Why is water entering through the undercarriage of my car?

July 6, 2015 1:08 PM

I took my 2004 Mercedes ML350 to the touchless car wash today and for the first time ever water entered through the undercarriage and was leaking around my feet.

I checked and the same thing was happening on the passenger side. This was a more like a strong leak/almost a stream of water. It looked like it was coming in through the bottom and then dripping back down from behind the dashboard.
Before I shell out $$$ to the dealer can anyone give me an idea why this happened?
Thanks

posted by ramix to Travel & Transportation (4 answers total)

On many cars, the air intake for the cabin air system is usually right below the wipers, along the front of the windshield. There are a series of baffles there to prevent water from making it through to the cabin, but debris and whatnot can obstruct them or the drain and so water flows in.

Cleaning that out is either easy or a real pain in the ass, depending.
posted by Pogo_Fuzzybutt at 1:15 PM on July 6, 2015

This looks like some instructions for that model. Dunno if the year is correct, but it should be similar. It doesn't seem too bad. It should be easy to fix, or at least eliminate that as the issue.

Also, it could mean a leak in the sunroof - water will get in, collect on the headliner and run down the A pillars. In this case, you'll need to drop the headliner or open up the pillar to have a look.
posted by Pogo_Fuzzybutt at 1:31 PM on July 6, 2015

Can you tell if the water is seeping up from under the carpet, or running/dripping down onto the floor?
posted by Thorzdad at 2:25 PM on July 6, 2015

Response by poster: It felt like it was spraying from below - so on the bottom side panel next to where the trunk release is. Thanks Pogo, I think you may be onto something there. There's a lot of pine needles right about where the cabin air system is. I'll try to clean that out and attempt to replace the air filter. If that doesn't work then I'll take it in.
posted by ramix at 3:43 PM on July 6, 2015