How to Repair Auto Body Rust Holes Plus Tips for Prevention

Rust is troublesome, especially on body panels or near suspension components. It can even compromise your vehicle’s structural integrity when corrosion moves beyond the surface level, resulting in rust holes.

Luckily, you can repair or prevent rust holes, depending on the severity of the issue. For example, small holes on panels not connected to critical components/systems are still repairable.

How to Repair Rust Holes on a Car

Repairing auto body rust holes is a tedious and challenging process, but with the right tools and steps, you may be able to do the job yourself.

Note that this process won’t fix bigger holes, as some can be damaged beyond repair. However, if the corrosion process hasn’t gone beyond the surface level, you can prevent it from spreading by preparing the following tools and following the steps below:

• Grinder or wire brush
• Rust inhibitor
• Fiberglass body filler or metal patch
• Sandpaper (different grits)
• Primer and paint
• Safety gear (gloves and goggles)

Afterward, follow the steps below:

• Step 1: Prepare your workspace. Ensure you’re in a spacious and well-lit area, ideally a garage.
• Step 2: Ensure you have all the tools listed above within arms reach to make the entire process quicker.
• Step 3: Wear your goggles since you’ll throw sparks around with your grinder. Similarly, a pair of work gloves will help you avoid cutting yourself on the sharp edges of the panel. And if you have some surgical-style masks, wear those in addition to long pants and a long-sleeved shirt to avoid damaging your skin from the sparks.
• Step 4: Prepare the area by removing any loose rust and paint around the hole using the grinder/wire brush. Afterward, clean the area thoroughly to ensure there is no debris.
• Step 5: Use a grinder or tin snips to cut away the rusted metal around the hole and ensure you remove all of it to prevent it from spreading.
• Step 6: Spray or brush a rust inhibitor on the exposed metal to prevent future rusting.
• Step 7: Patch the hole. If it’s a small hole, use fiberglass body filler by mixing it according to the manufacturer’s instructions and applying it over the hole. For larger holes, cut a metal patch to fit the hole before welding or using adhesive to secure it in place.
• Step 8: Sand the area to smoothen and level it with the surrounding metal. Start with coarse sandpaper and gradually move to finer grits.
• Step 9: Apply a layer of body filler over the patched area and sand it once it hardens.
• Step 10: Clean the area and apply a primer. Let it dry before painting the area to match the rest of the car.

What Causes Vehicles to Rust?

Rust generally forms because of a chemical reaction called oxidation, which happens when iron or steel is exposed to water and oxygen over time. The oxidation process eats away at the metal, creating visible surface rust.

Some things that may help start this process include moisture, salt, pollution, and poor maintenance.

Moisture

Rain, humidity, or even washing your car, can introduce water to the metal surfaces that start the rusting process.

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Road Salt

Road salt lowers the freezing point of water to melt snow and prevent ice from forming on roads and pavements. However, it can also accelerate vehicle rust buildup because it increases water’s conductivity.

Salt can get lodged in the vehicle’s underside, prompting moisture to react with it and form rust. This occurs because electrons move freely in salty water, speeding the oxidation process.

Similarly, driving near seawater may also result in rusting since the high salt content in the air and the excess saltwater moisture from the ocean may stick to your vehicle. As such, it’s best to wash and dry your car after driving through coastal towns and areas.

Pollution

Pollution also plays a part in rust forming on your car. If your area is prone to rain and is polluted, the pollutants in the air can mix with rain to form acidic compounds that can corrode metal surfaces.

Poor Maintenance

Neglecting regular maintenance, such as washing and waxing your vehicle, can leave your vehicle’s paint and protective coating vulnerable to corrosion damage.

How to Prevent Rust Buildup On Your Vehicle

Here are some maintenance tips to keep your daily driver rust-free.

Regular Washing

Clean your car frequently to remove dirt, salt, and other contaminants that may cause rust. Don’t forget the undercarriage and wheel wells since rust can form there and spread elsewhere.

It’s recommended to wash your car at least twice a month. Use a car soap or cleaning agent since they’re formulated for automobiles.

Waxing

Waxing your vehicle creates a protective layer on the surface, preventing rust from forming. Wax your car at least twice a year. If you don’t park in a covered garage, you should wax your vehicle more frequently as exposure to the elements can degrade the wax earlier than usual.

There are spray-on waxes you spray onto the surface after washing your car to make waxing easier.

Rustproofing

There are professional services that can help prevent rust from forming on your vehicle. For example, undercoating involves applying a moisture-repelling sealant to the vehicle’s underside to protect its structural base from damage caused by road salt and other debris.

Keep it Dry

The easiest and cheapest way to prevent rust is to keep your vehicle dry. If possible, park in a covered garage to protect your vehicle from the elements.

After washing your car, use a microfiber cloth to ensure you don’t leave behind any moisture. Without moisture on the surface, the oxidation process won’t start and won’t result in rust and rust holes.