After our trip to Fourth of July a couple of weekends ago, which involved a lot of intense 4wd driving followed by some high-speed dirt and pavement driving (during which time I was still in 4×4 — turns out with these auto hubs you have to reverse to disengage them, otherwise they will stay locked), I noticed after I stopped in Tajique that there was transmission fluid all over the bottom of the truck. So much, in fact, that it was dripping all over the ground. It appeared to be coming from the front seal of the transfer case and not from the transmission.
I drove all the way back to Bernardo with the hubs still engaged, because I didn’t realize that I needed to reverse to disengage them. An easy way to tell that they’re still engaged is they make a hell of a lot of noise on pavement. Lesson learned.
Anyway, after a couple of weeks I finally got around to checking the transfer case fluid level. I was a little worried that with the fluid loss, I might have run it too low and caused some wear. Well … not so. I pulled the fill plug off and fluid literally fountained out of the hole. The transfer case was a couple of quarts overfull.
So, I suppose that explains why fluid was working its way past the front seal, especially at high speeds. What I don’t understand is how you even would overfill the transfer case. You’d have to fill it some way other than the fill plug to even do it.
I doubt it caused any damage or problems other than a messy undercarriage, but I’ll research it. I also kind of wonder whether the transfer case being overfull can affect your fuel economy.
…later edit. So it appears that this is a not-uncommon symptom on an older truck with an automatic transmission. The transmission’s rear seal leaks ATF and it goes straight into the transfer case. Eventually it gets so overfull that it starts coming out places where it shouldn’t. That’s not exactly good news but since it’s not leaking while sitting and the transmission works fine, I’m not going to worry about it too much.
Rancho Zoidberg 