Seam sealer recommendations

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AuroraGirl

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Anyone have a good recommendation for seam sealer? The firewall seam on my truck is rusty and needs some sealer(being how rusty the truck is, im going to remove the rust, use some converter on it, plug a rust hole, and then use seam sealer to refinish. Id like to hit it with some paint after to vaguely match and seal up the converter.


But I know some seam sealer isnt paintable, it wouldnt bother me one bit if its not paintable. The only other thing I need to use seam sealer on is my car which are un-seen seams, so function over looks is fine by me

I saw some 3m stuff on their website that looks good, I have used their windoweld for non-window welding purposes with great success so i imagine their seam sealer is probably good too
 

bucket

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This stuff here is a very good sealer that works well in a lot of situations:

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It's thick enough that it holds it's shape on vertical surfaces, but thin enough that you can run a spreader over it if you need to work it into a certain area or give it a factory applied appearance.
 

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Oh nice. Is it "medium bodied" where it retains any flexibility after curing? My park avenue is unibody construction and the FSM says to use that because structural load is applied to all seams on the unibody frame portions, of which some is where im replacing.

This is why we cant have nice things
 

bucket

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Oh nice. Is it "medium bodied" where it retains any flexibility after curing? My park avenue is unibody construction and the FSM says to use that because structural load is applied to all seams on the unibody frame portions, of which some is where im replacing.

This is why we cant have nice things

Yeah, it stays rather flexible when it's cured.
 

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Yeah, it stays rather flexible when it's cured.
on non-structural sheet metal. if you had a puncture that didnt remove metal, it just pierced and left a piece raised in the floor now, how would you patch it? Say, for example, its the floor of the trunk which sits under a carpetting. And the bottom is the spare tire well underneath so road debris and stuff fling at it periodically. Could you push the pierced metal back into its original position, apply a HVAC duct metal tape to the bottom,fill with seam sealer, pull the tape off, sand , apply POR-15, paint to whatever heart content(something for auto body for sure), then do whatever desire on the inside?
 

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So something poked a hole in your trunk floor? Honestly, you could simply knock the metal back somewhat into place, smear some of that sealer over the tears, let it dry for a day, spray some undercoating on it and call it good. While not a 'correct' repair, it would be simple and work just fine.
 

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So something poked a hole in your trunk floor? Honestly, you could simply knock the metal back somewhat into place, smear some of that sealer over the tears, let it dry for a day, spray some undercoating on it and call it good. While not a 'correct' repair, it would be simple and work just fine.
because it has been pierced a while and i have NO idea what did it, and i have a lot of other rust damage in the rear portion that i need to fix, while it may be overkill i will be using said materials anyway lol. i was thinking the hvac tape ONLY if the metal doesnt fill enough of the original holes gaps(like if it broke a chunk off), i guess it might line up close. I would then sand, POR, paint both sides. i would not care about color, i would prob use ford blue or neon pink
 

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Based on how aggresive and how steep the angle is.. i am thinking it was a richochet of a projectile of some kind but if it was while driving... HOW DID I NOT NOTICE? and if it was parked WHAT WAS IT?
 

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Based on how aggresive and how steep the angle is.. i am thinking it was a richochet of a projectile of some kind but if it was while driving... HOW DID I NOT NOTICE? and if it was parked WHAT WAS IT?
on non-structural sheet metal. if you had a puncture that didnt remove metal, it just pierced and left a piece raised in the floor now, how would you patch it? Say, for example, its the floor of the trunk which sits under a carpetting. And the bottom is the spare tire well underneath so road debris and stuff fling at it periodically. Could you push the pierced metal back into its original position, apply a HVAC duct metal tape to the bottom,fill with seam sealer, pull the tape off, sand , apply POR-15, paint to whatever heart content(something for auto body for sure), then do whatever desire on the inside?

because it has been pierced a while and i have NO idea what did it, and i have a lot of other rust damage in the rear portion that i need to fix, while it may be overkill i will be using said materials anyway lol. i was thinking the hvac tape ONLY if the metal doesnt fill enough of the original holes gaps(like if it broke a chunk off), i guess it might line up close. I would then sand, POR, paint both sides. i would not care about color, i would prob use ford blue or neon pink

