The driver side of my truck's cab is leaking some where. Since I replaced my truck's carpet with the OEM rubber mat several years ago, I have to lift it up to see the water. I'm not sure how long this has been going on. I do know that it has been a problem for a little while. I originally thought that it was the windshield, since it had just been replaced. It was replaced again shortly after that since it got broken and the water still showed up. I can't seem to find the culprit. It appears to run down near the center of the driver side in line with the brake pedal or steering column. Is there a common spot on the firewall that is prone to leaking? It seems to only leak during extremely heavy down pours or when I wash it at self serve car wash. Does anyone have any advice on this?

 

My floor is always wet too. Thought it was something low down, but got in after it set for quite a while and when I moved it, got a shower from the trim around the top of the windshield. I guess when it moved regularly, it would just have the water follow the trim and end up on the floor. Haven't been into it yet to see though. A thought just crossed my mind . Have you got cab lights on top? I do and they have been off and on a couple of times without a new seal. Probably my problem. Hope yours is that easy.

Dave

 

The older trucks were prone to firewall flex, more so on manual transmission trucks, but I thought Ford had fixed it by 95. If you can look under the cowl where the windshield wiper arms are, there's a seam between the cab and the firewall underneath. My truck leaked just about where you describe and that seam had separated. I resealed it with some urethane adhesive from the glass company.

 

Hey

Dave, I don't have cab lights. That would be a good place to look though.

Eric, I was thinking that there might be an area under the cowel that could cause this. I'll probably look into that. I'm not sure what else it could be. I have looked several places. I even sprayed the hose in the engine compartment on the fire wall and could not see any water coming in.

 

This may not be your problem but I had the same leak onto carpet and after much searching found that the nuts holding the inside bracket to dash for the brake booster were about to fall off. Tightened nuts and no more leak; just trying to get carpet clean again was a pain.
Did you get above the booster when you were spraying the firewall?
Good luck.

 

I checked the nuts on the studs coming through the firewall for the brake booster. They are tight. I also sprayed the hose on top of the brake booster and don't see any evidence that it leaks. I still can't find where its leaking. I haven't inspected inside the cowl area yet.

 

Short of removing the trim around the side and top of windshield and leaving it off for a while, try getting help to slowly feed water into outside of cowl at fender while someone is looking inside, door closed; take your time and slowly move toward center at cowl especiially the wiper shafts. Hopefully can see some leakage, I had to pull the carpet back from firewall along with the insulation pad to be able to see anything.
If nothing at cowl go up along door joint to drip rail and to windshield seal. The drip ril sealer joint will crack and let water in from the top down the pillar.

 

I still can't figure out where its leaking. Are there any other common places that I should check?

 

Anyone have any additional useful information on this particular type of leak? Sounds as though OP has not fixed his leak yet either.

I do not see any evidence of leaks, with the carpet and foam pulled up out of the way, coming from the upper inside of the cab . I see water gather where there appears to be a vertical to small horizontal painted seem. I have dried up the water and wiped up dirt in an attempt to see which direction the water may be coming from as it is raining right now. My fear is that the water is coming from the very low left, near the hood latch or even closer to the left exterior wall, the area that does not allow access to properly view.

When I bought the truck, 1/2 year ago, it needed major cleaning and I unsucessfully attempted to remove the cowl where the wipers are to get the crap out of there...lots of old pine needles. I just have not found absolute evidence my leak is coming from up high as the higher foam does not feel damp. I have no idea if this area has leaked before but there does not appear to be long term leakage or damage.

I can get a couple of pics uploaded later, hopefully after more water has run so at least I can determine which side the water is coming from. Of course, that is if the water is not traveling from an odd location.

'94 F250 4x4 auto extended cab LB

 

I still haven't found where it is leaking. I am starting to think that maybe it is where the brake system master cylinder goes through the firewall. I was looking at it the other day on notced that it looks like some weatherstrip, like a seal or gasket, used to be there and either shrank or disintigrated. If you look between the master cylinder and the firewall you can see what looks like original paint that has been protected from some of the elements and is darker than the rest of the firewall. It just looks like something used to be there. Maybe its just me, but I also don't remember it looking like this. Is that gap supposed to be there? Is this pic clear enough to see what I am talking about. Does anyone else's truck look like this or is mine the only one. If this is normal, then its probably not the problem. Can someone else take a picture of theirs where the master cylinder meats the cab?

 

Mine leaks but its the "Weather Stripping" around the door it needs to be replaced.

 

I thought it could be that. It just seems like if it was then the area under my pedals wouldn't get wet. I have new door seals. I got a pair of them from NPD for 40 bucks. I wish someone would make replacement vent window gaskets for our trucks. They only make them for 91 and older. The only way I can find to get new vent window gaskets is to buy an assembly from LMC for $150 per side. Both of mine leak by the latch when I go to the car wash, so I just put a napkin or paper towel there when I wash it.

 

Don't know if it might help but,
Back in the day when we were looking for oil leaks on our motorcycles we would clean it real good and cover the area with Desenex spray foot powder. The white color would disappear where it was wet. You could follow the drip right back to the leak.

 

I may have missed it but did you try to fill the cowl area with a garden hose? turn the hose on slow, to prevent it from going into other areas and let it fill the cowl. The cowl is designed to drain down and out of the truck over time the drain areas can fill up with debris pine needles as mentioned prior etc. Once that happens it will dam the area up and water will do what it does and find the path of least resistance to get out.

I like the foot powder idea too it would give you an area to start from.

 

My drvier side seatbelt is wet sometimes after heavy rain. Door weatherstrip?