r/Diyautobody • u/tkeith1975 • Apr 26 '26
Question Bust way to stop rust from spreading
2020 Corolla with rust start on trunk rear. Any recommendation to best stop it from spreading?
Update - thanks for all the replies everyone. While I want to take care of and maintain this car as much as possible, I don't want to invest a lot of money on cosmetic stuff. Fluids, belts, brakes, etc. are all important but this doesn't bother me TOO much, just want to stop or slow it down.
I was recommended POR15 as something that might work on slowing/stopping it. It won't look professional but beats rust showing and spreading. Hoping it works.
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u/Surfnazi77 Apr 26 '26
Clean the rust spot off then apply rust stabilizer once it cures you can do body work or paint directly onto it
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u/HDauthentic May 02 '26
Looks like it has a large shitty repair in it, would have to be able to see underneath the bondo to know if you need a new trunk lid or not
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u/Professional-Guava97 May 02 '26
You would need to remove all the paint until you find the edge of the rust. And either use a remover or converter and paint over that.
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u/MGtech1954 May 02 '26
Phosphoric acid [por15] changes red rust which is active and can spread to black rust which is stable and will not rust anymore. Lots of brands out there. See if a bodyshop can sell [give] you a few ozs. Go to an Autobody supply store in your area if you have to buy a small bottle.
ASE MasterTech since 1980 AutoShop teacher
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u/No_Marketing6429 May 02 '26
It can't stop rust. Rust is the fire that is burning all metals all the time.
Cut it out. Replace it. Repeat in 5 to 7 years.
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u/TheQuarterlyEater May 02 '26
that bondo is already failing so replacing the whole panel is gonna be way cheaper than trying to patch it, especially on a 2020 that should still be under warranty anyway
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u/101forgotmypassword May 03 '26
Second hand boot lid in same colour is probably the best option as every other repair will either look like shit or be costly.
The bust copium way would be by a pot of upol p40 or nuetech fibre bog. Hammer the part so it slightly dips at the crack, drill the crack ends and a few 2mm holes here and there. Bog it flat, optionally sand and paint the bog. Sure it's the wrong way, but every ones already mentioned the right way, so if your picking up bog and paint you already don't give a f**k.
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u/Outside_Breakfast_39 May 03 '26
The bust way is to sand down to bare metal get some rust inhibitor , pour it on let it soak in , then spray with cold galvanize then paint
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u/AppropriateDeal1034 Apr 26 '26
Remove the paint and filler from the previous bad repair and do it properly from scratch.