This is 1000% NOT what seam sealer is meant to do. Think of it as caulking for cars. I understand some try to hold things together with caulking, but... it's meant to "seal" pieces that are secure. And also not meant to span gaps in structure.
While this may be the most odd ball damage I've heard of, that doesn't matter. You've got areas rusted out and you're worried about a (presumably small) tear in the trunk pan under the spare tire? If it's that worrisome, pound it flat, spray paint it and rivet a piece of flashing or an old license plate over it. And if it's not filling your trunk with dirt and debris, why does it even matter?
 

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Anyone have a good recommendation for seam sealer? The firewall seam on my truck is rusty and needs some sealer(being how rusty the truck is, im going to remove the rust, use some converter on it, plug a rust hole, and then use seam sealer to refinish.

Seam sealer is not bondo either. Not meant to be applied with a putty knife or kitchen spatula. Don't believe the "Flex Seal" infomercials. Regardless of how much you apply, your truck or car will not float!
 

Grit dog

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because it has been pierced a while and i have NO idea what did it, and i have a lot of other rust damage in the rear portion that i need to fix, while it may be overkill i will be using said materials anyway lol.

This is another example of dis-regarding or ignoring appropriate and helpful information, while providing unnecessary info or justifications.
Please don't take this the wrong way, but if the puncture in your car trunk is causing ANY real world issues, it could/should have been super easily fixed long ago and history by now...
If you begin to think of how you could be productive with your seemingly endless list of automotive tasks, it will help you get ahead on them.
 

AuroraGirl

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This is another example of dis-regarding or ignoring appropriate and helpful information, while providing unnecessary info or justifications.
Please don't take this the wrong way, but if the puncture in your car trunk is causing ANY real world issues, it could/should have been super easily fixed long ago and history by now...
If you begin to think of how you could be productive with your seemingly endless list of automotive tasks, it will help you get ahead on them.
I discovered the puncture just recently. I say it happened a while ago because my water issue in trunk area is newer because hte last time i had the carpet out was early summer. The issue has fortunately been mostly minor.

but i do like your ideas of fflashing or other patch material.
i am new to home and DIY use of caulking, adhesives(construction), sealants. And how they are not all interchangeable and etc.

I did not realize seam sealer couldnt span gaps. For the firewall, short of welding in new firewall, could i clean up the material and span the gap with a plate of metal, using seam sealer around THAT? I can make a piece of metal plating from an old snowmobile route sign that i can use a vice and put a bend in to contort to old surface. I was thinking clean up the surfaces, paint and seal, secure sign, seam seal, then finish paint beyond boundary of sign?

all this after fixing the origin of the damage(or at least it seems, hah, get it?) in the cowl

@Grit dog for my car, assuming the metal pounds back and there is relatively little difference in gap left, could I just seam seal and protect with paint or do you think it still needs a new backing material?
 

bucket

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I assumed it was just a small puncture. But maybe not?

The thicker seam sealers can fill small gaps, the OE's actually do that a lot, in joining corners of seams and whatnot.
 

AuroraGirl

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I assumed it was just a small puncture. But maybe not?

The thicker seam sealers can fill small gaps, the OE's actually do that a lot, in joining corners of seams and whatnot.
im thinking grit dog was talking about using seam sealer AS the means to cover a gap like lets say you had a 1 inch drop off where there was no metal(instead of overlap or welded in material over hanging) to use seam sealer TO try to fill the gap. It would be outside of its normal abilities i think. but like where he says use a license plate is to make that overlap in which you can seal the now small-seam around the thing.

and the hole is small, relative. im not sure what did it.. but its about 2 inch wide, 1 inch deep, but if i pound the metal down i might have most of it (allowing me to hopefully just use seam sealer to finish a now minor gap that would still have sheet metal connection. Here, ill go find a rubber mallet and show what i mean soon
 

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I would not be afraid to pound it as flat as you can, cut two pieces for top and bottom to cover the hole and use structural adhesive. The stuff is great.
 

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