Instructables

How to Fix Rust Spots On a Car

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I drive a 1985 VW Golf (diesel), and it's in pretty good condition for being 21 years old. There are three spots on the front left fender that have rust on them. Someone had hit the car and the paint came off, so it became rusty. These spots are not only an eye sore, but they are sure to spread in the salty Nebraska winters.

My goal in fixing these was function, and not so much glamour. The car is kind of a beater, so I wasn't too concerned with making it look perfect. As long as the rust was gone, it would look better, and I wouldn't lose a fender.
 
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Step 1: Assess the Situation/ Remove Wheel

Having never done this, or any other body work on a car, it took me a little longer to figure out what exactly I was going to do. My original plan was to take the entire fender off, but after inspecting it, that would be too much of a hassle and would require me to disassemble a lot of the front of the car.

Instead, I jacked the car up then I pulled the wheel. I unscrewed the plastic thing protecting the wheel well and set it off to the side. That gave me really good access to see up behind the sheet metal on the car. I was originally going to pound out the dent on the upper part of the fender, but space was tight and I couldn't easily do it. Having the wheel well open will help when I'm grinding and painting.

Step 2: Remove Paint

The first thing I did was remove the paint around the rust. I used a 4 1/2" grinder with a 120 grit 3M Sandblaster wheel. It worked really well for taking off the thick layers of primer and paint. I carefully worked my way around the rust spots and removed paint until I could see clean metal surrounding the rust.

I also used that wheel for removing all of the light rust that hadn't pitted the metal.

Note: Before grinding, cover up anything that you don't want to get dusty. The paint dust is super fine and covers everything. I had my hood open to help access some rust, so I got a tarp to cover up the engine. Having your windows rolled down here would be a bad idea.

Step 3: Grind Some More

After I got all I could with the sanding wheel, I changed over to a metal grinding wheel. When using this, be super careful because these can do a lot of damage. I worked really slowly so that I could get a nice finish on the metal. It was really good for taking the thick rust off and getting into those pits.

After 99.9% of the rust was removed, I sanded by hand (with 120 grit 3M Sandblaster sandpaper) to get a nice smooth metal surface.

If I wanted, I could have used Bondo to even out some of the dents, and fill the space where the paint is gone

Step 4: Prep for Painting

I went to NAPA auto parts to find some primer and paint. I found some really good primer that is ideal for painting on bare metal: Dupli-Color Self-Etching Primer. Then I found some auto spray that matched the color of my car: Dupli-Color Auto Spray in Sunburst Gold Metallic.

I followed all of the instructions on the back of the primer: I mixed up a little bit of car wash soap and water and washed the areas that I was going to paint. Then I got a 400 grit wet sandpaper and sanded the areas, then wiped clean. I then masked off the areas with tape, and then taped newspapers on all the surrounding areas within at least three feet. Paint spray can get everywhere because it gets suspended in the air and blown around and settles somewhere. Once everything was masked off, I was ready to prime.

Step 5: Prime, Paint

When applying paint, it is important to spray thin coats and keep it even. The paint that I was using was really nice, and went on very smoothly. I ended up spraying three coats of primer, waiting about two minutes between each coat for it to tack up. I let that sit all night and sprayed the paint in the morning. I had to spray the paint on even thinner, because it really wanted to run and sag. I ended up having five coats of paint on top of the primer. That gave me a nice color and a nice finish. I let it set at least 24 hours before I pulled off the tape.

The paint turned out pretty well, and it just looked like little patches over the old rust. The color wasn't quite the same as the old, but it was pretty close. It also had no clear coat on it, so it had a little different finish. I didn't bother buffing the edge of the paint so that it blended with the old paint.

Step 6: Wash and Wax

After the paint had cured a good 48 hours, I washed and waxed the car to bring back the shine. It ended up looking fairly good. It cost me less than $15 and 4-6 hours of labor. I spent an additional 4 hours washing and waxing. If I had taken it to a body shop, it could have cost me $200. So I saved a lot of money and got the satisfaction of doing it myself, which is the best part.
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BethBy3 months ago

Great write-up! But, there are other things you can fix yourself, which can help you save tons of money.

