I pulled back my carpet today to see what the extent of the rust was on the driver's side floor. From underneath there was only about a 6" area that seemed bad, but from topside it's a completely different story. Looks like almost the entire driver's side floor is going to need cut out and replaced. This wasn't what I was hoping to see.
I read on here before some forum members recommending heavy duty construction adhesive to install patch panels rather than welding, screwing, riveting, etc. Is there a certain point where too much has been cut out to rely on adhesive?
(http://photos.toast.net/ImageResizeCache/7a95bfdff4490a15fe23899d325bb209.jpg)
(http://photos.toast.net/ImageResizeCache/31e75f97f84f1cf9df47b4b285af9385.jpg)
(http://photos.toast.net/ImageResizeCache/884db2cbf00057fbe75c98f90c588480.jpg)
(http://photos.toast.net/ImageResizeCache/99b5ebe76d40f5db3fccb82e8623fb18.jpg)
On the upside, at least the frame rails look like they're in good shape. I still haven't figured out how the floor in this area got so rusted out when the rest of the car is generally rust free.
Yeah, that's definitely not what you wanna see when you pull the carpet up. Good luck on patching it up.
Looks like the handiwork of a leaky windshield.
Water leaks in around the windshield, runs down the inside of the firewall, and pools on the floor under the carpet. The floor gets rusted out from the inside, and no amount of undercoating on the outside will stop that. Sealing up that windshield is the solution.
As for the adhesive, go for it. Some new cars are completely assembled with it, so replacing a section won't be a big deal. Just be sure to leave good amounts of overlapping metal for the adhesive to bond to. You'll probably have to screw the panel in place while applying the adhesive, then after it has cured enough, grind the screws off.
The leaky windshield is a good theory. I know it definitely leaks on the passenger side because I get a wet glove compartment if it sits outside the garage while it's raining. At some point one of the owners had some serious rambler mentality and tried to seal up the windshield with some kind of black silicone stuff and made a mess out of it so I already know that's gotta come out and get sealed up properly, I'll leave that to the professionals. For some reason I was thinking the cause had to be more difficult than that, like a leak in the wheel well somewhere, but the windshield is definitely the place to start. I'm also going to check the cargo rack mounting points but they seemed pretty tight.
Thanks for the input.