cowl drain
Junior Member
Joined: Oct 2018
Posts: 32
Likes: 0
S430
Your title points to a known issue with the w220. The cowel drain has a rubber drain valve that can get plugged allowing the water to backup and go into the passenger floor. It is recommended to remove that valve so it can't clog. There are YouTube videos on it.
MBWorld Fanatic!
Joined: Dec 2012
Posts: 2,475
Likes: 439
From: Ball Ground, GA (N of Atlanta)
2003 S500 2007 GL450
First - Which side is the "driver's side"? You didn't tell us where you live...
If it is the right side, the plugged HVAC plenum drain is the most likely cause. And yes, this can cause a great deal of damage. The channels under the carpet will be full, taking the water to the major fuses under the right front carpet, and continuing back to flood the SAM (Signal Acquisition Module) and its fuses under the back seat. There are dozens of posts on this subject. Time is of the essence...
If it is the right side, the plugged HVAC plenum drain is the most likely cause. And yes, this can cause a great deal of damage. The channels under the carpet will be full, taking the water to the major fuses under the right front carpet, and continuing back to flood the SAM (Signal Acquisition Module) and its fuses under the back seat. There are dozens of posts on this subject. Time is of the essence...
Super Member
Joined: Jan 2009
Posts: 566
Likes: 261
From: In The Woods
2019 W222 S560 4Matic/2025 Yukon Denali
Blow out the drain with some compressed air. make sure there is nothing at the bottom. Then drill a 1/2in hole about 3 inches up on the front side of the housing to act as an emergency drain. In case the drain on the bottom gets clogged, you will have a back up drain on the side. Preventing overflow into the interior and making all sorts of issues. Should have been done this way from the factory.
