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severe rust on a car

Rust is one of the biggest car maintenance bug bears of drivers. It damages bodywork and, if left untreated, can cause all manner of problems. If your car is damaged in particularly hazardous places, even in quite obscure areas such as where the seatbelt brackets are mounted, it can result in an MOT failure and be fairly 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 proactively combat it, can save you no end of time and money in the long run.Here, we look at:

    What causes rust?

    ‘Rust’ is the commonly used word for iron oxide: the rest dust created when metal is corroded. 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 cars are galvanised (coated with a protective layer of zinc) to further protect against the damage rust can cause. 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:

    car driving through water

    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 a period of dry, warm weather or through parking the vehicle in a garage for a few days), these areas can become particularly prone to rusting.

    two cars with snow on them

    Poor weather conditions and exposure to the elements

    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.

    car tyre with rust on in the middle of a desert

    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. Salty sea water has a knack of finding its way to even the tiniest patches of unprotected pieces of metal. Salt water will cause an object prone to rusting in normal conditions to deteriorate considerably quicker. Furthermore, if your car is left somewhere particularly rural and very open to the elements, you are likely to find you have a bigger problem with rust than those in urban and sheltered areas.

    road gritter on a snowy road

    Salt

    Salt makes it easier for rust to form (which is why sea water is particularly effective at causing corrosion). To put it simply, 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 rust on vehicles if it gets under the paintwork.

    car that is in need of a wash with writing on it

    Neglect

    Many of the factors listed above are unavoidable if you live in certain areas of the country and don’t have the luxury of owning a garage. However, failing to take steps to prevent damage, or failing to act upon the early signs of rusting, will only make the situation worse. Even simply washing your car on a regular basis, 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 get rid of all the dirt, salt and grime that has built up. The important thing is to make sure it dries nice and quickly.

    road sign with jack hammer

    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 car, causing those problematic little scratches. Do you pay particular attention to your speed when driving on newly re-surfaced roads? Driving on re-chipped or gravelly roads flicks up even more debris than on tarmacked roads.

    How to spot rust

    The most effective way to prevent rust damage writing off your car is to act early. Knowing how to spot the early signs, and how to tackle them, will prolong the life of your vehicle.

    man looking at car spotting rust

    Regularly check your vehicle for scratches and dents

    If rust is going to take hold anywhere on the bodywork of your car, it’s going to be where the paint has been scratched away, leaving exposed metal. Get into the habit of checking your car for dents and scratches on a regular basis – 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.

    underneath of a car showing rust

    Don’t forget to check underneath your car

    Spotting scratches on the paintwork on your car is relatively easy, particularly for those of you who are fairly precious about your motor’s looks. Knowing what’s going on underneath, however, takes a bit more work. 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 under there anyway, keep an eye out for any patches covered in red dust, any bubbling and any small holes.

    rust on a car above the wheel

    Look out for small bubbles beneath the paintwork

    Small patches of bubbling paintwork are often what first alerts vehicle owners to a problem. As soon as you spot even a small bubble, act quickly to prevent the rust spreading.

    close up of a car day

    Be vigilant when considering second hand cars

    Spotting rust on your own vehicle is often not that difficult, providing you know what to look out for. However, if you’re looking to buy a second-hand car or van, you never know what’s been done to cover up an underlying problem. Keep an eye out for bodywork panels that are slightly different in colour. It may be perfectly innocent, but it may be hiding a cover-up job. It never hurts to ask.

    How to prevent rust from occurring

    The most effective way to deal with rust is to prevent it from developing in the first place. It’s a common problem, so you may not be able to eradicate it completely, but there are measures you can take to help your cause.

    three car garages

    Keep your car in a garage

    Keeping your vehicle in a garage, or at least keeping it covered up, will protect it from damage caused by adverse weather conditions.

    person waxing their car

    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 periods of bad weather. Pay particular attention to any pockets where water can build up, such as around the wheels.

    treating a small rust spot

    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. Rust is an extremely widespread problem, and it doesn’t take long to spread to other parts of your vehicle.

    How to treat rust

    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

    If you’ve spotted very small patches of red dust around a superficial scratch, before any paint bubbling has occurred, repair is fairly simple. Whenever you spot a small patch of rust, don’t delay in treating it – leaving it will only give it the opportunity to spread and cause much more damage.

    • Wash the area around the spot to make sure 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 touch-up car paint to cover the now repaired area

    Surface rust

    rust damage on a car

    Products and equipment to use

    Sander/wire brush/abrasive wheel (depending on how severe the problem is) Anti-rust primer Touch-up car paint

    man repairing surface rust

    Method

    The process of repairing surface rust, when the paint has started bubbling or even flaking off, 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. If you didn’t catch the problem soon enough, and the metal has rusted through leaving holes, more drastic action is required. 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. Halford’s Advice Centre offers a step-by-step guide to using one of these.

    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 structural integrity of the vehicle 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. 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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