Seam sealer recommendations

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Grit dog

Full Access Member
Joined
May 18, 2020
Posts
6,931
Reaction score
12,150
Location
Auburn, Washington
First Name
Todd
Truck Year
1986, 1977
Truck Model
K20, C10
Engine Size
454, 350
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?

so is the water coming from the puncture or not?
I’d presume not since the carpet is on top of the panel covering the spare and the hole is under the spare tire.
Either way, yes pound it flat and affix a plate over it if it’s troublesome to you or somehow spraying enough water in to get up to the carpet.
Put a bead of caulking, rtv, seam sealer, epoxy, bubble gum or weatherstrip around the hole. Stick a patch panel, license plate, flashing, sheet metal from a junk car or whatever and rivet or some self tapped screws into it compressing the sealer and you’re done.
Idk what the firewall rot looks like but same concept. Anything you compress under the peach panel will seal better than smearing it around the edge.
Again any of these materials will work as good or better than a $15-30 tube of seam sealer that will be junk the next time you go to use it after the tube is opened. And likely something you already have on hand for free.
Same question though on the firewall. Is it leaking into the truck? Or why does that need fixed? Presuming you’re going for function over form. This is not asthetic body work, right?
 
Last edited:

AuroraGirl

Full Access Member
Joined
Sep 8, 2019
Posts
9,693
Reaction score
6,865
Location
Northern Wisconsin
First Name
Taylor
Truck Year
1978, 1980
Truck Model
K10, K25
Engine Size
400(?), 350
so is the water coming from the puncture or not?
I’d presume not since the carpet is on top of the panel covering the spare and the hole is under the spare tire.
Either way, yes pound it flat and affix a plate over it if it’s troublesome to you or somehow spraying enough water in to get up to the carpet.
Put a bead of caulking, rtv, seam sealer, epoxy, bubble gum or weatherstrip around the hole. Stick a patch panel, license plate, flashing, sheet metal from a junk car or whatever and rivet or some self tapped screws into it compressing the sealer and you’re done.
Idk what the firewall rot looks like but same concept. Anything you compress under the peach panel will seal better than smearing it around the edge.
Again any of these materials will work as good or better than a $15-30 tube of seam sealer that will be junk the next time you go to use it after the tube is opened. And likely something you already have on hand for free.
Same question though on the firewall. Is it leaking into the truck? Or why does that need fixed? Presuming you’re going for function over form. This is not asthetic body work, right?
my bad hole is next to spare tire well and water does come up, the carpet soaks that stuff like a shamwow and it doesnt dry on its own. during summer is got steamy and distributed

yes i would think its leaking into the truck since there are now holes in the firewall, i figured its prob a hole into the cowl that debris and dirt collected over the years and rotted a spot, so when i sprayed out the cowl when i cleaned the truck underside, i must have opened up the drains on the sides because i got piles of dirt/rocks from the cowl and the cab stayed dry but a lot overflowed onto the engine it seemed. the seal on hood and cowl is still good
as far as patch panel goes, i think i can use an old trail marker sign with a fastener with a sacrificial coating or non-reacting metal to prevent aluminum on steel corrosion. I do need seam sealer itself tho, as the car has sheet metal seams around wheel wells and in the body that have just cracked and are now able to take on water/moisture. I was gonna research cleaning out old stuff and putting it in to reseal. Id imagine a small file and filling the cracks may work too
 

AuroraGirl

Full Access Member
Joined
Sep 8, 2019
Posts
9,693
Reaction score
6,865
Location
Northern Wisconsin
First Name
Taylor
Truck Year
1978, 1980
Truck Model
K10, K25
Engine Size
400(?), 350
also, its not a LOT of water per-drive, but in winter months snow gets slung up there and summer its just spray. being hwere its at, its hard to explain, but pretty sure the aerodynamics of the car raises air and water at the rear when driving. Like when driving behind a car in the rain, even if its barely sprinkling, the ground water is flinging up at the car behind them. on your car, the wheel wells catch most of that fling esp from tires, but there is still water on the underside and bumper etc, it just dries off most of the time, but if it goes into your super warm/ssuper absorbent trunk liner, then it gone take a while. i have been letting the trunk liner dry after cleaning it and it took 2 weeks at normal indoor humidity of my garage(Lower now since cold) to dry it out completely. Automotive carpets are the same way, that takes forever. 2 years ago I had to dry my car carpets for 2 weeks in 0 degree weather(lots of heating a small cardboard enclosure and using a dehumidifer inside my moms garage and the carpets literally weighed double from the water they carried.
 

wanderinthru

Full Access Member
Joined
Jul 23, 2020
Posts
1,174
Reaction score
2,079
Location
Mid Point Route 66
First Name
Shakey
Truck Year
81, 70, 75, 84, 89
Truck Model
K 10, C 30, K 20
Engine Size
350
You can get a polyurethane sealer at the lumber yard, it's good stuff, around 6 bucks a tube....come in alot of colors....
 

