Author Topic: Oct 65 - NJ Firewall Sealer/Sound Deadener  (Read 3152 times)

Offline Building 3

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Oct 65 - NJ Firewall Sealer/Sound Deadener
« on: July 21, 2020, 01:36:05 PM »
From checking prior posts I know that the engine compartment was spray painted a semi-gloss black prior to anything being attached to the firewall. Then all of the components were attached to the firewall except for the engine ground strap. My question is: Was there any strip caulk or dum-dum like material put around where the components went through the firewall prior to the spray sealer/sound deadener? For instance around the heater hoses or the heater blower motor, or anything else? Thanks
« Last Edit: July 22, 2020, 07:07:35 PM by J_Speegle »
1966 289 C code auto convertible December 1965 scheduled build at Dearborn.

1966 289 C code auto convertible
October 1965 scheduled build at Metuchen.

Offline CharlesTurner

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Re: Firewall Sealer/Sound Deadener
« Reply #1 on: July 21, 2020, 03:29:52 PM »
I've found strip caulk around the heater hoses and also the back of the master cylinder where it goes through the firewall.  The heater hose caulk is inconsistent between the plants, I'd leave it off unless you can find original examples close to your production date and assembly plant.
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Offline J_Speegle

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Re: Oct 65 - NJ Firewall Sealer/Sound Deadener
« Reply #2 on: July 21, 2020, 06:07:00 PM »
Not sure if your asking for your Dearborn or your NJ but in general the purpose for the sprayed on adhesive/sealant meant no need to seal the dozens of holes, attachment points and pass throughs.
« Last Edit: July 22, 2020, 07:07:44 PM by J_Speegle »
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Offline Building 3

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Re: Oct 65 - NJ Firewall Sealer/Sound Deadener
« Reply #3 on: July 22, 2020, 12:43:46 PM »
This question is for the NJ car. It's unrestored. However I have been trying to reverse "improvements" prior owners have done to the car. Someone thought it would be a good idea to spray bomb the engine compartment in Hot Rod Flat Black Paint. In doing so, they also removed whatever sealer was on the firewall.  Now I have removed the spray paint and I am down to the good Ford factory paint. So my next decision is whether or not I try to respray the sealer.  Before I do that (if I do) I wanted to know if I should apply any strip caulk or dum-dum. Now I know that I don't need to do that. I saw an older post saying that the Rust-Oleum Undercoating spray product worked well. I know with the engine in the car this will not be an easy job and, if I do it, will require a lot of masking to keep the spray off of everything but the firewall.
« Last Edit: July 22, 2020, 07:07:51 PM by J_Speegle »
1966 289 C code auto convertible December 1965 scheduled build at Dearborn.

1966 289 C code auto convertible
October 1965 scheduled build at Metuchen.

Offline Bob Gaines

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Re: Oct 65 - NJ Firewall Sealer/Sound Deadener
« Reply #4 on: July 22, 2020, 12:52:26 PM »
This question is for the NJ car. It's unrestored. However I have been trying to reverse "improvements" prior owners have done to the car. Someone thought it would be a good idea to spray bomb the engine compartment in Hot Rod Flat Black Paint. In doing so, they also removed whatever sealer was on the firewall.  Now I have removed the spray paint and I am down to the good Ford factory paint. So my next decision is whether or not I try to respray the sealer.  Before I do that (if I do) I wanted to know if I should apply any strip caulk or dum-dum. Now I know that I don't need to do that. I saw an older post saying that the Rust-Oleum Undercoating spray product worked well. I know with the engine in the car this will not be an easy job and, if I do it, will require a lot of masking to keep the spray off of everything but the firewall.
Rust-oleum will work as well as many others but doesn't have the exact look of the factory sealer.  3M spray adhesive when sprayed has a closer texture IMO.Getting it the darker color is the trick.
« Last Edit: July 22, 2020, 07:08:45 PM by J_Speegle »
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Offline 67gtasanjose

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Re: Oct 65 - NJ Firewall Sealer/Sound Deadener
« Reply #5 on: July 22, 2020, 02:01:55 PM »
Rust-oleum will work as well as many others but doesn't have the exact look of the factory sealer.  3M spray adhesive when sprayed has a closer texture IMO.Getting it the darker color is the trick.

