Transfer case dead

[Sparky]

Went to change the transfer case fluid today and the case looked slightly damp. Popped the fill plug and drain plug and the case was EMPTY I swear I never saw any signs of leaks previously. Filled it up and tested in the driveway and 4x4 did engage fine and it crow hopped like it should. OK... Didn't see any case leaks with it sitting.

Took it for a short drive and checked it after a couple miles. Was a bit wet underneath. Great. Drove home and on the way coasting down a hill I was hearing a gravelly noise underneath. Got home, looked underneath and I had smoke rolling from the exhaust pipes and transfer case oil EVERYWHERE. Looks like it might be coming from the tailshaft seal.

Anyway, given it was almost empty and the noises its making I'm pretty sure it's dead

I can get a used 2005 transfer case with just under 50k miles on it for $225 probably. How hard is it to replace a transfer case?

 

[yar02169]

I'm in a similar boat. My Bravada (AWD) has had the Service AWD light on for the summer, didn't drive it much because I was driving the convertible. Drained the transfer case fluid (got about 1 cup of fluid), and put in 2 quarts of new fluid. Took it for a test ride and the light stayed on, got back home and smelt the smell of burning fluid. Took a look underneath and there was a bit of fluid accumulation at the housing seam. Went to park it in the street so it can drip there, and did notice the idiot light was out. I think it would really suck to pull the transfer case out just for a gasket leak. Is it possible to put in some tranny seal or something that would clog up the leak? It's pushing 100lk miles and I don't want to spend tons of cash as there is now a list of things that this tired truck is in need of, and I don't plan keeping it forever.

 

[tblazerdude]

tail shaft seal is super easy to do. IIRC part was under $50.

 

[Sparky]

Do you happen to know that part number?

I drove it this morning and aside from oil spraying around I didn't hear the gravelly noise. Last night I wasn't thinking about the fact the road I was on was a tar and chip road that sounds gravelly to begin with. I may try just replacing that tail shaft seal first and hope the case is ok. A lot cheaper and easier.

 

[tblazerdude]

P/N I used was 88935685.

 

[Sparky]

OK Thanks. Just looked at the process for replacing the seal and it looks almost stupid easy.

It drove fine on the way home this evening, blowing transfer case oil EVERYWHERE though. Yikes. It completely coated everything from the transfer case back in oil. Gas tank, spare tire, rear pumpkin, exhaust (oh smelly), even flipped up all over the rear bumper and liftgate as high as the glass. What a MESS

Still no strange sounds so I'm going to just pop a new seal in there and hope for the best. I want to check the yoke however, just in case there is a rough spot somehow that tore the old seal. I don't want to put a new seal in and tear it again. That would suck.

 

[Sparky]

Replaced the seal and it is still blowing oil! The heck is going on?!

I'm starting to wonder if there is a vent tube like the differentials have that could be blocked (check valve sticking maybe), causing pressure to build up inside. Plausible? Anyone happen to know where the vent tube is on the transfer case?

 

[Harpo]

I think there is a vent tube on the top going down to the right side if i remember it correctly.

 

[meerschm]

http://www.gmpartseast.com/diagrams/small/56S/transfer-case-vent-tube-ts0402901.png

 

[Sparky]

Thanks for that diagram! Of course it looks to be hard to get to. Figures. Hopefully that is the problem.

 

[Mooseman]

Was there a wear groove on the yoke where the seal rides? I've seen that on differential yokes and the manual says to replace the yoke if there is a groove. Same thing on axles.

Edit: Never mind. Just remembered that it's a slip yoke so it doesn't stay in the same spot to have a wear groove. Maybe a bad new seal? Had that happen to me on the rear diff axle seal.

 

[Sparky]

I suppose it could be. Just would seem unlikely to have the new seal blow oil the same way the old did. Probably more likely to have another cause and the blowing oil is the symptom. So I figure I'll check the vent first as that doesn't cost anything more but time. I don't know how I'd exchange the seal for another one from Rock Auto since it is currently in the truck now.

 

[CaptainXL]

Just replacing a seal wont solve anything if there is internal damage. For instance a rear axle seal that is leaking might be due to a ground down wheel bearing due to lack of fluid. After installing a new seal it will keep leaking because the wear clearance will grind through the new seal.

