[garretthes]

Just discovered this. Knew I had rust here but not this bad. Buying another hood is just not likely. They are rare. A carbon fiber hood is $760, way out of my daughter's budget. I know I have to get rid of the rust but how?
All I know to do is clean it as much as possible and paint it with Duplo Rust fix. Problem is, I can't get to the underside of the shell.

[garretthes]

Forgot the images...

[skip99]

couple options...if you can weld and have the right tools..then it's just time and patience. otherwise... I would use a little picklex 20 behind the panel and on top to kill the rust. then maybe a little por 15 or whatever...poured in behind to seal it. then some sort of chopped fiberglass (duraglas) to fill the holes and get a thin layer on top to smooth, followed by bondo...

[garretthes]

Originally Posted by skip99

couple options...if you can weld and have the right tools..then it's just time and patience. otherwise... I would use a little picklex 20 behind the panel and on top to kill the rust. then maybe a little por 15 or whatever...poured in behind to seal it. then some sort of chopped fiberglass (duraglas) to fill the holes and get a thin layer on top to smooth, followed by bondo...

I do have a welder and some welding skills. This looks impossible to weld though because there are SO many holes. A lot of the rust is against the hood. I'm afraid to weld right on the hood steal because of warpage. Can you s[read por 15 right on rust?

[123pugsy]

There is no such thing as ''rust'' paint regardless of what is marked on the can. (IMHO)

Cut out the rust and weld in new metal. This is the only method that will work long term.

In the pics below, I had taken the skin and inner structure apart for the repair.

[deadbodyman]

Cut that section of the inner structure out ,clean it all up while its apart,epoxy it and replace that section with a fabricated one.Its just a couple of simple bends,if you dont have the skills you can go to a sheetmetal shop and have them bend one up for you while you wait....just remember ,the inner structure isn't welded to the hood skin...

[garretthes]

Originally Posted by deadbodyman

Cut that section of the inner structure out ,clean it all up while its apart,epoxy it and replace that section with a fabricated one.Its just a couple of simple bends,if you dont have the skills you can go to a sheetmetal shop and have them bend one up for you while you wait....just remember ,the inner structure isn't welded to the hood skin...

That would be my preference. BUT.....I don't think I can weld it back in without warping the hood. I will have to cut it out where the structure meets the hood. This means welding a 36 inch seam across the thin sheet metal.

[DanielC]

DeadbodyMan,
I have the same issue with some hoods I have for my project Datsun 521 truck. The hood has some inner braces, that originally bonded to the inside surface of the hood skin, with some hard rubbery material. Who knows what stuff Nissan used in 1970?

What would you use to bond the braces to the inner surface of the hood?

The process I am thinking of doing, is take braces and inner panels out.
Remove rust using electrolysis. This usually strips the old paint, and primer off the parts.
Clean up any remaining rust with Phosphoric acid solutions, and steel wool, wire brushes, and lots of elbow grease. (Detailed in Randy's rust removal thread.)
Do metal repairs as needed, and clean again.
Epoxy primer, and then a single stage top coat to match color of vehicle, on inside of braces and hood.
Put braces back, rewelding spot welds, and using bonding "stuff" between hood skin, and braces.
Spot painting areas where welding heat damaged paint.

Obviously this is not a business type situation where the main concern is beating the flat rate. If the process takes longer, but results in a better job, that is OK with me.

[swvalcon]

What kind of hood is it? If you just fill it I would put so spray foam behind it for support.

[willowbilly3]

Most of that stuff rusts from the inside out and what you think is solid metal really isn't. I have seen plenty like that on hood/trunk lips and roof rain gutters where the condensation collects inside on the unprotected metal. Just a couple pinholes showing and no metal left inside when you get in there. You have to completely get rid of all the rust to fix it right and if there's a seam, you can not get the rust all out of the layers of metal. Anything you do to it, the rust will eventually come back to haunt you. I'm not sure what kind of car you have but I think I'd bite the bullet and find a rust free hood and have it shipped in.

[35terraplane]

Originally Posted by garretthes

Just discovered this. Knew I had rust here but not this bad. Buying another hood is just not likely. They are rare. A carbon fiber hood is $760, way out of my daughter's budget. I know I have to get rid of the rust but how?
All I know to do is clean it as much as possible and paint it with Duplo Rust fix. Problem is, I can't get to the underside of the shell.

There are a lot of good answers, but you never told us what it is. You jumped from the metal hood saying it's rare, to carbon fiber, If someone makes a carbon fiber hood for it, it can't be that rare, I would think someone would make a metal one.

Bob

[OneMoreTime]

A lot of times the outer part of the hood is folded over the lip of the inner part so you can take a sharp chisel or bar and lift the fold and then pull the inner piece out..just reverse the process with installing the new/repaired inner piece. I have not met a hood yet that is not made that way/not saying that they are not all that way though..As far as the welding most of that sort of thing is spot welded so all one needs to do is to put in some tacks to hold it together..

Sam

[garretthes]

Sorry guys, should have told you it's a 79 280zx. This is a common problem with these cars. There is one hood on ebay and it has the same problem just not as bad.
There is rust in the seam. There is NO replacement hood available short of the carbon fiber which costs over $750. I'm keeping my eyes on craigslist and ebay. Painting is not for another 3 weeks or so.
I HAVE to get the car primed very soon because there is so much bare metal. I'm putting the hood off for a couple of days until primer is on.
So for now my plan will be to cut the rust out as much as possible and fabricate. I will not be able to get it all though.
Will post pics of progress.

[garretthes]

This hood was in pretty bad shape. I stripped the paint and wire brushed the rust away. There is a LOT of surface rust.

[tech69]

Originally Posted by garretthes

Forgot the images...

Just go to autobodystore.com and the site owner will show you how the "pros" really do it.


btw...I'm only kidding.

If you have a brake you can fab that up easily and the current rust will help you slide out the old piece easily after you peel it up some. Worst case, you can measure the space between bends, mark the bend areas and use a vise, then use the old piece's shape as reference.