Transfer case input seal question?
 

I know there are many threads mentioning this issue, but I have a few questions that I couldn't find answered on other threads. Any help you guys could give is much appreciated.
So my transfer case rear seal is leaking pretty good. I wanted to check the fluid level because I figured it was pretty low, and I read on here that if fluid pours out, then the input seal needs to be replaced. So I open up the fill plug and lo and behold it pours out like crazy. I'm assuming that I need to replace the input seal and the rear seal of the transfer case but I'm not positive if that is correct or if there are other seals as well that will need replacing.
I also read that if not fixed, I could get fluid into the vacuum lines and possibly the HVAC system. Could someone explain to me how this happens? I'd just like to know the mechanics of how the fluid ends up getting into those lines. Also, where would I look to find out if this has already happened to my truck? I got the truck recently so I don't know how long the input seal has been bad, but the rear seal just started leaking a couple weeks ago. Someone else mentioned that this could cause slipping and make the transmission fail. I'd also like to know how this happens.
Does the transfer case fill up slowly over time when the seal is bad or is it more like an open pipe? I'm asking because of the whole bunch of extra fluid that came out of the transfer case, and I'm wondering how much fluid I need to put into the transmission now that I let the extra drain out of the t case. The transmission fluid itself is low too so I'm not sure how much it needs, or if it all just fills back into the t case immediately? Sorry for all the questions, I'm just trying to understand what I'm up against.
My final set of questions is about how long I can wait to fix this. I know it is not wise to wait to fix something like this, but I have to take one more trip up to school tomorrow to get all of my stuff before I can stay home for the summer and actually work on the truck. I just came home for the weekend and found out that I have this problem. It's about 140 miles round trip. The transmission as of today shifts just fine and I've never had any problems with it. I plan on fixing it as soon as I get back. Now that the fluid is at the normal level does that bide me any time at all? or as in my previous question is the t case just going to fill right back up again?
Thanks for bearing with me and reading all of this. Please help!

-Melissa

The lines are under vacuum, but that pressure fluctuates when things happen (vents open/close, 4wd activates, etc) which can pull the fluid in. This occurs when both the input seal AND the vacuum switch leak. So if you have trans fluid in your vacuum lines at the t-case, you will want to replace the vacuum switch as well as the leaking input seal and anything else that is leaking at that point in time.

Thanks for the quick reply. I understand that much better now. Are the lines exposed to the top of the inside of the transfer case? I wasn't sure how the extra fluid would make contact with the lines. Sorry if that's a stupid question.
Do you know if it would be okay to drive it one more time before fixing it? I know you have no idea how long it's been messed up and neither do I, but I'm just trying to gauge whether or not it would be really stupid of me to make the trip tomorrow. I don't want to cause more damage but I really need to pick up all of my things at my apartment.

The vacuum lines connect to the vacuum switch on the transfer case. That is why you need a combination of failures to occur for fluid to get into the lines.

Won't tell you to go or noy bit you can pull the vacuum switch lines off and see if the have fluid in them. I certainly watch the trans fluid level. You're gonna have to pull the t-case to fix the front seal problem. The rear one you can do in the truck. It's not that bad of a job but get some hefty guys to help you. I just fiund it easier to unbolt the t-case and manhandle it out vs a jack (although you will nrrd ine. There is a bolt on the bottom of the t-case that;s usually hard ti see because when these things leak a lot of times it ruins the trans mount and it sags. I would plan on a new one of thodr too (about $15.00 - $20.00) and some new gaskets. On my 94 I had to get a rear seal for a 95 (if the seal is long you'll have to do this too) because that's how they are. Don't worry you'll be able to tell. The problem is that the rear of the trans has no seal by itself, just the t-case seal. By the way sometimes the screws on the front t-case seal can be very diffucult to remove. Need help just ask away. I've dine this to mine recently.

Thanks Swartlkk and Gimpy. Hey Gimpy, do you know if when the seal is toast if it's a slow leak from the tranny into the transfer case or if it all just kinda dumps back there pretty fast?

UPDATE:
I just went to leave my house and I couldn't get to the end of the street. Ugh. It's definitely slipping. It ran great just yesterday. Do you guys think that opening the plug and letting all of the extra fluid out messed it up? If I change the seals and fix the leak will it be okay or now that it started slipping do I need a new transmission? Like I said, I just drove to the end of the street. I am so pissed.

