Can repair rust holes in the body of my car, with gap filling foam?

by admin on August 18, 2010

I’ve got big (some 5 inches across, by 2 inches) rust holes in the bottom of my rocker pannels on my little chevy sprint, they’re right into the interior!
Is it okay to use rust converter, then patch the holes with that expanding foam from the inside, then spray with rubber sealer and rust paint on the exterior?
I’m afraid it’ll cost tonnes to get the pannels replaced…I need some advice please!

If you want to fix a hole this big, it will need a metal skin patch, which can be welded. You need someone who knows how to do this. The problem with a hole this big is that the hole is rotten around the edges and when you work on it you will need to cut it to the good metal. You will not have to replace the panels unless this problem is all over the panel. This is only if you want it fixed right. If you are looking for a quick fix, you might do like you were talking about.

{ 8 comments… read them below or add one }

cowboywheelock August 18, 2010 at 7:31 pm

You can take it to a body shop and they will replace it with bindo.You could also do it yourself.
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Steve-o August 18, 2010 at 7:55 pm

Its a real back woods way to do it. That will work, but I suggest using body filler on the outside, something like bondo. The body filler will make it look more like metal, because I dont think you’ll be able to get that thing inspected with rust holes. You could use fiberglass if you wanted to go a notch above the expanding foam and bondo trick. I’ve seen people use duct tape and just spray paint over it to pass inspection.
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krisnsally August 18, 2010 at 8:37 pm

I did this myself, it works. I removed the rust, filled the gaps with foam and then used plastic bondo over the foam. It turned out great.
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Corndog64 August 18, 2010 at 9:23 pm

Hmm,,,
I’ve never heard of such an unusual solution to this problem. I don’t see why it wouldn’t work…
A better (and neater looking) solution might be to treat and fill the holes as you planned, then cover the area with fibreglass patch. Then you can sand it down, spray-can it and it would look pretty good! Plus the "glass patch" is waterproof (unlike Bondo) and wouldn’t rust out again.
The kit to do this includes instructions. Hell, I did it on my old Datsun for the first time this Fall, and it looks fine!

Here’s the kit:
http://www.shopatmidway.com/pc-737-3-fiberglass-repair-kit.aspx
References :
http://www.shopatmidway.com/pc-737-3-fiberglass-repair-kit.aspx

lem604 August 18, 2010 at 9:33 pm

it’s funny that i see this question posted today because earlier i i had done this very same repair on a old car that had to pass a safety to be used as a winter beater for a customer of ours it’s cheap and it will get you down the road so why not!
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Dough Boy August 18, 2010 at 10:12 pm

If you want to fix a hole this big, it will need a metal skin patch, which can be welded. You need someone who knows how to do this. The problem with a hole this big is that the hole is rotten around the edges and when you work on it you will need to cut it to the good metal. You will not have to replace the panels unless this problem is all over the panel. This is only if you want it fixed right. If you are looking for a quick fix, you might do like you were talking about.
References :

dragontat123 August 18, 2010 at 10:46 pm

it won’t last….patch panels cut to the size you need and welded into the spot then grinded down flush, body filled with rage gold body filler, primed, painted , and then clear coated…rage can be bought at your local auto paint supply store…thats if you want it to last
References :
4 year autobody technician and classic car restoration

want2wild August 18, 2010 at 11:08 pm

If your rocker panels are rusted that bad then you need to replace them.These are part of the frame of your car
References :
Way to long in autobody repair

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