More: http://blog.unhaggle.com/5-maintenance-tasks/

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graphixv1 year ago
I've heard if you roll the tape in on itself around the area to be painted it will make a less harsh masking line. I'm taking out some rust on my car during a full top to bottom respray (an enormous undertaking). After cleaning using a wire brush on a drill, I'm treating the areas with rust killer then etch primer then regular primer. While Epoxy is the best primer to use on treated areas, it's a tough product to use for a beginner.
i wish things were this easy for me, but i have 6 cancer spots were i had to cut metal out and tack in some new metal and bondo over it, i have a few spots of bubbling rust and of course nothing is in an easy spot
i have a 96 golf that has a few rust spots, im thinking of doing this! it turned out really well.
skimmo4 years ago
is there an acids that remove rust, i have a chainmail shirt that i need to de rust and it will that to long to polish every ring
I know I am a couple of years late to this post. But....
The best way to derust a chainmail shirt is to do it with electrolisis. You will need A car battery charger, Washing Soda, 1 12 inch or longer Piece steel rod, or rebar.
In a 5 Gal bucket filled with watter put 1 cup of Washing Soda (not bicarbonate sodium), Mix thoroughly, Clamp the Positive side to the Steel rod, Clamp the Negative side to the ChainMail shirt, Drop it on the water, Hang the steel rod from the edge of the bucket making sure that it is close tho the chainmail but not touching. Turn on the charger and watch the rust go up in rusted bubble crust on top of the watter. Give it about six to eight hours.
You are completely done.
a non chemical way to remove the rust is to put the chainmail shirt into a sealable large container (5 gallon bucket with a lid is great for this) and add some fine sand (in a pinch you could use sifted playground sand) or other abrasive compound.

put the lid on tight, turn the bucket on it's side, and roll the bucket to aggitate the shirt and the abrasive.

after you get the shirt cleaned remove it from the bucket, clean it off, oil it well.
Rust-Oleum/8 oz. rust stripper
There's also phosphoric acid; you should find some form of it in the auto body supplies section, maybe under a brand name like Ospho or metal prep. Citric acid also eats rust; you can get that in dry form at home brewing supply stores. And, finally, sulphated molasses, from the feed store. Google these things along with rust and you'll find more information.
Muratic Acid, get it at a hardware store or farm supply
bluebelle7 years ago
i was just wondering what to do if the rust is all the way through. can you use bondo for that? the spot is about 14 cm by 8 cm.
For holes, you can use a backing material for Bondo to stick to. It is Bondo brand wire mesh that has self adhesive glue on back to keep it in place. You can use scissors to shape. Just follow instructions on the package. Prime and treat the back side of the patch if you can.
By a tube of rust converter. It converts iron oxide back into a quasi metal. It is a good idea to use it on any rusty area that you are not going to physically cut out and weld a new patch back into. If you don't the rust will most likely come back fairly quickly. Rust is like cancer, even the smallest amount of rust can turn into a horrible tumor. For instance before doing this step of the instructable I would still use rust converter to ensure there was absolutely no rust left. It isn't all that expensive either so it is a worth while investment. Hope this helps.
correction "Buy a tub of"
you don't actually need much the rust converter stuff is pretty thin and goes a long way
I wouldn't recommend using a grinder, use a wire wheel.
Agreed, using a wire wheel would a better choice than a the grinder. sanding is ok, but using a grinder like is done in the next step can cause more problems than it solves. I say this for a couple reasons

1 A wire wheel wont remove too much base metal
2 you can get rust out of pitted metal better with the wire wheel than a grinding or sanding disc

However, I will caution that if you do use a wire wheel that you must wear safety glasses, and if you put the wire wheel on a drill, to always rotate the wheel in the same direction. as the wheel gets worn the wires will bend, reversing direction will cause a lot of wires to break off and go anywhere the drill is throwing them
The sandblaster wheel is fine for this job. Its not a solid grinding disc that I think you suspected it was, its overlapping pie segments of 'sanding' material.
Awesome job on the the fender.

