APB - Check your cowl seam seals!

[80BrownK10]

Sumbsih had better be sealed up now. POR-15 Metal Prep, POR-15 paint, 2 coats of seam sealer, and 2 coats of Flex Seal.

Flex Seal is nifty stuff. Smells a bit like menthol, but it brushes on nice and self-levels like a dream.

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Ok so why the As Seen on TV flex seal? I personally would not have too much confidence in that type stuff for the long term.

 

[da_raabi]

Ok so why the As Seen on TV flex seal? I personally would not have too much confidence in that type stuff for the long term.

Honestly? I have heard and seen good things about the stuff. I wanted something that could create a final layer to prevent any/all water from even touching the seam sealer. Since I had already done this once before, and water got through the new sealer again, I wanted to ensure there was a "trough" of sorts preventing the water from ever even getting that far. I thought a long trough of aluminum would be best, but it would have been impossible to get it in place and would have rattled like crazy. So I thought I would try a coating instead. Like I said, I had heard/seen good things about this stuff so figured I'd try it. So far I really like it. I went on like a professional product. Very impressive. Longevity may be a different story, but as long as it does not break down it will be fine. Peeling is fine as long as it stays in one piece - again the "trough" concept.

So that's my story and I'm sticking to it. I figured I be the guinea pig on this stuff. Why not? It can't hurt!

 

[DoubleDingo]

Good find on the seam sealer and a good fix too. I like how you think outside the box. I have two trucks that need to be looked at. The '81 doesn't leak at all and it has sat out its entire life. Crusty Biscuit does leak and I bet this is the reason.

 

[80BrownK10]

Good find on the seam sealer and a good fix too. I like how you think outside the box. I have two trucks that need to be looked at. The '81 doesn't leak at all and it has sat out its entire life. Crusty Biscuit does leak and I bet this is the reason.

It's so random. So many of these trucks have this problem, yet you have an 81 that doesn't leak a bit? I have had mine for 1y years or so and it was rusted out in the classic floor places from this leak then. I have kept the cab under a shed or tarp and fixed this a few times over that period? We're certain shifts or plants better than others or did they just get it right every 10th or 20th time?

I just hacked a repair job on the driver side that consisted of some new metal welded in in the biggest spot along the side. Also some Bondo on the small holes and seam sealer to seal it all up around the new metal. Cleaned the bottom side where the pin holes were to make sure there was clean metal. Put a dab of seam sealer on the underside where the Bondo is seen and the. Painted it all back up. Yes the right way is to cut it all out and weld new in. But I don't have a show truck, I am fine with a 20 footer that doesn't have a joke that water is slug up through and solid for sitting in.

 

[Jeramie]

Going to have to redo mine again later. My welder is crap and just blows holes in thin sheet so I had to rivet a patch on for now. Bit at least it shouldn't leak for a few years.

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[OldBlueDually]

Sumbsih had better be sealed up now. POR-15 Metal Prep, POR-15 paint, 2 coats of seam sealer, and 2 coats of Flex Seal.

Flex Seal is nifty stuff. Smells a bit like menthol, but it brushes on nice and self-levels like a dream.

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I like that! That should last a good long time.

When I get to that point on mine I will get all cleaned up really good and I plan on using the OSI quad max silicone in the same fashion you did with this to help keep that seam sealed up. The OSI stretches up to 25% and the adhesion of this stuff is crazy. Hope it works.

 

[Jeramie]

Got some rust converter yesterday. Have some POR 15 and got some more seam sealer. Gonna get er done asap.

 

[Octane]

Got some rust converter yesterday. Have some POR 15 and got some more seam sealer. Gonna get er done asap.

I wonder if there is a seam at end of the cowl area behind the fender area? I shined a light and mirror in there and couldnt see far enough into it.

 

[Jeramie]

Goes all the down to the bottom of the inner kick panel.

 

[annettemarie]

Ha! So you found it! I'm glad to hear my troubles are helping out fellow square owners.

I just finished up the fourth step in the process. So I have:

1. Removed as much of the original seam sealer and rust as possible using a screw driver (seriously) to chisel and scrape it all out, vacuuming the remainder.
2. Liberally sprayed it down with POR-15 Metal Prep. I don't much like this stuff, but as long as you wash it off with water correctly it works well I guess. My hope was that it would get between the sheet metal layers and convert any rust in there.
3. Liberally applied two coats of POR-15. Used about one half of the tiny can of the stuff.
4. Applied 3M seam sealer. I used an entire tube to completely fill the entire crevasse. It's a bit messy but its filled.

Next step is to completely coat the entire plenum with Flex Seal. My hope is that this will prevent water from ever reaching the area again. I'd rather use a big U-shaped piece of aluminum or something across the entire thing, but there would be no way to get it in there, and even if I could it would rattle like crazy. I figure Flex Seal should do the same thing.

Hopefully at long last this will fix my issue. I was pissed when I saw how nasty my brand new carpet, mass-loaded vinyl insulation, closed-cell foam insulation, and foil-backed butyl insulation had gotten. Fortunately it never got to stinking, so I'll take what I can get. The carpet is stained, but only under the floor mat, so I guess its not too too bad.

More to come.

Hey there Adam, I'm curious if you did the flex seal thing over your seam seal. If so how did it go? Would you recommend?

 

[82sbshortbed]

I've used flex seal with good results. It's basically liquid rubber.

 

[da_raabi]

Hey there Adam, I'm curious if you did the flex seal thing over your seam seal. If so how did it go? Would you recommend?

Yes I did. After the seam sealer I painted on about 3 coats of flex seal (clear, though it does not matter) and boy did that stuff go on nice. It smells funny, but it's good stuff. I made sure to paint it right up the sides of the cowl, basically making a channel of flex seal. Water will likely never touch the actual sheet metal of the cowl ever again.

I'd recommend this process 110% and I wish I had done it sooner. This stuff works amazing!

 

[OldSchool C-10]

Thanks for the tip, just starting on mine so I'll definitely be removing the cowl to look down inside. While I was in process of replacing the six-cylinder with a V8, I took the time to fix this rusty seam.

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[annettemarie]

Yes I did. After the seam sealer I painted on about 3 coats of flex seal (clear, though it does not matter) and boy did that stuff go on nice. It smells funny, but it's good stuff. I made sure to paint it right up the sides of the cowl, basically making a channel of flex seal. Water will likely never touch the actual sheet metal of the cowl ever again.

I'd recommend this process 110% and I wish I had done it sooner. This stuff works amazing!

I did it yesterday. Just as you described. Ill give it a couple of days then run water thru. Now to repair a leaky windshield gasket and see why i get no power to the " Instrument fuse". I appreciate how detailed you were about your cowl process. HUGE help

 

[da_raabi]

I did it yesterday. Just as you described. Ill give it a couple of days then run water thru. Now to repair a leaky windshield gasket and see why i get no power to the " Instrument fuse". I appreciate how detailed you were about your cowl process. HUGE help

Glad it was helpful to you! This is one of those areas that often gets overlooked... Even by the original engineers!

Why they thought a major sheetmetal seam belonged at the bottom of what is essentially a water pipe is BEYOND me.

Post up about your electrical issue over in the electrical section. Betcha one of us can help you figure it out.