How to Treat & Prevent Vehicle Rust Damage
By FergusRust is one of the biggest car maintenance bugbears for drivers. It damages bodywork and, if left untreated, can cause many problems. If your car is damaged in particularly hazardous places, even in relatively obscure areas such as where the seatbelt brackets are mounted, it can result in an MOT failure and be pretty costly to repair.
However, there are preventative measures you can take to help protect your vehicle. Knowing how to spot the early signs of damage and how to combat it proactively can save you no end of time and money in the long run. Here, we look at:
Rust is an iron oxide, usually reddish-brown, and consists of hydrous iron (III) oxides and iron (III) oxide-hydroxide, typically associated with refined iron's corrosion. It is caused when an oxidised metal (i.e. the metal your car's bodywork is made from) reacts with iron, oxygen or water, leading to the breaking down or corrosion of the metal.
Many new vehicles are galvanised, which means they've been coated with a protective layer of zinc to further protect against the damage rust can cause. Unfortunately, the older your vehicle, the more susceptible it is to rusting. With age comes scrapes, scratches and dents, giving the elements more opportunity to get behind the protective paintwork of your car or van and attack pieces of bare metal.
The most common causes of rust are:
Water
Unfortunately, nowhere in the UK ever stays completely rain-free for long. Leaving your car outside in heavy rain or regularly driving through puddles increases the chances of rust developing. In particular, water has a habit of gathering in certain areas like the rear tyres, wheel wells and wings. If not dried properly (either by dry, warm weather or parking the vehicle in a garage for a few days), these areas can become particularly prone to rusting.
Poor weather conditions
As we've established, prolonged periods of torrential rain make your car more susceptible to corrosion. Snow has a similar impact if it hasn't been cleared properly. Hot, humid air will also attack any exposed metal on your car.
Geographic location
If you leave your car outside and live on the coast, you can expect rust to pose more of a problem than if you lived further inland. This is because salty sea water has a knack for finding its way to even the tiniest patches of unprotected pieces of metal. Salt water will cause an object prone to rusting in average conditions to deteriorate considerably quicker. Furthermore, if your car is left somewhere particularly rural and very open to the elements, you will likely have a bigger problem with rust than those in urban and sheltered areas.
Salt
Salt makes it easier for rust to form, which is why sea water is particularly effective at causing corrosion. The chemical reaction that causes rust involves electrons moving around, and they do so more easily in salt water. However, even motorists away from the coastline can still suffer salt damage. Grit used to treat roads in freezing weather is a mixture of salt and sand, which can accelerate the formation of vehicle rust if it gets under the paintwork.
Neglect
Many of the factors listed above are unavoidable if you live in some regions of the country and don't have the luxury of owning a garage. However, failing to take steps to prevent damage or act upon the early signs of rusting will only worsen the situation. Even simply washing your car regularly, particularly in poor weather conditions, can go a long way to prolong the life of your vehicle. It may seem counter-intuitive (after all, we've established that water helps rust form) but washing your car helps eliminate all the dirt, salt and grime that has built up. The important thing is to make sure it dries nicely and quickly.
The way you drive
Often overlooked is the impact that certain driving habits can have on the likelihood of rust damage. Chips and scratches offer an open invite for rust-causing chemicals to seep in. While you don't need us to tell you to avoid hitting things with your car, there are a couple of other things to consider: Do you drive too close to other vehicles? Lorries, vans and cars all cause small stones and pebbles to fly up and hit your vehicle, causing those problematic little scratches. Do you pay particular attention to your driving speed on newly re-surfaced roads? Driving on re-chipped or gravelly roads flicks up even more debris than on tarmacked roads.
Acting early is the most effective way to prevent rust damage from writing off your car. Knowing how to spot the early signs and how to tackle them will prolong the life of your vehicle.
Regularly check your vehicle for scratches and dents
If rust is going to take hold anywhere on your car's bodywork, it's going to be where the paint has been scratched away, leaving exposed metal. So, check your car for dents and scratches regularly – perhaps tie it in with your regular oil and tyre checks. While there may not be any rust visible yet, catching the early warning signs will save you time, money and effort in the long run.
