Transfer Case Problem

[07SMLT]

I have a bone stock 07 LT with only ~65,000 miles on it. Took it to the dealer today because I noticed a slightly humming noise when 4WD was engaged. I thought it might be the passenger side hub, but wasn't sure.

They call me back and say it appears to be something internal to the transfer case and that the fluid had metal shavings......I told them I bought it as a Certified Pre-Owned, just a few years ago and thought this would fall within the powertrain warranty....no dice, it's expired.

My question is, has anyone had any luck running this sort of thing up the ladder at Chevy to see if they'll cover some of the cost? They said it would be approximately $800 for a used one, and possibly double to tear it apart and try to diagnose......thoughts?

[TangoBravo]

I would ask what fluid came out of it. Better yet I would ask for a sample to "send off and have inspected" I say this because it is possible someone serviced the Tcase and didnt use the proper fluid. Which we all know can cause this kind of problem. I would see if they have any records that the Tcase fluid was infact changed at 50k from the previous owner. If they dont then I would ask if they changed the fluid when they certified it since they couldnt prove it was infact ever changed. When I worked at a dealership and we took a vehicle in like the TB and didnt know if certain services had actually been done then we went ahead and did it. Especially if it was getting certified.

[07SMLT]

The dealer where I have it serviced is not where it was purchased. I bought it at a dealer about 90 miles away.

I just picked it up. I didn't have a chance to ask them about the fluid. Should I call the dealer where it was purchased to see what they did to it?

The service manager says that GM won't do anything about it and that its up to the dealer if they want to cut a deal. He said that he'd cover about half of it. He said they'd tear it apart and either rebuild it or replace with a new factory unit. My cost would be around $1-1.5K.

Seems ridiculous for a truck with 65k....makes me question the durability of the truck since its never really been off road....

[TangoBravo]

Trust me the durability needs not be questioned, ten minutes in the random rig thread should suffice. What needs to be questioned is what I spoke of earlier. When was the Tcase serviced last IF EVER... Like I said if it were me I would contact where I purchased the vehicle and ask for the service record. EVERY USED AND USED CERTIFIED vehicle is REQUIRED to have at minimum a safety check done during, that time most every dealership does the maintenance on them as well and if it's going to get certified this is also the time that it would be combed over for that as well.

[The Roadie]

Excessive use of the A4WD mode can kill a transfer case in 1-2 years. The previous owner might have been a nervous nellie who was also a numbnuts who didn't know the difference between a full-time AWD vehicle and our part-time-but-almost-useless A4WD system.

[07SMLT]

Funny you mention that. Every time I get in the truck after my wife drives it in the winter (any snow at all), the truck is in Auto4WD mode. Sounds like that may have caused it.....she doesn't drive it a ton, but may have been enough to do the damage. Why is it bad to drive in that mode on snowy roads?

Also, does the 1-1.5K price seem like a decent price?

[TangoBravo]

Also, does the 1-1.5K price seem like a decent price?

If the failure was from neglectful service on the dealers part then yes. If it was caused from cycling in and out of 4x4 by using the dredded A4wd then it could have been worse and 1,000 depending on what they charge per hour is so so. Really though at this point I would get a used one or reman and swap it out in my driveway.

[fishsticks]

A $70 HF transmission jack and an afternoon would do the trick. The transfer case can be removed with hand tools.

A4WD shock loads the front output bearings in the transfer case when it engages. It's a poor design to try and satisfy the market segment that doesn't understand proper usage of 4WD.

[The Roadie]

It's a poor design to try and satisfy the market segment that doesn't understand proper usage of 4WD.

Oh, that is the MOST tactful way I've heard of to say what I would post: "Most, but not all, women plus almost all inexperienced chicken-poop drivers who don't know how their vehicle behaves on low traction surfaces because they never take it out on snowy parking lots to experiment."

If it's snowy and slippery enough to need 4WD, it's slippery enough to fully commit to 4HI. If it's merely wet, 4HI is overkill and A4WD is not necessary. 4WD gives you more acceleration from a stop. It does not improve cornering ability or especially braking performance.

The ONLY traction situation I've been convinced makes sense for A4WD is a T-intersection where you have to turn on dry pavement (making 4HI an undesirable mode because of driveline binding) followed by a traffic-induced need for IMMEDIATE straight-line acceleration on snow or ice. A very rare situation that can be waited out so you don't need to haul butt after the turn.

Take your wife out and practice using modes other than A4WD. And see if she's using it to try to improve braking performance. It's always good to see if the understands ABS and how important it is to SLAM on the brakes in an emergency, ignore the startling machine gun fire of the ABS pump, and why pumping the brakes is a bad idea. I can't keep count of the inexperienced drivers and some old-timers who need a refresher in ABS use after a short conversation around a campfire or something.

[07SMLT]

Ok, once I get it fixed I'll tell her she can't drive it unless it's in 2HI or 4HI and only 4HI if things are really dicey. I know she likes to drive it in A4WD for added confidence.....I've been wanting to lift and install more aggressive tires for a while and she says she won't drive if I do.....maybe that's my solution...... Oh, and I hate ABS....wish you could disable and just pump the brakes like my old truck...

