98 Suburban 246 Transfer case clicking/popping

I just recently bought a 98 Suburban to haul around the family. I noticed a popping/clicking noise coming from under the vehicle when in the neighborhood at slow speeds. I got up under the vehicle and it sounds like it is coming from the transfer case, near the tailshaft.

I read the other postings about the broken snap ring. I am not able to check on this model because the tailshaft housing is integral to the rear half of the case. I don't know if this model is susceptible to that as well.

Here's what I've gathered from the problem.

-Occurs only in 2wd mode, goes away in 4H or 4L.

-Sounds like to ball bearings impacting, or like a chassis frame popping/creaking.

-No rythmic or periodic pattern.

-With the rear axle jacked up and the transmission in neutral, the sound is easily reproduced by turing the driveshaft by hand, and sounds like it is originating in the transfer case. It is not speed depended.

-In 2wd, the noise occurs at light loads, or deceleration. Stepping on the accelerator makes the noise stop.

-It is a 246GM transfer case. I have 150,000 miles on the odometer.


Thoughts: The original owner had the transmission rebuilt. Is it possible the shop put the wrong fluid in it? Is there a re-learn procedure or adjustment for the encoder/stepper motor? The symptoms kind of sound like the shift fork is dragging and not retracted all the way.

Any thoughts, help, diagrams or troubleshoot procedures would be greatly appreciated.

-Ed

New Venture 246 Xfer case? There is a TSB from GM regarding the noises from this box and the use of a newer (fully synthetic) AutoTrak II transfer case oil to solve it. IIRC, you will need about 2.9L of AutoTrak II (P/N 12378508) to change the oil.

You are right... it is a New Venture 246. I got a little further on my problem. The sound was originating from the tailshaft area. I pulled the driveshaft and looked into the case through the rear seal and I noticed that all the ball bearings on the rear bearing are shifted to one side, or there are some missing. I also noticed what looked like a plastic retainer ring (maybe a bearing cage) loose around the output shaft. I noticed that there is a replacement driveshaft on the vehicle, so I wonder if the previous owner was out 4 wheeling one day, landed on a large rock, bent the driveshaft and broke the rear bearing cage. Does anyone have a picture of what the bearing should look like or how many ball bearings it should have? The noise was definitely the bearings smacking around against each other. I guess in 4wd, there is enough thrust load to keep them from crashing into each other. I also found out there is just plain ATF in the case, not the Autotrac fluid. I hope the clutches are ok. My plan is to take the transfer case out, change the bearing, put fresh fluid it in and hope for the best. The clutches seem to be ok. The 4wd works, and I don't plan on using it much. Thanks for the advice.
-Ed

Same vehicle and same issue. Not sure if I have New Venture 246 or not; presume I do. I have vehicle @ friends tranny shop. I am going to ask him to service the transfer case with the AutoTrac II oil and go from there. Have you solved the problem yet?:banghead:

Yes, It was the rear tailshaft bearing. I split the case, replaced the bearing (which was obviously the issue), replaced the tailshaft bushing for good measure since it was doing most of the work, resealed the transfer case and put it back in. The noise is gone and it works like a champ. What a dumb bearing design... It has a plastic ball cage that snaps in place from the back of the bearing and nothing retaining it on the other side. If the plastic warps or you jar the driveshaft really good, it looks like it can easily pop the cage loose. What I figured was that when you place the vehicle in 4wd, it loads the clutch pack, which loads the bearing and keeps the loose ball bearings from smacking into each other. That is why it made noise when coasting in 2wd. Also, GM thinks very highly of their two output shaft seals. They were over $60 each at GM. I didn't have much luck finding them elsewhere. I did use GM's AutoTrak fluid. Let me know if this is your issue, or if you need advice.

Thanks for the update. Just got off the phone with the transmission shop right after reading your post. Verdict is in for me as well: Tailshaft Bearing. It's good to hear that your fix for the problem was successful. Had I known, I probably would have attempted to fix myself (with a little help). Replacement bearing set they're using has a metal cage. Total fix is ~$700.
Will

Who did they get the bearing from? I sure would have preferred a metal caged bearing..... Was it in an entire rebuild kit?

Pretty sure it was a bearing kit - they replaced them all. I'll try and find out where they get them from and post it later.

I think I have the same problem on my '99 Suburban. :frown:
Exactly the same clicking sound when you get off of the accelerator.
Also found myself underneath trying to figure out where that noise came from.

I would like to replace the bearings myself but I'm not sure if you can split the TC without lowering the engine+trans. It seems there might be a (rivetted) piece of the frame in the way ??
And does it split without dropping several pieces??:yikes:

@ew0001 : any hints, help.


Greetz,

Borguy (Belgium)

Could anyone please post a tech drawing of a '99 (model '98) T-case.
I'd like to see what I am going to find when opening the thing.
Thx.

Check here:

http://www.rsgear.com/NV246.htm

@ Blue Bowtie : Thx

I've ordered a new tailshaft bearing (€80) and bushing (€100) at a GM shop.
With taxes it will come to approx. $260

I've read somewhere that you should put a NV246 T-case in neutral before splitting it. Are there any other things I should keep in mind when I start on it?
I hope no other things went bad inside cause I kept driving it ...

Thanks.

