water on the floorboard of the passenger side on 2002 BMW 745i

I found water on the floorboard, front and back, on the passenger side of the car. To be fair, I let my son drive the car on a rainy night ande fear he left a window open. He claims he did not so i'm left to seek answers elsewhere. I live in Virginia so salt treated roads are not an issue and the undercarriage looks to be in perfect condition. We do have a great deal of leaves that drop during this time of year and I wounder if a drain pipe is clogged and if the water would overflow into the car some how. Seems unlikely. Any thoughts?

by in Virginia Beach, VA on December 14, 2008
5 answers 3 comments
ANSWER by on December 15, 2008
Use a white paper towel to see if the fluid has a green or orange color if it does have color its more than likely your heater core is leaking, If the heater core is leaking your windows will stay fogged up. If your carpet dries out after a few days the window was slightly open during the rain storm. Heater core replacement is a very expensive job because its located behind the dash board.
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ANSWER by on December 15, 2008
Adding to what hemi said, a leaking heater core will smell like coolant inside the car (passenger compartment). Coolant has a very distinct smell, sometimes described as a sweet smell but not everyone notices the smell. Like you said, many leaves gathered at the base of your windshield can lead to a water leak on the passenger floor. If your BMW has a sunroof, those drains can clog too. If it's possible, park it in the garage with the windows cracked to dry out. Once it's dry, you can test for leaks with a garden hose, weather permitting
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ANSWER by on December 29, 2008
Water may be seeping through your sun roof and channeling down to the floor through the doors. It has happened to my car.
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COMMENT by on March 31, 2011
also experienced seepage at the roof control panel. did this occur with you as well?
ANSWER by on July 25, 2010
drainage tube is clogged from ac unit (condensation drain)
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COMMENT by on September 25, 2010
This exactly happened to mine
ANSWER by on September 25, 2011
Just had it fixed on my 2003 745li it seems to be a real big problem with these cars its your blower that is cracked under your hood that is the problem BMW fixed mine less than 5months ago it is cover under your insurance all I had to pay was my deductable if you let it go it will short out all your sensor underneth your carpet sad thing is mine is doing it again so I will have to put it back in the shop.
COMMENT by on February 17, 2012
I sure do hope that is the problem. I had that problem with my 2002, 745i. It shorted out all the wiring. I had the drain plug cleaned out and the channels from the sunroof. It happened again after that. I took it to a guy who specializes in finding leaks. I put window goo around the windshield and haven't had a leak since. that was in Aug 2010.