Using a Sacrificial anode on a car to suppress or at least help prevent rusting

Yeah, well, cars do get wet sometimes. And when I lived in Michigan, the wet was salt water all winter long.

'Dunno. It's an interesting idea. But having worked on some large boats, and having placed as many as six anodes on a hull to keep the current paths through the water within protected range, I have a hard time imagining how it would work on a car. But then, I haven't seen it or done it.

Reply to
Ed Huntress
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If you place different metals in contact with no electrolyte there is no corrosion. If you place different metals in contact with an electrolyte there is corrosion and if you add an anode the corrosion takes place at the anode.

As has been mentioned they are commonly used on boats and outboard engines and in saltwater cooled marine engines and even large stationary power plants engines usually have anodes.

Reply to
John B.

I have no idea of how effective the units for automobiles but I can assure you that the similar systems used on buried pipelines are very effective, certainly far more than anodes. I also understand, although I've not seen it my self, that all very large shipping use the system.

Reply to
John B.

It works fine; galvanized body was a feature of Americn Motors cars, at least the 1964 Rambler I used to own.

It's not as cheap as good paint, though.

Reply to
whit3rd

Well, galvanizing is a different story. Any spot that has to be protected is immediately adjacent to zinc in that case.

Reply to
Ed Huntress

Well I have a real good idea how well they do NOT work from the 3 examples I provided. They were a pretty common "aftermarket upsell" at many dealerships when I was in the business - and the dealer was the only one who got any advantage out of the sale other than the rust warranty (if it was vallidated by paying the dealer an annual inspection fee) - and even then it seemed the vehicles with the units installed needed a lot more rust repair than those that didn't - particularly those that got an aftermarket oil / wax type rust spray.

Reply to
clare

I imagine you could get a bunch of magnesium fire starters like Harbor Frei ght sells and cut each one into three pieces , put a hole thru each piece a nd attach with self tapping screws. Then you could have one mounted close t o every part of the car. But it would be a lot less work to paint places t hat need protection.

Dan

Reply to
dcaster

Having restored and repaired a few boat trailers that were regularly dunked in salt water, the best thing I ever tried was a zinc-loaded epoxy coating.

It was miserable to apply (very thick, and it drooled -- not thixotropic at all), and very expensive, but it worked great. I rotated the trailer 90 deg. after painting the top and bottom horizontal surfaces, and then coated tops and bottoms of *those* sides. You have to do that before the epoxy cures but after it starts to gel, or the amine will blush and the overlap won't seal it. Then wash off the amine with soap and water, rough it with steel wool, and coat with a good boat enamel.

Second best was two coats of zinc chromate primer, and then two coats of brush-on Rust-Oleum. That was the fish-oil based stuff that took a week to dry hard.

Reply to
Ed Huntress

For this to work there must be an electron pathway between the anode and th e metal to be protected (e.g., a wire or direct contact) and an ion pathway between both the oxidizing agent (e.g., water or moist soil) and the anode , and the oxidizing agent and the metal to be protected, thus forming a clo sed circuit; therefore simply bolting a piece of active metal such as zinc to a less active metal, such as mild steel, in air (a poor conductor and th erefore no closed circuit) will not furnish any protection.

Reply to
drewheckman

On Thursday, December 1, 2016 at 9:43:07 AM UTC-5, snipped-for-privacy@gmail.com wrote :

the metal to be protected (e.g., a wire or direct contact) and an ion pathw ay between both the oxidizing agent (e.g., water or moist soil) and the ano de, and the oxidizing agent and the metal to be protected, thus forming a c losed circuit; therefore simply bolting a piece of active metal such as zin c to a less active metal, such as mild steel, in air (a poor conductor and therefore no closed circuit) will not furnish any protection.

First, the issue is protection in a wet environment, so there is an "ion pa thway" (electrolyte). Plain, pure water is not much of an electrolyte -- bu t neither is it a severe corrosion problem. Salt in the water, or even many contaminants, produce more of a corrosion problem AND a better ion pathway .

The direct contact with the metal surface being protected usually is enough of a conducting path. Many protective electrodes used in marine environmen ts are just screwed onto the metal being protected, and they work quite wel l.

Reply to
edhuntress2

First, the issue is protection in a wet environment, so there is an "ion pathway" (electrolyte). Plain, pure water is not much of an electrolyte -- but neither is it a severe corrosion problem. Salt in the water, or even many contaminants, produce more of a corrosion problem AND a better ion pathway.

The direct contact with the metal surface being protected usually is enough of a conducting path. Many protective electrodes used in marine environments are just screwed onto the metal being protected, and they work quite well.

Reply to
Jim Wilkins

Wonder if the anti-static strips that are drug behind cars that work in the gas fields and other explosive places would work as the cathode to 'earth' connection ?

Mart> For this to work there must be an electron pathway between the anode and the metal to be protected (e.g., a wire or direct contact) and an ion pathway between both the oxidizing agent (e.g., water or moist soil) and the anode, and the oxidizing agent and the metal to be protected, thus forming a closed circuit; therefore simply bolting a piece of active metal such as zinc to a less active metal, such as mild steel, in air (a poor conductor and therefore no closed circuit) will not furnish any protection.

>
Reply to
Martin Eastburn

Reply to
Martin Eastburn

There are ALL KINDS OF ELECTRONIC RUST BUSTERS ON THE MARKET - SOME USING SACRIFICIAL ANODES, SOME NOT - AND none OF THEM TERRIBLY EFFECTIVE AT REDUCING OR PREVENTING RUST.

Reply to
clare

Not Nuts... My '02 sebring had magnesium strut cups that corroded and needed replacement in '14 and no rust . Replaced with aftermarket steel and rust started showing finally last winter after 16 years in new england.

Reply to
ramjyoung01

the rust prevention kits work by using two magnesium blocks attached to the front and rear of the vehicle body, and a electronics pod that is attached to each block and powered by the vehicles battery, the electronics pod app lies a high voltage low current charge to the blocks, charging your car wit h magnesium ions, thus preventing the rusting process. the down side of th ese kits is you get a shock every time you touch your car, a good way to te ll its working.

Reply to
areola.Peck

That may be the theory, but in practice all you are buying is an insurance policy that pays to repair the car when it rusts. In my experience they do NOTHING to prevent rust. My sister's neon, which became my daughters, rusted as badly as any other neon (which is BAD) A good friend had the units on 3 vehicles. The Pontiac had over $7000 worthof rust repair done to it over a period of 14 years (all covered) and each of his pickup trucks had in excess of $4000 done over the years. In comparison I had less than $500 bodywork done over 18 years on my "unprotected" chrysler and none on my "unprotected" taurus over a period of 12 years.

Reply to
Clare Snyder

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