I was at a CMA meeting today and bumped into a friend that I hadn't seen in a while. He restores cars, I told him about the problem with these aluminum panels. He knew what I was talking about the minute I mentioned it. He explained to me that it's the reaction between the steel and aluminum, similar to an outboard motor in salt water. He said he saw a big plow truck from NY ( lots of winter salt) the body was aluminum, he said there is a process, like zinc blocks on an outboard that eats the zinc rather than eating the aluminum. He wasn't sure what metal they used to stop the steel and aluminum reaction but that's what's happening. I may call a metallurgist to see if they could give me the solution. I'll let you know if I get any info. It may be as simple as a zinc or other metal washers installed on the bolts that secure the hood and lift gate.
Sounds like he's claiming its galvanic corrosion. I don't buy it but what do I know. I saw galvanic corrosion on my aluminum body snowmobile trailer ... where the aluminum was in contact with the steel suspension. That causes electrolysis
where they are in contact.
Salt water is an electrolyte so that would speed up or enable the electrolysis but water is sufficient also because water in the road environment is not pure H2O, contains ions.
This paint bubbling is not where aluminum is in contact with steel, hence I don't buy galvanic corrosion.
There is another theory put forward by most people that it had something to do with the dies used to stamp the aluminum parts. Something about contamination from previous use stamping steel parts. I never really understood it and I don't buy that theory either.
As I said ... I dunno and I have never hear another scientist/person repeat my theory.
Hot water heaters and boats and many other things use sacrificial anodes of zinc in a manner that seems like what your friend relates. As far as I know they are not successfully used in vehicles although you can find some sales of things like that or adding a charge to the steel on a vehicle to prevent corrosion, which also is a trick to get your money IMHO.
I sanded off the hood on my 2003 (as in my pic) partly because so many people were claiming that without the protective coating of the paint it would corrode in the road salt spray environment in no time. Zero corrosion in 3 years. Plus I just like to play and have a good time and it seemed like fun!
Expy's have been known to have galvanic corrosion in parts associated with the radiator due to dissimilar metals in contact with each other but I don't know much about that since I've never had to deal with it.
I did some studying on this once since I'm very interested in corrosion. Bare aluminum will almost instantly form a thin protective layer of aluminum oxide when exposed to air. It's so thin you can't see it but it protects the aluminum under it. Thats why my 2003 never corroded where I sanded the paint off.
