Rust is almost inevitable for any car on a long enough timeline, though newer cars are definitely more resistant thanks to all the polymers used in them. Despite advances though, you can’t outrun rust forever. If it gets bad enough you will need to do something about it and that means you need to know what the rust repair cost is going to set you back. Rust repairs can cost as little as $20 and get as high as $2000 or more depending on the extent of the damage and how thoroughly you want to repair it.
What Causes Rust?
As much as we take rust for granted not everyone seems to understand exactly what causes it in the first place. Rust is caused when the metal that contains iron in your car is exposed to moisture and begins to oxidize. Iron, the main component of the steel that the frame of your car is likely made from, and depending on the make and model of your car many other parts as well, reacts very readily with oxygen. That is why the term for rusting is oxidation. Moisture speeds this process up.
Salt also increases the chemical reaction that leads to oxidation so if you live in a part of the world where roads are salted during the winter months then the metal in your car is at greater risk of faster and more extensive rusting.
Because keeping your car away from moisture is literally impossible, rust is often an unavoidable concern for drivers to have to deal with. There are ways to prevent it before it happens and repair it after it happens, however. Let’s take a look at some of them.
What You Need to Know About Repairing Rust
The thing about rust repairs is that they can be unpredictable, and they are hard to categorize in terms of cost. Your car could have one rust spot at the edge of a side panel or the entire frame could be corroding. How much it will cost to repair will very much be based on the location of the rust, the amount of rust and, to some degree, the make and model of your car.
- Minor Rust Repairs: A very small rust spot on the body of your car is relatively easy to fix, as you might expect. Small spots of only a few inches in diameter can be repaired on your own if you feel comfortable doing the work. Instructions can be found online, and you can even lookup YouTube videos that will walk you through step by step.
You can buy a Bondo repair kit at AutoZone for only $20 that will allow you to patch a small rust hole. This option is really only good for very minor rust spots and holes on the body of your car and should be avoided for extensive rusty or rusting of the frame, as that will require a more involved solution.
If you’re not entirely comfortable trying it yourself you can get a mechanic to do the same work, just know that the labor cost will at least double the overall total, and likely will cost even more than that.
- Median Rust Repairs: Larger rust patches will require a little more work to fix. You’ll notice rust forms in flaky layers sometimes, almost like a pastry. If you can peel off a whole layer of flaky rust and there is more underneath, you have more than just a minor rust problem on your hands. Likewise, if you have spots or holes caused by rust that span an area or are in a large grouping you’ll need a more in-depth solution. A Bondo kit can work here but the more rust you have, the less sound your frame is going to be and also the uglier it’s going to look if you patch it extensively. These larger spots increase the cost proportional to the size or number that you’re experiencing, so while a $20 kit may have fixed a small one, you may be looking at $60 or so for these larger patches, plus labor costs if you go to a mechanic.
- Major Rust Repairs: The most severe rust repairs are going to be ones that deal with rust on the frame of your vehicle or rusting on the body that has gotten so severe there are holes right through panels or the floor. This could be an entire panel that’s rusted out and can only be prepared by completely replacing it or, in the case of rust on the frame, extensive welding of new materials.
Major rust repair costs are going to be very high relative to those small ones you can fix yourself. For instance, a new quarter panel can cost anywhere from $400 to $1000. Bumpers can get close to $2000 and so on. Any of these parts, if rusted out, could be very costly to replace.
If your car is rusted so extensively that it’s not cost-effective to even try to repair it, there’s always a chance you can salvage some value by selling it as a junker.
Fixing Rust On Your Own
Fixing rust on your own is a good way to save money on rust repairs if you can catch it before it becomes an issue that is beyond your ability to handle. You'll need a handful of supplies to get this done at home including;
- Sandpaper – ideally 40, 60, 300, 6000, and 1000 grit and a sanding block
- Primer and filler
- Masking tape
- Grease and wax remover
- Tack rag and microfiber cloth
- Poly sheeting
- Polishing compound
- Paint for touch ups
- Clear coat
If you plan to fix a rust spot on your car and paint over it, you need to accurately match your car’ paint job. Just buying red or black paint is not going to cut it if you want this to look good. Fortunately, all automobile paints have a paint code. You’ll need to find your paint code and match it to the touch up paint to ensure it looks as good as new when you’re done.
- You want to start by masking off the area you plan to fix. Use the poly sheeting to cover the areas around the rust spot that you don’t want to get covered in paint.
