Transfer case blown?

[99123456]

I've read all search returns, but looking for more info re transfer case failure.  Bought 1 yr ago with 36K, put on 15K.  Nickel yoke installed at 35K.  In stop and go last week, from start it revved up to maybe 1500-2000 and then clunked so hard in rear we thought we had been rear-ended.

 

Some very slight and intermittent noise from trans/trans case area for two days/200 miles and then loud squeeling from yoke area and no go.  Truck will go forward and reverse on level, but sits and squeals when load on, won't back up driveway.

 

I'm thinking swapping out transfer case, but hesitate to do so when the rear carrier may have caused the failure, as I've read here.

 

What to do?  Anyone hear of transfer case failure like this and can they be rebuilt when it happens?  Will I be able to see problem if I remove rear cover from case?

 

thanks for any help

[PFarkas]

I'd do some more troubleshooting first.

 

Do you have the same symptoms in all the transfer case settings - 2hi, 4hi, 4lo?

 

Have you gotten all four wheels off the ground, started the truck, set it in drive, allowed it to idle, and listened to all the places that may be making noise?

 

Have you tried running the truck with the rear driveshaft removed?  (of course, this would require that you set the truck for 4wd)

 

I'd want to exhaust all my options before I took apart the transfer case.

[99123456]

Thanks, good points.

 

I did raise rear and tried all transfer case settings and reverse, and forward selections.  It will power wheels when no load, in air or level ground.  I was thinking about driving without rear driveshaft until I tried it in the air and the rearend seemed fine.  The driveshaft doesn't even flinch when it's squealing, let alone try to turn, so I don't believe carrier is faulty.

 

I have EASE OBD-II scanner for my Vette and am going to check for any related DTC's and maybe see if I can scan for some relevant PID's while duplicating noise.

 

I'm wondering if maybe the torque converter could be faulty. Are there any clutches in the trans case that could explain torque on the output shaft with light load, but slipping when load on?  I don't see how it could slip sometimes, but not all times.  Seems like TC if no clutch like setup in trans case.

 

Hopefully fluids in trans case, tranny, and carrier will give clues, in that order of inspection.

 

Dealer said I wouldn't be able to see anything wrong if I took back of trans case off, but it looks to be covering up a lot to me.  Can I take the rear cover off without removal of unit?

 

thanks for the suggestions

 

So, no transfer case failures yet on '99?

[PFarkas]

The driveshaft doesn't even flinch when it's squealing, let alone try to turn, so I don't believe carrier is faulty.

 

I'm not sure what you're saying here.  A bad carrier bearing would cause a vibration that was tied directly to driveshaft speed (and consequently vehicle speed).  There is a TSB for replacing the two-piece driveshaft with a one-piece unit in the event that you observe this vibration.  I haven't read anything about the carrier bearing failing in a manner that matches the symptoms you describe.

 

Removing the rear driveshaft isn't a huge ordeal.  If you have a two-piece drive shaft, I'd remove both pieces, if you are inclined to remove the drive shaft as part of your troubleshooting procedure.

 

For the most part, my understanding is that if the output of the transfer case turns, that the case is working.  Unless your transfer case is completely dry and siezed, it will continue to transmit power to its output in a low fluid condition (of course, it will also destroy itself in the process).  I think it is unlikely that disassembling the transfer case will do much more than require you to replace about 2.5 quarts of fluid and a gasket.

 

There is kind of a "clutch like" assembly (I understand it's a conical thing) in the transfer case, however it's not part of getting power to the rear output.

 

Removing the transfer case could eliminate it from the list of possible suspects, except that I'm pretty sure that your transmission depends on its presence to keep its fluid inside itself.

 

 

The only things I can think of that change when the truck is on an incline are fluid levels.  

 

If your transmission is low on fluid, I would expect it to slip, with the amount of slippage being inversely proportional to the amount of fluid present (less fluid = more slip).  The torque converter must be full of fluid to operate properly (move the vehicle).  Maybe if the fluid is very low, when the truck is on an incline, the level isn't high enough to get drawn in by the trans fluid pump.

 

 

I'm eager to hear what your trans fluid level is like.

 

 

What have you done to determine the origin of the squeal?

 

What kind of "load" are you using to test the truck with?  What does it weigh (approximately)?

 

Can you tilt the truck enough through the use of jacks and jack stands to induce failure without having the wheels on the ground?  If this would result in an unsafe setup, you can park the truck on an incline, block the wheels and remove the front and rear driveshafts.

 

 

Have you considered that unless you are going to repair this yourself, that any decent mechanic you take this to is likely to repeat these troubleshooting steps.  I'd hate to have you find out that you were "spinning your wheels" (pun intended).

 

I hope the origin of your problem doesn't turn out to be "not enough trans fluid".

 

Good Luck!

[99123456]

ATF level is right on.  I checked that first thing after experiencing the initial revs increase at stoplight without forward motion, the loud bang and harsh jolt in rear carrier.  I also checked it last night, it is clear and not burnt.

 

I wasn't able to get it back in the garage last night to run it raised in the air with the EASE scanner on.  I was looking to read TCC sensors and tranny in/output shaft sensors relative to rpm and mph.  I did see TCC speed = to engine rpm when at idle and when reving to 2K in neutral and in drive.  And I did see tranny output shaft speed flash briefly to maybe 8 rpm's before the slippage occured.

 

I couldn't get it in the garage because now it won't back up at all.  I climbed under it while gf tried to back up and the squeal seems to be coming from trans/TC area.  

