Rust prevention

[cj847]

I have been wanting to post about this for a while. I've been waiting to get a bunch of clear pics and write a narrative. I've decided I might as well just start and invite others to add their input. Hopefully it will become something.

I'm going to make a bold statement that I believe to be true: Excluding air tanks, no auto manufacturer makes a sealed metal structure. In other words, every part of the body of a vehicle must have a drain. If not for water, for moisture.

I titled this rust prevention because a good portion of the rust problems in old vehicles is not that it doesn't have a means to avoid rust, but that something is making the factory method ineffective. This post is to remind us as enthusiasts to correct these problems.

So, I'll begin at the front: The very front lower section of the front fender. As you can see there is a nice drain in the "pocket" of the front fender. Unfortunately, every truck I have ever bought had this area stuffed with old rags, spare container of some fluid, mud, etc,etc

[cj847]

Next, Ill go to the door, one of my major pet peeves. No moving window will ever seal 100%. The door must have a significant drain. I have bought trucks that people have replaced the bottom and left the drain out. At least once a year, pull the inner panel and vacuum them out and insure that both slots in both doors are clear.

[cj847]

Well the windshield doesn't move so it's 100% sealed. No need far any drain there......but then why are there three drains at the front of the dash?
PS> If you're ever driving and your left foot or your passengers right foot are getting wet - check your windshield gasket. The point is, this is an area that wouldn't drain IF it ever got wet, so they smartly added a method just in case.

[cj847]

What if your cab becomes flooded with water? Cab corner to the rescue. Yes that is sunlight thru a factory cab corner. Again, keep it clean so it can do it's function.

[cj847]

The cowl area is a real problem on these trucks. Remove the outer cowl and vacuum up all the leaves you can. Then get the smallest vac hose you can find and snake it down the side. Then go inside, remove the vent door completely. It will look like this. Vacuum until it is completely clear and little grains of dirt and rust fall out the bottom. The last photo is evidence that mine is clean now.

[cj847]

The bed, another pet peeve. Your bed didn't rust due to poor design or bad metal prep. It rusted out because the drains were clogged for years with leaves or cow manure that got wet every time it rained. Also, in your restoration process, please do not forget a drain if you have it Rhino lined or other. My 71 has drains in the front panel. My 67 has holes in the valleys. Both are a little undersized for my taste, but easily remedied with step drill. PS> My 2016 GMC also has holes at the front of the valleys.

[cj847]

Rocker panels. These are problematic as they fill with mud when the farmer got stuck in the field 40 years ago. Clean the drains. flush them out until they are hollow again.

[cj847]

Heaters and HVAC fans. This area is a favorite nesting place for every rodent. Another thing I believe to be true: it ain't a barn find or a field find if the heater box doesn't look like this:

[cj847]

Moisture must be allowed out of any cavity of an auto body. Note that even though it has a gasket, the lenses have a vent at the bottom. If not, condensation would be an obvious problem.

[PbFut]

Excellent info for us new guys for sure. I have been clearing areas that are obvious to me as a new to the hobby member. My 72 is in pretty good shape in general but it does need attention to things like this. Post is helpful on those little ports not so obvious.The cowl area was actually next on list after another try at sealing the linkage shaft on the tranny so I can park on driveways again. Thanks again

[kwmech]

I've been dealing with some rust issues lately myself and I was talking to my local paint store. The gal that works there introduced me to a paint that is awesome. It's a bit pricey at about 13-14.00 a can but it works great. I bought it at the paint store which of course is cheaper than Amazon, but this link will give you an idea

https://www.amazon.com/General-Paint...910423&sr=8-18

[toolboxchev]

Nothing succeeds like an excess so the story goes, just as in the case of rust. If you paint over it, no matter what the paint it will come back, that is the scientific guarantee.

Your correct, they never coated the interior pieces of sheet metal in their entirety. Heck that lasted 50 years.

The only sure cure is every spec of it, Zinc rich epoxy prime then.....paint.

I have tried many things, surprising enough soaking parts in Vinegar which do not have seems or crevices works dam well.

Killing rust forever will not happen, its just the process you choose which can bring results.

[BASE]

Originally Posted by kwmech

I've been dealing with some rust issues lately myself and I was talking to my local paint store. The gal that works there introduced me to a paint that is awesome. It's a bit pricey at about 13-14.00 a can but it works great. I bought it at the paint store which of course is cheaper than Amazon, but this link will give you an idea

https://www.amazon.com/General-Paint...910423&sr=8-18

I've been using that XO stuff for years on old machine tools. Never thought to try it on the truck. The one thing about it is it's an alkyd enamel, so it can take quite a while to really harden up.

[sick472]

Great documentation of the drain holes!

The one observation that always pops into my mind when contemplating if I should put on another coat of paint in areas that are not exterior to the vehicle is that in all the rusty places I have sand blasted, treated with electrolysis, wire-wheeled, sanded, ect....the places where the original paint had runs...it was well preserved underneath it. I always add the second coat, maybe a third coat.

GM OEM procedures seem to have been...no paint where hidden and the lightest coat possible in others. Heck, I've seen F@rds with no paint on the under belly and others with just primer and overspray.

[Accelo]

Nice documentation of the drain hole locations.
It's the first thing I do when I get a "new to me" truck.
I typically use the rust conversion products on the inner cowl.
I spray it down and then pour some down into the areas I can't reach.
I avoid trucks with any evidence of rust showing at the top of the cowl from the motor side. I also peal back the windshield rubber, from the inside of the truck, to look for excessive rust there.
It's difficult enough to repair the areas I can get to like the floor and the cab corners. I am unwilling to go into the major areas when you can still find decent cabs if you look.
I know GM never intended these truck to last 60 years. However, for $5 extra they could have avoided a lot of issues with a little paint in the right areas.

[special-K]

My focus at the car wash has always been clearing the drain holes, spraying door hems, and flushing out up under the vehicle. All winter I only use rinse. The top side gets what's left on the clock.

I talked to an original owner (ordered it) of a '90 K1500 that was really clean and rust free. This is a PA truck that was a daily driver parked outside it's first seven years. When the truck got to the dealership they offered him this new thing for $150 that runs on 12v and it puts a light charge to the body for rust prevention. I guess it worked. I wonder why that never became a thing?

[cj847]

Owners of 67-68 will notice a drain below the parking lights. Also, the chrome or painted grill trim is symmetrical and could easily be installed upside down. Fortunately, there is a drain indicating the side than goes down.