STOP NOW!!! Your transmission is probably still OK but fill (not overfill) it NOW or it will be toast. You can pull the trans dipstick and smell the fluid. If it smells burnt, I'd first try changing the fluid and filter (I'm not a big fan of flushing the transmission) and see if that smell goes away. I guess you have a pretty good leak through the seal. I doubt if letting the excess out did it. That's a pretty big cavity between the trans and the t-case. Stay in touch.
PS How about your interior lights? I know they probably just moved down a notch or two on the priority list but did you get them fixed? (Memory like an elephant)

Don't worry, I just drove it to the end the street, realized I had a problem, and drove it back home. We're talking a couple hundred feet. I'll check it to see if it smells burnt.
I just checked the fluid level, it's at the right level, and does not smell burnt. Is it possible that the emergency brake was stuck on? I've been using it every time I park lately, because the truck likes to roll even when it's in park, which is a whole other problem. But not being able to get down the street felt a lot like the brake was on. I just assumed it was slipping because I pulled the e brake cable to release it before I left, so I figured that couldn't be the problem.
The interior lights have moved down a notch but another new development started today also (i have the best luck) that's going to make it hard to ignore. Whenever I turn the lights on, that annoying alarm that lets you know that you left the lights on stays on and won't turn off unless I turn the dimmer switch all the way to the left. Which is going to make night driving unbearable. Now that I'm stuck here I'll have time to fix it. But we can talk about that on the other thread I guess because it's kinda off topic.

Will try to look at the W/Ds and let you know about the buzzer.

Hey Gimpy, to update, it definitely has to do with the transmission/ some part of the electrical system. The guy at the garage said that the fuse must be a coincidence to the problem but all 3 times I have ever put the fuse in with the truck running it would lock up and the speedometer wouldn't move. He also said that it's starting out in second gear which is why it feels weird like it doesn't want to go. I don't know what this has to do with the fuse, but this problem has only happened when I put this fuse in. Today was different though. I was on my way back home and I was halfway down the road when it seemed to just lock up. I tried several times to remove the fuse and put it back in but the problem persisted. I had to get the truck towed home. Now I looked at the list of common 4l60e issues and I found 2 that sound like my problem. I'm thinking it has to be one of these two things, only problem is, I don't know how the fuse fits in with all of this at all. Let me know what you think.


5. Trans does not upshift out of first, speedometer reads zero at all times: VSS failure. Easy fix on rear of transmission, but xmember must come out to access VSS.

12. Car goes into gear but feels very sluggish like the brakes are dragging, but it will roll easily (starts out in 4th gear), you manually shift to 2 to get it moving, once it's moving you put it back in OD and the car shifts 3rd to 4th on its own and locks the converter at the appropriate time: ShiftB solenoid failed: Easy fix in the pan. Or a wiring problem from PCM to trans.. or PCM.


With the first one, the speedo is what's making me think the speed sensor might have something to do with it, but the fact that it also feels like the brakes are on and the guy said it's starting in another gear makes me think it might be computer related, especially when I have only noticed a problem when the fuse is involved.

UPDATE:
I took out the vss and it had metal shavings stuck to it and I cleaned it off and put it back in but it didn't help. I'm worried because the electrical connector part of it had trans fluid all over it when I detached it from the vss. Seeing as it is an electrical component I'm going to assume that that's not supposed to be there. Does anyone know for sure? I'm thinking it got in there when the transfer case filled up to the top from the input seal leaking. If the fluid is not supposed to be there I'm thinking I'll need a new vss, and possibly the electrical connector leading into it. If anyone can give me advice on this I'd really appreciate it.

I really need some help! I swapped the vss with my boyfriend's because we know his works and his blazer is identical to mine. I cleaned the electrical connector to get all of the atf fluid out of it. This didn't solve the problem at all. Still doesn't want to shift and still no speedo. I put mine in his truck also and it worked with no problems so it's not the vss. Do you guys think I need a new connector piece because it got ruined from the fluid? Or I also read something about a buffer, could anyone give me information on that? I tried to trace the wires back and it looks like someone was under there at some point because there is electrical tape around the plastic tubing that holds the wires. Gah I hate it when people mess with stuff. I haven't had this car very long and so I don't know what the hell people did with it. I'm so frustrated I'm ready to cry. If anyone has any ideas that will help it would be most appreciated.

I should also mention that this problem started out very intermittent, and now I can't even drive it because the problem exists most days now. It would do it randomly a few times in about 3 months, and then it started happening more frequently. I only drive it when it is not acting funny. The truck would always start right up but in the past few days I have trouble starting the truck and I it's like the battery isn't charging.

