Why cars rust

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iggys68dart said:
not to get off topic but was thinking of spraying underside of lawnmower deck with some type of undercoating because that seems to go wrong with most mowers arond fla the decks rust out
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Some fertilizers are corrosive especially if they have a high sulfur content. Wet rotting grass doesn't help either if its stuck to the bottom of the deck. A good coat of paint will keep the deck from rotting and if you wax the underside of the deck it will keep the clippings from sticking to the deck and make it easier to clean.
 
Salted roads
leaky windshield gaskets
soggy wet carpets
salty wet shoes
parking on grass or stone
vinyl tops that wick up moisture with only primer underneath them
stone chips with bare metal exposed
frame rails that have holes that easily allow dirt and moisture in
door drainge holes that get clogged
cowl drainage holes that get clogged
anyplace two pieces of metal are spot welded together is a potential place for rust to form
but what it all boils down to is anything made from steel that is exposed to oxygen and water will eventually rust
 
I have had great success with rust check in areas that are not accessable to abrade/clean for a refinish top coat. POR-15 for everything else( within reason).
 
my daily driver 1972 Coronet is originally from out of state ( don't know where from however ... ) , but has spent a better part of its 38 years in Ca.

the car's prior owner lived near LAX ( El Segundo , to be exact ) , which is a stone's throw away from salty beach air .
the upper "A" pillars where they meet the roof are rotted ; the lower "C" pillars are rotted ; the lower driver's side quarter panel is rotted ; the roof is pitted with rot ; and the windshield and backlight channels are rotted .

Why ?

damned vinyl tops !!!

A vinyl-covered roof is probably the single worst thing that can be applied to a car .
As much as I truly LOVE the Mod Tops , Gator Grain Tops , Paisley Top ( 1971 Imperial )
and the Dodge version of the Mod Top ( Peter Max-esque pattern ) , they were also the cause of rotted roofs , along with their ho-hum brothers ( white , black , blue , Gopher **** beige , etc. ).

Because of the extensive rot , and the necessary repairs , the roof won't be straight enough to leave uncovered ; another damned vinyl covering is , unfortunately , in order .
BUT I plan to rectify the problem by :
- Sealing the ever loving **** out of the metal
- Running a continuous bead of black sealer around the perimetre of the :
1.) windshield-to-trim
2.) windshield-trim-to-roof
3.) backlight-to-trim
4.) backlight-trim-to-roof
5.) "C" pillar and Sail Panel trim-to-roof-and-surrounding-panels

Hell , I'm even considering just spraying the roof with white-coloured bed liner stuff !

And , btw , this frickin' days-straight of rain are irritating the pizz outta me !! ALL of those rotted areas around the windshield and backlight are absolutely pissing and leaking water right-into my Coronet's interior !
And , no functioning heater / defogger / defroster = NO FUN .

"...it never rains in southern / California ..." MY *** !!
 
Cars since the mid-80's have less corrosion problems because they started using galvanized steel in body panels. This was to use thinner metal to save weight (better mileage) and the old method of "let her rust from the inside" wouldn't have outlasted the warranty, all the short-sighted bean counters cared. They had trouble getting paint to stick initially, which is why you see many with flaking paint, which was repeated in the late 90's from changed solvents mandated by EPA. Almost all trim is now plastic, which fails from uV but not corrosion.

What causes rust?

#1 Salt. Besides salted roads, I cringe at the ads in the 70's of a car driving on the beach at the waterline splashing salt water underneath, plus the cars we saw parked on the Fla beaches whose owners forgot about the tide.

#2 Leaks.
From rain or bad heater cores. This usually just rusts the floors since the carpet stays wet. This happens even on the west coast.

#3. Condensation. A car sitting outside, even if covered, can get condensation all over each morning if the surface temperature falls below the air dew point. This is less a problem out west. Even in Seattle when drizzling, the air feels drier than in the East. Cars don't seem to corrode terribly in the NW, despite the rain.

