71 GMC Truck with inner ceiling rust. Front upper rot out sections Are cut cut out for new panel replacement. I have long tube brushes to scrub the worst rust out between the upper ceiling and roof. Clearance is 1/4” to 3/4” to get brushes and some type of paint to be with a 360 degree nozzle. My question is two things:

1. What Type of long tube attachment or nozzle Via spray gun or aerosol are you using to get into these tight spaces?

2. What treatment are you using to treat the rust? I was thinking on a rust converter vs encapsulator then coat with epoxy primer. Pictures are attached. Thanks for your help.

I had a similar problem with my '68 Plymouth GTX.
Rather than take a chance I removed the roof skin and media blasted the structure before applying epoxy primer.

It looked like this on top:


But underneath was in much worse shape:


Media blasted everything: (you can see the roof skin against the wall)


Had to fabricate and weld in some patches:


Then 2 coats of epoxy:


More detail and pictures in the project thread: viewtopic.php?f=12&t=27038

Wow! Your doing some nice thorough work! Mine isn’t rotted any further. I had mice up in there so they went crazy up front inner ceiling and sides. I’m trying to avoid it. I purchased the front inner ceiling panel and had some side pieces fabled up. I’m thinking some rust converter and some epoxy after that. If they would have made a full ceiling panel I would have removed all of it. But lots of spot welds to remove. I should have never sold my 70 RR or my 61 Chrysler 300G. I kick myself daily but at the time work was a priority and I had no time to store or restore them. But now I have the time and space. I envy that you have a nice B Body.

If you use rust converter be advised that it has to be neutralized before you apply epoxy or anything else for that matter.

Once the rust is converted, apply another coat and before it dries wash it off with soap and water to neutralize the acid. Other wise it will cause adhesion problems.

I found out the hard way on my signature car when buffing the roof. A blister would form when I ran the buffer over an area, then go back down as it cooled.

Turned out to be the rust converter had formed a film over it and caused the adhesion failure.

Vorman
Jim Is 110% correct. That rust area your dealing with is a LOT worse inside! That Skin needs to come off and be Blasted! Your first two pics show that the rust goes a LOT further inside that you cant see but its their you probably don't wanna hear this but its the truth.
Their is pitted metal in your first two pics close to where you drilled out the spot welds where the top of the door would be that evidence Pitting rust inside! This is Rust from INSIDE you cant just cover this up and expect any repair to last longer than 6 months before rust comes back and destroys your paint all over again with out taking the skin off and blasting with Crushed Glass then sealing it with Epoxy. Cars and trucks Rust from the Inside out! Not the outside in through the paint.

Replacement Roof skins are available for older chevy trucks.

Chemically converting rust in deep pits is an option IF and when You can first Blast it clean Then treating it.
IF and when you can physically scrub it in! If you cant physically scrub it in you cant Scrub it off and clean it properly to remove it / Neutralize it.
If you cant properly neutralize the stuff then you'll have problems like Jim did with his Roof.

Another huge problem with rust repairs if and when its not all removed and cleaned properly is when welding, Rusty metal does not like to be welded on trying to weld rusty metal Blows out even with a Mig and special welding wire for rusted metal its just a bad situation best avoided.

It may seam like an impossible task to remove the skin and is definitely an intimidating task BUT if you feel confident enough to go as far as you have so far going the extra mile is within your ability's. Just go slow and take your time.

You both are probably correct in your assumptions. Where you see the spot welds drilled out I cut out a further section. I will reassess it further when I return from the weekend. I wish I could find a solid upper roof from a cab. Most I see are in the same shape unless you find a dry desert vehicle.

Try these guys: http://www.autometaldirect.com/body-com ... 1_142.html

This is where I purchased my roof skin and floor pans for my GTX. Quality and fit are excellent compared to others I have used.

I would get the outer Roof skin off seams like that's gonna be the easiest to find in the reproduction world, and then Blast and repair the inner as necessary like Jim Did.

I am not sure of the Year Truck your doing But AMD is probably the best fit BUT they have a Back log on certain years and are out of stock on others you may want to put your order in now for a replacement when available? just sayin.

The piece in your Hand wouldn't be all that hard to make although the curve would have me making a few pieces of scrap b4 I got it close enough.

I like to use DQAK steel its much easier to shape, very soft till formed than plain old cold or Hot rolled steel.
(Been trying to find a Supplier of Silicone killed steel Dam near impossible! so I use Aluminum killed easier to get) (One supplier of Silicone killed I found required me to buy an entire Truck load to get what I needed I couldn't afford that!)

https://stockcarsteel.com/cold-rolled-s ... -x-60.html

Its great for odd ball patches BUT NOT really for Structural stuff! Roof patches may be pushing it for this stuff as it is so soft. They have a Huge assortment though.
https://stockcarsteel.com/steel.html
Prices are good, shipping cost more than the product, delivery was fast.

I have had good luck Tig & Mig welding the stuff.

The truck is a 71 GMC C2500 That is being resto modded with a 6.0 LQ9 engine and 4L65E transmission. So I have the side pieces already Fabbed up. They turned out great. Attached are photos of the piece and a better example of the rust issues. Just on hold to treat the rust. I’m thinking on trying electrolysis to remove the rust. I was thinking on a 6’ baby pool and dip the cab partially approximately 6” deep. The section is opened up already and there Is an opening for the rear cargo light. There should be enough flow and line of sight for it to work. I have read that it will also remove rust between two pieces of metal. I figured it would certainly get into crevices more. The rest of the area Is vacuumed out of the rat/mice debris So it’s more visible. Have you tried this process? I have plenty of sacrificial pieces of metal for an anode. Trying to save a little labor. Lol!

Never tried Electrolysis for removing the rust never had a Big enough Tank.
If you can get it in something and buy enough Baking soda or what ever your gonna use for an electrolight Ya it should work removing the rust.

I do some Zinc and Cadmium plating of small parts myself never done the rust removal though, you'd be the first to try around here. Its gonna take a few days sitting in the bath.
Your still gonna have the Pitted metal to contend with after your done with the electrolysis and getting some sort of protective layer over the bare metal some how? Zink plating comes to mind but the special electro light would be cost prohibitive for one project.

I my self would remove the roof skin and blast patch and epoxy it.
AMD Has 5 skins left right now and there only $250 bucks. Its more work but you know what you got when its done not too mention the experience.
http://www.autometaldirect.com/product_ ... gLbdvD_BwE

just gave away a rust free 71 GMC 4x4 a few years ago on some deal I did, I came out on the bottom of the deal I know that. I have had a few Trucks I wished I kept.