Options:

- Krown rust control product/service
- canadian tire dripless control

OR

get the underbody sprayed with rubberized asphalt (or whatever that black stuff is)

Not looking for a 'cheap' product. Something effective as i want to keep my underbody rustfree.

Thanks

 

I was wondering about the same thing, i'm just about to buy my frist rx-7 and want it to last.

 

putting rubberized asphalt on an underbody that has even a little surface rust doesnt
do much, it will keep rusting under it. best to put this stuff on from new.
if there is surface rust coating it with por15 i think its called will stop the rust then
put the rubberized asphalt over that might be good.
matt

 

eesh yeah that rubber **** DOES NOT work...i have to peel it all off the rx7 i just bought...id say krown or CT

 

POR15. Aaron Cake can tell you about that stuff.

 

good bad ?

I used it once and it seemed good no long term results though.
matt

 

POR 15 is the best stuff to use. I just mentioned Aaron because when he was done with his car, he came to a meet looking like a cow. A thin, long haired cow.

 

Ya. Aaron Cake will tell you all about POR-15 until the cows come home.

 

Yeah, but who do you sucker into taking money to prep the underside and *apply* the POR-15?

Something tells me I won't be doing it myself

Cows. Just thought I'd continue the trend

Jon

 

I've seen very good results on our old 1987 Dodge Colt getting it Rust Checked. I get mine Krowned now.

What do you guys think about those electronic modules? Logically to me they shouldn't work, but they do use something similar in industrial applications.

 

I missed something the first time I read this

followed by


Why would you take your car to CT for anything? buying parts for your own work OK.. but taking it there?

Wankelingbeer said it best:

"The question 'should I take my car to CT' is like asking 'Should I sit on this bowling pin'
The answer to both is 'do you like to take it up the butt?' "

or something like that.... I'm writing from memory

Jon

 

we do undercoating here at the shop as an add-on service as well as something we do whenever we do a rust repair...

we use dripless OIL undercoating

IMHO - if you have minor rust on the underbody and aren't going to actually repair ALL the things wrong with it - your just looking for something that will slow down whatever is there and make it more difficult for anymore to start without spending a million bucks or weeks of labour - undercoat the **** out of it.

re-apply it annually on the underside....drill holes in the door jambs as well and soak them down

the other methods all work well - but the bottom line is if the rust is there and you aren't going to cut it out and replace ANY rusted areas with new stuff, putting a coating on is only a banda-aid, so why not bandaid it with an extremely effective and easily applied, inexpensive undercoating?

edit: bear in mind the difference between "cheap" and "in-expensive"

 

I have pretty extensive experience with POR-15 too. Didn't turn out being a cow; I took the hint when they sent a pair of latex gloves in the box along with a warning that reads something like: "Once POR-15 dries it cannot be removed from your skin; you'll have to wait for the skin to flake off naturally and take the POR-15 with it"

Anyways, if you have rust that you want to stop here's my suggestion:
- Grind away most of the rust down to bare metal. Leave the rust in the small pits and also be sure to grind a perimiter of good metal around the rust to ensure you have it all.
- Apply the POR-15 as recommended by POR-15, including the zinc pre-primer. The prep process effectively removes the last of the rust in the pits that were not ground away.
- If any holes are found that are not visible externally, they can be filled with fiberglass matt using POR-15 as the resin. It dries very hard but also flexible.
- Be sure to get BOTH sides of the rusting surface if the rust has crept through. Fixing one side will only help for a while.

I used POR-15 on my SE which was pretty rusty (esspecially the rear quarter-panels) and it's been fine for 3 years. From inspecting some of the worst spots I'm confident that the rust in those areas has been effectively halted where I was able to complete the process on the entire rusted area.

Whatever you do, DO NOT use the crap CT tire product which is orange and called Rust Destroyer. Also Rust Converter (clear/blue) solution which apparently 'dissolves' the rust is quite innefective. Mar-Hyde's "one-step" is ok to stop the rust but it's not durable enough to last and to prevent new rust from starting to form. Simply getting a shop to repaint any affected areas is counter-productive because they won't prep the rust sufficiently to halt it; the paint only helps the rust fester more quickly. Grind the rust away and use POR-15 - that's your best solution.

Once all of the rust has been fixed then the ashphalt undercoating might help to prevent new rust from forming. But IMO it should be applied methodically and with care to ensure that the surfaces are fully covered and that no moisture traps are accidently created. Simply spraying the crap out of the undercarriage won't help IMO, because the flat open spaces aren't where rust takes hold anyways; it's in the cracks and joints where you'll have issues, and hap-hazardly spraying tar won't help with those areas...

