The guy that had my blazer before me mixed up the vac hoses, I fixed the ones under the hood, but hadn't found until to late that he crossed the vac supply and the hose to the ft actuator. The only symptom was the ft actuator was slow to disengage. The transfer case had vac applied to the vent when in 2wd, and when the seal gave into the vac it sucked the tranny fluid from the tranny into the transfer case, and burned out the 3-4 clutch pack
Don't let it happen to you.
Steve

 

Sorry for the predicament that put you in, but some simple routine maintenance would have caught that problem LONG before it would have blew the transmission. Even just checking your transmission fluid would have been all that would be necessary to notice the fluid going somewhere. Sounds like nothing was ever checked...

 

Nope, I checked the fluids, maybe every couple months I'd top it off with a little, then it sucked 3 qts on 1 trip to town. I still had 1st and 2nd, only lost the 3-4 clutch pack, cuz I was in high gear when the fluid went. I grabbed a gal and took me most of it refilling it to get home. It really sucked.
Steve

 

I think he means that even though you were checking it and topping it off every time you should have suspected something was wrong. Oil just doesn't dissappear... unless it's a leak in the gulf I guess.

 

Even completely full, the t-case can only take ~4 quarts above it's ~2.3 quart 'full' requirement and it wouldn't be a fast pull either. Checking fluids monthly should have definitely caught this. Words of wisdom for folks reading.

 

There was a slight leak from the pan, not bad, but enough to spot where I parked. Topping it off every couple mo it didn't go below the add mark. I won some certs for free oil changes at the chev dealer, and it had only been a couple mo since they did a full lof. The guy also had put a bolt in the vent line, and it fell down so I didn't see it, so the t-case vent was getting full man vac. In daylight the day after it happened, I found fluid was dripping from the vac amplifier, the seal between finally gave into the vac, in 25 mi home from w/m it drank a couple more qts. I got a real good deal on the truck, he had just put a low mileage eng/trans into it, and it ran crappy, the eng vac lines were all messed up, even the pcv was open and sucking straight air. I fixed the vac lines in a day, and it ran great for about 8 months until this happened. I've had it less than a yr, but even with buying a used trans for it I have a little under 2k in it, so it's still a descent price, but was better before the trans. I hadn't even thought of checking the vac lines to the t-case, I saw they had been cut/spliced, but it went in/out of 4wd pushing the buttons, so I didn't ck farther. I thought it was worth posting a warning, so it doesn't happen to anyone else. Small simple things can cause big problems.
Steve

 

Betting the whole vac system is full of fluid, a major pita to get cleaned out.

 

Yeah, trans oil will swell up all those vacuum lines... Sorry to hear that. I'm guilty of not checking my fluids regularly enough either ...