(Well, I’m hoping that it’s not so mysterious to you car gurus, anyway.) I just moved home from California to Rhode Island (drove my car cross-country) and the last two times it’s rained, the floor of my car on the driver’s side (front and back) ends up with a LOT of water. Since the seats aren’t wet at all, I’m guessing that the water is coming up from below. Is there any way I can solve this on my own, or am I going to need to visit the mechanic?
I hd the same problem with a 2000 Blazer I bought in 2003. After a rain storm, the carpet on the driver’s side was always wet. I thought the water was coming up from below too.
To make a long story short, the leak was in the seam between the firewall and the inner fender on the driver’s side. The truck had been in a minor accident and the bumper and left fender had been replaced. I’m guessing the impact may have popped the seam. I found the leak by using a garden hose to run a stream of water into the windshield cowl while looking under the dash with a flashlight. The flashlight is a great help because it reflects off any running water.
The flashlight showed a steady stream of water running down the seam under the carpet and padding. The water would run under the carpet to the back of the truck and soak up through the carpet. An application of silicone caulk fixed the leak.
Other possibilities are a clogged sunroof or air conditioner drains.