I have patched the floor panels in my 70 malibu. The repair panels have been welded in place & sealed with caulking from above. I want to prevent water from sitting in the crevices underneath the repairs. Has anyone ever used the expanding foam stuff that you use on your house to fill crevices to keep bugs out? I was thinking of using that & then sealing around the edges with caulking & then undercoating over that. Will this work, or is there a better way? Any ideas??
Thanks,
Gramps

I can't say that I know a whole lot about this but here are a couple of things that came to mind. The foam may actually prevent the water from draining because of all the little cavities. It might hold the water. Also, some of the expanding foams expand with great force. You might wind up with some panels being pushed out of alignment. There are special automotive foams which will not push on a panel. Any good body shop supply store should be able to recommend a foam which will not expand with such force. Hope this helps.

I've had a lot of experience with expanding foam for HOME use, which is what I believe you are referring to. The stuff designed to keep out bugs is light weight stuff and pretty worthless. I'll never buy it again. The woodpeckers in Big Bear just love to peck out the stuff and it easily crushed and hard to use.
The insulating, non-water soluable, hard to clean up stuff is durable but messy.

If I were you I would look into Restomotive Lab's por-patch in a tube. It is por15 that is a thick past designed to fill in large gaps. Expensive but worth it. http://www.por15.com/preventrustpaint.html

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1967 Malibu
1967 Impala SS396 Conv.
"I don't have a solution but I admire the problem!"

The Por15 works very well for very small fills. (it is not very thick for large gaps)
I have a few places that have 1/8" gaps. I understand that they also make the foam that does not expand. My main concern is that it may hold water. Thought that if it was sprayed over with undercoating, it may stop that from happening. Any other thoughts??
Thanks

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1970 Malibu
Member# 407
ACES Member# 03774

I would not use FOAM expanding insulation on the uderside of the car.
TO fill the gaps 1/8inch you say.
use dow or 3m body seam sealer. in a calking
cartridge. Thay have a high build no run.
ButI can't think of whatits called !!!!
Any good body supply house will have it.
Wayne Kline
ACES 1556
TCg

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I know a guy who used this stuff in the roof of his 27 Dodge coupe. The next year he decided to install a sun-roof http://www.chevelles.com/forum/rolleyes.gif When he pulled the Expanding foam away from the metal, he found that it was corroding at an accelerated rate http://www.chevelles.com/forum/eek.gif http://www.chevelles.com/forum/eek.gif http://www.chevelles.com/forum/eek.gif
The X-panding foam has a lot water in it that gets trapped when it dries. This doesn't happen on your house because the wood lets it breath.
Like the guy at the auto body store said:
"Are you building a house or a car?"

My $.02 worth after seeing it with my own two eyes is, Don't do it!

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Dale
Lowered '67 Elcamino
ZZ430HP / 4L60
"Canyon Carver"
www.chevelles.com/showroom/elkydriveway1.jpeg (http://www.chevelles.com/showroom/elkydriveway1.jpeg)

[This message has been edited by Cardiac (edited 05-12-2000).]

[This message has been edited by Cardiac (edited 05-12-2000).]

Gramps98;

When I replaced the floor pans on my wagon, I sealed the edges with spray can underseal that I think was from 3M. The stuff expands a fair amount after being sprayed.

It's real messy and you should plan on wearing clothes that you don't care about!

Wes.

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Wes. Vann
Technical Reference section
Gold Member #5

Thanks for the info guys. I'll just have to visit the paint store & see if they have what I need.


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1970 Malibu
Member# 407
ACES Member# 03774