This is an interesting viewpoint. Feasible.

 

I have some knowledge of thermodynamics but it's not the metal that would be affected by the heat, it would be the paint. The metal won't change at all during even the hottest operating temperatures. If heat were the cause, it would be because the paint was reacting to the higher temperatures.

I open my hood after running a track or a speed event, but it's for the engine's and blower's benefit, not the paint or anything else. In fact, if it's possible I put a high-power fan in front of it while it cycles the coolant. It's more effective because the engine needs the air flowing over the intercooler to actively remove the heat. Simply lifting my hood only minimally helps the heat dissipate more quickly--especially since I have a heat extractor in the center of the hood.

 

Yes, the heat would affect the paint if anything. But yes, the hood release is for the engine and blower components, or in my rx7 case, the turbos and hoses, etc.

 

As I understand it, the problem is "galvanic corrosion" caused by steel contamination in the welds of the aluminum panels. The corrosion is caused by the two disimilar metals (technically metals with different galvanic potential) in direct contact with each other. This causes a small electrical current; and the current causes the corrosion, from the inside out. This is a known issue in other areas such as using metalic fasteners in a carbon composite structure. The only way to stop it, is to insulate the two metals from each other -- obviously impossible in the inside of a weld.

Temperature could accelerate it a little but I wouldn't expect a significant difference within the range of temperatures that we normally see on our hoods. If you could store the car at something like -100degF, that might slow it down quite a bit . . . but again not practical.

Once it breaks through the paint, then other things like moisture or salt might affect it also. But it is going to happen inside there regardless.

If you don't have it on your hood, I think it is simple dumb luck -- there is no steel inside the welds on your hood. Or maybe there is only a little so it's progressing really slowly.

It's about time!

I was wondering what was going to happen with those aluminum F150's . . . .

 

It's doubtful any of the aluminum panels are welded, they are likely riveted. I know for sure the F150 is all rivets (and S550 aluminum parts). It's from the dies used to stamp and hem the panels leaving residue on the panels which can rust, and also improper treatment before painting which would have probably eliminated said residue.

Just sayin', I built a good portion of the rivet lines for Ford's newer cars. The riveters are pretty cool, interesting concept and execution. Look it up if you get bored (henrob riveters).

 

I knew it was just a matter of time before you smart people started chiming in. Thanks for the perspective.

FYI, I checked again the other day when I got back from vacation - no rust bubbles! woohooo!!! almost 5 years and counting.

 

Take a look at the bottom of one of these hoods. You will see the folded / welded seam. No rivets there . . . unless they are the magic invisible kind that looks like a folded/welded seam with no bumps.

 

The hood is hemmed, which is to say it is sort of folded then sealed shut with the press. There is also a bead of sealant/adhesive there.

The rivets would be nearly flat, appearing almost like a spot weld. Remember - you generally can't spot weld the aluminum used for panels (not the right type, and way too thin), and any other sort of welding would need to be done by hand and wouldn't be practical to be done by machine.

There's some companies doing SOME aluminum on aluminum spot welding, but it's still pretty new stuff and is pretty expensive. I would imagine in the next decade or so it will become more prolific, but for now Ford is using Rivets en masse.

The adhesives used also play a big part. They can sometimes look like big, ugly weld beads considering the machines aren't as accurate as they probably could (and should) be.

All in all you'd rather have the rivets anyways. Doing destructive testing on those panels was a MAJOR pain in the *** compared to steel welds, it's ridiculous how tough the rivets were.

 

I always opened my hood after hooning in hopes that it would at least slow the corrosion problems...nevertheless, I have small bubbles growing on the leading edge (which wouldn't have suffered from engine bay heat anyway.

I tend to agree with the galvanic corrosion hypothesis but I have to ask: why does this virtually always happen on the leading edge and usually nowhere else (with a few exceptions)?

 

S550 fans: Nobody is safe!

Ford just doesn't care, I guess!

http://www.mustang6g.com/forums/showthread.php?t=56073

 

I disagree that aluminum spot welding is “New”. It has been used extensively in building aircraft structures since the early 1940’s. For instance, the fuselage of the Grumman Bearcat (F8F) was nearly 100%spot welded. The North American Mustang (P-51) employed extensive use of spot welding on many of its major sub-assemblies. Almost all of the spot welded sheets/components were no more than 0.100” and most are around 0.032” to 0.040”. The technique proliferated from there. It’s faster and more practical in many cases than riveting. However, some major draw backs of spot welding are: the need for surface prep of the panels being welded, an extremely tightly controlled weld process (Current and electrode pressure) and very high energy consumption. Those are all bad news when building 60 units per hour while attempting to control labor and energy costs.


A proper spot weld is going to be as strong as a rivet. When peel testing either joining method, the base material should fail before the attachment method. Poorly executed rivets are just as week as a poorly executed spot weld. The difference is, when a spot weld fails, it’s a big ZERO. When a rivet loosens it will still hold the panels together in close proximity to one another even though it’s no longer structural. Not a good thing but at least a “Smoking” rivet in view of an educated eye will send a warning of trouble…no such luck with a spot weld about to fail.


Here is a good primer on how the new F-150 is being built. I’m sure some of the tech has been pulled forward to the Mustangs few aluminum body panels (Just the hood as far as I can tell…and that was hemmed and glued on the -197).


http://www.assemblymag.com/articles/92728-assembling-fords-aluminum-wonder-truck


John

 

Whatever happened to the class action lawsuit concerning this? I will bet it will be resolved like any other class action suit. The lawyers will make a mint, and we will get a coupon for a free oil change (up to 5 quarts non-synthetic).

Edit - Here is the answer. I wonder how much the judge got paid under the table to make that decision.
http://www.carcomplaints.com/news/20...-lawsuit.shtml

 

****. Didn't realize that suit had been closed. I'm no lawyer but it seems like this one was destined to lose with two plaintiffs that both got repeated offers from Ford to repair the damage. Seems like it would have had a better chance of success with plaintiffs that were past the 36K warranty, denied repair and were still well within the corrosion warranty. Surely there's a lot of guys out there in that situation.

 

I'm still waiting for my million dollar lawsuit here in Canada eh.

 

Wait are you telling me the bubbly marks on the tip of my hood are NOT the previously owners poorly done touch ups?

 

Nah, more like factory defect. However if you go make a claim with Ford, they'll probably say it's the poorly applied touch-up paint was the cause.

 

It appears to me to be a bad touch up job over a spot of corrosion. There definitely is corrosion growing under the paint and in fact has broken the paint in two places that I can see.


John

 

This could be time to get a carbon fiber hood.

 

Yes, they should. However they don't want to spend money to replace all hoods. Best thing to do is go to the dealership and tell them to replace hood. Usually they'll replace it if its under 3years/60km.

 

Have you ever seen a recall from any domestic manufacturer over a cosmetic issue? Safety issue... certainly. Performance issue... sometimes. Cosmetic issue... not that I can recall (pun intended).