shifts fine, not erratic or lose of power anywhere... the level of sound matches speed... when you slow to a stop you can easily here it(it's there whenever you move) and its a lower growly noise, but when it gets to speed it turns to a higher wirrrrrr growl and increases in pitch with speed increase...



We ruled out torque converter when he got on the gas and it shifted where it should and had no signs of that...

It sounds like when you move the wheels when it's in the air and you get that low growly noise... it's just more pronounced and matches speed...

So now im trying finding out what number my case is so I can order a overhaul kit, and the bearing and shim that mates the 2 on the trans... the case does not have a I'd tag on it, but I found it to be a Borg warner az91d...

I might order a front diff rebuild kit and do it while its in the air... im sure it's never been done and I think it could use a 200k rebuild..

It's just money

 

[rockola1971]

What year and model? 4x4 or AWD? (Im assuming its the Denali in your avatar) Look in glove compartment (dash) lid for RPO codes. Have a NP8 or NR4 there?
Sounds like a bearing fail in transfer case but more likely to be coming from the transmission since it was the one low on fluid. The rear transmission seal is leaking and the front seal of the transfer case is only designed to keep fluid in the TC. It will not keep fluid from pushing its way past into the case from the tranny. Only 2 causes for this. (1) some idiot overfilled, but by 2 quarts? Dont think so. (2) Rear tranny seal failure.

Be very careful running your Denali on a lift in gear. You can overspeed the front Diff and ruin it. The chains on these TC's are slack when new so dont be fooled. During a rebuild be sure to replace them anyway. Bearings, seals, clutches. They are easy.

 

[D is for DENALI]

03 yukon xl denali... awd im not at the house right now so I can't look.

The trans is rebuilt... payed for the beefier parts(servo, shell, valves, input drum, etc) and has about 12k on it...

I changed the fluid(auto trac) on the transfer case the first time when I bought it.. looked like old fluid, not graphite so I was happy with that...

Changed the front and rear diff fluids wheni bought it also with royal purple, then when the pinion seal went out on the rear end we changed it again, so the rear only has maybe 3k on it.

The rear end was dry underneath, but you could see fluid on the trans and transfer case...

I won't be driving it anymore till it gets fixed so I don't burn the clutch packs or whatever else I could do to it.

And when it was in the air, all I did was put it in gear and take my foot off the brake.. it went up to 10 mph by itself and stayed there for about the ten seconds he needed to find out where the noise wasnt... then I did it and it was about ten seconds.. the abs light and service stability light came on, so we cleared the codes and it drive like it did before.. we weren't doing dyno runs...hahahha

 

[D is for DENALI]

Here are my code sets... I see an NR3, not NR4, and a NP5, not NP8... what does this mean?

I looked on rock auto and there are multiple diff sizes..

 

[mals]

View attachment 186642

Here are my code sets... I see an NR3, not NR4, and a NP5, not NP8... what does this mean?

I looked on rock auto and there are multiple diff sizes..

This is the GM RPO lookup site that I've used in the past: http://www.cadillacfaq.com/rpo/

 

[D is for DENALI]

Here is a little bit of what i found in a couple minutes.. hope this might help anyone scrolling threads.

RPO NR4 - AWD with 4 WD Low (AKA: AutoTrac)
RPO NR3 - AWD with out 4 WD Low (Denali)
RPO NP8 - Auto 4WD, 4WD, 2WD, 4WD Low

NR4 and NR3 use the same software algorithm to detect rear wheel slipage and put power to the front wheels, typically with in 300 ms.

Yukons come standard with limited slip rear unless the vehicle is equiped with Stabilitrac (begining in MY05, you can have limited slip with Stabilitrac).

Denalis come standard with Stabilitrac thus removing the limited slip rear and Stabilitrac is a option on the Yukons.

 

[D is for DENALI]

I havnt found many np8 overhaul kits, but i have found many np246 transfer case kits that come with rear half case, bearings, sprockets chain, seals , all of it.. I am having trouble confirming these 2 are the same cases... in the info bars it says np8 is an interchangeable part but In not 100% yet.

I will upload the kits I Found and you can giv e me your thoughts and hopefully helpful advice.. there was no id tag on the case so all I have is Borg warner az91d ID number on the case and a np8 code.

https://m.ebay.com/itm/NP246-Transf...960710?hash=item2a71af9c86:g:sMwAAOSwTM5Y1Zox

https://m.ebay.com/itm/NP246-Transf...960710?hash=item2a71af9c86:g:sMwAAOSwTM5Y1Zox

I havnt found a Borg warner kit on eBay yet but im mixing work and searching...

 

[rockola1971]

Your transfer case (NR3) is a Borg Warner BW4481 Transfer Case. Single Speed, Full Time AWD unit. DOnt believe anything is interchangeable with the NP246. But dont let this discourage you. They are fairly easy to rebuild. (Read as not rocket science). 2007 and up went to the BW4485 in the XL.
Heres one on ebay right now for comparison. https://www.ebay.com/itm/03-06-ESCALADE-YUKON-DENALI-TRANSFER-CASE-OPTION-NR3-23575-/263000098182

Not uncommon for one of the roller bearings to die. Typical for the output shaft needle bearing to growl and make noise and lots of it too.

 

[D is for DENALI]

Im going to have my mechanic friend rebuild it, but we were having trouble finding a kit for the nr3 specific...

So the info bar in the ebay ad is incorrect?? Is that what you are saying? Im not going to buy a used complete, I want to rebuild mine.. this different numbers stuff is frustrating.. i want a whole kit, but rockauto doesn't have it, im about to search Borg warner website directly..lolz.

Thanks for the info, it's very helpful!!

 

[rockola1971]

Parts you say?
Try Here:
http://www.manualtransmissionpart.com/BW4481.html

Ebay info bar show 03-06 esky, yukon, blah blah. If you go down it shows all years models and engine combos the NR3 is compatible with and yours shows. NR3 is a BW4481 Tcase.