Best way to stop rust!!!

Ryan Renko · Sep 13, 2013

I have a 2000 Ford F150 4x4 that is in great shape. It is starting to get a little surface rust on the inside of the doors at the very bottom edge. You know where the outside panel makes a 180 and has about a 1/4" lip visible on the inside?? I attempted to stop this rust on on door last year. I carefully sanded the rust off and masked the door bottom,put on good primer and painted. The rust came back after a year!! I think its kinda down in the 1/4' lip that I cant sand behind or prep better. What should I use to kill this rust thats were I cant get to it???? Thanks in advance!! Ryan

Old weldor · Sep 13, 2013

That's called a pinch weld. Your door is probably rusting from the inside out!

Motorcraftman · Sep 14, 2013

It is practically Impossible to Stop rust when it is rusting Inside out, Just replace the door is about the only option.. larry

notjustair · Sep 14, 2013

There is likely dust and dirt that has gotten past the window seal, gotten wet, and caused that rust. There's no stopping it. Make sure the drains on the bottom of the door are open, keep the thing dry, and hope for the best. When you first noticed it you were already past the point of no return. It had to rust through all of the layers to get to the place that you can see it. I'm not sure if opening up the door panel and pouring something like cosmoline in there would help but I would think it might. You need to seal out oxygen and moisture.

RC Brooks · Sep 14, 2013

You can try chassis saver. But you do probably have rust creeping along that weld. you could grind the weld apart to cut out all the rust, but a new door may be easier.

showcrop · Sep 15, 2013

It has pretty much already happened. I noticed it on my wife's Expedition when it was about 8 years old and the door bottoms were already rusting out. I am PREVENTING it on our current vehicles by the following method. I periodically lift the bottom of the door gasket and check the seal of the the joint where the outer skin laps over the inner skin. Once I found that the paint and seal were broken and rust starting, I used a large screw driver to run along the edge of the joint and clean off all the loosened paint and sealer. Once it was opened up I applied WD-40 liberally so that it would penetrate and displace the moisture. I then let it sit for a day, and then sprayed on aerosol chain lube. It goes on thin and penetrates then sets up thick. After two years I repeated and I don't see any further rust extension. A few years ago an auto body expert here told us that the paint and sealer cracking is from closing the door, and we never see the rust due to the gasket over it.

Best way to stop rust!!!

Ryan Renko

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Old weldor

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Motorcraftman

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notjustair

Well-known Member

RC Brooks

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showcrop

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