[bbrennan]

I have rust at the seam below both doors and on the driver’s side wheel well on my 2005 convertible. The driver’s door is the worst area. I’m having them sandblasted and repaired, by an excellent body shop, but they tell me that the rust WILL come back. This shop won’t normally do any work on rust for that reason; he’s just helping me out because I had $5,000 of insurance work done there a few years ago when I was rear-ended. The manager won’t cut them out as he says it is cost prohibitive, since you need to replace the entire door bottom section!

I love this car and had decided to keep it forever. I’ve never noticed rust on any PT’s before. Anyone else have a rust problem?

 

[Bob Lincoln]

At over 7 years old, it's not surprising. Most cars in the Northeast are showing rust somewhere by then.

 

[tazdevil]

Your body shop should be aware of a product called POR15. POR 15 will absolutely stop rust from appearing on the surface, indefinitely. Their surface prep must also be used to etch the applying area. The stuff absolutely works as advertised.

 

[ImperialCrown]

If this rust has permeated into the seam, it will come back. Like cancer, every last trace of rust has to be removed or it will reappear. If repair panels are available or can be fabricated for the lower doors, the rusted section can be cut out replaced.
Maybe a good set of southern or southwestern doors when the time comes, although PT convertibles aren't common.
Most shops can't guarantee against rust.
These rust 'converters' or naval jellies don't stop rust.
Rust never sleeps.

 

[Bob Lincoln]

Even POR-15 eventually fails. It's extremely sensitive to moisture, absorbs it and can trap it in there. So if you can't follow their instructions to the letter, it fails. Where I live, by the time it's warm enough for these treatments and paint, it's above the humidity that they specify.

You can slow it down. I have used Permatex Extend rust inhibitor and Rustoleum Rust Reformer. Both work well and are more forgiving in their application than POR-15, and are more readily available and cheaper.

 

[135SoHc]

Once rust has started in the hem flange its game over. Your only seeing the cosmetic portion and thats all that can be treated. Flooding the door bottoms with slushing wax/oil preservative can help slow down the damage.

About once a year I get a couple cans of this stuff and some other rustproofing products. Park the car on the lawn and just hose down everything inside the doors, rocker panels, hood, decklid ect. The shadow smells like paint thinner for a few days after this but its worth it.
http://www.easternmarine.com/crc-hd-marine-corrosion-inhibitor-06026