Gunfreak25
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A lot of GMC's are nearing 60 years old, lots of time for rust to form on the thin sheet metal body parts. Mine has been an AZ vehicle nearly it's entire life. I was quite surprised to find that there was a moderate amount of rust forming in and around the cab parts. I can't imagine how much faster vehicles can rust where it's humid, you southern boys have it real bad with the humidity.
The doors are actually very easy to take apart for servicing if you have not done it yet. 15 minutes tops, and there's no reason to dismount the entire 80lb door from the cab. After removing the access panel you'll want to roll the windows all the way down. At the bottom of the window frame are two slots where the window crank mechanism pivots in. Reach behind there and remove the two "C" style clips, dismount the crank mechanism and the window pulls right out of the door. After that you just start removing screws. Yes, all of them. No, there are no springs or other pieces in there that will go flying around. The door locking mechanism and window crank mechanism come out in 2 completely separate self contained pieces. Easy as pie! Clean up the inside of the door, make sure the bottom is the type with drain holes. If not, drill some!
Your window frames will likely be rusted, mine were. I caught it early and they are still very usable. The window frames come off real easy, just remove the 4 screws from the bottom and the bottom slides out, then the glass slides out. Very easy, the old rubber seals will be dry rotted and they like to seal moisture in instead of keep it out. Clean and wire-brush all your channels and spray a good thick coat of Rustoleum rusty metal primer (cheap at walmart) inside the frames as well as the inside of the frames. I let my primer cure a week before doing any assembly or painting work. When it comes time to reinstall the glass you will NOT find new glass seals. I used an indoor/outdoor black silicone calking to seal mine back in. Lay a 1/4" thick bead in all the channels, and with the top frame laying vertical on the ground I slid the glass back in. I keep the glass and frame in this position to keep it from shifting back and forth in the frame until the silicone sets up. Just keep it stood upwards and work with the calking around the glass to get a 100% watertight seal. Use your finger to push the stuff in the gap between the face of the glass and the frames. The excess is very easily cleaned up with a razor blade.
Next you will want to seal the cab cowl back up. There is a gasket made of rubber/rope that seals the two halves, it's visible from the outside in the form of a round bead all the way around the cab cowl. When the rubber part cracks away the rope likes to suck up water and rust the cowl. I used a scraper to remove the entire bead from the outside, it was really crunchy. After cleaning the channel out real well I sprayed a real thick coat of primer in the channel. I am sure it soaked in real well. After that cured I used a latex based outdoor calking around the entire cowl to seal it back up. It's very easy to work with and dries very flexible. Doesn't have to be perfect, in fact it looks like a bead of weld when it's dry and painted.
Next you want to fold your windshield assembly down. There is a large rubber seal underneath that seals the windshield frame against the top of the cab cowl. Mine was dry rotted and 50% gone. I believe they used an asphalt type sealant to glue most of the weather stripping to the body parts. Usually scrapes off easily. This is where I found the most rust. In fact it had soaked up so much water over the years that the rust ate a few inch sized slots in the windshield frame. I just knocked it all loose and will be patching it with JB WELD. Use a piece of tape on one side, smother some JB weld in the area and let it cure. Tape comes right off and the JB WELD cleans up and sands well just like bondo.
Be sure to take apart your windshield glass like you did the window glass. I am told that the weather stripping from the M35's will fit the windshield glass just fine. Obviously the GMC's have a wider window, so I was told that two sets of weather stripping will be needed to do both windshields. The door weather stripping from the M35's is also compatible. As for the seal under the windshield frame, I didn't replace it as I could not find a replacement and I didn't see why It needed one.
I also took the time to remove my dash panels and the panels underneath that direct hot air to defog the windshields on cold mornings. I found about 10lbs of dirt and dust under everything as well as a moderate amount of rust. Clean, prime and reassemble! Taking the dash pieces off really helped in removing the wiring harness too for rebuilding.
