After heavy rains in SoCal on Friday night, my Mustang got the dreaded passenger side water leak. I was visiting my mom's house for the holiday so it had to stay outside during the rain. The car was parked on an upsloped driveway so after I discovered it, most of the water had pooled to the back passenger side seat. The floor of the front passenger seat was mostly wet on the side of the floor where the fuse panel is. Never had this problem before during rain so I'm not sure how to make sure it doesn't happen again. Hopefully this was just a freak one-time thing. Had to use a shop vac to get as much water out and used air circulators after.

I read that this was a known occurrence for 2005-2009 models and read the TSB, but when I lifted the cowl cover I saw the 10-14 models don't have the cheap foam/plastic grommets. I saw another thread here that said it could be the cabin filter that's blocked. If that's the case, is there anything to do? I took the cabin filter out and everything looked okay in there. Also the drain plug when I looked didn't have any debris in it.

 

Only thing you can really do is to get a hose and have someone pour it on. You be underneath the dash and see if you can see it. May have to move/remove things to see where the water's comin' in.

Cabin filter isn't the issue. They're talking about the cabin filter drains, which you've already looked at.

The link is broken, it's missing a :, and MODS, that VigLink crud makes it really dang hard to figure out what the heck is going wrong!

https://themustangsource.com/forums/...er-leak-505943

Corrected link.

What's coming to mind is the weather strip, maybe, on the door, or the A/C plenum is plugged, which might cause the same problem? :shrugs:

 

Thanks for fixing the link and the tip. I realized I linked the wrong thread originally because I had a couple threads open about the topic.

I meant this one: https://themustangsource.com/forums/...-floor-534478/

 

Also check the drains on the bottom of the door itself. Sometimes factory sealer shuts them tight and water entering by the glass can't get out and the door fills and spills into car. You can open the door and put small stream water against the glass. Water should come out of the drains on the bottom. Sometimes can hear water sloshing while driving if this is the case.

Actually if the plenum drains are plugged, water fills and enters through the cabin air filter, so checking to see if the filter was wet/damp is a good thing.