I've had a spare transmission sitting outside for a little while, It was in good shape when pulled and I covered it and set it aside. When I took its the cover off and went to move it and I noticed rusty water seep out from where the t-case connects when I flipped it over (maybe 1 pint). It shifts into some gears, in others it doesn't completely want to. My question is, is there any salvaging it without opening it? I was thinking of topping it off with evaporust and let it sit for a couple days. Is that a bad idea?

 

No water has gotten inside the case. I wouldn't risk damaging the trans by operating it in that condition. I am going to recommend that the case be opened and the parts dissembled. They can be sent out to be ultrasonically cleaned and then reassembled. You could also try flushing the case with trans fluid but who knows how many flushes it might take.

 

I know its not an evo, but i had a CRX project a few years ago that had gotten water inside the trans. Im not sure how because the trans was still installed in the car. I drained roughly a cup or so of water along with the oil. I took apart the trans and it did have some surface rust inside. I just took everything and i mean every last bearing apart and inspected it. Most everything was coated in oil so it did not rust. It was mainly on the gears themselves. I cleaned everything multiple times with brake cleaner, spraying it with PB blaster until it looked normal again. I did scuff some parts with a scotch pad. Put it all back together and car drove fine for about 15k miles before i sold it.

At the very least i would take it apart and just take a look. If it seems like there is some serious rust, i would still contact an evo trans specialist before i condemn the trans.