What causes rocker panels on 3rd Gen to rust out? Any preventative maintenance to avoid this?

[914rrr]

We love our 2011 Navigator and are hoping to keep it long term. It was originall a FL car and now resides in E TN.
I've seen other 3rd Gen's for sale in more Northern climates with badly rusted rocker panels.
What causes this and what can be done to keep it from happening?

 

[Tiger Bob]

We use lots of road salt up here in the winter when it snows, which causes the rust. Rust never sleeps. regularly clean and apply a protective coating like an undercarriage spray or wax, ensure proper drainage by keeping drain holes clear, install mud flaps to minimize debris impact, and consider professional rustproofing treatments

 

[914rrr]

Thanks!

 

[2013EX]

Not many know this. Ford screwed Expedition owners on these. If you look in the rear wheel well on the front side if you feel around there is a hole that never got sealed from the factory. This directly dumps water into the rocker panel on the inside whenever there is snow or water thrown up by the rear tires. I don't believe for a minute that this was accidental. Rusted out rockers means car doesn't pass inspection and forces owners to buy a new one. If i can get a picture I'll post it up.

 

[914rrr]

Thanks! Would sealing up the wheel well hole and drilling additional drain holes in the rocker panel help?
Are there existing drain holes in the rocker panels that could be inspected and cleared / maintained?

 

[Tonka]

My passenger side is rusted snuck up out of nowhere

 

[JamaicaJoe]

Not many know this. Ford screwed Expedition owners on these. If you look in the rear wheel well on the front side if you feel around there is a hole that never got sealed from the factory. This directly dumps water into the rocker panel on the inside whenever there is snow or water thrown up by the rear tires. I don't believe for a minute that this was accidental. Rusted out rockers means car doesn't pass inspection and forces owners to buy a new one. If i can get a picture I'll post it up.

Please post a picture. I know my 1st generation has a bunch of silicon like goop squirted in at the trailing edge of the rocker panel near rear wheels. It is still very pliable after 24 years. I would assume there is a drain somewhere forward of the seal as they do need drainage.

 

[Tonka]

Rusted

 

[Trainmaster]

This is an old thread, but I'll add this information for future readers. The inner rockers have large holes in them, probably to drain the corrosion coating when the bodies are dipped before painting. Those holes are sealed with rubber tape from the factory.

The tape comes off and now the holes catch salt, mud and mung, which rot out the panels. You'll probably find this out when you replace the outer rockers. After that seal up the holes again with rubber tape (like Gorilla Tape) and keep an eye on them.

 

[Tonka]

Thank you. I was looking at it today i need to spray it and try to slow it down some but then i looked at the oxidation on the trunk and was like need to spray that too lol that oxidation crap is on parts of my hood but really bad on my trunk, but I’m going to clean it real good and paint as best I can.