AuroraGirl

Full Access Member
Joined
Sep 8, 2019
Posts
9,693
Reaction score
6,865
Location
Northern Wisconsin
First Name
Taylor
Truck Year
1978, 1980
Truck Model
K10, K25
Engine Size
400(?), 350
You can get a polyurethane sealer at the lumber yard, it's good stuff, around 6 bucks a tube....come in alot of colors....
Shouldnt a seam sealer meant for automotive seams be used for applications where you have a seam on an automotive application?

I guess I dont know what it is made of, but i figured it was used for a reason
 

wanderinthru

Full Access Member
Joined
Jul 23, 2020
Posts
1,174
Reaction score
2,079
Location
Mid Point Route 66
First Name
Shakey
Truck Year
81, 70, 75, 84, 89
Truck Model
K 10, C 30, K 20
Engine Size
350
Shouldnt a seam sealer meant for automotive seams be used for applications where you have a seam on an automotive application?

I guess I dont know what it is made of, but i figured it was used for a reason

It is the same seam sealer used in automotive, same as on cattle trailers, grain trailers, where ever a seam sealer would be used. At the lumber yard, it's sold for putting in windows. Though, winder putter inners will not give the price of the fancy dancy seam sealer, so, they buy the exact same stuff for alot less money. Think that is called marketing now days? We used to just call it look around, use your head. Grin! It is a semi liquid polyurethane in a tube. It's all the same stuff, you are more than welcome to go buy black polyurethane in a tube labeled for automotive fer 16/ 20 bucks a tube? Or you can go buy the exact same polyurethane in your choice of color at the lumber yard. I have used cases of it, up on top of aluminum cattle trailers, no matter the color it is polyurathane, it seals, never gets hard, is a bitch to get off, etc...
 

AuroraGirl

Full Access Member
Joined
Sep 8, 2019
Posts
9,693
Reaction score
6,865
Location
Northern Wisconsin
First Name
Taylor
Truck Year
1978, 1980
Truck Model
K10, K25
Engine Size
400(?), 350
Oh, if that is the case I can do that.. I already have polyurethane sealers, caulk, etc. I have 3m windoweld that is black and really viscous but super hard when cured. for windshields i think. then i have some house stuff meant for putting in windows i think. but it has to be used with another step for holding it is just meant for the sealing aspect. then you can buy different "bodies" and ultimately 1 or 2 step, and cured flexibility.
 

wanderinthru

Full Access Member
Joined
Jul 23, 2020
Posts
1,174
Reaction score
2,079
Location
Mid Point Route 66
First Name
Shakey
Truck Year
81, 70, 75, 84, 89
Truck Model
K 10, C 30, K 20
Engine Size
350
Oh, if that is the case I can do that.. I already have polyurethane sealers, caulk, etc. I have 3m windoweld that is black and really viscous but super hard when cured. for windshields i think. then i have some house stuff meant for putting in windows i think. but it has to be used with another step for holding it is just meant for the sealing aspect. then you can buy different "bodies" and ultimately 1 or 2 step, and cured flexibility.

Seam sealer, or all I've seen in the transportation industry, is polyurathane. As is the "stuff" at the lumber yard. It is not called "seam sealer" but is polyurathane has the same make up and charactistics as transportation seam sealer.
 

bucket

Super Moderator
Staff member
Super Moderator
Joined
Aug 3, 2010
Posts
30,399
Reaction score
28,179
Location
Usually not in Ohio
First Name
Andy
Truck Year
'77, '78, '79, '84, '88
Truck Model
K5 thru K30
Engine Size
350-454
A lot of the stuff meant for sealing external joints and seams on buildings is not rated for use in an enclosed passenger compartment where smells and fumes can be an issue.
 

