Ok so I may get laughed at for this but in due time I will find out if this will work and may be able to help someone else in the future.

On my 86 Lariat I had noticed that the carpet was wet after it rained for awhile. One day I pulled the carpet because it was nasty from the age and also from staying wet alot. I then used the hose to try and find where the leak was hoping it wasn't the windshield. When I sprayed water right in front of the driver's side I noticed a trickle of water run down the inside of the firewall right above where the brake booster bolts up. Now I have a location but needed to know why, still anticipating the worst that the metal around the windshield was rusted out. I jumped on the forum and searched and had found where these trucks are known for the sealant between the cab and cowl to break and crack leaving a gap where water can enter. So know I have a reason for the water leak but have to fix it now.

After reading other who posted about what they did I of course had to do my own thing. They said you have to remove the hood to remove the cowl...which is true. I unbolted the hood hinge but left it attached to the spring so it was easier to maneuver by myself than having to lift it myself especially when putting it all back together. I did unscrew the cowl first though. Unbolting the hood this way gave me ample room to do what needed to be done.



After removing the rest of the screws in the top of the cowl I was able to remove it and as the legend has it the sealant was lifted from the metal so water could leak down.



As you can see from the picture there was some visible rust. I have to remove the old sealant anyway to get to the joint anyway so I had to inspect to see how bad it was....





Needless to say you can tell why it was leaking and I am very surprised that I wasn't driving around in a pool from all the holes. When I bought the truck the cowl had pine straw and such in the cowl but after removing the cowl for this job I found this as well...



Fuzzy picture but it was as bad as it looks.

I was able to remove the access panel behind the kick plate and dig all of the crap out of there. All that I am sure was thanks to the family of rodents that had made a home on top of the engine before I bought it.

On to my solution. Since I had so much rust and I AM NOT in any way shape or form a body man I called a guy that had bought some parts from my other truck to come take a look at it but wouldn't be till monday and since I am a little impatient and could anticipate the cost to be higher than I wanted I needed to come up with a solution.

How many of you have seen the commercial for Flex-seal, takes a screen door and turns it in to a boat....I figured hell if he can do that I can fix the holes in my truck. Now I must back track some....I did wire brush to the best of my abilities all of the rust and make sure any loose material was removed and then used Ospho on it very liberally and let it sit for over 24 hours. Anyway, I went to wal-mart and bought 2 cans of the Rustoleum version of flex seal (Leak-seal flexible rubber coating) and a roll of duct tape (everything fixes with duct tape right??)

I got home and sprayed a first coat on everything and then made strips of tape to cover the bigger holes and laid them down over the first coat and the holes. I made sure that the tape laid down flat and then sprayed another coat over it all to start the sealing process. After 6-7 coats I am leaving it alone for now to cure and then will reassess if more needs to be applied.









Pictures don't really do it justice but as I said I may have to apply more, pictures make it look like there are more gaps than there are but all the rust holes are covered and sealed at the moment and also the seam itself.

Let the fun begin

 

Straw and leaves falling through the cowl and collecting inside the kick panels or on the heater resistor (FIRE HAZARD!) is common issue with these trucks. Ford addressed this with redesigning the cowl in 1987 by using small holes instead of the long slots of the 1980-1986 version.

You can easily replace the 1980-1986 cowl panel with one from a 1987-1991 truck. It's a direct fit and the hood lines will match up perfectly.

 

Love the duct tape line, made me


Flex seal works pretty good. Shortly after I moved into our house down here in NC we had a week of rain. The roof started leaking and in the attic the wood looked like new but water coming in thru roofing nails thru the wood. A can of clear Flex Seal (did not want to see a ghetto fix) did the trick. Even thru little storm Mathew we had last weekend.


I got to say I think you did good on the fix as I would not have thought of that. Can you get to the bottom side of that area to clean and "Flex Seal" it also?
I got to check that area on mine to make sure it is in good shape. If I don't use seam sealer I may use the Flex Seal on it.


Again good job on the fix.
Dave ----

 

Once I go to swap the duct work and box on the inside I will examine it then and apply what is needed.

 

nice job! Great way to fix it.

 

You can also use that aluminum tape that is sticky on one side. That was a very difficult area to repair, I see nothing wrong with what you did.

I have used roofing tar before myself. They didn't have that flex-seal type stuff back then.

 

Fire hazard is right. I bought a rust free cab in NC that caught on fire. Dash and windshield are toast but I have replacements.

 

Thanks!! You have saved me hours of work, because I have a similar leak and I am sure I will find the same problem on my truck.

 

Can't say I'd ever seen it, so I searched on YouTube. That search brought up plenty of other late night TV commercials. One thing led to another, and before I knew it, I was placing my order for this:


You see, all my adult life, I've suffered from ECD. That's Egg Cracking Disorder. One of my daughters, a professional cook, has the one-handed Swoop 'n Crack down pat, but not yours truly, much to my shame. I can't wait to see her face when I can finally keep up with her, thanks to modern technology making up for a lack of talent. Won't she be jealous...

So there, some good has already come out of your fix.

 

I know it's been some time, how long did this fix hold up? Or is it still holding up? And if u could do anything different what would it be?

 

I can tell you my roof fix on the house is still holding and we have had some good storms and a tornado come thru.

JK yea would like to know also.
Dave - - - -

 

Really glad to find this thread. Wanting to keep the discussion going in one place since this thread was easy to find.

Found myself in the same spot this evening after a heavy rain yesterday. I haven't removed the cowl yet as I am not looking forward to removing the hood but I did look through the slots and can see a bunch of pine needles under which has to be the 2 or 3 inch long rust 'slot' that I can barely see from inside in the top corner above the firewall insulation on the drivers side.

I would also like to know if the OP's solution has held up but also what are other options. Even with the cowl off it's tough to get into the corner right before it drops into the side channel so I would think welding a patch in that area from above is out. From the inside it would take a complete gut of the dash to get to it.

Since my rust slot looks to be in about the same spot of the OP's I assume this is a common spot so just thinking that other ideas might help others down the road (and me today ).

 

So...my fix did not work as well as I had hoped. I ended up swapping out my cab. I was lucky to find a sonar truck and get a lot of parts from it. It is a very tight spot to get in to and if you do a search, there are other threads out there with the same issue. Using the spray like I did did help but didnt fix the leak entirely but mine was in pretty bad shape. Maybe some of the insulation spray foam might help in your situation. You can get in with a hand held wire brush depending on the location of your rust area.

 

Thanks a lot for the quick response and update to your method. It sounded like a pretty decent fix. I'll keep researching other threads but always nice to know what did and didn't last.

 

Well as I said, my cab was in pretty bad shape. And since I was able to find a donar truck that had a decent cab I was able to just swap it. My fix may work well for you. I would spray it on heavy and let it run down to the affected areas that I was not able to get to. I would wait till summertime or do it in a garage so it will dry and seal as it should.
Good luck with your endeavours and post pictures to keep the thread going. For those that posted and I didn't respond before...my apologies for not answering earlier.