 

[Sparky]

There was no damage to the slip yoke, nothing obviously visible at least. That's why I'm thinking it is probably either pressure build-up, forcing the fluid past the seal, or the output shaft bearing is shot and wobbly. Although you'd think if it was doing that it would be noticeable when sliding the driveshaft in, and/or cause a vibration. That's what I don't get.

 

[Sparky]

First off I just want to mention I myself didn't do the seal replacement. I had the shop around the corner do it in the interest of time and also they could check stuff like the output shaft bearing and whatever while they were at it.

I crawled underneath it tonight again to take a look at the vent tube, and while I couldn't really get to it where I was what I DID see bothered me a lot. My slip yoke is rusty which is no surprise. BUT the issue that I am seeing is it looks like it is rusty going INTO the seal! Now tell me that wouldn't tear up the seal in short order and make it leak horribly. Thing is, I'm not entirely sure if this is the case because there are two lips on the seal -the outer lip, which is more of a dust boot more than anything and does not fit tightly over the shaft, and then the inner lip which is the actual seal. I can tell the rusty part of the yoke extends past the boot portion of the seal, but not sure if it goes all the way to the seal lip.

So what I'm going to do is call the shop, tell them my concern, have them double check this, and if this is indeed what is going on see what it will take to replace the yoke. I will ask them about paying for another seal since they should have noticed this issue to begin with, and maybe a partial labor credit.

If they do confirm this is the issue then I guess I'll need a new yoke, thing is I can't figure out where to find one or how much it will cost.

 

[Mooseman]

Those yokes can rust up to the maximum point where it would slip into the case. You should see a bit of shiny metal just outside the seal. This would be the point of maximum rear suspension travel that would push in the yoke. One possibility is that the new seal extends out more than the original or it was not pressed completely in so it would ride on the rusty part. That's why when I would change this seal on any tailhousing (transfer case or tranny) I would remove and polish off the rust from the entire yoke just in case. Another things is that you have to push the yoke all the way in to be able to re-connect the the u-joint to the differential. If there was still rust, it could have damaged the new seal. If you saw bad crusty rust on the yoke, this could be the reason.

 

[Sparky]

It is bad crusty well past the outer part of the seal. If I push the seal flap towards the case housing to see more of the yoke it is all rusty there too. With the suspension loaded I cannot spot a single shiny spot. It is rusty enough I don't think you could just sand it down and get it smooth again.

I wonder if I can get a driveshaft from a junk yard with a yoke that would be free of rust like that? I'm not having much luck searching for just a yoke.

Part of me wants to shoot this thing lol.

 

[Sparky]

I was going to edit my recent post but it won't let me, so...

I called the shop and explained the issue and he pointed out yet another thing I totally missed. When I pulled the dust boot of the seal back a bit to check the yoke it was totally dry! So if it is dry that means it can't be leaking out that tail shaft seal. Great. So what we're going to do is I'm going by the shop in the morning, they'll clean it all up, then take it for a short drive and put it back on the lift so we can see exactly where it is leaking from. Complimentary, no extra cost to me for this which is nice as I already feel really really stupid for replacing the seal that didn't need replaced

 

[meerschm]

I was going to edit my recent post but it won't let me, so...

I called the shop and explained the issue and he pointed out yet another thing I totally missed. When I pulled the dust boot of the seal back a bit to check the yoke it was totally dry! So if it is dry that means it can't be leaking out that tail shaft seal. Great. So what we're going to do is I'm going by the shop in the morning, they'll clean it all up, then take it for a short drive and put it back on the lift so we can see exactly where it is leaking from. Complimentary, no extra cost to me for this which is nice as I already feel really really stupid for replacing the seal that didn't need replaced

I hate when that happens.
:banghead:

 

[Mooseman]

When you mentioned that it was still blowing oil, I Ass-U-Me d it was blowing out by the seal. That tech sounds like he knows what he's doing except I would have still cleaned off that rust. I'm just anal like that

 

[Sparky]

Heh, yeah, I assumed the same thing. But I guess it might have been better for me to check everything FIRST before assuming the seal was shot to begin with. It just seemed the most logical source.

At least I know my new seal is working OK

 

[Sparky]

Update.

The seal is bad. Again. Was dry because the case was running low again.

