So recently I have been doing the rounds and servicing all of the gear boxes on my 99 Blazer LT. Got to the transfer case last (4 button w/ auto 4wd) it's been shifting in and out of 4wd kind of slow so I suspected it might be low and I expected there to be blue auto track II in the case but it looks like pink ATF and was oozing out suggesting to me that it was over filled a bit. I then decided to check the tranny fluid and it seems to be over filled by quite a bit (over a half inch above max on the dipstick). I also have noticed that my tranny dipstick pops up out of the tube every time I drive. Is this related to it being over filled?

Anyway, do you guys think it was just serviced poorly/ tranny fluid overfilled and wrong fluid in transfer case? (I've only had the vehicle since October and the previous owner did not have any service records but the fact that someone had apparently put thread sealer on the t/c fill plug and sealed in a bunch of dirt and crap on the threads makes me suspect this) or might there be something more going on? I'm thinking about leveling out the tranny fluid and swapping out for the blue stuff in the t/c to see if they are mixing. Any thoughts would be appreciated.

 

The Autotrak fluid hasn't always been blue. It was changed at some point so that owners knew it was something different/special that was required in their transfer case. But if it was somewhat clean looking (not dark, but more like fresh ATF), I would suspect an issue as if it was never serviced since new it should be dark.

When you say it oozed out, what plug did you remove? If you removed the upper plug on the back of the t-case and fluid oozed out, then the t-case is over full. If it was the lower plug and you did not remove the upper plug, it is possible that the vent to the transfer case is not properly allowing the case to vent resulting in poor flow from the drain port.

As far as the transmission being over full, when you checked it, the engine was running with the vehicle on a flat/level surface, transmission in park, correct? The transmission dipstick should not pop out while driving. The vents for both the transmission and the transfer case come together under the truck with the hose coming up into the engine compartment typically zip tied to the transmission dipstick tube. If the trans dipstick is popping out, that would go along with my theory that there is a problem with the trans/t-case vent system.

 

The transfer case fluid looks like just a little less than fresh ATF and yes it was the upper fill plug I took out. The truck was pretty much level (maybe a little off) but I did not have it running, forgot about that one. I'll recheck the tranny fluid and do it proper this time.

As for the vent tube that is tied to the dip stick, I thought that was just for the front diff. I thought the tube hanging off of the drivers side of the tranny was the tranny vent tube. If not then what does that one go to? I can't see where any of them connect on top of the tranny, it's too cramped. Anyway I've checked the tube tied to the tranny dipstick and it looks fine, no dirt in it and there is no fluid coming out of it. Would you recommend blasting some air down through it?

 

The front diff vent runs up next to the radiator. If you have a line hanging down on the driver side of the transmission, that likely is what tees into the vent line from the transfer case than then runs up to the top of the trans dipstick. They can be a pain to get back together if they come apart.

If your t-case had what looks like ATF in it and was overfull as well, then the first thing I would consider is dropping the t-case and replacing the input seal. The only way it can get additional fluid into it is via a failed input seal that would allow transmission fluid in. From there, I would drain the t-case and fill it with Autotrak 2 fluid. Drive it for a few thousand miles and then drain and fill again to make sure that all of the ATF is out of there. ATF is not good for the front output viscous clutch.

 

Thanks swartllk. If the clutch is wearing from ATF in the transfer case could that be what is causing it to shift so slowly?

 

It isn't helping anything in there, but using the wrong fluid typically shows when in Auto4wd mode while turning on high traction surfaces. The clutches do not slip like they are supposed to and cause the drivetrain to bind up which will make the truck jump around while turning like it normally would when in 4HI.

Slow shifting can be a number of things.

 

Do you know of a good brand to go with for the input seal? I don't want to settle for anything cheap with something like this.

 

Use Timken seals and bearings and Fel pro gaskets. The only complaint you'll hear is they are expensive. The peace of mind is worth every penny.