Product number please?
« Last Edit: July 22, 2020, 07:08:36 PM by J_Speegle »
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Offline J_Speegle

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Re: Oct 65 - NJ Firewall Sealer/Sound Deadener
« Reply #6 on: July 22, 2020, 03:19:35 PM »
This question is for the NJ car. It's unrestored. However I have been trying to reverse "improvements" prior owners have done to the car. Someone thought it would be a good ................. I saw an older post saying that the Rust-Oleum Undercoating spray product worked well. I know with the engine in the car this will not be an easy job and, if I do it, will require a lot of masking to keep the spray off of everything but the firewall.


That's for replying back. So we have a Dec 65 NJ car  to focus on. What many in the same situation, yes have done this on other people's car when they could not bring themselves to do it, is to take some sheets of aluminum foil and run it down between the top of the transmission and the back of the engine and the firewall. Of you push and manipulate the product it was form it's self to the shape pretty well. You can take separate sheets and fold the edges together to create larger sheets. Product will tear and shread if your not careful but just add another sheet over or under the torn area.

Just focus on the area at the bottom of the firewall to catch any misdirected spray and if you want you can lay a sheet and fold it over and press it along the firewall to cowl pinch weld. to protect that area. You don't want it around the face of the firewall or side panels (inner fender panels) where some overspray might get blocked and produce a visible line in the spray - giving your short cut away.

have you found or do you have pictures of what the product that they used at NJ looks like or do you need additional ones?

Hope I've explained that well enough



Product number please?

They keep changing product lines, numbers and so on. Have not used it on a car for this purpose yet though have suggested the possibility based on the look for years. In spray outs it can look very convincing. 

Challenge so far has been to figure out how to take away the tackiness once in place. Have not been able to experiment yet but though dusting it with powdered graphite or just dust might work. Since it originally was an adhesive it likely was tacky for a while and the surface gathered dust from the plant and from the parking lot prior to the cars being shipped. It is often has a brown tint to the product. This light spider web looking product was typically applied and had this some look. There are some abnormal  where the product was put on very heavy but you rarely see those examples during 65-67 at San Jose

Must mention that IMHO this would be closer for San Jose 65-67 only not for the other two plants that year.

One of the two product numbers would be #38808 

Thing we've gotten off of the threads focus though
« Last Edit: July 22, 2020, 07:08:09 PM by J_Speegle »
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Offline Building 3

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Re: Oct 65 - NJ Firewall Sealer/Sound Deadener
« Reply #7 on: July 22, 2020, 05:55:31 PM »
No, I do not have photos but of course they would help a great deal before I started if you have any or direct me to where I can find them. I'd like to make it as close as i can to what was there when it was built in NJ. Thanks  (I do have one set of photos for Dearborn. Very liberal application at Dearborn. Lots of sealer/deadener on the firewall.

Everything was on the firewall except for the engine ground wire. How about the brake lines? Were they attached to? I have one horizontal brake line near the bottom of the firewall (before it starts to bend under and becomes the transmission tunnel.)  Would that have been installed and therefore have sealant on it or not?
« Last Edit: July 22, 2020, 07:08:16 PM by J_Speegle »
1966 289 C code auto convertible December 1965 scheduled build at Dearborn.

1966 289 C code auto convertible
October 1965 scheduled build at Metuchen.

Offline J_Speegle

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Re: Oct 65 - NJ Firewall Sealer/Sound Deadener
« Reply #8 on: July 22, 2020, 07:06:52 PM »
No, I do not have photos but of course they would help a great deal before I started if you have any or direct me to where I can find them. I'd like to make it as close as i can to what was there when it was built in NJ. ............


Thanks what we're here for so will find and post some. Know I don't have allot to offer for this plant and year. Maybe other members will have examples to offer also

This is where finding 6 cylinder cars for example is a good thing. Less stuff in the way of pictures and the view :)



Everything was on the firewall except for the engine ground wire. How about the brake lines? Were they attached to? I have one horizontal brake line near the bottom of the firewall (before it starts to bend under and becomes the transmission tunnel.)  Would that have been installed and therefore have sealant on it or not?

Yes brake lines but of course the intent was to seal where the brackets and screws were located and not all of those spots always got done. The other surfaces of the brake lines could have gotten splatters of overspray from the pattern laid down by the guy applying the material to seal other locations

Pictures should show some of this once posted

« Last Edit: July 22, 2020, 07:27:09 PM by J_Speegle »
Jeff Speegle

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Offline J_Speegle

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Re: Oct 65 - NJ Firewall Sealer/Sound Deadener
« Reply #9 on: July 25, 2020, 07:32:46 PM »
Looked through my pictures and all I have from the winter of 65 for NJ cars are pretty poor when it comes to resolution and details. Many were taken from Ebay ads and such :(

Because of this and still wishing to help out I focused on a later period where I had more examples so I offer those below in hopes that they will help and substitute at this point unless other better (closer to Oct 65) is posted.  Will post some as the original picture followed by a highlighted version as I have in the past. For some of the coverage I'm looking at sometimes more than one picture to make that determination. So multiple angles instead of just one one shown

Remember they idea was to cover/hit each of the holes or attachment points. Depended on the worker and how much effort they took on each car.