AuroraGirl

Full Access Member
Joined
Sep 8, 2019
Posts
9,693
Reaction score
6,865
Location
Northern Wisconsin
First Name
Taylor
Truck Year
1978, 1980
Truck Model
K10, K25
Engine Size
400(?), 350
A lot of the stuff meant for sealing external joints and seams on buildings is not rated for use in an enclosed passenger compartment where smells and fumes can be an issue.
good consideration esp in summer heat. the front wheel wells and floor would be areas of concern. the trunk area(being vented to atmosphere) and any other outer parts of the car might not be bad.
 

Raider L

Full Access Member
Joined
Sep 1, 2020
Posts
1,892
Reaction score
1,001
Location
Shreveport, LA
First Name
William
Truck Year
1974
Truck Model
C10
Engine Size
355
Grit Dog, AuroraGirl,

When I was an aircraft mechanic from time to time the aircraft would get a strike of some sort. Now, this is aircraft carrying people. The FAA is very specific what kind of repair to the aircraft would be saving people's lives. They would not allow just any 'ol fix. But Grit Dog may have been right when he said clean it and patch it with some alum. and put the sealer over it. Well, that's almost what kind of a repair the FAR 43 would call for with a small puncture. You cut out a patch of alum. pop rivet it to the plane, or if you could get to the back side then you would use solid rivets, and coat around the edges with sealer. And that was considered safe enough so that patch wouldn't come off, was structurally sound, and wouldn't come off ripping a bigger hole in the wind slipping over the skin of the plane doing damage to the integrity of the planes skin, thus endangering the lives of the passengers.

So if it's good enough for the FAA then I think it would be okay for you AuroraGirl.
 

AuroraGirl

Full Access Member
Joined
Sep 8, 2019
Posts
9,693
Reaction score
6,865
Location
Northern Wisconsin
First Name
Taylor
Truck Year
1978, 1980
Truck Model
K10, K25
Engine Size
400(?), 350
Grit Dog, AuroraGirl,

When I was an aircraft mechanic from time to time the aircraft would get a strike of some sort. Now, this is aircraft carrying people. The FAA is very specific what kind of repair to the aircraft would be saving people's lives. They would not allow just any 'ol fix. But Grit Dog may have been right when he said clean it and patch it with some alum. and put the sealer over it. Well, that's almost what kind of a repair the FAR 43 would call for with a small puncture. You cut out a patch of alum. pop rivet it to the plane, or if you could get to the back side then you would use solid rivets, and coat around the edges with sealer. And that was considered safe enough so that patch wouldn't come off, was structurally sound, and wouldn't come off ripping a bigger hole in the wind slipping over the skin of the plane doing damage to the integrity of the planes skin, thus endangering the lives of the passengers.

So if it's good enough for the FAA then I think it would be okay for you AuroraGirl.
i havent said it isnt.. im more or less talking about the chemical side.. like bucket actually mentioned. That is a valid reason to be concerned because its actually something we have learned over time. I just decided to order the basic seam sealer but i found a small tube of it because it will be a while before i need it on other seams but so i dont have VOCs or harmful vapors melting glues or brain cells or any of that other fun stuff the kids like
 

Snoots

Full Access Member
Joined
Jan 23, 2013
Posts
8,709
Reaction score
17,993
Location
Georgia
First Name
Roger
Truck Year
1973
Truck Model
Jimmy Sierra
Engine Size
350 w/203
I just scuffed up the area and applied 3M Seam Sealer to mine and then sprayed rubberized undercoating over it. Worked ok so far (years).
 

AuroraGirl

Full Access Member
Joined
Sep 8, 2019
Posts
9,693
Reaction score
6,865
Location
Northern Wisconsin
First Name
Taylor
Truck Year
1978, 1980
Truck Model
K10, K25
Engine Size
400(?), 350
I just scuffed up the area and applied 3M Seam Sealer to mine and then sprayed rubberized undercoating over it. Worked ok so far (years).
do you think a can of NAPA professional rubberized coating in a spray can is 1) still good 2) if no propellant, i could add compressed air?
 

Snoots

Full Access Member
Joined
Jan 23, 2013
Posts
8,709
Reaction score
17,993
Location
Georgia
First Name
Roger
Truck Year
1973
Truck Model
Jimmy Sierra
Engine Size
350 w/203
If the propellant is gone the product may have set up but it's worth a try.
Best to wear gloves and a face shield while trying to fill it tho.
 

Latest posts

Forum statistics

Threads
44,071
Posts
948,805
Members
36,143
Latest member
Cooltx
Top