 

The old farmer trick to prevent rust on machinery that's stored outdoors is to take a sprayer and mix oil and kerosene (kerosene mainly to thin the oil enough to spray it). Supposed to work like a charm on car underbodies, though I've never tried it. Unlike the asphalt stuff, it works whether there's existing rust or not, and won't dry and crack and hold moisture in. It does need to be done at the beginning of each winter tho'. I imagine it would be a bit messy, and you'd want to make sure you didn't let it get on pavement where it would wash into storm drains, or on soil.

 

more detail on this please?


as for the conventional methods of rust proofing, i think the Krown or oil-based systems work best, although for some of them it's probably a good idea to apply every year if you are driving all winter. these can be kind of messy though.
and of course these all work best when there is no existing rust to begin with.

if there IS existing rust, and you really want to get rid of it, the whole underbody must be cleaned and prepped and then treated with something like POR-15, THEN you can apply additiaonal undercoating.
i was thinking of doing this to get rid of some of the surface rust under the car, but the effort just doesn't seem worth it to do myself...so i just get it oil-coated and i don't drive in the winter.

 

^ They apply a voltage throughout the chasis theoretically changing the ion charge making the metal less likely to react and form rust.

 

I can't remember where I read this, but I did recently read an article (about a month or two back) about rustproofing. It specifically mentioned the "electrostatic" rust protection devices and explained how they couldn't ever work (much better then I could). Indeed it went on to say how several of the companies are under investigation by the appropriate authorities for essentially selling a fraudulent product. I just wish I could find the damn article....

My choice still is POR-15, even if slightly messy application can result in the user gaining a whole new career down on the farm...

 

Copied from: http://www.dansdata.com/danletters153.htm

This isn't the article that I read, but for the most part it's accurate.



I'm sure the RustStop works perfectly, provided you remember to dig a big hole and bury your car in it after installing the device.

You could also drive the car into a lake. Or the ocean. That might screw up the electrics, though. The RS2000 will probably only keep working (battery charge permitting) if the car's buried.

The reason why this thing won't work on a car that's above ground is that there's no circuit between the sacrificial/impressed current anode and almost all of the rustable parts of the car. The conductive tape that you stick the anode(s) in place with means they'll protect the metal right under them just fine, but, y'know, paint'll do that too.

Passive galvanic cathodic protection (your standard "sacrificial anode" system, like when they bolt chunks of magnesium to ships below the waterline) and active impressed current cathodic protection (as used for underground pipelines and other Big Things where there's a long and lousy current path between the anodes and the metal they're protecting) both rely on the fact that the things they're protecting are lumps of metal surrounded by an electrolyte - water or earth.

Iron and steel rust essentially by forming tiny electrochemical cells anywhere that water and oxygen can get to the metal. Zero humidity air: No rust. Iron in a big box full of humid nitrogen: No rust. Iron submerged in salty water that's got no dissolved oxygen in it (which can almost be the case, deep in the ocean): No rust.

The particular curse of iron is that its rust is flaky, so more metal is continuously exposed to the air. Aluminium is much more reactive than iron and corrodes much faster, but its oxide forms a hard thin layer over the rest of the metal and protects it - if something doesn't cut the oxide layer, almost all of the metal survives indefinitely.

To protect flaky-rusting metal like iron, you attach a more reactive metal to it, applying current if necessary to boost the electrochemical path from the iron through the surrounding electrolyte to the sacrificial anode, which corrodes away instead of the iron.

You can demonstrate this effect yourself at home, quite easily; in a bucket of salty water, immerse one "tin" can (which'll actually be made out of steel these days; "tinfoil" was originally tin as well, before aluminium became cheap) and one otherwise identical can with a chunk of magnesium attached to it. Lightweight metal pencil sharpeners are cheap, and for some reason are made from a magnesium alloy, as everybody who had a cool science teacher in high school should already know.

Any way of attaching the magnesium that gives it metal-to-metal contact to the can will do - not glue, but just tying it on with some steel wire would do.

Can A will rust. Can B should remain pristine, while the sharpener slowly disappears. If you leave it long enough, the magnesium will vanish entirely, and then Can B will rust.

Try the same stunt with the two cans just sitting outdoors exposed to the elements, though, and the piece of Can B right under the sharpener will stay unrusted, while the rest of it rusts as normal, because there's no surrounding electrolyte. Rain will form a current path from the magnesium to the steel for a short distance around the sharpener, but most of the can will be unprotected most of the time, and applying a voltage to it won't help.