I'm curious, how many miles per gallon do you get on your VW Golf? I'm thinking about buying a diesel. Somebody told me they burn cleaner than gasoline and the engines(if well-maintained) can last a million miles.
I currently drive a volkswagen jetta TDI they do certainly burn cleaner, and once upon a time diesel was far cheaper than gas which is unfortunatly not the case anymore. I get an average of about 50 MPG and it costs me about 60$ to fill from empty i get 800km to a tank easily. HIGHLY HIGHLY reccommend anyone to go diesel. only real downfall to diesel is the cost of maintenance but if you compair that against the life span of the car you end up saving in the end as the life span is nearly double that of a gas car.
spinach_dip7 years ago
looks pretty good. I no longer care too much about appearance, because I drive beaters, but whenever I would grind out rust and prime and paint, the rust would return in that same spot within a year. I think the grinding removes all the galvnizing. Although I haven't done any cosmetic bodywork with it, I've had good luck on other things with primer that says it containes zinc. They are also known as cold galvnizing compounds.
Did you try magic oil.
I read on another site mercedessource .com and found out that there is magic paint that can stop the rusting right away. Can you try?
Galvafroid for instance
robbs3 years ago
I need a bit of advice with my rust spots. I have them on the roof and hood. The rust hasn't eaten into the metal yet. So, I need to hurry up before it does. Can someone give me the procedures? I plan on hand painting with roller. Its a '91 Buick Skylark. Not quite a "beater," but its getting there. BTW, I'm a female taking this task on! Thanks for the input!
ac1D robbs3 years ago
Usually, this work:
Sand the rust using normal sand paper, start with something like 150 and end with 2000 (these are the size of the sand on the sand paper)
Then spray paint it.
Rishnai6 years ago
The fact that the new paint is not metalflake is really annoying when trying to paint any metalflaked car. Of course, since yours was mostly just a quick and dirty rust repair, it's okay. My Milan is metalflake silver, and I had to paint a spot where, promptly after buying it, someone keyed it. Then I managed to open the door into the mirror on my dad's car, making more horrible scratches and dents which required a large area of sanding and repainting. Of course, the patch paint the dealership sold me wasn't metalflake, so in just the wrong light the repair is obvious and still drives me insane. Moral of the story: non-matching paint can suck.
I don't know if it is the same in all countries, but in Australia you have a plate in the engine bay that states the VIN, engine number and paint code. If you take that paint code to an auto parts dealer, they can make you up a spray can of the right coloured paint. Depending on the age of the previous paint job and condition of the paint in the surrounding areas, it should be an exact match. The places around where I live do a spray can with 20mL of paint for approx AUD$30. If you have a spray gun you can get 250mL in a tin for the same price. But for small jobs the spray cans are ideal.
Thanks for the tip! I finally talked to a local auto-paint supply store and discovered that here in the US (dunno about in Australia), the paint code is on a sticker inside the driver's side door. They loaded up a spray can of the proper metallic, and now the door's good as new.
Glad I could help. Was it very expensive for the metallic where you live?
No, actually. All of the auto paints formulated to match factory paint cost the same. As I recall, it was $40 for a pint(~470 mL), and $12 per spray can that they loaded, no matter how much paint of what sort was in it. I bought a pint and put half in the sprayer and half in the tin, since I can always come back and have them pressurize another can, but once a can is pressurized, you're stuck with it even if the proppellant leaks out.
 $40 per pint comes out to $320 per gallon; I wonder why automotive paint is so expensive.
The raw materials that are usually used are more expensive then those used in most house paints, especially if it is a metallic paint. Also, I'm willing to bet that if you did buy a gallon, it would be a lot less. (Considering two quarts of house paint cost more then a gallon here)
Even then, you have to still take into account the wear of over 20 years of UV damage to the original paint... It would be VERY difficult to match... at that point, you might as well want to respray the whole car... Looks like a great job, just "funny" looking because of the patches... reminds me of my younger years and the jeans with the patches on the knees.. hahaha
BrianJone53 years ago
For your first body work, this is excellent. Certainly better than my first attempt.

Aerosols can't deliver the flake, so you'll never get a match. If your mask was outside the paint area (i.e new paint over good paint around the repair) you could soften the line with rubbing compound and a microfiber cloth.

One thing to add to your next repair is a degreaser. This is a solvent that removes all the wax and grease and road grime everywhere you want the paint to stick. They sell it where they sell the paint.

My second suggestion would be to 'feather out' your sanding. Try to sand each layer to an inch-wide stripe. This gives you less of a step to deal with in filler and paint. Change to a less aggressive abrasive and smooth it all out.

Most importantly though, you have stopped the rust in its tracks, and from 20 feet, no-one can see the repair. BTW with older cars, one way of assessing their state is in feet: "Its a 20-footer" explains how close you have to get to see noticeable defects. As you might expect, a 10-footer would be in really good shape.
jperez1283 years ago
You could have used Rust-Oleum/8 oz. rust stripper to get some of the rust off also.
http://www.autozone.com/autozone/accessories/Rust-Oleum-8-oz-rust-stripper/_/N-25uj?itemIdentifier=660016&_requestid=550873
why rust must be removed?
because rust slowly desolves your metal and destories the pain job along with the back metal now i dont know about you but having square cut outs of replaces metal looks worse then a crap paint job
so do it right
hand sandpaper it
then use hole filller prefeerd for cars and undercoast
then hand sandit again.... and then use a sander
until smooth and roughed
put under coat on usualy white
then get car coulour then clear coat
this will make it very pro,d and not like bad or noticable
Do you know how to speak or write? desolves? Destories? Pain job? Replaces metal? Prefeerd? Undercoast? Usualy? Car coulour? This will make it very pro,d? Go back to kindergarten dude
Troll! Btw, you didn't put a period at the end of your last sentence. Give useful advice, or go away.
I have a 1986 F150 and to fix the rust spots I just put duct tape over them and then paint over that, because I'm to lazy to actually tend to the rust spots
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