I had a feeling this fender well would be my problem child and these rust bubbles are "new" in that I hadn't noticed them last summer when waxing my truck all the way through this summer up until a few days ago. The previous owner was an elderly farmer and I think he cut a corner near a post to get the wrinkle job along this wheel well which compromised the metal.



My truck sat mostly in the driveway from May until now. There was nothing wrong with it and I did drive it to work one day every other week; just my daily drive was 120 miles round trip each day so I logged those onto the car to save the truck and on fuel cost.

Last year, I used Dynax S50 all over the under carriage, in the rockers, throughout the quarter panels and I think it does a great job but this is surface rust under the paint in a damaged area is a different beast. I am not even remotely a specialist in autobody work by any stretch of the imagination, but I am a self imposed stickler for doing any job I need to do right the first time. There is a billion youtube videos on how to's, I would just like your thoughts and opinions on how to tackle this project. The wrinkles don't bother me as much as the rust coming to the surface.

Thanks Guys,

Eric

 

Chasing Rust forever on that truck is your new life goal, check underside of your rocker covers.

 

Those rear fenders rust from the inside out. The backside where they rust is not in your wheel well opening, but above that. An area that gets missed by most.

It’s not surface rust and I don’t believe the damage had anything to do with it either.

Look up from under the rear bumper and you’ll see that area. There is a cavity where they use some type of foam up there. It traps moisture, salt and dirt. Every rust belt steel pre 2015 truck will rot out there eventually.

You can either cut out the metal and replace, look for a southern bed as there is a lot more rust behind the paint than just the small bubbles are showing, or get oem fender flares, cover that area and spray a gallon of rust preventative in the upper wheel well area and hope it doesn’t grow much.

 

the metal didn't need to be compromised for rust to start there. It's one of the problem areas. Ford used an open-cell foam insulation between the inner and outer sheetmetal in that location. Once it gets wet, it that's the beginning of the end, because it basically never dries out. The metal slowly decays from the inside out. You can reach your hand up inside the wheel opening and it will be clean and dry there. Completely rust free. But the bubbles appear nonetheless. My 2013 spent most of it's life in Arizona. Spent a year in Mississippi, then a few months in VA before I bought it in Oct. 2022. Appeared to be completely rust free. Now after a snow-less year in MD I already have those bubbles in the same area you have.

 

I plan on installing fender flares on mine so a least I won't see it and have it bother me, it seems it's inevitable on these trucks. My 2013 has the same issue.

 

Any recommendation on the one's you are looking at? I have a 2013 and just started to look this weekend.

 

I can’t speak for anyone else, but I’d recommend the oem or oem style. The giant fender flares just look ridiculous unless you have wheels sticking way out.

 

As for the OP's rust. Here is what the top side of the rear fender openings on my 2012 looked like when I cut the bed tops off for rust repair. My truck only had 151k km (just under 100k miles)



I had a rust bubble too. Here is what I found when I opened it up...

From the outside

Just the sheet metal cut out

Some of the foam scraped off

I found a hole in the inner fender and patched. Other metal cleaned.


Then I sprayed Fluid Film over the repair and the entire inner fender area.

 

These are the ones I am looking at.

 

Here’s a link to some that’ll actually look good and cover the rust.

https://www.ebay.com/itm/27362023444...mis&media=COPY

OP, You have a couple small bubbles on the arch, no reason to get the giant ones that scream rusty truck, trying to cover it up.

You might even luck out and find them in white. I did for my old 2008 F150 that I used to have.

04-14 will all fit your truck.

My old truck with OEM white fender flares i
found on eBay for $125. That truck didn’t have rust, I just liked the look.