This is one that's bugged me for a while;

The formed framework on the inside of the hood was originally attached to the hood skin using some type of adhesive material. I've never seen what this stuff was like originally (soft, hard, other), but have only experienced it as hardened clumps of blackish rocklike wads that rattled around inside the structure until I took off the hood and shook them all out.

It's been a long time since the framework was atcually attached to the skin anywhere much except the edges. Time to fix that.

Anyone know for certain what adhesive/filler was originally used to do this bond? Was it resilient, or rigid? It looks like it was kind of foamy... at least, the old stuff has a lot of bubbles in it.

 

Check with your local autobody supply shop. I'm sure they can recommend something.

 

ive used all kinds of stuff, an autobody supply shop will sell you seam sealant, but silicon (the kind you need a caulking gun for) works well too. pick a color thats close to yours (black on a black car)

just go most of the way around all the openings, you want water to be able to drain

and then enjoy the mercedes hood closing noise instead of the trash can sound

 

Autobody sealant comes in various colors in caulking tubes. Ive used the stuff with good results for other projects. As the poster above said, its basically just caulking like you would use in your bathroom, maybe a little different because its paintable and such. Im not sure if its the same as what was originally used in there, but it will work to quiet it down. Expanding foam might be another choice for some areas if theyre large gaps?

~T.J.

 

Expanding foam would be a definite no, sorry.

 

I did say might be. If he was trying to make it more rigid without adding a lot of weight or something. Ive seen rally cars use it within the panels to stiffen things up without adding a lot of weight. I actually remember someone who did that here too on their FB. I was thinking fill inside, trim, then seal with the autobody sealant. Oh well.

~T.J.

 

Expanding foam likes to expand. Too far. You would have bumps and whatnot all over the hood.

 

If you don't need the stuff to accept paint, windshield urethane works great -- it remains flexible, it's tough as nails, and it sticks to everything. Since it's made to work as an adhesive, it's stronger than silicone.

The original stuff you had there is generally called "gumdrop adhesive". It's low expansion structural adhesive (glue) that will accept paint, which is why the OEMs use it. They glue the hood together, hem it, seal it (optional), then paint it. The bubbles you saw are characteristic of expandable adhesives -- that's where the expansion comes from.

 

Thanks for all the replies, folks!

I do want to enjoy "the mercedes hood closing noise instead of the trash can sound" - - exactly; that description is almost too perfet. Far too reminiscent of "DI alarm clock" for comfort.

Elwood; any idea where I could get some of the "gumdrop adhesive," or what it's formal name might be? Where possible, I'm trying to keep much of the car stock.

 

The issue with the gumdrop adhesive is that I think it needs to cure in the paint ovens, and it's made to adhere to bare metal. In reality, since you're not planning to separate the inner from the outer and strip the parts down, the urethane or silicone is a better way to go. If you're worried about appearances, you can mask off the inner beforehand, and clean up excess afterwards -- or you can use clear silicone, which won't be so obvious if you make a mess.

 

Excellent; thanks for all the help, folks!

 

i know a guy that tore up a quarter panel when he was trying to fix a rust hole with that stuff. stronger then you think is the word i would use lol.