UPDATE: Hey Gimpy, I think I may have figured it out, and in record time too! I checked the fuses and the IGN/GAU fuse was melted on one side of the plastic. I changed the fuse out and started the truck but it was dead. I got it jumped and the speedo popped right up to where it should be and I drove the car away like it's good as new! I've been researching my problem a lot and read that the IGN/GAU fuse controls many things including the alternator (which would explain the dead battery) the door jamb switch which I've always had problems with, the transmission/vss buffer, (which would explain my transmission and speedo problem), and if messed up it can cause the buzzer to come on when you turn the lights on which has happened to me recently. Maybe putting the horn/dm fuse in while the truck was running was somehow screwing up the ign/gau fuse. It's hard for me to believe that one little fuse could mess things up so badly. I'm wondering if this is a temporary fix or if the wires for one of these things that goes to this fuse are frying somewhere. If the plastic on the fuse starts to melt I'm assuming it can't be a good thing. What do you think about all of this?

I think that the plastic on the fuse isn't supposed to melt. If it's running OK now there isn't much you can do until it messes up again. I'd watch the fuse for some more signs of pverheating. Do you have the correct fuse in it? I know you had some issues with this before.
You really need to get the seals fixed. It's not really that hard but I would be concerned about finding metal on the VSS when you pulled it out. What kind of metal was it? Colorwise. You can change the rear seal in the truck but the front one requires pulling the t-case. You might try draining the t-case fluid and catching it through a paint strainer or cheese cloth. That would tell you a lot about the type of metal. There is an oil pump in the t-case and the pick-up tube for the oil does have a small filter (or strainer) on it. I would pull the t-case and disassemble the rear half which means VSS, tone ring and oil pump. You can get the pick-up tube out from there. The thing only holds 1 liter or 2.2 pints of ATF. Make sure you replace the gaskets on the adapter to the transmission and you might want to look at your trans mount. Mine was so saturated with ATF it ruined the mount. Costs about $20.00 for a new one. Suggest you get a good manual that covers this stuff. Haynes and Chilton are lacking in some areas. Sometimes the screws that hold the front seal in are pretty tight and tough to get out. Anpther word to the wise about the rear seal. They make two different kinds and I had to get a 1995 one for mine. The difference is in the length. For a 94 the parts book showed a short (1/4" thick) seal. Mine was about 1 1/2" - 2" long. Just lucky the guy at the auto parts store kind of knew about some of this stuff. Hey, you're learning. Keep up the good work.

I'm really thinking that the fuse melted because it was under a heavier load than it should have been. I just found out that the previous owner had a heavy duty alternator in it before for the plow setup and all that. I don't think he changed the fuse or anything else to compensate for that so perhaps it's residual damage. I think this took a long time to happen as things slowly kept getting stranger with the electrical system. The fuse in it is the correct one. I am going to fix the seals very very soon. The metal was little itsy bitsy pieces of metal, like if metal were grains of sand, and it was silverish dark gray. It was stuck to one side of the vss magnet. When I removed the vss from my boyfriends truck his was the same way so I assumed it was normal. I looked at the t case fluid when I pulled the drain plug 2 weeks ago because all of the excess drained out. It was red. A darker red but the fluid still looked good and I didn't see any metal in the pan I drained it into.
Where is the trans mount? I looked around but I'm not sure what it looks like.

The ttrans mount sits under the adapter from the tranny to the t-case. It's black in color (even new) and bolts to the crossmember. You don't have a tailstock on your transmission because it's 4 wheel drive so you have am adapter between the trans and t-case. If is's soaked with fluid you can bet the rubber part is probably shot. I took handfuls of it out mine was so bad. You'll probably need to pull it anyway when you drop the t-case.

Okay, I got the transfer case out. The trans mount is fine. The seal was so bad that it's coming out in tiny pieces and being a serious pain. I'm going to have to spend a tedious amount of time getting it all out of there tomorrow. Also, I found out that I need a new vacuum switch because there was fluid in the lines so I'm going to grab one of those tomorrow and suck as much of the fluid out of the lines as possible. I'll update more when I get everything back together. Thanks!

Sorry I missed the beginning of this thread. However hopefully this will help answer some of your questions.
Your main concern here is the tranny. The 4x4 tranny does NOT have an output seal, the seal is located in teh t-case. IF that seal fails your t-case will fill with tranny fluid, hence when you remove the service plug you get a gusher. No doubt this is also why your rear t-case seal failed, the t-case has too much fluid and it keeps coming from the tranny.

As for the HVAC (heat, ventilation, and air conditioning) being affected by the t-case it goes like this. There are 3 vacuum hoses attached to your t-case, one of those hoses provides vacuum from the engine, and this hose is also tied into your HVAC system, and all of your vacuum systems. The 2nd hose provides vacuum to your front axle to lock in 4x4. The 3rd hose is for ventilation of your t-case, it runs up into the engine compartment next to the distributor cap. If that vacuum switch fails, your t-case fluid will get sucked up into the vacuum system, and eventually affect your HVAC system, very bad, very, very bad. That little switch is part of a unit, a $150 unit.

