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2011 3.7l Water Leak Under Dash driving me nuts!!!!!

4K views 9 replies 4 participants last post by  roosta 
#1 ·
So this has been been a bit of a hassle, but I feel I am getting close to the problem. In my Gf's 2011 Mustang 3.7l v6 there is a water leak. The water drips underneath the dash onto the carpet from the Mounting bolts from the Brake pedal Assembly. I'll attach a picture below. There is no water anywhere else from what I can see and I have looked and looked underneath the dash. I have gone through the TSB for the water leaks on these issues, and have done all the fixes listed on the service recommendation: Cleaned rubber drain grommets under cowl, resealed Cowl seam in the valley, re sealed Pinch seam under plastic cowl, sealed the ten cowl clips, and sealed both window trims for the driver and passenger window.

I do notice however that when the car is parked on the driveway with the front angled up the drip seems to happen more often. All other items under the dash is dry the only place that the water is coming from is these bolts.

I could just reseal the bolts, but if the water is entering in from the outside i would like to find the source of the problem instead of a bandaid fix.

Any help on this would be awesome, or even if someone has had a similar experience who solved it would be awesome. If someone even knows whats on the other side of these bolts it could give me just enough information to find it.

Thanks in advance to anyone who replies to this!
 

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#2 ·
Could it possibly be leaking around the windshield. The car will flex more than the glass sometimes breaking the seal if it was put in thin.
I take it you have had all the cowl off and cleaned all the crap out. Another thing, have you checked the A/C drain and made sure it was not running out of the Evaporator.
 
#3 ·
I was maybe thinking that but the seal around the glass looks pretty solid. I will have to bust out the polyurethane again and seal that off to at least eliminate that as well.


And the the cowl is clean nothing blocking the drains or cowl grille.

Would it be leaking out of the evaporator even with the the car and A/C off?

Thank you so much for the reply!
 
#6 ·
I would make sure it was draining. It drains on top of the transmission tunnel. I found pictures of where it goes through the floor and were it come out underneath the car.
 

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#7 ·
okay ill definitely check that but i brought the car into my mechanic so it could be on lifts and he said the A/C was all working good and draining in the summer.

That picture you showed me of the interior completely stripped down though is quite helpful. Where I circled is exactly where those bolts are mounted, and from that picture all that looks is above it is the cowl valley where wiper motor is mounted. Either that or is coming in from the windshield, or coming from the corner near the fender and running to that lowest point.
 

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#9 ·
You mentioned cowl, and I'm unsure if you mean the same thing I'm about to say... but I know this exact issue because I had it on my car at one point.

I have a 2012 Black GT/CS and my first issue was the rubber drain plug on the passenger side where the cabin air filter is. (I think this is called the cowl drain, but I'm not 100% sure of it's name. That was fixed...

However, I started feeling my floor get wet on my driver side (second issue) and I checked the driver side by removing my wiper blade and such, and ...sure enough that side was full of leaves and gunk and what have you that had it stopped up.
I will note,that when I pulled that drain plug out, even clogged, it actually leaked INTO the car when it drained w/o the plug, so be sure you don't completely remove the plugs. I haven't had issues for a year now... but I check them every few months because I don't have a garage :(

Especially if it's sitting up hill, It's bound to be coming from that area in general, maybe just the windshield seal?

Edit: missed the last post, glad you found it :)
 
#10 · (Edited by Moderator)
So I know this is kind of an old post, but I'm having a similar issue with my 2011 Mustang 3.7L. I read about the cowl plug clogging issue, so I checked mine and sure enough they were packed with mud, decaying leaves, pine needles, etc. Grabbed a garden hose, turned it on a fairly low pressure and flushed the crud out, and then replaced the disgusting mildew wrecked cabin air filter. I was sure this was the source of my moldy passenger side carpet woes. A few weeks go by, being summer in Texas currently, the soggy floorboard problem slipped from my focus since we don't see more than a scattered sprinkling every few weeks. A descent afternoon downpour rolled through over the weekend, and I just happened to be replacing the blower motor and floor actuator behind the glove box. To my dismay, when I laid down on my side in the passenger floorboard to unscrew the glove box, my left arm was greeted with warm soggy carpeting.

About 2 years ago, I went to my local Ford Dealership to cash in a free windshield replacement voucher given to me by a different Ford dealer I purchased the car from (they damaged the windshield while washing it up to get it ready for me to come pick it up after purchasing it). The local dealership did a less than satisfactory installation and damaged the rubber guard at the top of the cowl that lays on the windshield. Over the past two years that damage has led to the rubber totally cracking and disintegrating. I didn't think that little piece of rubber mattered that much, but it apparently does. Without it, water that hits your windshield would normally rundown over that rubber bridge and into the cowl channel, cowl grille, and eventually down through the cowl drain plug and out the bottom of the engine bay. Without that rubber bridge the water can't fully span the gap and runs down into places it shouldn't like directly down the engine bay side of the firewall and into the cabin air filter and housing, in my case anyway. The clogged drain plug does the this same thing but kind of the opposite since the plug gets clogged and water backs up until it reaches the cabin air filter and then has somewhere to escape into...like your floorboard.
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