Rain entering through ventilation
 

Can someone explain the ventilation path from the cowl under the wipers to inside the cab.
Is there supposed to be a drain in the plenum somewhere?
My 1984 F250 has air conditioning. I don't see a drain under the evaporator in the engine compartment or under the fan.
I get water coming in in heavy rains on the passenger side floor. And, when driving in heavy rain, on the drivers side also.

Down low, very low on each side there are rubber "drain valves" your whole drain area (on each side) may be plugged with years of leaves and crap.
Not sure you can access the area from the inside kick panels, since AC cabs have plates blocking them off, but you have options....

Option 1; (highly recommended) Remove cowl and dig out crap on both drivers and pass side, flush with garden hose and you will see the rubber drains hiding at the bottom of the cab by where the fenders bolt on, Now remove all of the old sealer and re-seam seal.

Option 2; remove side kick panel (steel plates) hiding behind plastic kick panels, dig out crap and flush with garden hose. This does not remedy if your leak if it is coming from cracks in old seam sealer.

Option 3; from laying on the ground, there is an access hole in the fender and you can barely see the rubber drain, try to open (very difficult) clean what you can and pour water into the cowl and help it drain, (kinda useless doing it this way cause you cant completely clean the drain.......

Thank you. I'll try and search for those drains. Ie start at option 3 and work my my up!

Just wondering, how do you remove the cowl panel? I don't see how without removing the hood and that's a two man job, I tried and couldn't get the panel loose and clear the hood pivot brackets but it was a losing battle so I put the panel back and screwed it down.

It can be done without removing the hood. Take out the screws holding the cowl to the cab, remove wiper arms, remove sprayer hose.
The trick is have the hood only open about 2-3 inches, tis a tight fit, but the cowl can be removed this way.
If too tight, mark the position of the hood hinges/brackets and loosen them (dont remove) slide the hood forward.......

I would remove the hood if you have a good paint job. I removed mine on my old 80 without removing the hood, but there was some wrestling involved and I probably did scratch the paint some but it barely had any paint on it anyway.

Good info. Hopefully I get this fixed from the bottom. I will remove the cowl if I decide to go ahead with the paint job.

When done with care, it can be done without a scratch,
also try taping (with auto painter tape) the edges of the hood and cowl to prevent direct contact.
But as mentioned, cleaning from the bottom is almost a waste of time because, like me, I had to pull the plugs out and then clean because of years of crap packed in there, and as soon as the cowl comes off you can see the old seam sealer is cracked and/or missing.

NOTE do NOT use a silicone sealer, RTV or anything like that, Only use a auto Seam Sealer.....

Here's a link with photos of those drains. All the 80 to 96 trucks have them.
https://www.ford-trucks.com/forums/1...he-get-in.html

On each of my trucks, I removed those drains and never had problems with plugging up with crap again.

But now you have a "mouse highway"
BIG problem with mice chewing wires, my neighbors 2015 Toyota Rav4 was just totaled by insurance solely because of mice eating the wire harness in quite a few areas.

Look up "the incredible edible car"

Scary Sh**

https://cimg6.ibsrv.net/gimg/www.for...0c4aba5cf2.jpg
As Reamer said, trying to clean it out from the rubber drains up under the inner fender was a waste of time. I then took off the kick plates and cleaned out 3 cups of dirt from each side. I will probably have to remove the cowl in the end and redo the seam sealer. I guess there was no easy way.

Yes, this is an involved "mini" project, but worth it to reseal the seams, any crack = leak.
Try a bucket of water into the cowl and see it that side drains.....

Why can't we use RTV or silicone on the seams? Do we have to dig out all the old seam sealer. How hard is it? I think my problem is the seams. A bucket of water will free flow out the drains on both sides. My underlay is soaked from the last heavy rain. It must be running down the inside of the firewall.

Silicone actually rots sheet metal, And if you have some on your hand and touch the hood, fender, what ever, you will have massive defects in your new paint.

Silicone is a big screw up, just ask any auto body.
I can remember back years ago, when these bullnose's started to leak, it was the butyl tape that binds the windshield glass to the frame.

Some yo-yo would put a bead of clear silicone on the paint-to-the-chrome trim, (and of course the water just went around the trim and leaked anyway), but years later when they actually removed the trim to get to the butyl seal, peeling up the silicone also took the paint, primer, and produced a huge hole under the silicone!
This is why they make "seam sealer"
Dig out as much loose sealer as possible, some may actually be still good.

Clean everything really well and spray the entire under cowl area with a few cans of rustolem leak seal.

There is an advantage to creating a complete 'bladder' rather than sealing just the seams.
​​​​​​​less likely to crack and no edges to lift, or for water to get under.