[lstout89]

My 05 Mustang (V6) is leaking water from the passenger side behind the dash and onto the floor. I have read majority of the postings about this topic already. We've been trying to diagnose the problem for months now. I live on the North Coast in California where it rains A LOT. I have been driving without a passenger seat and with the carpets propped up. I also have taken out the glove box and it's in my trunk. I've been putting a heater in it on the weekends when it is wet to dry it out. I have done the following trying to fix it:

-Replace the cabin air filter
-Cleaned out the rubber drain
-Took off all plastic cowl grommets and put a sealant over them and around cowl area

We also looked at TSB 07-14-6 and did everything it stated but we still cannot figure out where it is coming from. Sometimes you can see the water dripping down and sometimes it all pours out once I put it into drive or reverse. I've attached a photo of where the water is showing up at. Help please!

 

[Yadkin]

I followed TSB 07-14-6 to the letter and it fixed my leak perfectly. And it rains a lot here as well, plus the car is normally parked outside.

I suggest that you remove the plastic cowl cover on that side completely, remove your cabin air filter and inspect the chamber to make sure that the drain is not clogged. Then carefully inspect your previous caulk work. You should not use silicone caulk but urethane as the TSB requires.

If necessary run a hose over everything while a friend checks the interior so you can pinpoint where the leak is.

 

[marylandGT]

The arrow you have pointing to where the water is showing up at, is that also pointing to the cluster of wires that go through the body into the door? Did you check the grommets that the wires pass through? The one between the door and the body is a large rubber one and is easy to check. The other one, on the inside, you have to lay on your back, with a flashlight, with your legs outside the car to see it. That one is a harder plastic if I remember right. Hope this helps.

 

[Yadkin]

Good point marylandGT. You can jack that corner of the car, remove the wheel and then inner fender and inspect the corner of the chassis there. You may find additional wire grommets. On my (used) Mustang I found a open hole from a car stereo installer that was also leaking.

 

[lstout89]

A urethane caulk was used and over every grommet in that area. We've double checked and have done hose checks several times. Guess it doesn't hurt to do it again. Will have to try those suggestions. Not only is it irritating I haven't yet been able to diagnose the leak but I'm afraid the water is going to cause electrical problems because it is dripping onto the wires and into the white where the wires are.

 

[Yadkin]

Is the cabin air filter wet or have water stains? If so it's probably the drain below it clogged with leaves and crud. If you get a hard rain water flows down your windshield, into the cowl, can't drain out fast enough so rises up into the chamber and then flows through the filter.

 

[lstout89]

No, the filter was not wet and it did not have water stains.

 

[RedFire281]

Here's an interesting place the OP found that leaked water into the same area as the passenger side grommet. Might be something to check.

Found another Water Leak Area! And a fix! Lots of pics.. - MustangForums.com

 

[s197gt]

I live in a place where it usually rains a lot. Yet has not rained for s**t this year. LOL.

Look at this updated TSB which has more tech illustrations and actual pictures at the bottom of TSB.

http://www.stangpit.com/wp-content/images/docs/s197-tsb/08-26-07.pdf

You may need to remove the Smart Junction Box or just remove bolt retaining it, and pull it away from the sheet metal...for a better look at where the water is coming from.

Most likely water coming from ABOVE where you show in your pictures...gotta get in there with a bright flashlight, while someone running water with a hose on outside of car....and find EXACTLY where the water is entering the cabin...then and only then can you fix the leak.

I will PM you with my phone number .

 

[s197gt]

Now rereading all that's been written above...

Since you say it is leaking onto the white plastic connector, then the first thing to eliminate as a possible cause would be a leak from the window weatherstrip retainer...as mentioned, and shown in that newer TSB.

That is the hard black plastic piece on the outside of the car, just above where the side windows seal at their top.
You can tape with blue masking tape between that hard black plastic piece and the colored metal body of the car...along the entire length of the retainer. Then run water over that area of the car and see it it still leaks. If leak is stopped, then that is the problem area, and window weatherstrip retainer can then be removed from car body and new foam tape installed behind it.
If leaks does not stop by masking this area, then leak is from any orifice within sheet metal of car...in the cowl-firewall, or fenderwell area of car.
It is never necessary to remove dashboard of car to find location of leaks...all can be found under and behind dash with a flashlight.
Sometimes a front fender needs to be removed, yet even that is a last resort, after all other areas have been checked.
It is quite common to find leaks due to poor sealing between welded together pieces of sheet metal at the cowl-firewall area of car...repairable from underhood easily.

 

[s197gt]

If throwing the car into reverse or drive after it has been parked in the rain, causes more water to slosh into cabin, then most likely water is getting into the cowl-firewall area of car.

If you look closely at the technical illustrations in that TSB, you can see there are actually three pieces of sheet metal spot welded together at the cowl. One vertical (firewall), one horizontal (above dash and under cowl), and one at a 45 degree angle (cowl itself). Water can enter cabin anywhere that these three pieces meet.

So look at the video supplied by another person above (link to) and that is the area which should be sealed. Must first remove cowl cover or cowl grille for access. I would seal all horizontal (beneath cowl cover) and vertical (near hinge of hood) areas where there are seams.
It is best to use urethane sealer, NOT weatherstripping adhesive.

 

[cape6]

when I got my 05 mustang I had the same issue... It was still under warenty from the ford dealer so they fixed it.