As for the rest of the truck, it's like taking care of a battleship. In the Military there is always a crew dedicated to sanding, scraping, wire wheeling, priming and painting round the clock to reverse the affects of salty air or moisture. I am almost done with all my body work. Under the chassis I just use a wire brush for the chipped areas, prime and paint. That's it. No sanding needed and any real oily places near the front axle get a thorough degrease job. It really is something when you look at your GMC and see nothing but purdy olive drab from top to bottom, inside and out. I am at a point now where I can crawl under the truck and turn some wrenches and I don't even get dirty. Don't worry about minor chips, runs and drips in the paint. It's all part of the vehicles character. Dents are only a plus, but I took care of any major body damage.
As for your old brittle wiring. No need to replace it all. Remove the harness, unwrap all the old crunchy electrical tape, put several inches of shrink tubing on the end of the weathered exposed wire to replace the insulation, put a new rubber grommet on to keep the connection waterproof, new electrical tape over everything and your done! I found the wiring was in factory fresh condition underneath the electrical tape, no need to throw away several thousand feet of good wire. Or Instead of the shrink tubing, you can spend a few extra bucks and just replace the last 12 inches of each wire too with brand new wire. When it's all taped back up, it will look brand spankin new and will save you over $800 in wiring costs compared to going with new wiring. No special tools needed aside from a little dialectic grease for the rubber fittings, needle nose pliers and a good soldering gun. All the douglas connector parts are easily found too from many parts suppliers. I keep 14g wire and douglas connector parts in my bin for all custom projects I have going on the truck. Keeps things looking neat!
Just some tips I have found when working on these old ladies. Money is quite tight all the time for me so I spend a lot of time taking things apart, cleaning them, rust proofing, painting and servicing stuff. You name it, it's probably been tackled already.
The doors are actually very easy to take apart for servicing if you have not done it yet. 15 minutes tops, and there's no reason to dismount the entire 80lb door from the cab. After removing the access panel you'll want to roll the windows all the way down. At the bottom of the window frame are two slots where the window crank mechanism pivots in. Reach behind there and remove the two "C" style clips, dismount the crank mechanism and the window pulls right out of the door. After that you just start removing screws. Yes, all of them. No, there are no springs or other pieces in there that will go flying around. The door locking mechanism and window crank mechanism come out in 2 completely separate self contained pieces. Easy as pie! Clean up the inside of the door, make sure the bottom is the type with drain holes. If not, drill some!
Your window frames will likely be rusted, mine were. I caught it early and they are still very usable. The window frames come off real easy, just remove the 4 screws from the bottom and the bottom slides out, then the glass slides out. Very easy, the old rubber seals will be dry rotted and they like to seal moisture in instead of keep it out. Clean and wire-brush all your channels and spray a good thick coat of Rustoleum rusty metal primer (cheap at walmart) inside the frames as well as the inside of the frames. I let my primer cure a week before doing any assembly or painting work. When it comes time to reinstall the glass you will NOT find new glass seals. I used an indoor/outdoor black silicone calking to seal mine back in. Lay a 1/4" thick bead in all the channels, and with the top frame laying vertical on the ground I slid the glass back in. I keep the glass and frame in this position to keep it from shifting back and forth in the frame until the silicone sets up. Just keep it stood upwards and work with the calking around the glass to get a 100% watertight seal. Use your finger to push the stuff in the gap between the face of the glass and the frames. The excess is very easily cleaned up with a razor blade.
Next you will want to seal the cab cowl back up. There is a gasket made of rubber/rope that seals the two halves, it's visible from the outside in the form of a round bead all the way around the cab cowl. When the rubber part cracks away the rope likes to suck up water and rust the cowl. I used a scraper to remove the entire bead from the outside, it was really crunchy. After cleaning the channel out real well I sprayed a real thick coat of primer in the channel. I am sure it soaked in real well. After that cured I used a latex based outdoor calking around the entire cowl to seal it back up. It's very easy to work with and dries very flexible. Doesn't have to be perfect, in fact it looks like a bead of weld when it's dry and painted.
