opinion before I take it apart

I have a leak, well, I don't, my car does. The SX4 is leaking and leaving spots on the shop floor but only after a drive. It does not leak while sitting. The spots are dripping from the car's floor underside onto the shop floor.
It's an interesting sort of pattern. There's a pattern on the bottom of the car around the front end of the driveshaft, then you can see where it sort of runs to the low spots of the car's floor and drops to my shop floor. It leaves spots on the shop floor not in the middle but on each side of the middle. The middle is clean and dry on the shop floor.

My thought is that this is coming from between the yoke at the back of the transfer case and the transfer case output shaft. It's not the seal as that should leave drips at the low point of the seal itself. The seal never really feels or looks wet and you never see a single drop coming from the transfer case - it only drips from the car's floor. The outside of the yoke is also not as wet as I'd expect if the leak was where the yoke and seal met. The inside feels slick all the time.
That's why I think it's being thrown up against the bottom of the car as the yoke spins-  out from the CENTER of the yoke, past the nut and being spread like a grass seed or fertilizer spreader broadcasts your seed - or fertilizer as the spreader spins.

It's not the vent above - the top of the transfer case is dry, the vent is dry - dusty but dry, free from oil.

The transfer case uses ATF. That means it's "thinner" than oil and not dark like oil would be. It is more easily spread or fan-sprayed - IF I am correct.

Now to figure out a solution if this is indeed the source of the "leak".......

BTW -  the transfer case isn't worn out, it's brand new, the whole thing is new. It was a NOS transfer case in a crate I bought and installed when I did the engine swap. It came with the yoke pre-installed, ready to put in the car except removing the plastic plugs and putting fluid in it.

Note that the spray pattern on the floor is wettest directly over the center of the u-joint. It's fairly dry directly above the seal, and the seal is always dry with no red fluid on the seal or the outside part of the yoke that runs in the seal. That surface never shows red, or fluid drops at all.

The first, third and fourth photos really show the pattern to be directly above the u-joint, though, and looking straight up from below the shaft it's much more wet, more shine, a larger amount of fluid in a line straight out fro the center of the joint, as if the fluid was spraying out of the ends of the u-joint itself.
Every seal I've seen leak that had fluid directly behind the seal in contact with it at all times shows wet at the seal lip. The seal lip in this case won't leave a film on your finger or a cloth.
The seal was my first suspect until I started really going over the photos and the spray pattern from a distance and different angles.

Here's a better shot of what I mean.......

Apparently the machined surface at the very front end of the yoke and the machined surface it is pressed against when you tighten that nut don't mate well and fluid can get between them and then come out past the splines and out the nut - and we know that standard threads aren't a snug fit that can hold back fluids. If you screw a nut onto a bolt, hold the bolt vertical and place a drop of thin oil where the nut and bolt meet, you'll see oil out the bottom of the nut threads after a while. They aren't an interference fit.
You'd think that the two machined surfaces I mentioned would hold the fluid back. They need a seal between the yoke and the splined shaft it fits over I guess-  unless that nut isn't as tight as it should be. It came crated NOS but I never checked it to be sure it was properly torqued.

The more I look at the larger photos of different angles, the more I'm convinced it's leaking past the splines and out past the nut.
Either way the drive shaft must come out, rats.
I've already got enough to do without this sort of stuff, too.
Now - to figure out how to seal that - at least it won't have fluid sitting up to the shaft level.
I'll be able to dry it off good to seal it up since the bulk of the case where the fluid resides is a lot lower than this. No fluid actually sits against the back of the seal when it's sitting.

If I can drive it to a distant car show and back without stopping to add oil, I ignore it.

6768rogues wrote: If I can drive it to a distant car show and back without stopping to add oil, I ignore it.