A $70 HF transmission jack and an afternoon would do the trick. The transfer case can be removed with hand tools.

A4WD shock loads the front output bearings in the transfer case when it engages. It's a poor design to try and satisfy the market segment that doesn't understand proper usage of 4WD.

I'm looking into this option. I've got a new friend of the family who owns his own shop about 30 mins from my house. What would you guys recommend for a new unit? New from GM, used from salvage yard, rebuild? I was told that rebuild costs about as much as brand new unit...

What's the difference between NP4 and NP8 options?

Any tips besides using the GM Auto-Trak II lube? Never even come close to trying something like this myself....

[The Roadie]

...she likes to drive it in A4WD for added confidence......

For going or stopping? You have to explain traction physics to her.

[Sputnik312]

Roadie always nails these topics so well ! It's honestly so enjoyable to read

[07SMLT]

...she likes to drive it in A4WD for added confidence......

For going or stopping? You have to explain traction physics to her.

Going....she's never really driven a RWD vehicle, so she freaks out a little when the back end pops a little loose.

Any thoughts on transfer case replacement that I mentioned earlier?

[The Roadie]

...she freaks out a little when the back end pops a little loose..

Really? I wouldn't consider her safe until you get her more training. When our daughter started driving, we sent her to a Bob Bondurant skid pad school at Portland International Raceway. Drivers (every single one) MUST (I repeat MUST) know where the edges of their vehicle's performance and traction envelopes are so they know when to back off and not lose control.

Otherwise they're mere passengers instead of pilots.

On the transfer case issue, I've never dropped mine, but I'd get a junkyard or Ebay one if you can be assured the donor vehicle has 50K miles or fewer so you don't care if they neglected the first fluid change. Or check car-parts.com

NP4 is the NVG126 transfer case, used for Bravada and the like that have AWD mode only. No low range. Shun them. NP8 is the transfer case we use.

A driver who "freaks out" at all needs more training and experience. Don't let her go through life in that suboptimal state. I suppose it's too late to unmarry her. [JK]

[07SMLT]

Yes, really. However, note that I said "freaks out a little". She drives her '03 Acura TL-S 99.9% of the time unless I need it to travel out of state. It's only her second car and before she had a '93 Taurus that she bought in high school.

The Trailblazer is the first RWD vehicle that she's ever driven. She's a very safe driver, but just a little uncomfortable in the Trialblazer, mainly because she doesn't drive it much, it's bigger and she isn't used to the RWD. She gets slightly upset when I drop into a snowy parking lot, turn off the Stabilitrak and slide around a little.

Thanks for the info on the transfer case. Looks like I'll probably be putting a used one (replace seals and fluid) with 57K on it for around $550.

Way too late to unmarry her, she's a great woman. She even agreed to 4 days of backpacking for our honeymoon......Just need to convince her that a lifted Trailblazer outfitted for long weekends trips offroad would be a fun adventure for the enitre family. Working on it.....

[The Roadie]

.. She even agreed to 4 days of backpacking for our honeymoon.....

I take it all back. She's a keeper.

[07SMLT]

Welp, got the "new" transfer case installed today. I had a family friend who owns his own shop do the work as I don't have time. He found a used unit with 57K on it. It had decent AutoTrak fluid in it. He swapped the seals and put new fluid in it, he said it looked like a quality piece. My total out the door is $568.13, not too bad!

He also mentioned that the old case fluid definitely had regular tranny fluid in it at some point. The fluid wasn't the clean blue even though GM dealer just recently changed it (when I took it in for the noise). That really got me upset because we bought it GM Certified from a Chevy dealer and have had it serviced at Chevy dealer since we purchased it......of course, there's nothing GM will do about it at the dealer or GM corporate office. To me, the failure it totally on them because the wrong fluid was present and almost positively created the problem. Way under the mileage on powertrain warranty and just over the time (5 months). Seems like they should have stepped up to bat, but screw ‘em.

Anyway, back on the road for a reasonable cost. I think I've found a new mechanic, no more trips to the dealer for me!!

Still need to work on the wife about the lift and wheels/tires......

[Conner299]

Since we're on the topic of transfer cases, changing the fluid was one of the first things I did when I got it a year ago, and again last month. The reason, so soon between the two(approx 1yr), is because the first time I changed it, the fluid came out looking greenish in color. Wasnt happy. Bought it used from a Chevy dealer, not certified. No problems so far.

[fishsticks]

Greenish is normal.


Also, it's possible the rear seal on the transmission can fail, causing some ATF to mix into the transfer case.

On BITOG, there has been discussion indicating that AutoTrak II is simply modified ATF. From a design standpoint, it makes sense. Wet clutches in both, and having incompatible fluids separated by a small seal would be silly.

[Conner299]

I read a bunch of threads on other sites about possible replacement fluids as well. The jist I got was that while mostly compatible, the other fluids may contain one or two things that could possibly be harmful to components in our transfer cases. I went with safe and just got the Auto Trak II. I picked mine up from the dealer, and they were pretty cool. Quoted it over the phone at retail price, and they ended up giving it to me for wholesale at the parts department. 14$ overall for two quarts.