Corrosion / rust

Whilst giving the car a good polish at the weekend I came across what looks like the early stages of rust bubbling under the paintwork on the driver's door. Now surely we all have doors made of aluminium which don't rust?!?!?

Of course it could be something else altogether and I would value your opinions as to what it may be before I visit the stealer for their opinion.

My car is a 2001 SE spec so well outside the 3 year paintwork warranty but well inside the 12 year anti corrosion warranty.

Pictures (couldn't get the camera to focus any closer, sorry):
http://www.flickr.com/photos/54257934@N00/381632141/
http://www.flickr.com/photos/54257934@N00/381632143/
http://www.flickr.com/photos/54257934@N00/381632146/
http://www.flickr.com/photos/54257934@N00/381632148/
 

doctor

Member
Aluminium can oxidise, but would have expected the paint to be perforated for this to happen:confused: Has there been a chip that has been repaired in that area.
doctor
 
No chips or repairs made.

I don't know if this is linked to it, but all the water from the door rubber drains away and down the side of the door from this point so it does get a lot of water running over this point.
 

Skipton01

Well-Known Member
It looks like oxidization to me - there's probably more if you lift up the rubber boot.

This can happen at the factory, or should I say have the seed sown at the factory.

If there is a drop of moisture left under the paint when the door is made, it can fester away for a while, eventually appearing many years down the line.

I'd get your dealers opinion, but beware, the corrosion warranty is actually called an anti-perforation corrosion warranty - they may tell you to sod off unless there's a hole through the panel.

Cheers,

Mike
 

Mark Brigg

Member
Water on its own should not cause corrosion, especially as it is from under the paint. It may be that the panel is not fully painted under the rubber seal. Maybe in the past the seal was removed -repairing a side window and the paint damaged.

Aluminium does not rust like steel but under certain circumstances it can corrode. The alloy used for outer door panels is normally robust and withstands water and salt water very well.
 
Hi Mark

I've owned the car from new and the door has never been repaired or the window replaced or the rubber lifted!

I'll take it to the dealer for a look over later this week but I do expect them to tell me where to go. I guess I've got another 6 years for a hole to develop whilst it is still under warranty!
 

doctor

Member
It might be easily treated by yourself if Audi refuse to do anything, but I would work on Audi plenty before taking up this option.

doctor
 

Jörgen

Member
Yes aluminium does rust but afaik when it comes in contact with oxigen. When that happens it will get a thin layer of aluminiumoxide, that will even prevent further corrosion.

Have you checked if there is any damage on the inside of your door? It looks like damage you get when a screw has got in too far...
 

lyndonbuck

Member
I've got exactly the same on my BMWs mirror housings, but then that car is almost 20 years old. It hasn't got any worse in the 6 years I've owned the car, so although its a bit unsightly I wouldn't worry unduly about it.
 

Xiter

Member
I'm surprised to see that part of the door in that condition. I suspect oxidized aluminium under the paint. This is an easy fix though if your dealer won't do anything. Remove the rubber, sand down the damaged area, prime and paint and it should be okay.

I'm more concerned about the black plastic trim at the very bottom of the doors. I've found grit, dirt and salt water gathering in the tight space between the door panel and the plastic trim. I'm thinking of sealing this space to prevent dirt and salt water from rubbing against the paint. I very bad design, probably the worst regarding the A2 and it's corrosion protection.
 
I used to have a Lotus Elise which has an aluminium 'tub'.The floor inside was bare aluminium with a thin rubber mat glued in place.From what I remember this caused the floor to 'sweat' an led to corrosion.It was a problem on most Elises,a few had to have a complete tub changed under warranty,Lotus advised to remove the rubber and keep the floor dry for the most part and you could have free set of carpet mats for your trouble.WOW!!Mine was only 4 years old at the time.
 

lyndonbuck

Member
..and of course BMW are being sued in the USA for Z8s having terminal aluminium chassis problems, it will be interesting to see how A2s fare in the long term.
 

