Common Rust and Cracking on 1st Gens?

Woody35

New member
Been away from diesel trucks for awhile. Found a 1st gen that was “restored” a couple years ago on Craigslist. Wants 10,900 for it which seems a bit low for what it looks like in the pictures and from what I’ve seen elsewhere.

So is there any places these things like to crack. The frame had the POR-15 treatment and looks good but I’m a little worried about the price and walking into any headaches

Its a 91 regular cab long bed 4x4. K27 turbo, newer rims and tires. Looks like the suspension was redone.
 
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The frame can crack near where the steering box mounts. I dont live in a rust area but mostly seems like the spring hangers are rusted out fairly often.
 
Above the windshield, driver side is common rust area. Frame crack at steering box area. Floor boards rust from the under wide where they come up to the rocker. Right near the seat corners, straight down at the floor.

U-bolt plates in the rear can hold dirt and salt for northern trucks. Spring hangers have the same problem. There is also an area where the cab front and firewall meet the fender that leaks water. I’ve never laid eyes on this area, but have read where several folks reseal that area with body sealer.
 
The roof and drip rail above the windshield is the most common location for corrosion. The cab has a dual skin roof and the drip rail is the pinch weld that joins them together. Neither panel was treated/coated prior to assembly and therefore they rust from the inside out. Having cab clearance lights could increase the rate of corrosion due to a higher likelihood of water intrusion.

My D-350 has it pretty bad and I'm considering replacing the entire cab rather than opening a can of worms with the existing. With the replacement, I have plans to cut an access out of the inner skin and treat what I can reach with a treatment and/or preventive coating from Eastwood or the like. Then reattach the cut section from the inner skin.
 
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Good information. I did not know what exactly started the cancer on these trucks. Dual skins, makes sense. Much like the 73-80 square body GM trucks on the lower front fenders and lower quarter panels, dual skin.

I have a replacement (surface) rust free cab for my 91 in the barn for future replacement of the existing rusted out cab. Guess I need to cut out the inside and spray a coating. I have only seen the driver side rust, but I imagine the passenger side has the same issue.

My current fix is vinyl tape and roofing tar for the cancer area. It doesn't leak!
 
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Speaking of common rust on a 1st gen. PS floor board.
 
Cowl cracks are also a big problem.
Water leaks through, down the firewall and causes rusty floors.

Not a great fan of the archaic antiques called 1stgens.

Mark.
 
Yeah we know Mark you like them rusty thing's you call truck's from Nebraska :) if you shut the door and the cab doesn't cave in you roll with it flint stone style Right :)
 
The most common area for rust is above the windshield. The roof structure is double skinned and makes a great condensation/moisture trap. If the roof structure is still solid, drill some access holes in the inner skin and treat it with something like Eastwood's.

The next worse area is rocker panels. This is another enclosed space that wasn't treated well by the factory, however the factory did switch to galvanized metal, in the 80s but they can still rust as the zinc is worn off or consumed (galvanic corrosion).

Frames on these trucks don't usually crack unless severely fatigued. Cowl areas can crack. This could occur due to body flex. If there is a crack in the cowl area, suspect the frame too. Many old frames that were worked hard will have worn out or missing rivets which will allow the frame to flex a lot and some of that flex is transferred to the cab. The common rivets to wear or disappear are those that connect cross members to frame rails.

Ed
 
Hmm.
Then explain to me why a V-6, automatic, shortbed truck has cowl cracks and leaks to the floor.
Not much work going on there and certainly not any flex.

Face it, it was a poor design, by a cheap ass company.

Mark.
 
Speaking of rust on a 1st gen. The guy from SafeLite laid a nice head of their sealant in there for me. Said he can’t guarantee it, but it’s gotten me by for a few months now.

Sealed up the cab lights with some silicone and the cab had been pretty dry so far.

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I just recently cut a 3x9” hole across the inside roof of the 79 to vacuum out all the rust. Not pretty. Inner layer of sheet is completely gone. I used eastwoods internal frame coating to coat all the way across to the pillars. Hopefully buy me a year or two until the outer skin caves in :bang
 
Hmm.
Then explain to me why a V-6, automatic, shortbed truck has cowl cracks and leaks to the floor.
Not much work going on there and certainly not any flex.

Face it, it was a poor design, by a cheap ass company.

Mark.


When I said "worked hard" it had nothing to do with the power of the engine. The cab is being flexed until the metal fatigues and results in a crack.

Ever took a piece of metal and bent it back and forth until it snapped?? A portion of the cab is being "worked" back and forth, and this only occurs when the cab is forced to flex. The cause is likely a frame thats been worked, such as carrying heavy loads over time or driven on rough roads, or just plain age.

These trucks weren't any more poorly designed than any other contemporary truck built in their time. And the issue wasn't that Chrysler was any more cheap ass than any other make, but by the 80s Chrysler was in danger of going out of business and couldn't afford a newer, better design until the early 90s.

Ed
 
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