Next you want to fold your windshield assembly down. There is a large rubber seal underneath that seals the windshield frame against the top of the cab cowl. Mine was dry rotted and 50% gone. I believe they used an asphalt type sealant to glue most of the weather stripping to the body parts. Usually scrapes off easily. This is where I found the most rust. In fact it had soaked up so much water over the years that the rust ate a few inch sized slots in the windshield frame. I just knocked it all loose and will be patching it with JB WELD. Use a piece of tape on one side, smother some JB weld in the area and let it cure. Tape comes right off and the JB WELD cleans up and sands well just like bondo.
Be sure to take apart your windshield glass like you did the window glass. I am told that the weather stripping from the M35's will fit the windshield glass just fine. Obviously the GMC's have a wider window, so I was told that two sets of weather stripping will be needed to do both windshields. The door weather stripping from the M35's is also compatible. As for the seal under the windshield frame, I didn't replace it as I could not find a replacement and I didn't see why It needed one.
I also took the time to remove my dash panels and the panels underneath that direct hot air to defog the windshields on cold mornings. I found about 10lbs of dirt and dust under everything as well as a moderate amount of rust. Clean, prime and reassemble! Taking the dash pieces off really helped in removing the wiring harness too for rebuilding.
As for the rest of the truck, it's like taking care of a battleship. In the Military there is always a crew dedicated to sanding, scraping, wire wheeling, priming and painting round the clock to reverse the affects of salty air or moisture. I am almost done with all my body work. Under the chassis I just use a wire brush for the chipped areas, prime and paint. That's it. No sanding needed and any real oily places near the front axle get a thorough degrease job. It really is something when you look at your GMC and see nothing but purdy olive drab from top to bottom, inside and out. I am at a point now where I can crawl under the truck and turn some wrenches and I don't even get dirty. Don't worry about minor chips, runs and drips in the paint. It's all part of the vehicles character. Dents are only a plus, but I took care of any major body damage.
As for your old brittle wiring. No need to replace it all. Remove the harness, unwrap all the old crunchy electrical tape, put several inches of shrink tubing on the end of the weathered exposed wire to replace the insulation, put a new rubber grommet on to keep the connection waterproof, new electrical tape over everything and your done! I found the wiring was in factory fresh condition underneath the electrical tape, no need to throw away several thousand feet of good wire. Or Instead of the shrink tubing, you can spend a few extra bucks and just replace the last 12 inches of each wire too with brand new wire. When it's all taped back up, it will look brand spankin new and will save you over $800 in wiring costs compared to going with new wiring. No special tools needed aside from a little dialectic grease for the rubber fittings, needle nose pliers and a good soldering gun. All the douglas connector parts are easily found too from many parts suppliers. I keep 14g wire and douglas connector parts in my bin for all custom projects I have going on the truck. Keeps things looking neat!
Just some tips I have found when working on these old ladies. Money is quite tight all the time for me so I spend a lot of time taking things apart, cleaning them, rust proofing, painting and servicing stuff. You name it, it's probably been tackled already.
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Just 30min and they rebuild a car.
Sounds like you are doing one heck of a job thought.![[thumbzup]](https://www.steelsoldiers.com/images/smilies/icon_smile_thumzup.gif "Thumbs Up [thumbzup]"){kind=icon}
This gives me that much more to add to my to do list. Lets see I can put that on page 3,583,495
I will be using those 50 grit stripping pads that attach to an angle grinder to strip the inside of the floor, then it will get thoroughly primed. I swear those pads will eat through a fender if you let them. This truck is going to look practically brand new when it's done. A slightly modernized G749, done for all the forgotten Korean war vets out there. As this truck truly was forgotten too.