Interior Water Leak Ideas?

[V6Raptor]

Fellow FRF members, I have a 2019 with 48k miles and with the recent heavy rain we had here in SoCal, I discovered a water leak coming into the driver side rear floor. Headliner stays dry but the carpet by the door sill gets wet. Unfortunately, my bumper to bumper warranty is over so I’m certain the dealership won’t cover it so I’m looking to self remedy.

At first I thought it was the sunroof and upon checking it, water does seep through the driver side which apparently is how they are designed. The water does follow the drainage and the drain hole is not clogged. I also checked the drain hose connection up top and bottom and they are connected.

I’ll attach pictures here but I found the water building up right next to the drain hose connection on the bottom and eventually flowing down to the door sill.

I’ve tried to look as best as I can without removing the rear seats, c-pillar, etc. but can’t seem to figure it out.

Any ideas? Maybe third brake light?

Edit: did some deeper research and could possibly be the rear vents behind the seats. Anyone have this issue?

 

[The Car Stereo Company]

highly doubt its the vents. i would say partial clog of the drain tube or in my case, a bad install on the rear window replacement

 

[John813]

IIRC the Gen 1's, one of mine included, had an issue with water getting into the cab via the 3rd brake light. Not sure if the Gen 2 has the same issue or a better gasket was used by Ford.

I would get a garden hose and test out spots that may be the culprit. Start by applying water to the sunroof for a few minutes. Stop check.
Dry?
Try water by the vents.
Try water by the 3rd brake light etc...

I had a seal go bad on mine which only reared it's ugly head after heavy rains as the drains were still clean.
I wish I still had the paperwork but the dealer covered the cost and I'm not sure if I ever got a proper breakdown since it was free.

 

[Shane361]

When my bass would hit I had water coming in the closed back window along the track. Doubt it is the vent also, usually it's the roof drainage, then the window. If it was the heater core it would be up front. That's about.....can always take your third brake light off and inspect it. Maybe lube the gasket and clean mating surfaces.

 

[Old-Raptor-guy]

Center brake light, seen a few.

 

[Silverburst]

Not exactly sure about your situation but yes, I noticed the carpet was damp in the rear on the passenger side by the step plate. And I do not have a sunroof. When I started searching around on other Ford f-150 forums I found it's a common problem if you have a truck tonneau cover and have rain water run-off directly down in-between the cab and leak through into the rear vents. And during a rainstorm if you are parked at a downward angle there is basically a waterfall draining straight down between the cab and bed. Someone suggested stuffing a 6ft, 3/4" foam pipe insulation at the top between the bed and cab to help divert the water. So far, it's worked for my issue and I haven't noticed anymore dampness in the carpets... really dumb design!

Everbilt 3/4 in. x 6 ft. Foam Semi-Slit Polyethylene Pipe Insulation ORP07812 - The Home Depot

www.homedepot.com

 

[MurderedOutSVT]

@Irregular F150 had issues with the satellite antenna gasket

 

[V6Raptor]

Thanks everyone for your responses. Took some time today to investigate since we have some rain coming up in the next couple days and found the problem. It ended up being the driver side rear vent. The top two clips were out to the point I was able to push the vent out from the inside. Fixed the clip and no more leak!

@Silverburst I’m going to use your idea nonetheless just incase the vents gets loose again or parking downhill cause I noticed when the front side is lower, water seeps through the vents regardless.

 

[vondong]

Were you able to figure it out? I have a similar leak on my 2019. I have water that runs along the driver door channel and ends up in my driver footwell. The local dealer did water tests and said it was the rear window seal and they replaced the whole thing. Said it wasn’t the sunroof. It was just about dry inside and now it’s soaked again, so this obviously wasn’t the fix. Any help is appreciated.

 

[V6Raptor]

Were you able to figure it out? I have a similar leak on my 2019. I have water that runs along the driver door channel and ends up in my driver footwell. The local dealer did water tests and said it was the rear window seal and they replaced the whole thing. Said it wasn’t the sunroof. It was just about dry inside and now it’s soaked again, so this obviously wasn’t the fix. Any help is appreciated.

Yes, it was a loose vent that’s behind the rear driver side seat.

Based on what I’ve researched, anything leaking from the front driver area could be the sunroof drainage hose, assuming you have a sunroof. It also wouldn’t hurt to check your rear vents too cause I can see that water eventually making its way from the rear to the front. Easiest way is to look between your cab and bed and there should be a rectangular piece with a rubber seal around it. Check and compare both driver and passenger side and if that rubber seal or vent is not flush with the cab, it will leak.