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C5 Underbody Corrosion

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Old Jan 25, 2024 | 12:09 AM
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Default C5 Underbody Corrosion

Bought my 02 base recently in Illinois with 30k on the clock. Didn’t realize until after purchasing, but the underbody of the car seems to have pretty significant corrosion in some areas, and none in others. The corrosion looks like little white dots, but to me it seems like the beginning of rust.

I am the second owner and the first owner said it was stored during winter, but I’m starting to think that wasn’t the case every year. Or that it was driven in the salt on a few occasions and wasn’t cleaned. Has anyone seen corrosion looking like this on their C5?



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Old Jan 25, 2024 | 12:55 AM
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Almost looks like some kind of etching, maybe road salt? I'll let those who don't live in Calf answer but can you pressure wash if off?
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Old Jan 25, 2024 | 08:18 AM
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What are we looking at? Is that a frame rail? Looks like something hit it, where the small rust is starting to show. I would hit it with some rust etching primer or whatever it’s called that inhibits rust and then prime and paint the area and move on. Honestly, by the time any sort of rust impacts the driving ability of the vette, you probably won’t be driving it. Actually you probably won’t be driving, period, if you know what I mean.
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Old Jan 25, 2024 | 08:40 AM
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That is not likely salt corrosion.

‘’it is likely just a bad spot in the frame coating.

just clean it up and paint it. You will be long gone from this mortal coil before it is a problem even if you are very young.

Por 15 will cover it.

Last edited by hyperv6; Jan 31, 2024 at 07:32 AM.
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Old Jan 25, 2024 | 08:52 AM
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Cosmetic not Structural. More Pics might help

I have seen this on a “”well cared for” ...But damp garage car

One trip in salt Dust and calcium and this gets started

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Old Jan 25, 2024 | 09:28 AM
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Is this under the battery???
If it is they had a leak in the past, Neutralize with Sodium Bicarbonate/ baking soda. Mix a solution with water (distilled if your ****) and agitate with a brush of some kind, then rinse with water.
Regardless even if its not under the battery. If your gonna paint it let clean with mild soap and water, dry and use some king of self etching paint (wash primer) and then top coat with a paint of choice. If your not going to paint, I'd put some Corrosion X or ACF-50 corrosion preventive on it once the area is dry.
Edit: I have a wet battery and put one of these under the battery (cut to fit) to prevent an acid spill:
https://batterymat.com/mats-rolls/
Amazon Amazon
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Old Jan 25, 2024 | 09:30 AM
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Originally Posted by nitromainia
Cosmetic not Structural. More Pics might help

I have seen this on a “”well cared for” ...But damp garage car

One trip in salt Dust and calcium and this gets started
The picture in my previous post is the frame next to where the diff mounts. These are some more pictures I have of the corrosion on the car.

Seems to me that some areas are definitely worse than others, especially the underside of the rear crash bar. I think that it was driven in snow at some point and just never cleaned off properly. Being the previous owners garage was similar to mine and I know mine gets pretty damp, I wouldn’t doubt it.






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Old Jan 25, 2024 | 09:31 AM
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Originally Posted by Prop Joe
Is this under the battery???
If it is they had a leak in the past, Neutralize with Sodium Bicarbonate/ baking soda. Mix a solution with water (distilled if your ****) and agitate with a brush of some kind, then rinse with water.
Regardless even if its not under the battery. If your gonna paint it let clean with mild soap and water, dry and use some king of self etching paint (wash primer) and then top coat with a paint of choice. If your not going to paint, I'd put some Corrosion X or ACF-50 corrosion preventive on it once the area is dry.
Edit: I have a wet battery and put one of these under the battery (cut to fit) to prevent an acid spill:
https://batterymat.com/mats-rolls/
https://www.amazon.com/Original-Batt.../dp/B098TRXXW1
this would be the rear of the car, front of the car has no rust/corrosion really at all
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Old Jan 25, 2024 | 09:47 AM
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If it is really bothering you, if you can get access to a dry ice blaster, that will clean all of that up and look like new, then you can paint the areas where you had some rust. I wouldn't be too concerned. Or just get a wire brush and a dremel and clean up what you see, paint it and enjoy the car!

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Old Jan 25, 2024 | 10:03 AM
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I'd just wire wheel and hit it with a little paint. NBD. I'd be more surprised if cars of this age didn't have minor corrosion spots that need touched up.
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Old Jan 25, 2024 | 10:18 PM
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Originally Posted by black02c5
The picture in my previous post is the frame next to where the diff mounts. These are some more pictures I have of the corrosion on the car.

Seems to me that some areas are definitely worse than others, especially the underside of the rear crash bar. I think that it was driven in snow at some point and just never cleaned off properly. Being the previous owners garage was similar to mine and I know mine gets pretty damp, I wouldn’t doubt it.




Mine had similar white deposits...

I scuff pad-ed with wax and grease remover

then used Metal Prep with another scuff pad

and final cleaned with microfiber

taped off. And also used aluminum foil,mask technique

hit it it with a. NON Self etching black spray primer

then single stage semi matte black

Looks original. You’d never know it was touched up
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Old Jan 26, 2024 | 07:43 AM
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I had a 2001 for a couple of years that had seen some road salt. It had very similar corrosion that while ugly was a non issue. However, check your brake and fuel lines. One of my brake lines in the rear was highly corroded. Since the other side was not as bad I suspect it might have been replaced already but I could see no evidence of that. I was concerned about brake line rust through for safety.
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Old Jan 31, 2024 | 06:09 AM
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Originally Posted by Midwayman
I'd just wire wheel and hit it with a little paint. NBD. I'd be more surprised if cars of this age didn't have minor corrosion spots that need touched up.
Does not look unusual for a car that is the age of a C5. Clean it up, paint it and enjoy the car for many more years.
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Old Jan 31, 2024 | 08:08 AM
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Not the worst I've seen. Correctible. I don't mind superficial oxidation, though on my daily it has spread to the rack and other areas. If you just bought the car then I would suggest addressing it and certainly cleaning the car's underside annually after winter if driving it in the salt/chems.
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Old Feb 16, 2024 | 11:09 AM
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My friend bought a C5 and it was driven in the winter months. Same corrosion as you have in your pictures. He cleaned up the corrosion and he bought this from Eastwood and it looks great.

https://www.eastwood.com/eastwood-ru...ce=google&wv=4
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Old Feb 16, 2024 | 11:17 AM
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Even car that never see salt can rus in areas where fram coating is not thick. Even then it is surface rust and it will never be an issue Just touch it up and wipe it down now and them. I used Bones from Chemical guys to wipe down my under body to detail the frame and pan. The aluminum cleaner from NAPA takes away the oxidation.

Cars degrade from day one. the Corvette does so too but at a rate with care that will out live you.
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