New Guy with t-case Qs

[DruBlazer]

Hey folks. This is my first post.
Intoductions first: My name is Drew and I have recently bought a 71 4x4 Blazer after spending years looking and wanting. It currently has a little lift with some engine mods, but besides that, pretty stock. Which is how I'd like to keep it. The guy I bought it from didn't know much about it, or any mechanical thing, at all. And I can tell. He did some things that I've spent time undoing.
That leads me to my question. As I'm crawling through my rig I noticed that the output shaft on the t-case is leaking. So my thought was that until I can fix the leak, the least I could do is keep it full of gear oil. When I pulled the fill plug, not the drain plug, ATF came pooring out. Could there be a problem with both the output seal of the TH350 and the input seal of the 205 that would cause the ATF to get into the t-case? Has anyone encountered this problem? Ideas?

Thanks

[MAC67]

hi there and first off welcome to the board from illinois , also where ya from and if it all possible post some pics of your blaze , we love seein them ,, again welcome to the best site on the web ,, now youll run into this alot , im asuming its a np205 transfercase , some guys use atf , why i dont know , i always use 80 90 , drain it and refill with 80 90 , if your tranny is leaking into the transfer case it will generally fill up if all the seals are good and start coming out the vent tube on top , or at least thats what mine was doing , i would say someone has filled it with tranny fluid , go ahead and drain it and fill it back with 80/90 , pull your drain plug in a few weeks and check the level to see if it has gotten more in it or not , that will tell you if your tranny is leaking into it

[jamie72]

there are two seals in the adapter that will let tranny fluid into the xcase if they get weak.
you`ll have to drop the xcase and change out the seals it will be fine.
jamie

[DruBlazer]

Thanks guys. I was looking for something to do this weekend.

By the way Mac67, I'm in the Sacramento area. I'll work on getting some pics posted.

[71jimmy]

Welcome DruBlazer, I'm in Fair Oaks got a 71 Jimmy I hope to be driving by Spring......well maybe Summer. Hope to see you around. Post some pics so I know what to look for.

Later

[Leinie]

There are 2 different kinds of connections between the tranny and transfer case. ( At least there was in 72)
#1 A simple female splined tube that connects the tranny output to the tcase input -- with a seal at each end of the adapter.

#2 is a female splined tube ( yoke ?) with bearings and seals on each end inside the adapter.

I had 2 - 72 Blazers - both 350/th350/np205/3.73 drivetrains and hadtwo different adapters in them. Both leaked at fluid into to t case.

I replaced the adapter seals in both-- but the one without bearings went bad again within a year. The dealer parts guy told me the splines in the yoke get bad and it needs to be replaced when you do the seals. I never did it

I replaced the seals in the one with the bearings as well and it never leaked again after about 2 years of daily driving.


I would drain and refill your t case, Fill your tranny--- and then monitor the level of both every 100 miles or so.

If your A T fluid level is dropping and t case level is going up-- just drop the case out and have all new seals put in the case and the adapter and if your adapter doesn't have bearings, replace the yoke.

If you have any intentions of putting in a 700r4 now would be the time. If the age and condition of the tranny are unknown- it would be a good time to get it "built". Hey while your at it it would also be a good time for an engine overhaul and buildup

Good luck and Good Blazin'

[bouncytruck]

Welcome to the board. Pictures are, of course, manditory for new members.

Please take a moment and fill out your profile while you are at it, at least your location. There are a lot of members on this board and someone might be right around the corner from you with all the help and parts you need.

Let us know how the t-case goes. I have heard of a lot of people filling their t-cases with tranny fluid too.

[FRENCHBLUE72]

Welcoem to the board from southern oregon.

[DruBlazer]

Well, the tranny is leaking into the t-case. I think I'll keep the fluid up and find a rebuildable 205 to rebuild. That way my down time of dropping the tcase and replacing seals is down to a minimum. Anyone have one their getting rid of cheap?
Anyhow, I have some pics but I don't know how to post them. Tips?

[DruBlazer]

By the way. Thanks for all the tips folks.

[jamie72]

if you get the right seals it won`t take just a few minutes to install them and put everything back togeather, i just got done with one.
good luck jamie

[dtlilly]

Welcome to the truck forums!