Aluminum Hood....

[MrBhp]

My underhood insulation has been laying on a shelf for 6 years. Took it off to paint the hood. No wreck. Just fixing extensive rock chips. No problems so far.

 

[pass1over]

It was still sealed off from oxygen if it was still corroding. Leaving the bubble on was a mistake. Most start under the edge of the hood and spread to the top. The trick is to remove them before they do. None of the bubbles I removed ever returned. Most of them were smaller than a dime when I removed them and exposed the bare aluminium to the air.

Compared to many other metals aluminium has good corrosion resistance. This is because aluminium develops a thin oxide layer on the surface when the metal comes in contact with oxygen. The oxide layer protects the aluminium against corrosion and if it is damaged, it will immediately regenerate, provided there is oxygen present.

https://www.alumeco.com/knowledge-technique/general/oxide-layer/#:~:text=This is because aluminium develops,provided there is oxygen present.

nope, I could shove a small pick inside the big bubble or push it and squeeze water out

Doesn't really matter now, the hood has been replaced. Just sharing my experience.

 

[crjackson]

My 2014 started to bubble at the front lip. Ford body shop told me this happens because of iron contamination, usually from the manufacturing process. However, iron is in our environment, and an uncontaminated hood can become contaminated by exposure (paint chipping, or poorly sealed). If the aluminum itself was contaminated during the manufacturing process, apparently it can’t always be decontaminated, so it’s highly likely it will return at some point. They don’t want to handout continuous free repairs.

They didn’t want to fix the hood either, because to ensure a problem wouldn’t occur again, the whole hood needs to be stripped, treated, skim-coated, painted.

They just gave me a new Shelby hood and slapped on a fresh coat of paint. It’s been a few years now, and I’m watching for the dreaded bubbling.

Good old fashion zinc-chromate primer/sealer if you can find it. Been used on aircraft for a hundred years.

Oddly enough, it appears that Ford invented that process in the 1920’s
https://en.m.wikipedia.org/wiki/Zinc_chromate

 

[Juice]

If you notice the bubbling early enough, it is clear that it started at the edge of the sheetmetal. Next to the spotwelds. Iron contamination or not, if you sand and spraybomb the underside before it reaches the leading edge, outside paint damage can be stopped.
Ps:it is not just mustang hoods that do this.
Pps: what about the flaking white paint on crown vics, and vans....but I digress...lol

 

[Robert Larimer]

If you notice the bubbling early enough, it is clear that it started at the edge of the sheetmetal. Next to the spotwelds. Iron contamination or not, if you sand and spraybomb the underside before it reaches the leading edge, outside paint damage can be stopped.
Ps:it is not just mustang hoods that do this.
Pps: what about the flaking white paint on crown vics, and vans....but I digress...lol

Yes it can be stopped and that is what I did. I have been thinking about why the corrosion always starts on the inside edges of the hood and I think it is because the iron contamination came from the crimping machine that folded the top and bottom edges and crimped them together. The jaws must have had iron particles on it and they were forced into the aluminium. I had bubbling all along that crimp line and nowhere else.

 

[Ret]

I don't think it had been in a wreak, at least according to Car Fax. I actually, bought from a little old lady from Pasadena type. Actually, her family as they were getting money so they could put her in an Assisted Living Home.

Anyway, I am curious as to why, even though I no longer have that Mustang. My 2012 has more insulation than any car I've ever owned.