Tranny Fluid in transfer case vacuum switch lines ????

1996 Blazer my 4x4 has been sluggish and irratic to engage and sometimes would not disengage for 10 minutes or more. I disconnected the 3 hose plug from vacuum switch and tranny fluid came out of the hoses. I disconnected the hoses at vacuum bulb and front diff acuator and blew them out with compressed air and also the vent line. I put a new vacuum switch in from GM and it seems better but still a little funny. I removed the 3 hose connector and tranny fluid is in the lines again any ideas what is happening ? Fluid levels are normal and nothing was done to tranny or transfer case recently.

Unless you cleaned out ALL the vacuum lines, there's probably leftover fluid there. It can get into the diff actuator and the HVAC control lines too.

The rear seal of the transmission is leaking fluid into the transfer case, overfilling the transfer case and forcing fluid into your vaccum lines. Must remove transfer case to replace seal. Or visit a trans. shop.

The rear seal of the transmission is leaking fluid into the transfer case, overfilling the transfer case and forcing fluid into your vaccum lines. Must remove transfer case to replace seal. Or visit a trans. shop.

Is this a common problem ?? or have you seen it happen ?? I figured the vacuum switch would have some type seal or oring otherwise it would try to draw a vacuum on the whole transfer case and eventually suck up fluid anyways.

Unless you cleaned out ALL the vacuum lines, there's probably leftover fluid there. It can get into the diff actuator and the HVAC control lines too.

Lines were flushed with brake clean and blown dry with compressed air so I would have to say its new fluid.

Is this a common problem ?? or have you seen it happen ?? ..

Had it happen on mine last year. Also know that you might have tranny fluid collecting in the front axle actuator and in vac lines going to intake and vacuum ball. It gets "sucked" up there while in 4WD if the transfer case is too full of fluid. The tranny fluid will soften the diagphram material and cause it to fail early.
Search old forum posts and you might find something.

http://www.automotiveforums.com/vbulletin/showthread.php?t=772350&highlight=transmission+seal+transfer

http://www.automotiveforums.com/vbulletin/showthread.php?t=757002&highlight=transmission+seal+transfer

Thank you herkyhawki I was searching by vacuum switch but either my key words were wrong or I read right over the transmission part. thanks for pointing me in the right direction.