i took the carpet out of my car today and was scraping the sounds crap out a little.....and i poked through all the way and i realized it was rust.....how can i patch the spot up so water doesnt come up when im driving because i dont plan on putting the carpet back in?

 

Sheetmetal....cut a piece to shape and weld in. (Got a buddy with a mig welder?) Spray with rust paint.

 

that's the only way to stop it. Also, if it's done correctly you wont be able to tell