Today the greater SE Michigan area was hit with about 36 hours of continual rainstorms. When I got home I parked closer to my apartment, but it was in a low-lying area of the lot, and two hours later when I went back out, the car was flooded up to just past the bottom of the doorsills. The engine cranked slowly at first but ran fine, and I spent the next hour bailing about 4 gallons worth of rainwater out of my car. It is for the most part dry right now (no standing water), and I plan to take it to get it vacuumed out in the morning, but what kind of undercarriage damage should I look for? Is there anything I should be worried about (engine, transmission, etc.)?

 

Your body should be fine -- its the interior you should be worried about. With water soaked in the carpet and suck, inside nooks and crannies, you will more than likely get some mold, even if you shampoo the carpets with disinfectant.
You just cant get it all. Keep some pouches of baking powder in there, and replace them often for a few weeks.
You -might- get rust damage on some interior metal, stuff that wasnt coated well or something. But I dont think it will be noticeable.
I had a faulty trunk in a previous car, let a weeks worth of rain leak in through the trunk, go through the back seat, and inches of water sat at the bottum of the car.
Was an uphill battle for 2 months keeping it clean, mold free, and fresh. The bottum of the trunk did rust quite a bit too, but it was old, and parts were unpainted.

Too bad most insurance companies dont insure cars against flood damage anymore

 

There's product in home depot that works better than baking powder. It's called "Damp Rid" and similar. I would air out the car as much as you can and buy a ton of that stuff and put it all over your car.

 

Thanks for the advice. I'm gonna go vacuum what I can out of it now, as water has continually seeped in all day. I've been trying to towel it up but it hasn't been working.

 

You need more than damp rid. You need a commercial dehumidifier and fast. You can rent one from Servicemaster or a company that you find in the yellow pages under moisture control or flood damage.

You need to get the humidity inside the car to zero. The faster the better. Mold is everywhere and takes only hours to take hold.

I know - four hurricanes in last year.

You need to sit the unit inside the car and run the power cord and drain hose out the window and then tape up a good seal. Be sure the vent is in recirc. Probably take 48 hours to thoroughy dry it out.