Today I drove the blue 928 after a couple of days of heavy precipitation. I
noticed the floor on the passenger side was soaked completely from the
carpet down to the padding. Has anybody ever experienced this problem?
Thanks in advance for any hints.
Yes the drain in the firewall in front of the heater blower motor is blocked with debris . Water is building up and draining into the heater blower motor and dropping down on your fuse panel board and all the relays the excess is making the carpet wet ! The drain is a rubber flap on the passenger right side near the cylinder head next to and below the coolant reservoir . Open the hood pull off the rubber strip along the top of the firewall remove the thin black plastic "cover" over the wiper motor and heater ducting and clean out all the junk trapped in front of the heater blower motor . Water is designed to run off the windshield and drain out the flap valve .
Open the hood. Feel the firewall immediately behind the passenger-side cylinder head, and find an oval rubber flap covering an opening in the firewall. Reach into the opening and remove any leaves and trash blocking the opening.
Sometimes these leaks can come from unexpected directions. I was getting wet carpets too, both front and rear foot wells. after a lot of attempts at finding the leak it turned out to be the rear quarter windows. The water was leaking behind the interior quarter panel into the rear seat bucket and then overflowing into the rear footwell which then seeped into the front carpets. I have just had the rear windows removed and refitted with new rubber and it seems to have worked. anyway the point is that the water doesn't have to be coming in at the place you experience the wetness, it might be worth a quick scout around out of area.
Thanks to Wally Plumley and Jim Bailey for the advice about the water leak.
This morning I attempted to clean out the area behind the rubber flap. Not as easy as it seems. I removed the air filter box, the rubber strip along the top of the firewall, and the plastic cover over the wiper motor. I removed the oval rubber cover over the opening. It is attached with two rubber "arms" onto a rubber grommet around the opening. When taking it off I accidentally broke one of the arms at the midway point. I put my hand as far as it would go into the opening. There was nothing in there blocking it. I put a coat hanger wire in the gap between the heater blower motor and the firewall and poked around. No debris or other foreign matter came out of the drain..
Replacing the rubber flap cover was not easy. It took a bit of maneuvering to get it back in place. I am not sure it is going to stay put, so I may use epoxy to hold it in place.
My next step is to get a garden hose and see if I can follow the flow of water.
OK, the common and easy answer didn't work.
The hose approach is probably the first thing to check. Start at the bottom - flood the area below the windshield first, to check for a bad seal or gasket on the HVAC system. Then check the bottom of the windshield, then the side, then the top, then the sunroof.
If none of these are the problem, you may have to get under the car and check the HVAC case drain - not easy to get to. Sometimes the case seam on the HVAC case leaks.