As for your tranny problems, I didnt read everything posted, however if your tranny fluid is low, your tranny wont shift properly, and if its really low it may not shift at all.

Now that you have the t-case out, I would replace both the input and output seals, and the vacuum switch. Check your hoses for cracks or other wear. If you run your hands up and down the vacuum lines and they come back black, replace the hose. Assuming this black isnt from a leaking oil cooling line or general road grim. One of the first signs a vacuum hose needs replacing is the black residue, and second sign is soft rubber, and Id be surprized if you didnt have cracks especially are the ends where it attaches to fittings.

If you have a vacuum leak it WILL affect your engines performance, and then it WILL affect your tranny shift points. Everyone assumes its the tranny, when in fact the tranny is only doing what the puter told it to do, and the puter is getting its info from teh engine sensors, and they are reading fals info because you have a vacuum leak. The leak will cuase a rough idle, hesitation, bucking, odd shift points, etc, especially under light trottle.

? ask

is there a way to put a rear seal in the transmission? or a "better" T-case front seal available? this seems like a common problem, dad has had it happen to 2 of his. (a '96 & a "98). i may be getting the '98 soon. trying to learn all i can about the upkeep of these vehicles.

No to adding a rear tranny seal. Yes to a better input seal, get the double lipped seal.

I want to clarify something I posted earlier. Teh little swicth Im referring to is your HVAC control switch (dial in the cab of the truck that you trun to change from heat to ac), that is $150 or so. The vacuum switch on teh t-case is $12 or so.

Thanks for your info. I've been having a lot of luck finding information about my issue and so I'm pretty up to date on all of it but you clarified some of the stuff I was unsure of. I already bought a double lipped input seal, just have to keep slowly working the old one out. :( My questions now are, what would you say is the best method to get the atf out of the lines, and how do I know if the fluid has gotten into the HVAC? Thanks for all your help.

Having a few drops in the lines is no big deal. If it were my truck, and me being hte cheap !astard I am, I would pull the vacuum lines off the vacuum switch and at the intake maifold, then let it drain for a couple hours/days. Dont forget to reconnect them.

The best thing is to replace the vacuum hoses with new. Fortunately vacuum hose is cheap, unfortunately its not an easy thing to swap out. The biggest headache will be the top passenger side tranny to engine bolt. The bolt holds a clamp and that clamp holds your vacuum hoses to the t-case in place. The easiest way to get at the bolt is to lower the tranny while still attached to the engine, tip it back until the distributor almost hits the firewall. 3' of extensions and a wobble socket. One of those hoses goes under the battery, you have to remove the battery and battery tray, the other two go next to the distributor, one is vacuum feed and the other is a vent, look for teh plug on the end. The vacuum line attached to the intake splits at a tee, and it runs into the cab of the truck. Depending on year depends on where it goes into the cab, older truck in the middle of the firewall, newer trucks in past the drivers side fender. Dont forget the hoses running to teh EVAP system (charcoal canister).

ATF in the HVAC- HVAC will stop working properly.

Hey guys, I replaced all the vacuum line that I could find. Does anyone on here have a diagram for the vacuum system? I replaced the lines going from the ball to the t, from under the battery to the t case, from the t to the cruise control, and from the t to the transfer case. I didn't change the vent hose that goes to the t case because it's in good shape. I can't find the line that runs into the cab. Is it smaller than the other hoses? Also, I have no idea where the evap canister is... I didn't have to move the transmission to get at the lines bolted to the passenger side of the tranny. Me being a girl, I luckily have tiny hands that managed to squeeze up there from the side. :)

Vacuum diagram should be under the hood someplace. GM puts a sticker under the hood on every vehicle. Vacuum routing changes so much from year to year it was easier to put in a sticker.

Keep looking, vacuum comes off teh engine behind the intake manifold next to the distributor. Follow it!!!

I have officially finished this project! I replaced all the vacuum lines, and the input seal. When I found fluid in the lines after pulling them off the transfer case I replaced the t case switch. I put it all back together and I am very pleased to say that not only did I fix the seal but my 4 wheel drive works! It didn't work when I bought it so this is pretty exciting for me. This is also a good example of how when you get a trouble code you shouldn't always just replace the part that the code says is the problem, because something else might be causing that part to malfunction. My 4 wheel drive code was a 2, for the encoder motor. But apparently the t case switch was behind the whole problem. So I paid 20 bucks for a part that fixed the problem instead of 200 bucks from assuming that the encoder motor was broken because that's what the code said. Yay. Thank you everyone for all of your help!:icon_dance-cpatch:

Good job.

Its always a great feeling when things work as they are supposed to. :icon_bike:

thats great to know you fixed it