In Reply to: Sacrificial Anodes posted by porker on 05/18/00 at 4:00 AM:
Good question, dude. I've been trying to answer the same question myself.
One of your respondees said that a sacrificial anode will not work on a thing such as a car because there is lack of a electrolytic medium. While this might appear to be a valid statement, wouldnt the rainwater that falls on a car provide this necessary solution? After all, iron oxidation is an electrical process that occurs when water is present.
I have an outboard motor which is designed primarily for use in fresh water and it has sacrificial anodes on it, so i dont think that its anode uses are limited to saltwater applications.
One problem i do see in using a sacraficial anodes in cars lies within the fact that the connections of the metal are not as consistent, as they are as say a solid ship's hull. Estremities on a car such as doors, fenders, trunks, etc. (esp when painted) dont often allow for a low resistive closed loop pathway, a condition often necessary for a sacraficial anode to work properly. I hear that impressed sytems that use an applied dc current can overcome this problem, but i dont know if the typical usual -12V grounding of a vehicle would interfere with taht setup somehow. A problem with impressed systems (besides requiring a power supply) is taht it can be pretty difficult to determine how much current is required so that it is works correctly can be rather complicated.
My advice: try a magnesium sacraficial anode and weld or braze it to to a solid area under the hood and see how it goes. The cost of the anode will only be ~ $10, and certainly won't do any harm. It should be intersting to see what happens.