Rust is the enemy of any car. So when you see rust developing you should try and neutralize it immediately. So how do you go about fixing rust on a car?
Depending on the severity of the rust on your vehicle the steps involved could be as little as a coat of paint or very complicated as I recently found out.
My auction find Ford Escape hybrid was hiding some nasty rust underneath its rocker panels. It was almost completely rotted out. I quickly realized how severe this was and knew that the only fix was to completely remove all traces of rust and weld in new metal.
There are some ways to learn how complex your repair will be just by identifying the exact type of rust your vehicle has.
Type Of Rust
Rust is iron oxide. The result of a chemical reaction when the iron particles (which make up steel) are exposed to oxygen or water.
Check out this video by Reactions on the exact chemical process behind the formation of rust.
Chemically it’s all the same but generally when car people refer to “type” they generally mean how severe.
Surface rust or rust penetration. Surface rust can be taken care of relatively easily by sanding and grinding the rust away. Following up by priming and painting the previously rusty area and it should be good as new.
Rust that has penetrated more deeply has compromised the integrity of the metal and generally calls for removal and replacement. There’s little to few alternatives when rust eats through metal.
Depending on the part, location and overall function of the rusty piece, things can get very complicated.
What Part Is It Affecting?
First you want to figure out if the rusty part is structural to your vehicle. Meaning, does the rusty part give actual strength and rigidity to your car or is it just purely aesthetic? Your plan of action depends on the answer to this question.
If a part is structural you want to plan how you can remove it without doing further damage. You don’t want to attack it and weaken other parts, or more seriously yet, destroy your car.
For example, rocker panels are a common part that get rusty on most cars and trucks. Replacing them can be wildly different however.
Trucks, which are usually body on frame, have rocker panels which are non integral to the structure of the vehicle. Cutting them out won’t hurt the structure of the vehicle, because they have an independent frame from the body.
Cars are unibody. Their rocker panels impart structural rigidity to the entire car. Replacing them will take a strategic approach as to not adversely affect the structure of the car.
Big undertaking. It’s exactly what I had to do to my Ford Escape. It’s unibody rocker panels rotted to the core so I had to order new metal. Just check out the images.
I suggest looking at repair videos on youtube with your car specifically or at least something similar to it. Look up repair manuals to see how to approach such a task.
Methods To Repair Rust
Surface rust steps
- Identify the rust area, clean thoroughly with soap and water then let dry.
- Using a wire brush grind away the larger rust areas.
- Use finer sandpapers 100-200 grit until you reach bare metal. Clean debris.
- Spray with metal primer. Use a few coats to lay to ensure adhesion.
- Add a top coat of paint to seal (to match if finished area).
Deep or Structural Rust
- Identify the rust area, clean what you can.
- Create a detailed plan ensuring what you remove will not damage further.
- Cut away and remove as much damaged area as you need to ensure replacement material will be properly secured.
- Using wire brushes, metal grinders remove remaining rust to prepare for welding of new material.
- Additional metal may be required to brace structures- prepare for welding.
- Test fit replacement metal, cutting and fitting as necessary.
- Prime bare metal areas with weld through primer. Don’t use regular primer as you will be unable to weld on top of it.
- Coat areas that will be closed off with a rust converter.
- Weld in new metal, grind down welds to a smooth finish.
- Use fillers (bondo) to create a smooth finish.
- Sand fillers in preparation for primer.
- Prime with a high build primer, then paint to match.
How To Prevent Rust In The Future
There are many products that claim to prevent and protect from rust but generally you want some type of oil based product to prevent moisture lingering on the metal.
In the old days people even used waste motor oil on rust prone areas. The key is really keeping prolonged moisture away from metals.
That means in particularly rust prone areas like the northeast, washing away salt and debris in the winter is paramount. In summer time prepping your car with rust preventative will ensure your vehicle stays rust free.
Here’s a top tip. People tend to ignore small chips and cracks on paint on metal but this is often where rust begins.
Paint and primer are the first lines of defense and can work great if there is adequate adhesion. Fill in any paint chips as soon as they happen and you can prevent rust from forming.
Protect your paint by ceramic coating it yourself. Check out this diy tutorial here.
Rust sucks. Do your damndest to prevent it before it ever appears. If rust does catch up to you however, all is not lost. Theres always a way to fix things and fixing rust on a car is just one of those things that takes time and money. So Good luck and watch out.