My daughters A4 has some rust around the top of the front windshield most likely from a botched windshield install. I told her she needs to scrap any loose peeling paint away immediately and put something on to stop the rust from getting worse.

Now for the big question, what should I have her put on it to stop the rust until she can get it properly repaired?

Jeff B

Click to view attachment

https://www.google.ca/search?q=rust+convert...zGFU7_HZfgIM%3A

Rust converter,and a touchup paint for appearances.
The rust is worse than you think,lifting the paint already.

How old is the car ?

You're right. Scrape away any bubbling. Bubbles or flakes will hold moisture against the metal, accelerating the decay. Once the loose material is removed, a rust converter should be applied following the instructions. I use MetalPrep 79. Once that has been applied and cleaned up, some sort of 'seal' needs to be applied. This won't be pretty, regardless of material or technique. Tape off the area around the rust and the glass. Spray paint will work, a high zinc primer is a decent choice. A paint shop could mix up a small quantity of automotive paint with activator and it could be brushed on. Whatever 'sealer' you use it needs to be heavy enough to not leave microscopic pinholes. One coat of spray paint will have TONS of holes, 3 or 4 is starting to approach the correct coverage.

It is a 2009 so I was rather surprised. She took it to the Audi dealer and they told her that it wasn't an OEM windshield so they couldn't fix it. She has had the car for about two years so the windshield was replaced before she owned it.

Jeff B

Jeff,

Before she does anything with it - if it's still under the factory original or CPO warranty, then she & you should press Audi to fix it since the body/paint should still be covered under the rust-through aspect of the body/paint warranty regardless of the windshiield (unless they can point to a specific wording in the warranty to defeat it) - that is, if it's still covered as a 2009 in 2016 (or whenever she first took it to Audi dealer as the report date if earlier).

If not covered, then the cleaning, rust converter, prime & touch-up paint route is the best temp solution. Either paintscratch.com or drcolorchip.com should be able to match the paint from the paint code, in paint pen, small bottle to cans & rattle cans - depending on the area to be covered. You should be able to find a store which supplies paint shops to get the range of grit up to 2000 to do color sanding for an unnoticeable finish.

But you might want to use Wurth Zinc Rich Primer (or Eastwood's), to give a sacrificial zinc coating similar to the original body hot dip rust proofing, since it will continue to be subject to road-spray laced with the winter road salts - which is the likely cause of the rust, perhaps brought on by a chip or flaw in the paint in that area.

The paint at the windscreen frame should've been a continuous covering under the gaskets & glass etc., & therefore protected by the warranty - so it's surprising to me to see it rusting there so soon, but that frontal area is subject to a lot of wind & turbulence induced road-spray.

Good Luck!
Tom
///////

It should be covered on the ten year corrosion plan but since the window was replaced at some point (based on the current window is not OEM) that voids the warranty for the rust around the window according to the Audi dealer she went to. I will have her look at the wording as you suggested to make sure they aren't just trying to get out of it.

Thanks for all the advise and I will forward it to her so she can decide what to do.

Jeff B