Hello everyone, long time no see.

Anyways, I have this problem here: A long time ago (1/2 a year or so) my 4wd started engaging into 4hi while I didn't push it and I was going around 70 mph on the interstate. So I didn't know what was wrong with it and just took out the fuse for 4wd and that temporarily fixed it (it just did not engage the front axle). Then one day I also noticed that in the vacuum tubes (for the t-case) there was ATF in them. So someone told me on this forum that it could be the little 3 "prong" thing or switch or whatever you want to call it that resides on the t-case, change that - same issue. So I left it alone for a while.

Today I was driving it and noticed that the transmission would start jerking once it switches into fifth gear (it's an automatic). I stopped and checked the ATF level, it was all the way at the bottom!!! So when I came home I filled it up to level and thought while I'm at it might as well check the t-case fluid level. When I unscrewed the (top) plug on the t-case, the fluid just poured wright out, about a quart or so.

So what my question is, could this have happened because the transmission fluid somehow migrated or flowed from the tranny into the transfer case, and that cause the level to go up in the t-case and up the vacuum tubes and that is why my 4wd would engage all of a sudden for no reason???

Any help is very appreciated. Thanks!

 

Just a quick guess without any research......transmission output shaft seal leaking, trans oil goes into the transfer case, overfills transfer case and oil level is so high that it travels thru the transfer case switch to the vacuum hoses.

 

I concur. You'll need to drop the t-case to replace the seal.

 

Okay, so I drop the t-case. Is there any special instructions on how to change the seal and do I just buy it in Advance (what is the exact name of it)? If I fix that, will the 4wd work fine then, or do I have to clean out the vacuum tubes and if that, then what else should I clean for it to work fine?

 

Alright, where to begin.

Seems like I write this all the time, one of these days I should do a short version of the tranny removal thread and 4x4 no worky thread.

Yes, your t-case input seal is toast. Its a $5 part at most autopart stores. There is no tranny output seal on a 4x4 tranny. If it were a 2wdr tranny then teh output seal would be in the tailhousing, since this is a 4x4 there is no tailhousing.

Read this thread on the vacuum lines.
https://blazerforum.com/m_52228/tm.htm
YES, clean them out, they go into your HVAC system, and if you get tranny fluid in your HVAC controls, your looking at some serious coin to get it fixed. Read the thread and you will understand.

As for the repair, simple. Take off both driveshafts, you did block the wheels right, and put on the e-brake? Drop the t-case. Use a screwdriver/hammer to pry/pound the old seal out, and use a big socket to drive the new one in. Put a coat of tranny fluid on the rubber part BEFORE you attach it to the tranny. Make a new tranny to t-case gasket with RTV. REinstall.

 

I think I need to do this sometime too. When I went to change all my fluids (diffs and transfer case) the same thing happened, but my transfer case still works good so I havent messed with it yet since it seems like a pain to do. On a rating of harder or easier, how does this dropping the transfer case compare to balljoints and hub bearing replacement?

 

That depends on who is doing the work.

I cna do a hub bearing in about 1 hour in my garage, and 45 minutes in a shop with a lift.
Ball joints suck no matter who does them, air chisel helps, but they still suck.
Dropping the t-case is pretty easy and I would compare it to the hubs, although it will take longer. Say half to a whole day your first time around, longer if this is floor shifted model. It's pretty much just unbolting things to get it out. Skid plates, cables, wiring harnesses, vacuum lines, driveshafts, tranny cross brace, t-case. The t-case weighs about 100 pounds and isn't too bad to bench press in adn out. If thats too mcuh for you, use a jack and get a buddy to help you. Don't tip it over, it will leak out fluid from both ends, and if your not carefull when it leaks on your stomach you will over react and it will leak on your face. Then if you panic you may eat it. [:'(]

 

Thank you all, I do appreciate all the help! I just bought the gasket that goes between the t-case and the transmission end housing or whatever it is called. Should I put some ATF fluid on the gasket or will it ruin it?

Thanks again

 

Paper gasket? Just put a little rtv on both sides. Let it dry to a tacky consistency before reinstalling the t-case. The T-case seal needs to be well lubricated with ATF BEFORE you install it, or, you will get to change it again soon....

 

Okay, thanks