Where did this ATF come from?
 

I have/had an intermittent ATF leak in my 89 Suburban (350 with Turbo400 and NP241). The leak started in 4 wd when I noticed some smoke at low speeds. Got under there and ATF was everywhere. I couldn't find a particular source. It was on both drivelines, dripping from the skid plates, on the exhasut, everywhere.

Here is where it gets strange. The transmission and transfer case are full, I haven't added any fluid. But I did some work on the transfer case (swapped my cable driven speedometer for an electronic one, but changing out the tailshaft housing), and pulled almost 2 qts out the transfer case without cracking the drain plug.

So did some idiot really put way too much atf in the transfer case and by having it 4wd it was enough to push it out the vent?

Re: Where did this ATF come from?
 

Was it just overfilled or is it still leaking?

Re: Where did this ATF come from?
 

Doesn't seem to be leaking. I've put about 200 miles on it since then and haven't spotted any leaks. I just can't wrap my head around how someone could literally overfill a transfer case by 2 quarts.

Re: Where did this ATF come from?
 

I'd go hit the car wash and clean it all up. Then check and see if you get any further oil somewhere. If not, than overfilling was probably the issue.

When my 2004 Yukon got a pin hole in it's t-case, the leaking oil coated the whole bottom side of the truck. It doesn't take too much to look like a big mess!

Re: Where did this ATF come from?
 

I don't know how you'd get it in there without filling at the vent.

Re: Where did this ATF come from?
 

The vent from the t-case should be connected to a rubber vent hose. Check to be sure it's in place (#1), if it is in place, then clean around it carefully with pressure washer. Just don't go in full force directly to the t-case vent.