Spray foam : filling car rust body holes

No pics today.

but anyone do this? use like triple expanding foam to fill in rust holes in old cars? I've heard alotta bad reports and see it done lots of times. My car's got a lot of rust holes. big ones, too big to even get good bondo over.

My approach's been to remove as much as possible with a wire brush, drench it in rust converter, coat it in paint or primer and fill the holes with 3x foam. easy to cut and shape and fill afterwards and solid enough. it's not ideal but seems like the best option. I tried welding panels over a few spots and riveting panels over spots but those see to wind up creating really brutal crevice corrosion in addition to the HAZ rusting faster, plus it sticks out and looks crappy (yea, way crappier than 3x foam, hard to believe, sure). mesh screen bondo is a mess and difficult to line up and get to stay put, and hasn't held up any better, just cost more and more difficult and less finished looking.

So I'm going for it. Not seeing much for alternates and the spots I did last year still look good.

Thoughts? Experiences?

Re: Spray foam : filling car rust body holes

first name last name /

I think it's going to give you a false sense of structural security I've seen cars from the East Coast show up out west and get put on racks for mechanical work and have seen the cars actually cave in from the underside kind of looks funny when it's jamming the seats into the headliner.

Re: Spray foam : filling car rust body holes

Done it several times, not to area's of structural integrity, just holes, works just fine, plan all the spots you need, as once you open the can you need to use it up at one time, it hardens in the can after a while, don't over do it, that stuff expands like crazy, let it cure for a while, like a day, but yeah if you care it can be sanded and painted. I have also used it as an adhesive of sorts to hold plastic patch panels in place, prep as you outlined above, lay a bead, place patch panel in it, put a weight on it and let it sit a day or so, u can also use a small piece of cardboard like a finishing trowel on concrete once it sets up a bit to smooth it off, almost like bondo. Wear gloves, the shit is super sticky. It's kind of fun to play with if you are not concerned with looks, I had it last through 2 winters in the kick panels of an old s-10, water tight when the truck was sold. :)

Re: Spray foam : filling car rust body holes

Andrew Squiggman /

If you do make sure it's closed cell foam. Open cell will turn into a sponge

Re: Spray foam : filling car rust body holes

I did it on an old VW that was rusting out. I used bubble pack plastic to try and form the foam as it dried. It still expanded where I didn't want it to and stuck to the plastic but it cuts with an exacto pretty easy.

If you don't care and don't want to spend a lot of time repairing small holes in rockers or fenders it works pretty good.

Re: Spray foam : filling car rust body holes

I filled every bit of space in my metro with it cause I got 5 cases for free

Re: Spray foam : filling car rust body holes

^pics

Re: Spray foam : filling car rust body holes

Ungapped rings to bind them all /

Held more than a few MI car and truck wheel wells, lower quarters & door panels, etc. together with foam back in the day. It sticks to everything, seals and supports the surrounding area for a decent temporary fix. Rattle can or under coat to blend.

Re: Spray foam : filling car rust body holes

Just remember where you put the foam before you start welding something

That stuff burns real well

Re: Spray foam : filling car rust body holes

Born to be WillD /

it's body on frame so i'm just filling body holes. frame's plenty rusty on its own but solid. filled in big holes in the rocker and some spots even under the back wheel wells where it was rusted through and spraying water into the back seat last year. those patches are still solid. Just filled the new holes on the other side rocker and some spots I missed last year as I ran out. there was no hope for bondo, holes too big. ran a flat bar plate to give it some stability and for the side flares to mount to, filled in and around with "large gap" foam. got some bondo I'll fill in on top of it. she's no beauty and I beat the fuck out of it, but this seems like a legit last resort to prolong the life of this thing. I wont let it die.

Re: Spray foam : filling car rust body holes

In a pinch , Spray foam make 4 pretty good fix-a-flat 2 ...i have 2 wheel barrows as proof ...

Re: Spray foam : filling car rust body holes

Born to be WillD /

definitely got a tomos once with a BMX tire filled with multiple flat tubes all jammed in there and the rest of the space filled with great stuff

Re: Spray foam : filling car rust body holes

ephraim zimbalist jr /

its so great...you should eat the shit...like whipped cream

Re: Spray foam : filling car rust body holes

Sounds like one of my old peds

> Born to be WillD Wrote:

> -------------------------------------------------------

> definitely got a tomos once with a BMX tire filled with multiple flat

> tubes all jammed in there and the rest of the space filled with great

> stuff

Re: Spray foam : filling car rust body holes

I filled in some cab corners of my old 79 dodge powerwagon with it. I mainly did it to keep the mud from packing up in the huge holes because the truck was specifically a mud truck. 6 inch suspension lift, 4 inch body lift, 35x12.5 BFG Mud Terrains ... 360 small block, dana front and rear axles.. NP 203 transfer case.. removable top.. man i miss that truck.