#4. Cheap and minimal paint inside doors and underside. The factory barely sprayed inside the doors in the 60's and almost no paint at the tops or in the crevices. Treat those whenever you have the door panels off. Scrape and use rust converter paints.
 
BillGrissom said:
Cars since the mid-80's have less corrosion problems because they started using galvanized steel in body panels. This was to use thinner metal to save weight (better mileage) and the old method of "let her rust from the inside" wouldn't have outlasted the warranty, all the short-sighted bean counters cared. They had trouble getting paint to stick initially, which is why you see many with flaking paint, which was repeated in the late 90's from changed solvents mandated by EPA. Almost all trim is now plastic, which fails from uV but not corrosion.

What causes rust?

#1 Salt. Besides salted roads, I cringe at the ads in the 70's of a car driving on the beach at the waterline splashing salt water underneath, plus the cars we saw parked on the Fla beaches whose owners forgot about the tide.

#2 Leaks.
From rain or bad heater cores. This usually just rusts the floors since the carpet stays wet. This happens even on the west coast.

#3. Condensation. A car sitting outside, even if covered, can get condensation all over each morning if the surface temperature falls below the air dew point. This is less a problem out west. Even in Seattle when drizzling, the air feels drier than in the East. Cars don't seem to corrode terribly in the NW, despite the rain.

#4. Cheap and minimal paint inside doors and underside. The factory barely sprayed inside the doors in the 60's and almost no paint at the tops or in the crevices. Treat those whenever you have the door panels off. Scrape and use rust converter paints.
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I really agree with this. I have lived in Seattle besides a short stint of living in L.A. my whole life, so have my parents and we have had numerous 60's and 70's cars and one 50's car.

I think it has more to do with mainenance and upkeep, and a little bit of watching what your driving in.

My parents bought a 64 Custom 880 and a A108 68 Dodge van brand new. the car was a daily driver till 1988, the van was a daily driver till 2005.

The car was never driven in snow, the van was taken to the mountains skiing all the time in the winter. The car was completly undercoated, the van wasnt.

Both were garaged most of their lives, the van till 2005, and the car till 82, when my parents bought a K car, then the 880 sat outside.

The van when sold did not have any rust on it, anywhere, the car, with the undercoating, had started getting rust around the rear quarters, typical of mopars. I think the undercoating which is meant to save the body actually contributes to the rust by eventually holding the grunge in and letting it corrode.

My Coronet is undercoated completely on the bottom, its probably helped it last 40 yrs, but it too has the rust around the lower quarters where all the crap on the road gets thrown and gets stuck in the undercoating.

The Satellite i had was done in by the leaking wiper pivots as the floors were rusted and i think the trunk leaked too and it rusted through from the leak above and not the water below.

I agree with the humidity statement too, even if your car leaks inside, like mine, the Coronets drip rail molding is bad, so the water runs down the gutter, right into the door gap and into the drivers footwell, it will dry and be fine, and not mold or stay damp like a more humid states carpet would, i think that has a lot to do with the corossion starting too. Just my thoughts
 
iggys68dart said:
not to get off topic but was thinking of spraying underside of lawnmower deck with some type of undercoating because that seems to go wrong with most mowers arond fla the decks rust out
Click to expand...

Yep, my Craftsman looked GREAT on top and rusted out under the deck and almost put my eye out when the blade caught the deck and sent a chuck of it flying upwards.
 
My theory as to why north-west U.S. cars ( non-desert areas of Oregon and Washington ) don't typically have the rot issues as much as a southern Ca. car would --- especially a coastal / beach city car --- is due to the consistent rain . This consistent flow of water certainly washes-out the drains , window channels , etc. , thereby not letting any impurities stagnate in nooks and crannies .