Modern steel-bodied cars have high quality galvanised panels as a matter of course anyway, which has largely eliminated the rapid-and-serious rust problems that people used to know and hate. They'll still rust eventually, of course, but if you don't scratch the finish and/or expose it to lots of particularly inclement weather, I wouldn't be surprised if a 2005 Toyota Corolla remained cancer-free 20 years from now. Maybe even longer.

A 1985 Alfa Romeo will, of course, probably fit in a matchbox today.

The only really foolproof rust prevention system, of course, is to use one or another "stainless" metal. We may see more stainless steel used in cars in the future, but seeing as it's historically been more expensive than aluminium - which, in turn, is far more expensive than carbon steel - I wouldn't hold my breath for it to show up in many affordable vehicles, if I were you.

There've been a few cathodic protection gizmos for cars in the past, none of which have worked, but the RustStop people insist their product isn't like all those other Scams Engineered By The Barely Literate.

RustStop is stated on various pages to be "the only system to successfully combine both Impressed Current and Sacrificial Anode technologies"... except that impressed current is just a way of making sacrificial anodes work better, so, uh, every impressed current system, uh, combines the "technologies".

They also say that the RS2000 has been "independently tested by an unrelated company" and shown to work, but they won't say who that "unrelated company" was, or where the results can be found. They mention the "tests" over and over, but keep unaccountably forgetting to fill in those blanks.

Instead, they offer testimonials.

No, wait - those are some other equally reliable testimonials. The RustStop ones are here.

And, in a side point, the ruststoponline.com domain is registered by my fellow Australian, Paul Barrs. As get-rich-quick artists go, he does not appear to be a particularly notorious one. But he's still a get-rich-quick artist. Make of this what you will.

While you're making of it what you will, you might also like to make what you will of the RustStop site's numerous irrelevant-link pages, presumably intended to make it look all hip to search engines.

A concept related to impressed current cathodic protection, by the way, is electrolytic rust removal. It really works, and amazingly well; you can use it to do tricks like cleaning up ancient tools so well that you can read the maker's name stamped on them.

To do it, you need an alkaline bath. Some sodium bicarbonate or carbonate in water will do; professional shops use sodium hydroxide, but bicarb or washing soda won't turn your hands to soap nearly as quickly. I've found a large cat litter tray makes a great cheap bath for various hand-tool-sized objects.

You also need a DC power supply. A car battery charger or surplus PC PSU should be just dandy; some sources recommend quite weedy power supplies, because they are weak and have no honour. If you're de-rusting something really big and want the job done inside a week, you'll need a lot of current capacity and enough voltage to push that current through the solution, so something scary like a DC arc welder could be called for.

The last piece of the recipe is a piece of iron you really don't care about. For small jobs, another "tin" can will do. Any plain iron or steel is suitable, but, as a reader reminded me, you should not use stainless steel for this sacrificial electrode unless you feel you need more chromates in your diet.

Connect the object to be cleaned to the negative terminal of your power supply, the sacrificial iron to the positive terminal (don't dip a positive-terminal alligator clip into the bath unless you want it to get eaten), submerge both pieces of metal in the bath without letting them touch, and turn on the juice.

The result will be bubbles, the rapid destruction of the sacrificial iron with lots of 'orrible red gunk accumulating in the bath, and the mystic disappearance of the rust on the object to be cleaned. Just running some water over the cleaned object should remove the loose gunk sitting on it afterwards.

This process verges on the magical the first time you see it, but all it does is remove iron oxide while preserving iron. Actually, technically, it eats a tiny amount of good metal where rust used to be, converting it into a super-thin layer of black oxide. Shiny steel won't be changed.

This process won't, however, regenerate the maker's name on some amorphous blob of oxide that someone dropped in your garden in 1952. The makers of some RustStop-ish gadgets apparently make regenerative claims (or their testimonials do, anyway...). The continuing health of the Bondo Corporation would appear to contradict them.

But since, to borrow a quack medicine favourite, healthy tissue is not harmed, this is by definition the world's least destructive de-rusting technique.

Electrolytic de-rusting does leave a very, very rustable fresh surface, though; anywhere that used to be rusty will now be black and ready to rust again, so as soon as you pull the item out of the bicarb bath, you should give it a coat of oil.

For in-situ de-rusting of bits of cars, houses, battleships and so on, the best quick solution is phosphoric acid products - phosphoric acid is the active ingredient in various "rust converter" paints. The very thought of "naval jelly", however, induces involuntary twitches in many of the world's military personnel for very good reason. If you're going to have to use much of the stuff, serious thought should be given to just selling the car or ship to a suitably gullible person or nation.