Today I was searching for a location to mount a Kenne Bell Boosta Pump on my 2004 FX4 and noticed my drivers side carpet was wet just under my dash!! I got online here and saw ALOT of guys having this trouble anything from 3rd brake light to windshield to wire harness or grommets leaking in firewall for ideas. I pulled off my drivers side sill plate and the entire channel with wires in it was full of water so I dried it out and first I poured gallons and Gallons of water around my 3rd brake light...No water. Then I poured gallons and gallons of water all over my windshield and cowl around windshield wipers...No water!! Then it started raining here for a little bit and then the clouds cleared and stopped raining, the roads were still very wet so I decided to drive around with everything still ripped out of my truck and the carpet pulled back...the water seems to be seeping up between a spot welded joint right where the sill plate humps upwards to the rear passenger area! (forgot to menton its a supercab) The joint runs from the front of the cab all the way to the rear under the rubber weatherstrip, Its actually the joint that the gold clips attach to for the diamond plate looking sill plate to snap on. Also I found alot of dirt around the grommet around the emergency brake cable so Im gonna dry this up good and silicone the entire spot weld joint and emergency brake grommet and Ill repost with my results!! Im very confident that water is coming from the spot welded joint, not so sure about the grommet but we'll see...

 

Any chance you can post a pic of this location? It would be great for future searchs on this topic.

 

Iv been having some trouble like that but it's my passenger side. I think it has to do with the ac. Under my floor mats the carpet is wet. Anyone know what it could be??

 

This is a common issue that a lot of people have/had. Have you researched it?

1. 3rd break light
2. AC rubber valve, need to get new "L" shapped one


Yes, OP can please post a picture of where you found the leak? Thanks

 

Yep....A/C drain tube may be clogged. Ford issued a TSP on this, so they may repair it for free. Check with your dealer. I don't know the TSP number, but do a search on "AC drain tube"; it will come up. It requires an extension that's installed I believe.

It's a PITA to get to!

 

Yes, I will post some pictures later tonite where my leak was coming from. Its my drivers side only(I already checked passenger side) I could see the leak at the spotweld joint just under the one piece rubber weather stripping. The water on road was somehow getting forced up through this spot...

 

this is the point where my leak was. rubber weatherstrip still attached....(drivers side)




rubber weatherstrip removed...sorry didnt take a pic before I siliconed the spot welded joint. I also siliconed it from where the hump is in rear compartment all the way up under my dash.






close up of where I applied silicone....there originally was a small part of the spot welded joint that wasnt pulled together real good and I couldnt see any sealer between the sheet metal. Water was seeping up between the sheet metal here as I drove around at Highway speeds on wet roads. Finally the last picture is a close up of where I applied silicone.You can obviously see the 2 thick sheet metal pieces the weatherstrip pops onto but what you cant see is a piece of sheet metal about half as thick as the 2 obvious ones and It only comes up to about half way to the top of the two edges shown. Sorry I didnt take pics before I siliconed everything. I also put a generous amount around my emergency brake cable grommet since it was deformed a bit. Ive ordered a new 3rd brake light assembly too just for good measure. I need to wait for wet weather now to test it out...