Join Date: Sep 2000
Location: Shrewsbury, MA, USA
Re: Freeze plug bad really r u kidding me?
What kind of zinc you using? Unless you get some high purity zinc Aluminum is still anodic to zinc by a few millivolts. But when you put the the zinc inside the aluminum radiator its a much closer couple than the cast iron block that at least a foot away and separated by mostly non conductive radiator hoses and rubber radiator mounting blocks, so only the coolant is conductive (and if your using pure water its not very conductive). If the radiator isn't grounded to the chassis of the car, you have no return path for the electrons to migrate from the block to the radiator, or the zinc and no (or very little corrosion will occur. But since you hanging the zinc inside the radiator, you do have a complete circuit path for a concentrated corrosion cell to occur using the wire the anode is hanging from.
I used to do corrosion work on pipelings and pilings under power plants, so I know a little about cathodic protection systems.
Lithium is best its about 3.5V negative to steel, but its kind of pricy, and if you could find it and put it too close to the metal your protecting it in a high conductivity environment it can cause hydrogen embrittlement in the metal its supposed to protect. I've actually seen impressed current catjhodic protection systems that were set too high form hydrogen inside the steel surface and bubble out the surface of steel pipes and tanks, like a burn blister.
If you had to use anything use magnesium, that is anodic to zinc, cast iron, steel, aluminum and most any other metals you will run across in a car, but as long as you fill your radiators with demin water, and change it once a decade or so you really shouldn't need any kind of zincs inside the cooling system.
1969 Indy Pace Car
350/300HP RPO Z11
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