Reason the seal is bad? Heh, my front U joint is half frozen. It moves freely on one axis but is really stiff the other, so it is just tearing that seal out. Probably explains the random vibration I was getting also. Rear U joint is a little rough too, so I'm getting new U joints on both ends of the driveshaft. Oh, and yet another new seal lol.

Hopefully this is the end of this saga.

 

[BRomanJr]

Update.

The seal is bad. Again. Was dry because the case was running low again.

Reason the seal is bad? Heh, my front U joint is half frozen. It moves freely on one axis but is really stiff the other, so it is just tearing that seal out. Probably explains the random vibration I was getting also. Rear U joint is a little rough too, so I'm getting new U joints on both ends of the driveshaft. Oh, and yet another new seal lol.

Hopefully this is the end of this saga.

Not trying to make it any worse....but,
There is a bushing to the inside of that seal, if you are getting enough movement to damage the seal, the bushing is not doing its job anymore.

I would check the slop in the bushing before the new seal goes in, and possibly the outer surface of the front yoke of the drive shaft that rides in the bushing.

 

[Sparky]

OK an update:

U joints were replaced last Wednesday. I washed the rear window and drove it on the interstate that night and I had NO oil mist spots on it :wootwoot: I still had some oil burning off the exhaust, but I couldn't tell if it was just old stuff still left over or fresh. It was less I knew that much.

By now if it wasn't leaking at all I would think there would be no more drips or spray on anything, but it does seem that I am still getting a little bit of a leak. Nothing near as bad as it was, but I had a couple drips off the bottom of the transfer case today when I checked it, so it appears to have a slow leak. At this point I'll probably just keep an eye on the level and top it off every so often if it isn't leaking too badly.

I'm wondering about what the guy said about the yoke having been rusted and now pitted into the seal area a bit. Well, maybe I should put a lift on the truck to extend the driveshaft out a bit and put the seal on a perfectly smooth spot if this is indeed the case

I'll give it a few more days of driving and see where we are at then go from there.

Oh, I did notice that I don't hear a click-click noise when driving by a building or wall with my window down anymore. That clicking had been bugging me for a little while as I couldn't track it down. Now I know where it was coming from, heh.

 

[Mooseman]

Maybe try using brake cleaner on the whole transfer case and let it sit overnight or even 24 hours if possible. Check for the leak or if it's sweating through a seal or joint. I'm just hoping it's not the seal between the two halves of the case itself. What about the front driveshaft seal?

Just a thought... maybe it's something else leaking now? Maybe a tranny line since they are infamous for rusting out and leaking.

 

[Sparky]

Definitely not a trans line as I've already replaced them 2 years ago and the leaked fluid is blue.

It is dry around the front shaft seal. The only wet spot on the case is the output shaft snout. It runs down the snout and makes the case damp but I don't think it is coming from the case halves seal. Maybe I'll crawl under there and spray everything down like you suggested. It would also tell me a little more on how fast it is leaking.

 

[Sparky]

Well it still isn't leaking as bad as it was as it doesn't get all over my liftgate and bumper anymore, but it is still leaking I haven't had a chance to crawl underneath and spray it down yet due to a really heavy work schedule this week but it still looks to be coming from that seal as that is where all the wet starts.

Now what... New yoke? Where do I get that from?

 

[meerschm]

View attachment 24190

is 7 what you think you may need?



2002 Chevy Trailblazer 4WD - TS0501204 Prop Shaft, /Rear - W/O

 

[meerschm]

View attachment 24191

or 19

2002 Chevy Trailblazer 4WD - TX0402701 Transfer Case, Part 1, Case

 

[Sparky]

7 in the first pic. It was all rusty and pitted. I have a bad feeling that it will need yet another seal lol. Might replace that bearing or bushing or whatever it is behind the tail shaft seal (#17) too just for the heck of it since well I'm tired of fighting this daggone thing.

Bugger they star out the first couple digits of the part number.

 

[meerschm]

7 in the first pic. It was all rusty and pitted. I have a bad feeling that it will need yet another seal lol. Might replace that bearing or bushing or whatever it is behind the tail shaft seal (#17) too just for the heck of it since well I'm tired of fighting this daggone thing.

Bugger they star out the first couple digits of the part number.

I am sure they will fill it in when/if you order the part.

 

[C-ya]

Oh, I did notice that I don't hear a click-click noise when driving by a building or wall with my window down anymore. That clicking had been bugging me for a little while as I couldn't track it down. Now I know where it was coming from, heh.