 

Interesting thing is that it will go forward.  I went about four feet and then I did not have any more room to go forward, so I verified that forward gears work by powerbraking.  I took it to almost 2K with brakes on in drive and the truck was trying to overcome the brakes with no squealing at all!  This is weird because when it started to make grinding noises 200 miles after that initial bang, I was heading down a steep hill (on the way to cross the bridge the Vette flies off in XXX, BTW).  I did a quick 180 to head back up the hill and it began to squeal and lose thrust, so I barely got it turned back around and off the shoulder.  I tried reverse on the grade and it just squealed.

 

When I put it in reverse and release the brakes at idle, it backs up a foot or so and then slips and squeals real loud.  The speedo registers mph when this happens, relative to the engine rpm/throttle.

 

Where is the VSS located on this vehicle?  I think that may be a clue.

 

I could have a buddy help me tow it into garage and do all the diagnostic stuff, but I think I'll AAA it to the dealer for their diagnosis and then take it from there.

 

And this is the same tranny that lives in my Heads/Cam/Headers/etc.! Vette  ???

 

thanks again for any help/ideas/sympathy  

[PFarkas]

It looks like you've narrowed it down yourself pretty well.

 

If you had a problem with the transfer case, it would be showing up in forward and reverse.

 

I submit to you that this is not EXACTLY the same transmission as the one you have in your vette, as you are not complaining about the one in your vette now working.

 

 

It sounds to me as though your transmission is broke.  

 

If you're registering speed on the speedometer that is appropriate for the engine RPMs, then you've certainly got a problem between the VSS and the trans output - otherwise you'd be moving.

 

If you have a lot of time and a long bench to take it apart on, you could probably find the problem and repair it yourself.  Something that makes the kind of noise that you are describing shouldn't be tough to spot.

 

 

I recommend against dealerships in general for anything but warranty work.  In my experience, they only fix what is broken, rather than determine and resolve the cause of failure.

 

I can recommend an excellent transmission shop in Defiance, Ohio, but considering the amount of travel involved, they may not be a cost effective solution.

 

 

Best of luck!

[99123456]

PFarkas, thanks for the input.  I agree, I don't see how transfer case would work in forward, but not reverse.  Sure seems to be tranny.  

 

You make another good point about dealer vs tranny specialist, but I was only going to use dealer to nail down the diagnosis and then r&r the tranny with a used one myself.

 

Reason I mention Vette tranny is cuz timing is almost right for me to swap with car's tranny.  Trying to sell the '98 H/C car and put a SC on an '03, so I thought I might be able to put the Vette tranny in the Silverado, send the sick one in for a core on a built FLP for the SC's output, and kill two birds with one stone.  But timing is off by a month or so.

 

Thanks for the suggestions and I'll let you know how it shakes out.

[PFarkas]

Unless you're interested in swapping the guts from the Vette's transmission into the housing from the truck, you aren't going to be doing a direct swap from the car to the truck. There's that whole "no yoke on the output of the truck's transmission" thing to deal with.

 

Unless, of course, you have a 4wd Vette.  I understand that these are pretty rare...

 

 

Hope you get this squared away before the holidays.

[99123456]

Don't need no stinkin yoke on rear of tranny.  The C5 is only a 2X (at WOT), but with the torque tube, transaxle (in rear) setup, it only has CV joints on the axles. Probably lots of other reasons why it wouldn't work though, maybe not. I AM running truck heads on the vette, mixing and matching is getting more common all the time.  (Like when I used to buy 944 parts and they were stamped "VW"!)  I could reprogram the new car tranny with my LS1Edit, but I'd have to have dealer reflash the truck.

 

I figure after pulling the torque tube/trans/rearend on the car, the truck ought to be relatively easy. Can you steer me toward some DIY site for the tranny r&r?

 

I managed to use a come-along last night and got it in the garage after an hour and a half.  I raised rear and EASE scanned it while going through the gears.  OD (fourth) and reverse make the most noise, and I believe they are "shared" in the tranny, so it is the likely suspect.  Weird that no DTC's are being thrown.  I guess you don't need a code to tell you your truck ain't moving.    

 

Would really appreciate a reference to DIY info/site, like torque specs, tools, parts, fluids needed, order of op, etc.

 

Thanks!

[tfpary]

It sure sounds like your reaction shell in the transmission broke at the weld. You didn't say which transmission (or I missed it) but from your discussions it sounds like you have a 4l60e, which is famous for this problem. The two halves are welded together and the weld breaks. Mine crapped out at 60,000 in my suburban.  If you so desire, this can be replaced without a total rebuild, but you have to take most of the parts out of the transmission to get to it.

Have fun!

tad

[99123456]

Interesting.

 

Yeah, it's a 4L60squEek.

 

Would the reaction shell breaking still allow me to drive forward without noise or slipping and power-brake up to 2000 rpm (couldn't drive any farther forward because no room) without any noise or slipping?

 

When in reverse, it squealed and slipped without moving the truck on level garage floor, but I could go to 1 and powerbrake.

 

When I watched it shift into OD via scanner with wheels up, the squealing began.

 

So the reaction shell is independent of 1,2, and 3?

 

In any case the used tranny is sitting by, but I'm having a lot of fun working on the bellhousing bolt located at 12:00.

 

Going to backflush the atf cooler, is the top inlet the inflow?

 

Am I gambling not changing the TC seal on used tranny, using the TC that came with the  used unit?  It looks OK.

 

thanks