Passenger/Heater side

6T243xxx




6T251xx





6T286xxx




Center section

6T243xxx




6T249xxx




Driver's side

6T249xxx





6T286xxx






Appears that the application is not a real heavy one and the product is more sound deadener/undercoating like - different that the San Jose product, more like the product Dearborn used
Jeff Speegle

Anything worth doing is worth doing concours ;)

Offline sgl66

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Re: Oct 65 - NJ Firewall Sealer/Sound Deadener
« Reply #10 on: July 26, 2020, 12:52:18 PM »
“ Appears that the application is not a real heavy one and the product is more sound deadener/undercoating like - different that the San Jose product, more like the product Dearborn used”

Interesting observation about what N.J. used. This is the only picture I have from my engine compartment when I first bought the car in 1980 before doing the high school kid engine compartment restoration with a wire wheel and rattle cans. The wire harness photo shown is also consistent with what I remember.
66 GT 6T09K12---- scheduled Oct 14, bucked Oct 13 '65

Offline Building 3

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Re: Oct 65 - NJ Firewall Sealer/Sound Deadener
« Reply #11 on: July 27, 2020, 01:33:47 PM »
Thanks, the photos are a great help, especially the highlighted ones. So a light application to cover the holes through the firewall (except the engine ground hole and the engine ground wire) with the 3M product. Use the aluminum foil to cover adjacent areas and to prevent drips. Great help!
1966 289 C code auto convertible December 1965 scheduled build at Dearborn.

1966 289 C code auto convertible
October 1965 scheduled build at Metuchen.

Offline J_Speegle

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Re: Oct 65 - NJ Firewall Sealer/Sound Deadener
« Reply #12 on: July 27, 2020, 05:37:24 PM »
Thanks, the photos are a great help, especially the highlighted ones. So a light application to cover the holes through the firewall (except the engine ground hole and the engine ground wire) with the 3M product. Use the aluminum foil to cover adjacent areas and to prevent drips. Great help!

My usage of "light" was in comparison to later NJ production years and Dearborn. In comparison to 66 San Jose its a heavier application in general. Could vary with each car, workers effort or attention level at the moment. On the electrical connections looks like the typical three sides of the blocks got a good sealing IMHO
Jeff Speegle

Anything worth doing is worth doing concours ;)

Offline Building 3

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Re: Oct 65 - NJ Firewall Sealer/Sound Deadener
« Reply #13 on: July 30, 2020, 12:19:48 PM »
Got it.  I will study the other applications on this site and do as you say. I'm going to make sure I have everything covered up with aluminum foil before I start.  Thanks for that tip.
1966 289 C code auto convertible December 1965 scheduled build at Dearborn.

1966 289 C code auto convertible
October 1965 scheduled build at Metuchen.

Offline sgl66

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Re: Oct 65 - NJ Firewall Sealer/Sound Deadener
« Reply #14 on: August 05, 2021, 02:45:19 PM »
In addition to this thread, I've also looked through https://www.concoursmustang.com/forum/index.php?topic=6575.msg143918#msg143918 and started to play around with application techniques using the suggested Rustoleum product.

I had some extra marble tile laying around to use for practice and because it's light it shows better contrast. In the side by side in image B, the tile on the left was done using just the nozzle on the can. There is lots of overspray on the sides and the application is thin. Overspray can partially be reduced by not pushing the nozzle all the way down and holding 1-2" from the surface. You can apply multiple layers to build it up but I'm not sold on that technique yet.

The tile on the right (and some slop on the left tile) I did spraying through a turkey baster. While it prevented the fine overspray and I think gives a more realistic look, controlling how the build up in the tube shoots all over the place still needs to be worked out. I tried cutting the baster tube shorter and tried 1/2" (picture A), 3/4" and 1" (picture B) openings at the end. I think somewhere between 3/4 and 1" is best. I'm going to try a funnel to reduce the build up in the tube.

Has anyone had luck with another method or ideas?

66 GT 6T09K12---- scheduled Oct 14, bucked Oct 13 '65