Wet floorboard (auto, gasket, Audi, biggest)

[skinem]

It's been raining a lot here lately. It was just noticed that the right rear floorboard carpet of my wife's 2000 Buick LeSabre is just soaked. Don't know how long, as people rarely ride in the backseat.

I haven't had time to look at what the problem is, so just wanted to ask if y'all could tell me what I should look for.

I figure I'll get under the car first to see if there are any spots rusted through. (The floor FEELS solid.) She also thinks she hit something some while ago that made a loud thump "somewhere under the car", so I'll look for any obvious damage. Of course, my biggest fear is rust.

I'll also look for (and I hope this is the problem) any drains in the door that may be plugged up causing it to leak into the cabin.

If anyone knows if this is a common issue for this model car I'd appreciate it. Any tips on what to look for, or where to look will also be appreciated.

Thanks in advance.

[Gimme3steps]

If you can, sit in the back seat and have someone spray all around the doors and windows with a water hose and using a flashlight, look for any signs of water coming in.

An auto glass shop will hose down the outside of the car and use compressed air from the inside to trace a window or door gasket leak. Kinda like looking for a leak in a tire.

[caution]

I know some older GMs would leak from the condensation of the AC (even in winter since it flips on for defrost) into the cabin, but it was normally up front -- of course, it's hard to tell where the water is coming from since the wet spot you found may be where it pools, not where it originates.

I'd look under the pan first. Then check seals. I seem to recall a video online about "how to check for leaks" in a car where the helpful dude was doing all sorts of tricks. Maybe google that up.

[M3 Mitch]

I had something similar happen in an Audi 4000, the A/C drain was stopped up, and was actually draining along the body and coming out in the passenger's side rear footwell.

There is a drain "teat" that typically has a fish-mouth like drain end pointing down, all I had to do was pinch it between my fingers, it was just stuck shut. This thing is typically on the passenger's side firewall, fairly low, it may be easier to see from under the car.

[skinem]

Thanks all, I didn't even think an AC drain problem might be the issue...figured it'd be up front...I'll check the above things. If I figure it out, I'll post it...might be useful for someone else in the future.