- Scrape off the flaky rust first and then use the 40-grit sandpaper to sand the rust down to the bare metal. You’ll want to sand a slightly larger area than the rust spot and using a finer grit to feather the edges.
- Use the tack rag to clean the area.
- Fill any pits caused by the rust with body filler.
- Clean the entire area with a soap that cuts through grease. A household dish soap will do the trick. Make sure you dry thoroughly and wipe clean with a lint-free cloth. The surface needs to be perfectly clean to apply the prep solvent before the paint.
- Spray down some self-etching epoxy primer and filler primer according to the directions on the can. You’ll want two to three layers allowing about 15 minutes to dry between each coat and then an hour after for the epoxy primer to dry.
- Sand the epoxy primer with 1,000 grit sandpaper then wash with water and dry.
- Pain with lacquer filler primer, at least two or three coats allowing the recommended drying time between each.
- Sand the primer with a 300 to 320-grit sandpaper to get rid of any dried and uneven drips. Then sand the whole area with the 600-grit to smooth the primer and get those edges feathered. Then use some wet 1,000-grit for one final smoothing.
- Spray the base coat of color slowly from left to right in even layers. Allow drying between each coat. You'll want maybe 3 coats in total and let it dry to the touch, at least an hour.
- Only sand this base coat of color if there were uneven drips. If that happened, sand them with the 1,000-grit until smooth and then respray the touch-up areas.
- If you're satisfied with the color coat and the match with the rest of the paint job, spray on a clear coat. This will again require waiting for the coat to dry before applying another coat and then one final coat. This may be the hardest part because the clear coat is very thin and will run if you overspray. Smoothing out the clear coat after it’s dried can be time consuming. You’ll have to give it 48 hours to fully dry, then sand with the 1,000-grit and try again.
If there are any parts you are unsure of, there are many videos on YouTube that can guide you step-by-step so you can see it yourself. This removes a lot of the guesswork and should help your confidence if you’re new to this kind of work.
As you can see this process requires a number of materials that may cost you at the very least $100 and will also require a significant investment in time as well. If any steps go wrong, especially that clear coat, this process can take up to three days to complete. So, dealing with rust, if you want it perfectly repaired, is much more in depth than it at first seems. With that in mind, you want to do what you can to prevent rust as much as you possibly can. This is the best way to save time and money on rust-related repairs down the road.
How to Prevent Rust
The most obvious way to prevent rust that most of us have heard of is the application of a rust coating which you can have done at many body shops and mechanics. Rust proofing is usually sprayed under the car to protect the bottom, which would naturally have the most exposure to water and salt as you drive. In general, you can invest in two kinds of rust proofing for your car.
- Permanent Rust Proofing: This process is meant to be a long-term rust fighting solution. If you’ve ever looked at the underside of a car, you’ll notice the steel components are painted black. That black coat is a rust-proof sealant you can buy an apply yourself. 3M, for instance, makes a rubberized undercoat derived from asphalt that not only seals and rust-proofs the car, it also helps deaden road noise.
A second aspect of the permanent rust proofing that many cars will receive is a paraffin-based sealant such as ZeeGuard. It protects against water, mud and salt and will last several years.
You can expect to pay about $500 or so to get a permanent rust proofing done at a shop which seems steep, but if this is a new car you’re looking at upwards of 10 years of rust protection, which makes the expense more than reasonable.
- Annual Rust Proofing: You can also invest in regular rust-proofing methods with things like Penetr-Oil. This is a dripless spray applied under your car that will halt the growth of rust and prevent any new rust spots. It’s meant to not drip off the car to leave any streaks on your driveway, and it should be applied once a year. This kind of rust proofing should cost around $100.
- DIY Rust Prevention: There are general and simple steps you can take to prevent rust at home. It’s not an option for everyone, but parking indoors is a great first step if you have the ability to do so. The less exposure to the elements, the better.
Get your car waxed before winter arrives as an extra layer of protection. It’s a small measure but it will offer a layer of protection.
Keep your car clean. Wash it regularly at a touchless car wash so you can spray under the car and get into the cracks and crevices where mud and dirt will accumulate and start the corrosion process. The cleaner your car is, the less likely it will be to rust.
Clean your mats. A lot of people overlook this, but the floor mats can remain wet for a long time, soaking through and eventually rusting out the floor of your vehicles.
The cost of repairing rust damage can get fairly extensive if it’s been allowed to go for a considerable period of time, but with a little maintenance, it doesn't need to be so extreme.