As I've mentioned before ( please bare with me if you've read this before ) , cars in a Mediterreanian [sp?] climate such as southern Ca. are subjected to :
- Blast Furnace heat ( look at that pilot 1967 Valiant sedan in Arizona !! )
- Dry , shitty , windy days ( Santa Ana Winds )
- Cool / Cold , damp winters ( been raining for 4 days straight as of today !!! )

The heat kills everything that's plastic , rubber , etc. ; the dry windy days kick-up dirt , dust , leaves , grasses , weeds , sand and other grainy **** , and dispense of these things in window trim , under vinyl tops , body drains , cowls , etc. , etc. ; then the cold , wet winters dump rain / cause fog , which the sand , dirt , leaves , etc. , retain , thereby causing rot .

Not sure if eastern Washington and Oregon have that same problem , as those are Arid and Semi-Arid climates ...
 
LH23H2R said:
My theory as to why north-west U.S. cars ( non-desert areas of Oregon and Washington ) don't typically have the rot issues as much as a southern Ca. car would --- especially a coastal / beach city car --- is due to the consistent rain . This consistent flow of water certainly washes-out the drains , window channels , etc. , thereby not letting any impurities stagnate in nooks and crannies .

As I've mentioned before ( please bare with me if you've read this before ) , cars in a Mediterreanian [sp?] climate such as southern Ca. are subjected to :
- Blast Furnace heat ( look at that pilot 1967 Valiant sedan in Arizona !! )
- Dry , shitty , windy days ( Santa Ana Winds )
- Cool / Cold , damp winters ( been raining for 4 days straight as of today !!! )

The heat kills everything that's plastic , rubber , etc. ; the dry windy days kick-up dirt , dust , leaves , grasses , weeds , sand and other grainy **** , and dispense of these things in window trim , under vinyl tops , body drains , cowls , etc. , etc. ; then the cold , wet winters dump rain / cause fog , which the sand , dirt , leaves , etc. , retain , thereby causing rot .

Not sure if eastern Washington and Oregon have that same problem , as those are Arid and Semi-Arid climates ...
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This is true, the heat kills the rubber and plastic, and then people dont replace them causing the nastiness to get it.

There are a lot of nice cars that survive in Eastern Wa and Central oregon. I dont think they use salt on the roads, or at least they didnt untill recently. They use that deicer a lot now, which here in Seattle it gets washed away when it does rain.

I think they use sand in Eastern wa and central Oregon. We go to Bend/Redmond, Mt Bachelor a lot and i havent seen anything but sand/deicer trucks, and i think in the high desert central oregon, it stays cold enough where the snow melts off the road during the day, and the roads get bare and dry and stay that way till the thaw comes.
 
66cuda said:
for daily vehicles
1. ziebart or some similar kind of rustproofing
2. undercoating with tar, rubberized product, wax/paraffin
3. visit a car wash weekly that has a bottom sprayer

ALL you can REALLY do is delay the inevitable and fix it when it happens

my two centavos
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do you still recommend bottom sprayer for california daily drivers?
I've been avoiding those machine washers.....


George R said:
I've sprayed the inside of the doors, inside of fenders and over the wheel wells on my 90 Dodge truck every spring & fall since it was new. I am the original owner. It doesn't get driven much anymore, but it used to go out daily as it was my only transportation until 2006. It has over 200K miles on it right now and NO RUST anywhere.
When it was about 15 years old the power door lock motor needed to be replaced in the drivers door, and when I removed the door panel there was a layor of this thick grease looking stuff in the bottom of the door from all the coats of WD40 I had sprayed in through the drain holes. I still spray it down twice a year with the stuff. I use a whole can in the spring (after a full rinse with a garden hose) and a whole can in the fall. Works great, it's easy to apply and the stuff is cheap.
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love it, time to go get a costco supply of wd40... easily done...
and look for a place in california that has rust check..
looks like rust check is not something I cant buy and use an air compressor to apply myself?
 
I have read all of the comments on rust.They're quite interesting.I undercoated vehicles in south eastern Ontario back in the late 70's early 80"s and was a quality control inspector for my company travelling to dealerships that used our product.There are so many factors as to why vehicles rust from the way the metal is manufactured to the way a person maintains their vehicle.Whatever has worked for you in the past KEEP using it!
 
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