A number of years ago I did a summer work term with a Toronto area Water Works Dept. We got to spend a lot of time observing various projects in the community as we were students. (Yup, I was one of the 8 gov't workers standing near the work that was being done but not really doing anything)

Anyway, one day we were at the scene of a watermain break and once they had the water shut off and the break located and dug up, they put a giant collar around the old cast iron pipe and then welded a giant piece of zinc (3 feet long by 10 inches in diameter) to the pipe to act as a sacrificial anode. This was to prevent further oxidation and hence weakening of the pipe.

I can access zinc pot draw samples from a local galvanized steel manufacturer. I have a zinc sample now that is 3 inches in diameter and 5 inches long. If I were to bolt this to the frame of my 914, would it help to reduce futher oxidation in the same way that the various zinc primers etc. work?

NO. There used to be a number of products on the market that did somethig similar.

They used to be in the old JC Whitney catalogs. They really didn't work all to well. I think the problem had to do with the lack of continuity of the chassis (welds, seams, etc.).

One way to make it work is to coat the chassis with zinc (ala galvanizing).

I know of one 914 that is galvanized (recently restored by a guy named Kelly up in Indiana? or Michigan). He has the pretty blue 914 that won an award at the mid-west Classic this year.

Neat car!

I don't think so, as it would not be part of a 'circuit' like a buried metal pipe. Also, these sacrificial anodes are usually in contact with water, where it's eaten away before the pipe is. They used to use them in 'swamp coolers' here in the Southwest.

Good point. I guess rust would probably not do much for electron flow either. So basically you need to put a large number of sacrificial anodes all over the car to compensate for the lack of conductivity AKA galvanized coating. Hmmm, oh well. It sure is a pretty lump of zinc, maybe it would make a nice table lamp.

I saw a gadget on the Two Guys Garage show on Speedvision that supposedly slowed down corrosion. I'm definately no expert but I think it placed a small amount of current to the body.

Good luck,
Tom

Basically, for it to work the assembly needs to be in an electrolyte. For water mains, that means ground water. For ships, and in particular ocean going ships, it is the seawater. That is about the only applications that I know that really makes use of a sacrificial anode. One interesting use of zinc appears to be a strip of zinc sheet used on the peak of a roof. I think the idea is that the acid rain dissolves the zinc, and these zinc compounds prevent the growth of lichen and moss on the roofs. I know my roof is affected except under the mains stack. There one can see that nothing grows below it.

I thought that a sacrificial anode only works in water and in the presence of electrical flow. Boats in a harbor use zinc as a sacrificial anode because of the high alkalinity of salt water and stray current from boats.

Yep- bury it and we can protect it forever.

the rust preventer seen on tv shows is for older pos + ground vehicles, in a + ground vehicle the battery is tring to strip electrons from the metal, when steel rusts it frees electrons. so a + ground system can speed up rust. where as a neg - ground system is always putting electrons in to the body,so the body does not seek em from o2.

years ago toyota did not ground there truck beds which is why they rusted so bad. noway days they put in a ground strap.

this is not 100 % accurate chemistry but the lamens version. basicly steel (iron) needs some electrons to be stabile, which in nature it gets from o2, the battery pumping in electrons slows the attraction of o2 electrons

now zinc needs even more electrons than steel to be stabile so in a wet environment the zinc rusts ( joins with o2 ) due to a concitration of the electron flow at the zinc. it is a simply battery suppling electrons to the steel