I took the doors and both trunk lids from my car to Redi-Strip in Roselle Illinois a while back to have them dipped in thier alkaline solution. I called them today to see how the progress was going. The guy there told me that the parts were pretty much stripped but he asked me something that I wasn't sure of. He asked if the factory would have put any foam in the rear trunk lid. The alkaline solution wasn't getting rid of it and he was wondering what it was. I told him I didn't think the factory would spray any foam in that area and that the only place I knew of that they did was the body. At the rear of the quarter panel above the taillight area and where the recessed area was for the door handle.
The rear trunk lid had a spoiler on it that I removed before taking the parts to Redi-Strip. I thought maybe someone might have sprayed something in the channels at the back edge of the lid on the inside to help seal it up. Possibly to prevent rust or to help stiffen the lid. I really don't know any other reason why you would need anything in that area.
Does anyone know if that area would have had foam sprayed in from the factory or why anyone would want to spray it themselves?

Both the lids have polyurethane foam inside the ribs to help stiffen the parts. Not sure how far up but at the latch areas anyway. The body has some in the sail panel area.

Yep, foam at the lips, even on 911's. I would think acetone would disolve it but leave a gooey mess. It's a sponge for moisture and rust even if it's a closed cell foam.

I am not sure what they used back then, but if it is anything like that "Great stuff" polyurethane foam you can't get it off. No solvent will remove it, just mechanical abrasion. Believe me, I tried everything short of hydrocloric acid to remove it.

See the FAQ here Questions #1 and #2...

Dow Great Stuff

You can always burn it out.

gasoline is what I heard would take it out...

QUOTE

bondo Posted on May 16 2005, 01:34 PM -------------------------------------------------------------------------------- You can always burn it out.

Seriuosly? I have a small rust spot on the rear deck lid that I suspect was caused by the foam, I would like to remove the foam when I fix the rust, can I use MAP gas on it? Or will it warp the sh_t out of the deck lid?

QUOTE (Lou W @ May 16 2005, 01:43 PM)

QUOTE bondo Posted on May 16 2005, 01:34 PM -------------------------------------------------------------------------------- You can always burn it out.   Seriuosly? I have a small rust spot on the rear deck lid that I suspect was caused by the foam, I would like to remove the foam when I fix the rust, can I use MAP gas on it? Or will it warp the sh_t out of the deck lid?

Never done it on a decklid, but I did do it above the taillight. All it took was a regular propane torch. Might want to try it on a spare decklid first.

The factory foam in the rear deck lid is a seriuos problem if your trunk leaks. Water gets in the trunk (say from leaky tail light housing seals, or any other way.) Once water is in the trunk, depending on temperature changes (cold nights, warm days) the water will condense on the inside of the deck lid, and naturally run down to the lowest spot, which would be the rear of the lid (if you're parked on level surface). The water collects in the foam, allowing rust to start from the inside.

Installation of a rear spoiler on the lid, often causes leaks, that natuarally will run down the lid to the foam also. So if you install a spoiler, be sure the thru holes to bolt the spoiler to the lid do not go thru any of the lid frame structure. You want to be able to get to the bolt holes, and seal them with silicone rubber or other caulking, to keep water out.

For repair of lid that already has rust thru, it is tough to do it right (ie expensive, or time consuming) simply pounding down the rust area, and building back with bondo will give a temporary repair, not the choice for a full quality restoration!

You can cut out the metal,and weld in new. Problem is that you might still have moisture, and the beginnings of rust from the foam, that you cannot see (yet!) The rust might appear again on a different spot shortly after you got the car restored, bummer!

For a high quality restoration, a new deck lid (new used) is probably the best choice, cause it is difficult to assure the rust wont happen again on an old lid that had rust.

In your case, with the lid being chemically stripped, you got he problem of the chemical left behind in the foam, the left over chemical can cause corrosion later. or bleed out and ruin paint.

I believe there are chemical strips that will desolve the foam, but you'll have to ask around on what that might be. Burning it out will likely warp the lid beyond repair.

This is one of the problem with dipping a car to strip the paint, it is tought to get all the chemical cleaned out, and in order to prevent future rust, you have to find a way to repaint the inner panels that the chemical stripped (of course after a complete nuetralization, and rinse of the chemical.)

I do not like chemical strips of a car in most cases becuase of these problems; hard to remove all the chemical from the inner areas, and very hard to re-apply paint or other corrosion inhibators in the inner panels and seams. The chemical strip makes fast work of removing the main paint, so it saves on sanding or media blasting, but it takes a lot of time and planning to deal with foam, trapped chemicals, and repaint. You may even have to dip the car parts in primer to restore any original corrosion protection.

for what it is worth, you now have to deal with chemical contaminated foam in the lid, you still have rust thru, and likely more rust thru coming (it just hasn't broken thru yet) If you are doing anything other than a cheap re-paint on the car, I would consider a different, better deck lid to start with at this point.

You can peel back the lid structure and remove the foam by hand, evaluate the rust from the inside, and weld in new pieces, but deck lids are not that rare to make all the effort worth it. I have given up on rusty lids for these reasons, and instead grab my trusty magenet, and go looking for lids that do not have this problem, which is all too common.

The lids would not have this rust thru problem if the factory did not put that damn foam in the lid, and instead provided some drain holes.

The only real prevention is make sure your trunk remains dry, fix them leaks, as a leaky tail light, or spoiler mounting hole will cause the lid to rust from the inside out.

Sorry about it, but I think you would be better off with a differnt lid at this point.

good luck