Re: Spray foam : filling car rust body holes

Bad Cadillac™ /

> Don Sumpter (OFMC) Wrote:

> -------------------------------------------------------

> In a pinch , Spray foam make 4 pretty good fix-a-flat 2 ...i have 2

> wheel barrows as proof ...

Nice! Won't lose air then because it'll be all foam!

Re: Spray foam : filling car rust body holes

If you use it in an area that gets wet it will hold the moisture and cause worse rust than you started with.

Re: Spray foam : filling car rust body holes

Andrew Squiggman /

> Tim A Wrote:

> -------------------------------------------------------

> If you use it in an area that gets wet it will hold the moisture and

> cause worse rust than you started with.

If you are stupid enough to use open cell foam.

Re: Spray foam : filling car rust body holes

Born to be WillD /

yeah the worse problem is when I pack all the cavities and holes with mud. mud definitely holds moisture and makes rust worse. it's definitely just prolonging the inevitable but seems very certainly to be working much better than nothing, and it looks decent filled smoothed and sanded. Basically only other option at this point seems to be new panels, which I'd rather cheaply put off. +1 for foam fans. i'm sold

Re: Spray foam : filling car rust body holes

Ungapped rings to bind them all /

.. yep.. its a cheap 2-3 year fix, but for a dead end beater or rust bucket, who cares?

There's a time and place fo everything.

Re: Spray foam : filling car rust body holes

Lemme see them sanded and painted pics. Could spray paint it I assume?

Re: Spray foam : filling car rust body holes

Stephen Lopez /

Exactly what is it you are trying to say ?

Using spray foam is better than nothing at all !

Yea, you could replace the entire panels but that's only if it's available...

Spray foam as the writer is explaining has a low cost simplicity to using it and it keeps out the moisture from getting into areas that moisture wouldn't get in .

Basically it slows down the progression of rust .

As for structural integrity, look at the source closely and rethink your antidote!

Body panels add structural integrity, they don't perform the main ability to safe gaurd the vehicle's impact in a crash ,it's the 2 lateral frames running from back to front that reduce the force . Body panels are tack welded on ,flimsy and designed to disintegrate over time...

From the time the panels are made at the factory, the developers have predestined its longevity. Body panels are designed to detiriate more rapidly because the use an inferior process so that it can rust !

That's the reason! So you GO BACK TO THE SHOWROOM or used car dealer and get a newer one.

Re: Spray foam : filling car rust body holes

Pushrod Fifty /

Great for filling holes in moped tanks I can imagine. I need some to seal my windows, the replacements were just screwed in, not sealed in foam.

Re: Spray foam : filling car rust body holes

> Pushrod Fifty Wrote:

> -------------------------------------------------------

> Great for filling holes in moped tanks I can imagine. I need some to

> seal my windows, the replacements were just screwed in, not sealed in

> foam.

I don't see how it could be gas safe

Re: Spray foam : filling car rust body holes

Born to be WillD /

3 years later the body filler foam is mostly still good

However I did fill in some floor holes with it also, and just last month I had to go back through and rivet in some sheet metal plates cut from an old washing machine, but now the floor is (again mostly) intact, and the body panels are as fucked as ever but better with some filler than being just a gaping hole.

The other thing I was thinking lately is that spray rubber shit, like flex seal, and just drenching some old shirts or whatever and laying those over stuff for patches.

Re: Spray foam : filling car rust body holes

And if your wheel wells are all foam filled, your car will float when you crash into a canal!

Re: Spray foam : filling car rust body holes

I used ordinary 5 min epoxy to glue patch panels onto my golf. Held up for 2 years so far.

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Re: Spray foam : filling car rust body holes

Not a perfect color match but my car is usually too dirty to notice.

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Re: Spray foam : filling car rust body holes

Blaine- The artist formerly known as Plumber Crack "(OFMC)" /

Black duct tape on spray foam. Good shit.

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Re: Spray foam : filling car rust body holes

Awww Yeah! ;)

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