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1983 GMC Caballero
55 Posts
Discussion Starter · #1 ·
Hey all,

I picked up a 1983 GMC Caballero a few weeks back.
The only rust I could find on it was at the pinch welds at the bottom of each door.

I checked the drainage hole on each side and it wasn't too plugged.
Here's a roughly cobbled together collage of the rust on the driver side door.
Vehicle Asphalt Automotive tire Wood Automotive exterior

The plan here is to remove the rubber seal, grind the rust down to clean metal, mask it off, and prime it.
My main concern here is overspray onto the good paint on the outside of the door.

Should I go spray can here? I found some touch up paint that comes in a bottle that can be brushed on.
Maybe that's better for preventing overspray?

I've been meaning to take the door panel off and make sure it's not rusting from the inside out.
Well earlier this week the electric window on the driver side started failing intermittently.
I popped the top of the panel off to look down in the door while actuating the motor. I saw sparks and a little smoke.
I took the entire panel off and found a rats nest of wires, wire nuts, and electrical tape.

I redid all the wiring to the switch with properly insulated wire butt crimp connectors.
It's working much better now (but not perfectly. Subject for a different thread) and no smoke.

Anyway, while I had the panel off I checked for rust.
Here's a shot of the driver side door with the panel off:
Automotive tire Hood Bumper Automotive exterior Motor vehicle

There is some spot rust but I'm not sure if that's a cause for concern.
You can see my hopefully clean wire connectors going to the electric windows.

Here's two shots of inside the door:
Liquid Fluid Wood Automotive exterior Material property

Automotive tire Automotive lighting Water Wood Bumper

Do I need to address the surface rust on the inside of the door?
There are enough holes in here I am not too worried about it holding water and rusting out.

Let me know your thoughts.
If anything jumps out at you that also needs to be addressed please don't hesitate to bring it up.


Premium Member
1987 GMC Caballero, 350, Holley Sniper EFI, 200-4R
1,073 Posts
Jason, what caused the rust at the pinch weld? Your truck has been painted. Did the printer not prep & preserve that area, because it looks the same color as the outside of the door.
If that was my truck, I would mask off the outside areas to the best of my ability. Remove as much compromised paint as possible. Seal it really well, either with an epoxy primer or similar product. A couple of coats of primer and a couple of coats of top coat would be my recommendation.
As far as the rust inside the door; if you had never showed us, only you would know. You may consider replacing your outer window seal on the door near the mirror. They're not that tough to change out. One of your manuals should explain how. Double check the drain holes before reinstalling your inner door panels

1,000 Posts
Rust at the bottom of these doors is very common but yours do not look too bad. In fact, they're pretty good when you consider the age of these cars. Depending on what and when you plan to do a repaint job any time soon, do some rust treatment/rust conversion followed by some undercoating inside the bottom 6 inches of the door. Pay some particular attention to sealing off those bottom pinch welds.

1983 GMC Caballero
55 Posts
Discussion Starter · #4 ·
Jason, what caused the rust at the pinch weld? Your truck has been painted. Did the printer not prep & preserve that area
I noticed on the outside of the driver side door you can sort of 'see through' the paint as if they didn't put on enough even coats.
There's also a lot of orange peel and even a bubble or two in the paint.

Because of that I have a feeling the paint job was not done all that well. If that's the case then I suppose they might've painted directly over rust on the pinch welds.
Not 100% sure. Eventually I will have the whole truck repainted but it's near the bottom of the todo list.

As far as the rust inside the door; if you had never showed us, only you would know.
True. I mainly want to make sure I am doing things right. I don't want surface rust to come back and bite me.

1984 Conquista
754 Posts
my '84 (owned since 86) has always been garaged, 86-92 driven and garage kept, went overseas from 93-2001 and stored it in my moms garage, then 2001-2005 driven but garage kept and then just garage kept in 2005 to present. so with all of this constant storage. Each of my drain hole plug areas had mild rust and all of the rubber plugs were gummy and semi denigrated. i believe the plugs contributed to the rust and so after i painted it again in 2019(first repaint in 1990) i just left them off.

Deputy Director Region 8
2,863 Posts
Hello Jason,,
Scrape the seam sealer off the entire door, ( I would if this was my ride) and you will be surprised at the amount of surface rust underneath. Use a good rust converter on the inside and outside, use a good expoxy primer, put on new seam sealer and primer and paint.
Matty man

1983 GMC Caballero
55 Posts
Discussion Starter · #8 ·
Thanks all for the tips. I finally got around to working on this today.
We just moved my Grandparents here from Texas so things have been busy.

I applied the rust converter to the inside of the door using a spray bottle and spreading it around with a gloved hand.
It was too tight to get a brush in but my hand worked fine. I was able to spread it all around.
1st coat:
Road surface Asphalt Electric blue Wood Soil

I waited 15 minutes and applied a second coat spreading it down into the crevices where I felt a rough surface (rust):
Gas Automotive tire Landscape Cloud Event

For the pinch weld there was bondo/caulk (Like Matty Man mentioned) down the entire length.
It was easy to scrape off as there was rust underneath most of it.
I did this for the drive and passenger door. The drive side had much more rust. Some of it higher up than the pinch weld.
I used a plastic wire brush on a drill to knock as much of the rust off as I could.
Here's a panoramic picture of the damage:
Water Tire Automotive tire Asphalt Wood

I masked it off, sprayed it with rubbing alcohol to get oil from my hands off the surface, let it dry, and then put three coats of grey epoxy primer from a rattle can on it.
I let each coat dry for 15 minutes which was way more time than needed. It dried quickly.
After three coats I let it dry 30 minutes and parked the car.

Tomorrow afternoon I am going to put another few coats of the epoxy primer on it (can says it's good for 4 days once mixed).
I'll take pictures and post them sometime tomorrow when I'm done.

I need to find an auto paint place that can get me color match paint.
For now it's going to be ugly primer grey.

Question about the touch up paint. What form should the paint be in? Rattle can or in a small paint can that I can brush on?
I am concerned with overspray but I can mask it off again just like I did for the primer.

Thanks again!
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