Did it go away when you let off the gas and coasted? Mine is doing that.

 

[Sparky]

No it didn't go away but it wasn't as loud I guess.


Another update:

I'm starting to think that my transfer case is no longer leaking. I thought it was, but now I'm not so sure.

Yes, I still have wetness underneath. However, something has changed. The blue drips and wetness has now turned orange. Yes, orange, and I now have a fairly steady orange drip coming off the bottom edge of the transmission bellhousing. Yes, I'm certain it is orange, not red. That was my first thought too that it was transmission fluid. I blotted it with a white paper towel to be sure and it is definitely coolant.

I don't doubt my transfer case had been leaking because it was obviously empty, and after I filled it I had oil spray all over the underside and the liftgate. But ever since I replaced those U joints and the seal I haven't had any more oil on the back bumper or liftgate.

Now who knows how long I've had this coolant leak. Late summer/early fall when I replaced my AC clutch I had noticed my coolant was a bit low. I didn't think too much of it, just topped it off. But something has changed and it is a much faster and certainly noticeable leak now. My reservoir was almost empty (engine temps have been fine).

So what is near the back of the engine, more towards passenger side, that carries coolant that could be leaking? Aside from the wet spots underneath and some dampness I can see on crossmembers when looking from the top I see nothing obvious. My first thought was the heater core or the hoses on the firewall, but all that is dry! I'm not sure how it is getting far enough back to get the cross bar wet (near where the fuel filter is), or the forward part of the fuel tank, but there is orange on those too. Geez.

This is the worst time for this crap. Work has gotten insane this week and I won't even have a weekend. I simply do not have time for this. Don't even have time to go to the shop and have them look at it for me. Well heck I might be forced into making time, somehow.

 

[jrSS]

Maybe the the line from the resevoir to the radiator has a hole.

 

[Sparky]

Could be. There is another line underneath the tank isn't there? The small line is dry and above the low level right now anyway. I didn't see any wetness running down the inside of the fender though.

*edit* I just refilled the reservoir (took about 3/4 gallon to bring it up to the cold line) and looked back underneath. It isn't actively dripping right now, so the truck has to be actually running for it to start leaking it appears. I'll double check it in the morning.

 

[Mooseman]

Did you check the A/C drip tube to see if it's leaking from there? That would indicate a bad heater core. There are a few connection points for the heater hoses around there but you said they were dry. Apart from that, I don't think there's anywhere else for a leak like that. I don't even think these engines have freeze plugs. Speaking of which, do you have a block heater? If so, check that too.

 

[Sparky]

I didn't check the drip tube. I don't remember where it is. Probably not easy to get to with it still on all 4 wheels. I did check the inside carpet and plastics as I've heard of heater cores getting the interior soggy, but everything I could see was dry. It was dark when I noticed all this however (was getting gas and peeked under the truck as something was smelling different), so it isn't like I could see all that well. I'll have to check it in daylight and when I can get it up on jackstands.

Where ever it is coming from, it is making a mess. First I got an oil undercoating, now I have an antifreeze undercoating. Joy

 

[NJTB]

Rent, borrow or buy a radiator pressure checker. It screws in where the radiator cap goes, and has a hand pump with a gauge.
When the truck is COLD, put about 15lbs pressure in the radiator and look for your leak.
I'm guessing the heater control valve near the firewall.

 

[Sparky]

I don't have one of those but I did find that it does not leak until I start the engine. Once I do, it starts dripping soon after.

Where is this heater control valve located? Everything is completely dry where all the hoses and stuff go into the firewall. Actually all of the firewall that I can see from the top is dry, and the very top of the transmission/bellhousing that I can see from the top also is dry, but further down it is wet.

Baffling.

 

[NJTB]

Just went out and looked at mine, it aint there (the heater control valve, guess they eliminated them). They used to be on the inlet to the heater core on the firewall side, and if they leaked it would drip on the catalytic converter area.
Don't forget, antifreeze could drip down a hose and the leak may be some distance from where you could see it. If the top of the bellhousing is dry but you see wetness on the side, it almost has to be one of the heater hoses or connections. Any chance you could get it on a set of ramps and look from underneath?
If you get the pressure tester, the engine don't have to be running for it to leak. Maybe Autozone lends/rents them?