I've started on splitting the T-case but soon found out that the crossmember which holds the torsion bars has to be taken out in order to get the T-case far enough backwards.
But after trying for more than 3 hours with different kinds of tools it won't work :(
Do I have to disassemble part of the front suspension to lower the torsion on these bars? In my opinion that's the only way .... ??

Another possibility is to take the entire T-case out and in that case I have to take another crossmember out but this one only supports the T-case.

If I try this then I have already a next question:
Which part do I take off ? Only the T-case or also the part between the transmission and the T-case (15-20cm approx.)
Does it slides off or what is the next catch...

Thanks for any help, burb is out and now I have to drive my wive's Toy starlet ...

Did a search on "torsion bars" and found the procedure.
Will try it this evening. First have to get me the right tool.. :)

Did a search on "torsion bars" and found the procedure.
Will try it this evening. First have to get me the right tool.. :)


I would suggest removing the transfer case instead of torsion bars or cross member. It is a pain and sometimes impossible to get torsion bars or cross member out.
This link covers transmission repair but also covers transfer case removal.
http://72.19.213.157/files/4L60ERepairs.html

@ MT-2500 : thank you for the link.
Like you suggested, it would have been a lot easier to remove the entire T-case instead of trying to split it still attached like I did last night !!

I managed to get the torsion bars and cross member out with a "modified" bearing puller :wink:
Splitting the T-case was something else :banghead:
Finally got it out by sliding the chain off of the front driveshaft sprocket.

Now I could place the damn thing on my workbench and see/reach the bearing retaining ring from the little hole on top.
Notice : remove the two speed sensors or you won't be able to slide the shaft with bearing and all the rest out :wink:

Found exactly the same situation as ew0001, the originator of this thread.
All the bearing balls where sitting on the bottom of the bearing because a little corner of the plastic ring to hold them spreaded was broken off. This probably enabled that ball to push the plastic ring out of the bearing.

To reinstall I've put the shaft and chain back in on the part that was still attached under the car.
Then to get the backside cover back on you have to somehow hold the retaining ring of the new bearing open. For that I used a small piece of wood, exactly the same size as the little hole on top of the t-case. Pressed it in between the ring to hold it and once the cover was slided over and secured, I could retract the piece of wood and the retaining ring clicked in place :)

In the mean time it was past midnight and the rest will follow this evening....

@ MT-2500 : thank you for the link.
Like you suggested, it would have been a lot easier to remove the entire T-case instead of trying to split it still attached like I did last night !!

I managed to get the torsion bars and cross member out with a "modified" bearing puller :wink:
Splitting the T-case was something else :banghead:
Finally got it out by sliding the chain off of the front driveshaft sprocket.

Now I could place the damn thing on my workbench and see/reach the bearing retaining ring from the little hole on top.
Notice : remove the two speed sensors or you won't be able to slide the shaft with bearing and all the rest out :wink:

Found exactly the same situation as ew0001, the originator of this thread.
All the bearing balls where sitting on the bottom of the bearing because a little corner of the plastic ring to hold them spreaded was broken off. This probably enabled that ball to push the plastic ring out of the bearing.

To reinstall I've put the shaft and chain back in on the part that was still attached under the car.
Then to get the backside cover back on you have to somehow hold the retaining ring of the new bearing open. For that I used a small piece of wood, exactly the same size as the little hole on top of the t-case. Pressed it in between the ring to hold it and once the cover was slided over and secured, I could retract the piece of wood and the retaining ring clicked in place :)

In the mean time it was past midnight and the rest will follow this evening....


You are welcome and thanks for posting back on how it is going.
Hope all goes well.
And let us know how it does.
MT

Just finished the testdrive and so far all goes well :bananasmi

Once the T-case was back in yesterday, I kind of knew the rest would be easy. Just assembling everything (cross member, torsion bars, driveshaft...)


But while I was under it I noticed that the U-joint on the front driveshaft has a little slack. It doesn't produce any vibrations yet but that's probably the next project to work on :rolleyes:

Back in 2007 I replaced the rear tailshaft bearing.
Now, 45000 kms further on the road, same problem again :disappoin

This time I found the plastic ball cage intact around the tailshaft.
Pushed the cage back in place and it looks like new.
But I already bought a new one (€120 !!) before I started the work...

The difference with this bearing is that the plastic ball cage is put in from the other side of the bearing. So it can't come out and "hang" around the tailshaft. It will sit against those "splines" where the sensors read.

Hopefully better luck this time ...

FYI to all searching these forums on the 246 like me :(

there is an updated rear bearing that is sealed. You can get it at riverside gear. There is also a fix to the case wear problem (if your transfer case is leaking from a hole made by the oil pump).

oil pump hole fix:
http://www.riversidegear.com/categories/transfer-cases-and-parts/g-m-transfer-cases-and-parts/products/product-630.html

updated rear bearing:
http://www.riversidegear.com/categories/transfer-cases-and-parts/g-m-transfer-cases-and-parts/products/product-632.html

Bet your a$$ im getting these both when I rebuild mine soon!!

I have a '01 Suburban 3/4. Has AutoTrac II TC. The clutch burned up. Fluid was dark. Stealers replaced TC. 4 months later with approx 100 miles of 4x4 in the sand and a few miles on mountian terrian 4x4 does not pull in reverse and seems to not pull as much as it used to after the TC was replaced. Defective? I smell a slight odd burning odor. I'm about sick of this Autotrac Crap! Granted my Sub is Supercharged via Whipple. Do you think the whipple is eating the TC?
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