[zupta82]

Hello everyone, I think I just made a really stupid mistake, hope this makes sense. A few months ago when I bought my 2001 s10 blazer I changed all the fluids including the transfer case. I can’t remember remember the exact amount I put in, i kept pumping fluid til it started running out of the top
Everything was perfect up until the other day when I went to work and I was using the 4wd. I got out of work and found a small puddle under the vehicle maybe no more than 8oz. I drove home which was only a few miles and lifted up the car immediately found fluid coming out of the vent tube.
I then drained the transfer case and found about two quarts in it. So I looked it up in the Haynes manual and it says it takes a little over a quart. I refilled with that amount and checked the transmission dipstick and it was reading low, not even in the cold mark while at idle. I added about 1/4 of a quart and rechecked by driving and it was still low and finally added 1/2 and it is still low?
Could I have inadvertently added too much and blew the input seal?? I’m afraid to add any more fluid in the transmission. Now there is no leaking from the vent tube. I drove it to work and back and rechecked the transfer case by draining it a second time and I have exactly 1 quart after maybe driving maybe 20 miles. Everything shifts great
Lastly, it seems the dipstick is kind of hard to read when at idle.‘it’s like the fluid is almost like a watery consistency and runs off the stick. When I shut the car off I can see the stick clearly and it is in the hot level. Maybe I’m not letting the car warm up to get an accurate reading. Is there some other way that I can ensure the exact amount that is in the transmission

 

[Brawndo]

Thre is a seal between the transfer case and the transmission. Basically it isolates the trans fluid from the transfer case. If the transfer case is leaking and getting over full that is the problem. The excess fluid is coming from your transmission. Check trans running while warm. Until you get the seal repaired keep a close eye on the trans fluid level. If you dont add trans fluid back it will go too low and smoke your transmission if you continue to drive.

 

[Brawndo]

@Rhotpursuit may want to move this to correct for better visibility

 

[Brawndo]

Maybe I’m not letting the car warm up to get an accurate reading. Is there some other way that I can ensure the exact amount that is in the transmission

Dipstick is only way. If you are not seeing fluid on the dipstick while running it is way low. Excess fluid you are finding in the transfer case is trans fluid. If you are draining an extra quart from the case youre trans is at least 1 quart low.

 

[Tranzman]

Here is the scenario I used to see all the time.

The transmission has a squirter hole in the back of it. In the picture it appears in the 7 o'clock position(the shiny spot). this hole is designed to spray or squirt fluid to the rear extension housing seal on a 2wd. on 4x4 seal gets hard and squirts fluid directly at the input seal lip of the TFC. Because of that the transfer case gets overfilled. Change the seal and the issue is solved.
The input shaft seal is a National seal part # 710298

 

[oldeerslayer]

When adding ATF to your trans if you over fill it don't worry about it. You don't have to be that careful because it will not harm a 4L60E to be too full. What it doesn't tolerate well is being too low.
On the other hand the transfer case being too full can cause serious problems in the vacuum system. Try not to let it go much over full. When the TFC is over full it's easy for the ATF to get sucked into the vacuum front axle actuator and dissolve the diaphragm. Over time it can get up into the heater controls that are vacuum operated. That can be a major repair project.
A good safety measure is to replace the transfer case's vacuum switch for the actuator. It's on top on the front drivers side. Get the improved Genuine GM 89059420 replacement. It's designed to not allow ATF into the vacuum hoses.
Spend the time to find the right one. Most parts store carry the Dorman POS valve which doesn't fit correctly, only lasts a few months and leaks like it just drank a 12 pack. A step in the wrong direction.
All of this is irrelevant if you have the 4 button Auto Trac transfer case as that uses a different system with an electric vacuum switch on the firewall.

 

[Walleye Hunter]

I just did the seals in mine for this very reason. I abided by oldeerslayer's advice.

 

[zupta82]

I figured I give an update, I’m almost ready to drop the case the bolts are all that is left. However, it seems that the rear extension tail housing is right on top of the torsion bar crossmember. Should I unbolt this and reseal with silicone. Also should I use some permetex no 2 non hardening sealant on the metal part of the seal. I’ve used this before on rear axle tube seals

 

[Tranzman]

Silicone sealer is what is used from the factory. I personally use the Permatex black ultra sealer.

 

[Walleye Hunter]

I left the tail on mine. It wasn't too hard to slide it back and dip the nose down to get it out and reverse to get it back in. But I had help both times. Coming out, I left it jump around a little on a floor jack and bring it down. Going up, we used the floor jack to get it part way up then two of us got it up into place. I found two 10 mm bolts in my hoard and cut the heads off to make guide pins for installation alinement and slid the gasket up onto them after the transfer case was up in place. I also cleaned my bolts and threads up so the bolts would be easier to put back in.

 

[zupta82]

So I got it out, I left the tail shaft on. The seal was definitely cracked by the vertical split in the rubber lip. Now how would I get the old seal out without damaging the aluminum surface on the case. There is no ledge to pry up on. Attached are some pics

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[Walleye Hunter]

Your gasket is hiding some facts there. I believe that those four bolts come out and that plate come off and you can have your way with it on the workbench. Mine has Allen heads and they wouldn't let go so I screwed deckscrews into the seal and pulled it out with some pliers. It was pretty stubborn and I had to use two screws side by side and grab them both at the same time to get it to move. I think I had three sets of screws in and worked my way around the circle. Don't go too far with them and make sure you get any debris out that might fall in there. I didn't have much in there.

 

[Tranzman]

So I got it out, I left the tail shaft on. The seal was definitely cracked by the vertical split in the rubber lip. Now how would I get the old seal out without damaging the aluminum surface on the case. There is no ledge to pry up on. Attached are some pics View attachment 374228 View attachment 374229

That line you are pointing at is more likely a casing flaw than a crack. If you wire brush it good it will open the crack or polish up. Then you can tell what it really is. There are 2 cut outs to pry that seal retainer up and off. Then the old seal can be pressed out. Once it's out you can feel how hard the rubber has gotten over the years. Just make sure the drain back hole line up on both. If I remember right it will only bolt on 1 way because the holes are irregularly spaced..

 

[zupta82]

So if I remove the four bolts the plate should come right off. Hopefully there is no gasket between the plate and the case

 

[Walleye Hunter]

So if I remove the four bolts the plate should come right off. Hopefully there is no gasket between the plate and the case

I believe that's sealed with RTV. I think it's a black version for that application.

 

[zupta82]

Well, it’s all set everything is back together. Thanks for the help everyone