Yup, sounds like you've got it narrowed down. Once you get that fixed, you've got to see how far through the vacuum system that stuff travelled. I would start by pulling off the HVAC controls in the dash and seeing if the vacuum lines there have fluid in them. If they do and it's in more than one, you're going to have to pull the lines off at each of the actuators (no simple task) and clean each line out. Then move on to the vacuum lines in the engine compartment because you don't want that stuff making its way back into the HVAC system again...

Good luck! It's a daunting task to say the least. What a mess from what seems like such a simple system... Let me know if you need vacuum schematics and I'll see what I can dig up.

 

Yea, sound like a ton of fun. Well, I'm off to the store to get a new seal. Thanx for all the advice.

 

Kyle,

I found the information on the s-10crewcab site. It was related to having fluid in the HVAC system and not working properly and finding trans fluid in the ashtray.

I do agree with you that if fluid levels are normal there should not be a way for the switch draw(suck) fluid from the trans case. I believe like what happened to rustbeast that the seal between the trans case and tranny has to be leaking enough fluid to raise the level close to or submerge the switch location from inside the trans case. From what I have read is that GM realized the the internal seal for the switch was failing to hold back the fluid so they redesigned it and then released the part to dealers for this problem and for specific model years that were having this problem...I don't think the AWD Bravada has the switch. So you would not find it listed.

 

I agree that at normal fluid levels this switch sould not be anywhere near the fluid aside from a little splash here and there, but being that my t-case was almost a gallon overfull I am sure the thing was submerged. I just don't know if it was the switch drawing fluid out or if it was drawing it out of the the vent, because the vent is tee'd in with one of the lines on the switch.

 

Pulled it apart today. The input shaft seal on the t-case was rock solid, but not torn anywhere. I picked up a new one from napa and got it back together. So far looks like good news as the trans fluid stayed but I haven't taken it for a long drive yet. Just have to go through the vacum lines now.

 

Sorry I missed this thread earlier.
Your problem lies in the front seal on the t-case. I posted up about this some time ago. Search the site for it. Look in other t-case, tranny, or heat-a/c thread for more info.

To check the vacuum lines, pull the line off the tee behind the distriburator cap. See if there is tranny fluid up to there. If so, keep going and you may need to clean out all the heat-a/c controls.

 

I'm having a similar issue with my 97 4WD, but I read on Automotive forums that the 4L60E's have have this symptom when the champfer tolerances in the front pump widen. I haven't checked for any of the symptoms listed in theis thread yet, but are there any thoughts on whether mine could be the same issue? I have noticed some issues with my heat selector "hissing" when I switch it, and it doesn't seem to actually switch entirely to defrost for instance. I thought the trans and transfer cases were completely electronic in the 97's thought. Thoughts and help appreciated before I yank the tranny out of this thing.


Thanks in advance.

 

The easiest way to tell if you are having the same problem would be to pull the fill plug on the transfer case and see how full the t-case is. If fluid pours out then you know the seal is bad. It sounds like the vent problem could be a bad switch though if you can hear it hissing. Does it hiss only when switching between positions or does it do it all the time? I checked on alldata and acording to it in 97 they were still using the vacum operated front axle.

 

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Thanks Rusty - yup appears to be same issue. Got about a gallon out of the Tfer case, and the seal was cracked. Changed it out yesterday, we'll see what happens. Thanks for the reply.