Alan_uk

A2OC Donor
lyndonbuck said:
..and of course BMW are being sued in the USA for Z8s having terminal aluminium chassis problems, it will be interesting to see how A2s fare in the long term.
I'm not too sure what is being referred to here (i.e. a "corrosion" problem?) but whilst doing a google on the subject I came across a very long thread in the BMW Z8 Board from Jan to July 06 about Z8s sustaining frame damage due to potholes.
http://www.bmwz8.us/vbb/archive/index.php/t-400.html

I hope A2 frame's don't suffer the same problem given the known wheel (and suspension?) damage from potholes.
 

lyndonbuck

Member
$65k+ to get a new chassis, now thats quite expensive. The wheels on Audis are made out of cheese to stop you damaging your chassis, they break first, or thats what I've always been told, but then what do I know, just ignore me, I'll get my coat
 

Mark Brigg

Member
For the Z8 I think it is more to do with the semi aluminium chosen for the "tower domes" rather than corrosion. The mileage seems to me to be irrelevant -25K or 8k miles is so little by what is expected today. Also the comment that 50% in the US against 25% in Europe could suggest different road conditions. Anyone ever been to Detriot will know why American cars are so big - so they don't completly fall down into the potholes. So it could be impact damage (these towers probably will be castings - like A2 wheels) or an outside chance of corrosion through the hot coastal climate of Calfornia. Impact I suspect, 25% of European owners suffer the same fate not the same climate.

orry Jimbert, the corrosion on you door definately looks like oxidation, similar to steel. I think you have been very unlucky. As Exiter says it is a relatively easy fix, just time and money.

The point about this thread really is that aluminium is still a new material to be used in body construction. It seems BMW have fallen a cropper and there is a flaw in their design, they and others will learn from that. Glad the A2 does not suffer the same.
 
Interesting comments guys, thanks for your input. A bit of an update on my situation.....I took the car to my local dealer and the warranty administrator there had a look and agreed that it was some kind of defect under the paintwork. But my dealership doesn't handle bodyshop repairs so I've been asked to visit the larger area dealer who can give the final nod to get the repair carried out, or not, under the terms of the warranty. I'll be ringing for an appointment later today. Watch this space....
 

humps

A2OC Donor
I think member Jorgen has the best description when it comes to aluminum. Pure aluminum is easily oxidised by atmospheric oxygen and forms a layer of very inert aluminiumoxide. The door panel would have an oxidised surface with an hour of exposure to air before being painted. But A2 has 'aluminum alloy' which might be different and my gf will be able to give you more details on it. It we understand rust as Ironhydroxide turn oxide (hence rust is caused by water+air), then no, aluminum doesn't rust. But if you understand rust as a form of oxidation, then yeah, just that aluminum skips the hydroxide phase and goes straight to oxide.

So without all that chemistry stuff. I think your problem is at the layer of matellic paint and not door panel itself! Worst case would be a repaint, after a carefully primed surface.


Jörgen said:
Yes aluminium does rust but afaik when it comes in contact with oxigen. When that happens it will get a thin layer of aluminiumoxide, that will even prevent further corrosion.

Have you checked if there is any damage on the inside of your door? It looks like damage you get when a screw has got in too far...
 
A further update... Just got back from the larger dealership that handles bodywork repairs. The manager there thinks that it is corrosion, probably caused at the factory when fitting the rubber seals, and the paintwork got nicked during installation. It has taken this many years to show through.

He will now submit the claim to Milton Keynes for approval. He said they will either pass it for repairs or send down a representative to inspect it first. I should know either way by the end of next week.

Fingers crossed that it is passed for repair under the warranty!
 

Xiter

Member
Being unaware of the problems with the BMW Z8 aluminium chassis I made a comparison with the design of the A2 frame.

A significant advantage of the A2 frame is the location of the suspension strut mountings (c on attached picture), welded and riveted to the windscreen cross member and the longitudal member (d), not out in the open like the case with the BMW Z8.

This brings us to the following conclusion:
From a force like a bad pothole, the A2 frame stands a lot better chance to withstand the torque due to the very short torque arm imagined between the center of the suspension strut mounting and the longitudinal member.
 
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