Why do all rust?

[Meatman]

So does anyone know if there is some specific flaw that makes them rust out at cab corners and under extended cab part?



I ordered the extended cab corners yesterday. My cab corners look good, but its rusting and bubbling all along the flat area. The plan is to cut out all the rusted area, clean up and rust proof underneath with POR15 and then patch in new metal. Then do bed liner on the whole lower portion of truck.

I just wanted to know if there is some sort of flaw in the design of the trucks like where moisture gets in or cant get out or something that I can remedy when I fix it.

[speedygonzales]

I'd like to know the same thing. My farmer neighbor has one that is rotted out but I noticed his dirty all the time. Farm use will do that. Mine is on road only and washed regularly but has no issues.

I may ask a friend at a body shop.

[loudnlifted88]

i dont know why they rust out but i have hear that the color white doesn't have the right pigments in the paint to help fight agains rust or something like that

[dan42]

Hmm. Not seeing that problem out here. Not yet anyways.

[72lb4x4]

There's probably no paint on the inside and the rust comes from the inside. At least that's what it looks like in the pic...

[89chevsj]

^^^ agreed, the way i ca see it is water gets up under the body. there is a bit of a "shelf" under therocker panel that water can collect in. this is especially bad in areas that salt roads. i was lucky enough to find one with very and i mean VERY little rust. the only real remedy is to wash regularly putting some bedliner up under that area or even all the way around on the underside won't hurt.

[Meatman]

Its a rarity to not see a truck with it around here. Mines not that bad at all. My truck came from Arizona originally but spent last several years in Missouri. Even the newer style trucks, 99+ have the rockers and rear fenders rotting away. Some one told me once that they had some sort of foam in there from the factory that holds moisture? Mines definitely doin it from the inside out.

[89chevsj]

foam? never heard of that. haha yours doesn't look to bad but its better to get it right away than to let it go to hell. i saw a mini van in IL that was all rusted out on the fenders and rear doors. it was like an 03. I thought they were plastic!

[95 S_Trucker]

there is foam in between the inner and outer body panels. in an extended cab, you can pull the plastic storage pocket out of the trim piece, and stick your hand down there and you can feel the foam. the purpose of the foam is to reduce noise and vibrations

[TURFKING]

In the corner is a seam that runs horizontally with an inner shelf inside the cab with foam on top of it. I tried to get to the corner from underneath but couldn't. Took a turkey baster and shot por-15 into the seams. Don't know if it worked.

[Bob B.]

Yes, there is a sprayed in foam substance in there. The rust is caused by salt. Never see them rust out here, unless they have been back east.

[knightfire83]

Never seen any foam in my '94, but like most vehicles:

These are the areas where road dust & dirt accumulate. Add moisture from condensation or poorly sealed seams it never dries out and the rust process starts.

The front lower fenders have a brace in them towards the cab that the drainage holes at the bottom plug up and the process above starts.

Have to say though, GM had a good idea to use anodized metal or whatever for the construction of the trucks. You can see where the paint is missing on some trucks, yet there is no rust. If they didn't use that, all these trucks would be way worse off.

[jb1016]

Moisture gets inside from somewhere (I've heard that it gets in around the rear window, but I don't know) and can't get out. My body guy said the cab corner had no drain hole from the factory, but he showed me the hole on the patch panel.

I replaced my driver's side cab corner a couple years ago. It had rusted through, but there wasn't so much as a bubble on the passenger side. I think this is because of the infamous "Chevy Lean." Since the gas tank is on the driver's side, the truck leans that way just a little. It doesn't help that my fat behind sits on the same side.

[QKENUF4U]

its a pocket , heating and cooling will create condensation (moisture/water) which in turn collects in the cab corners... thats what ive been told and makes the most sense.. being from the east coast its a normal everyday thing... i always took my old oil and oiled the crap outta my undercarriage every winter (couple times a winter) and kept the truck clean underneath after each snow storm..
my 90 has started to rot out a little bit but its a washington truck so not suprised... now that its in the dry its pretty much stopped rotting (or slowed WAY WAY DOWN)...

[collins10672]

there is foam inside of the cab corners for deadening road noise.i have been thinking about trying to shoot some motor oil up in there to keep rust from forming on my 94.when i first bought my truck 2 years ago i took out the drain plugs on the inner rocker panels and flushed them out and then let it dry before putting the plugs back in.the cab corners do have drain holes at the rear(at least in the regular cabs).i know salt will cause any vehicle to rust,but i'am not so sure in the case of these trucks.most of the trucks i see here rust up close to the body line.if it were from crud,salt and dirt then the rust would be down lower beacuase of gravity it would collect down at the bottom instead of higher up.start looking at these trucks when you are out on the road and see if they are rusting up higher close to the bodyline.i think it is from the foam being sprayed in there because that is close to the location where the foam is sprayed.i wonder if you took the interior trim panel out then pulled and dug out all of that foam if you could get into the cab corner and put some paint in there to keep rust from starting.where i live you will see 88-98 trucks in all sort of body conditions from rustfree to very rusty.so far i have not found any in mine and hope i never do lol.

[Trucks are me!]

I have owned many chevys, old and new with rust seeming to be a major problem. I pampered the trucks as they were garaged and kept in great shape. Being here in the south I would think rust would not be an issue but as with the chevys it seems to be universal. I have owned them all and I have to admit Ford seems to build a better body than chevy, especially the new models. Chevy and dodge are missing something on the manufacturing process on their paints. I bought a new 1995 F150 and used it as a work truck. It was never cleaned or garaged and had the hell driven out of it. Twenty years later, no rust to be found and 362k in miles. Starter replaced, 2 alternators and one radiator and it still runs. As bad as I hate to admit it, ford has been a better truck for me.

[Tom]

Originally Posted by Meatman

So does anyone know if there is some specific flaw that makes them rust out at cab corners and under extended cab part?

Yup. Its called living in a rust belt. Move to AZ. Rust problems fixed!

[OutlawDrifter]

holy zombie thread!

[special-K]

Truck cab corners have been rusting out ever since the Advanced Designs. Tiny particles in the water, whether it be salt, sand, dust, road grit deposits are left by the water thrown up by the tires. It builds up and there is no way to blow water directly on it to flush out. This debris holds moisture. In areas that salt the roads roads, this process is spead up. But, in time, trucks rust in this area no matter where they are. Just takes a long time. This body style holds up much better to rust than prior years, is what I have observed.

To me, the $1,000 question is why do the brake and fuel lines rot out on 88-98s when all the earlier trucks I have owned never had this issue. It's a common problem on these trucks