[Closed] Rusty bits on car - what to do?

Only thing you can do is grind them back completely to bare metal, treat with an etch primer and re-paint. Anything else will leave the tin worm spreading.

So if I used a dremel to grind and finshed with some fine grain paper would that be effective? I've already bought some loctite rust repair which I assume is the etch primer?

Yup, a dremel should take it back to bare metal. Loctite rust repair isnt really an etch primer but it'll do a non-perfect job - grind out all the rust you can see and then put a fine layer or two of the rust treatment on, then get your matching rattle-can from somewhere like halfrauds and the simplest method is to simply mask off most of the rest of the wing with tape and newspaper and just blast the area affected. It'll leave a "seam" of paint but you say you're not bothered about appearance.

What usually happens is you grind the bubbles away and go right through the wing as its worse than you think, and it ends up requiring filling anyway.

I've actually managed to treat stone-chip sized rust by dremel>rust treat>nail varnish.

thanks, good advice - fingers crossed it isn't too bad!

The only way to get rid of rust is to cut it out. Rust treatments only prolong the inevitable...

dont touch it. Audis come with a 10year anti corrosion warranty. Look into this before you do anything as buffing down to bare metal might exempt this warrenty.

If a car that old is doing this I woukld say that this area has been accident damaged. Painting onto bare metal can not be done with just a spray cay. this needs to be prepped properly, cleaned with a tack cloth, acid etch to slow down the rust coming back (nothing will stop this) and then blend in the paint to match existing body work. Not an easy task on some colours. Might end up a total eye sore

I know at least one spot is from a ding (city living = poor parking = dings) the others are not. Looking around online it seems that the warranty is only for "perforation from behind" (ooer) so I guess my bubbles aren't included.

The car's not worth a lot (nearly 100k miler) and I don't know if a proper repaint / body shop job would be cost effective.

Try a local dealer and see what they say. Nothing ventured nothing gained.

I am not nesesarly saying go to a pro and spend a couple of hundered pounds on it, but if you paint straight onto bare metal the chances are it will all flake off in a few weeks. Without proper prep the rust will be making its way back through the paint before you know it. I am not a painter however I have learned from mistakes. I have not long finished preping a full car for a respray that a friend done and you wouldn't believe the work I had to do. Rust will never stay away for ever unless you replace the pannel but again that is very costly.

Advice for rubbing down. Use a medium to light grade sand paper from a body shop rubbing over the effected area lightly allowing the edges to feather. this means that you are not rubbing the paint away meaning that when you spray it you don't see a bug indent where you have been rubbing like a mad man. You know the edges are feathered when you see a white/grey of the primer around the paint. You might find that you need to sand further than the effected are. After this get a much lighter paper and us water to rub over all the area as well as a few inches all around the area to allow you to blend paint. Use acid etch as first coat. allow a few hours to dry in a warm dry place. Us a tin of high build primer to cover any sanding marks indents in the body work. Again leaving for a few hours. There are a few different colours of primer but a good paint shop will tell you what one you need. Take the car along to that shop and show them the effected area. they will use swatch cards to make sure they give you a colour as close to what is on your car. Although the paint code on your VIN tells you this paint does fade so there are usually a number of different shades available. they will put this in a spray can for you. If its is a solid colour 2 pack paint will do you if it is metallic you will need the colour and a lacquered to finish. Again leaving time between coats. Leave a bit to dry (metallic will take a few days 2pack can take weeks). Use a really fine sand paper P300 maybe with water and fairy liquid and then use a buffer and a light compound to buff it.

lordy - that's a big job!

Yeah but it will be worth doing it right so you dont need to do it again in a few months time. Now you know why a body shop charges you so much. Their advantage is that they have ovens and dust free areas that cut down on the work.

Only other thing I would add is always use a sanding block to ensure a smooth finish.

Where are the rustspots? If on a wing or door etc (not on the C pillar) then I wouldnt bother too much.

Or, assuming you're not keeping the car forever or trying to maintain its value massively, just grind back to bare metal (grind it far enough and you're essentially doing the same as cutting it out), etch prime and spray quickly. Obviously you cant spray paint directly on to metal, but you can often spray straight onto rust treatments without issue (check the tin). I've done minor repairs to a couple of cars that show no sign or recurrance using this simple, quick method. Nothing quite beats the full blown paintshop methods, but most people cant be arsed with the expense on an older car.

I fear I'm going to have to get heavy with the angle grinder on this 🙁 :
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I'm taking the old lady down to the Audi body shop to see if I can get a freebie (50k to 1 shot?) and will get some advice from them.

If it comes down to it then I'll go with the quick and dirty method. From previous experience (stone chip and blowout damage paint repair on a subaru) getting it done at a body shop will be around a grand and it's only worth 2.5k max. Might as well keep it until the body condition has little impact on pricing.

Hora, there are two main spots (and a couple of bits around a parking ding) - one next to the boot opening handle and the other on the pillar between the front and back doors.

Good luck mate. Hope you get something sorted. I agree with coffeeking there are some quicker workarounds, just a personal thought that I wouldn't do it any other way. My second car is a 1986 Land Rover defender and this is the process I went through on this, but on thje whole car. Was a killer.

Warranty is for the owner surely?

Easy area to have rust/repair.

Longshot- how long is Audi's perforation body warranty? How long has the Audi service history been maintained for?

Better idea. Get two quotes off of two chipsaway guys this week first.

Once I propped up my bike upside down (wheels off) alongside a Honda FRV that I once owned. Bike fell oversideways and put some really nasty deep gouges (3 or 4) down the side. Chipsaway guy sanded down, filled and resprayed over. Good as. Alternatively you sand back, smooth over and get the chipsaway guy to do it.
ALOT cheaper than a raping at a sprayshop.

Are bubbles of rust not likely to be from rust coming thru? its a fair bet it will be a lot worse than it appears.

Second the warranty!

I just had a phone call today to say Ford has authorised repair of my '03 Mondeo 🙂 All the doors have started rusting at the bottom on the inside, repair involves removing the clinched flange and sealant and all rust, then repair/respray. Expensive week long job so very happy its been OK'd.

This is surface rust, the anti-perforation rust warranty is what you'd probably be claiming under. If its under warranty, it'll cover you even if the car is secondhand. Mine was OK'd even though the bodywork check stamps are missing from the service book.

Nice one spooky-I thought the warranty was for the original onwer.