Don’t forget to check underneath your car
Spotting scratches on the paintwork on your car is relatively easy, particularly for those who are reasonably precious about your motor's looks. However, knowing what's going on underneath takes a bit more work. So have a look around under your car on a fairly regular basis, particularly in the winter months, to make sure there are no causes for concern. While it's likely to be a bit on the dirty side, keep an eye out for any patches covered in red dust, bubbling, and small holes.
Look out for small bubbles beneath the paintwork
Small patches of bubbling paintwork often alert vehicle owners to a problem. As soon as you spot even a small bubble, act quickly to prevent the rust from spreading.
Be vigilant when considering second hand cars
Spotting rust on your vehicle is often not that difficult, provided you know what to look for. However, if you're looking to buy a second-hand car or van, you never know what's been done to address an underlying problem. So, keep an eye out for bodywork panels that are slightly different in colour. It may be perfectly innocent, but it may hide a cover-up job. It never hurts to ask.
“Rust can be classified into three types: surface rust, scale rust, and penetrating rust. Penetrating rust is the most damaging, and may require you to replace parts or panels on your vehicle.”
The most effective way to deal with rust is to prevent it from developing in the first place. Unfortunately, it's a common problem, so you may be unable to eradicate it, but there are measures you can take to help your cause.
Keep your car in a garage
Keeping your vehicle in a garage, or at least keeping it covered, will protect it from damage caused by adverse weather conditions.
Wash your car regularly
Keep the body and underside of your vehicle clean of dirt, grime, grit and salts by washing it regularly, particularly during bad weather. Pay particular attention to any pockets where water can build up, such as around the wheels.
Tackle any small rust spots early
As soon as you notice any rust developing, no matter how small, remove it, apply an anti-rust primer and repaint it. This relatively small maintenance job will save you time and money in the long run. But unfortunately, rust is a widespread problem, and it doesn't take long to spread to other parts of your vehicle.
Knowing what causes rust and how to spot it is one thing, but what can you do to treat it?
Superficial rust damage - products and equipment to use
- Sandpaper
- Anti-rust primer
- Touch-up car paint
Method
Repairs are relatively simple if you've spotted very small patches of red dust around a superficial scratch before any paint bubbling has occurred. Whenever you spot a small patch of rust, don't delay treating it – leaving it will only allow it to spread and cause much more damage.
- Wash the area around the spot to ensure it's clean from grit and grease. This will prevent any further accidental damage
- Once it is completely dry, use masking tape around the edge of the damaged area to protect the surrounding paintwork
- Using dry sandpaper, rub the rusted area. Use a reasonable amount of pressure, but don't scrub too hard – you want to get rid of the rust, not cause further damage to the metal underneath
- Once you're happy all the rust has been removed, remove the masking tape and wipe the area clean with a damp cloth
- Cover the sanded area with an anti-rust primer to prevent the problem from developing again
- Once the primer is dried, use the touch-up car paint to cover the now-repaired area
Surface rust
Products and equipment to use
Sander/wire brush/abrasive wheel (depending on how severe the problem is) Anti-rust primer Touch-up car paint
Method
When the paint has started bubbling or flaking off, the process of repairing surface rust is much the same as above, but you'll need something a bit sturdier than dry sandpaper. Try an abrasive wheel for moderate damage or even a wire brush and grinding wheel to knock any roughness into shape, then use sandpaper to smooth the area. Then, follow the same process as above with anti-rust primer and car paint.
Permeating rust - products and equipment to use
- Replacement bodywork panel or;
- Fibreglass repair kit or metal patch for welding
- Sander
- Filler
- Anti-rust primer
- Touch-up car paint
Method
Unfortunately, this is where car rust damage removal gets tough. More drastic action is required if you don't catch the problem soon enough and the metal has rusted through, leaving holes. However, depending on the size of the hole and your mechanical competence, you may be able to use a fibreglass repair kit to repair it yourself.
However, if the holes are numerous or large, you may need to cut the rotten parts out and weld a patch panel in place or even replace the entire panel. Rust to this extent on your car's frame or in other integral parts, such as where the seatbelt brackets are mounted, will mean the vehicle's structural integrity is compromised. If you are in any doubt, have the repair work carried out by a qualified professional.
As you might expect, this can be pretty pricey. Unfortunately, it's also an unavoidable cost at this point: anything that impacts your vehicle's safety or structural integrity in the event of a crash will result in an MOT failure.
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