Mark,

  A sacrificial anode needs to be a block of metal electrically connected
to the metal you are trying to protect. So I do not think metal disolved
in the coolant would do what you want. The anode will end up as a disolved
salt in the coolant when it is corroded instead of the metal you are protecting.
In essence you are creating a battery with the 2 different metals and the
electrolite (Autobahn, etc.) For protection to occur, there must be an
electrical connection between the 2 metals.

Bob

> Date:    Tue, 22 Sep 1998 14:32:38 -0400
> From:    Mark Gajewski <mgajewski@MANVILLERUBBER.COM>
> Subject: head electrolysis cure?
>
> Just went for a long drive in my '85  and realized again why we all love
> these things...also had lots of time to think...
> has anyone ever tried using some sort of sacrificial anode in the water
> jacket to reduce/elimate the reduction/oxidation reaction that results
> in pitted heads and leads eventually to leaking heads?  i.e. electric
> hot water heaters last for 10-15 years without rusting/rotting partly
> due to the sacrificial magnesium or aluminum anode that is placed in the
> tank.  The anode gets reduced but not the tank as the magnesium or
> aluminum is preferred in the red/ox reaction to the steel tank or tank
> lining.  Similarly, underground storage tanks are protected by using
> large Zinc blocks that are strapped to the tanks.  I believe ships use
> something similar, or at least the concept is similar.
> Perhaps some dissolved zinc in our coolant would work, being preferred
> in the red/ox reaction to the aluminum of our heads?  Any chemists or
> metallurgists out there who could comment on this?  I am not certain of
> all the details but I believe the concept is correct...although if it is
> wouldn't VW have simply added this "anode" material to the Autobahn
> coolant to prevent/eliminate the leakage issue and all the irate
> wasserleaker owners...have changes been made to the coolant since the
> leakage problem arose?  I suppose that would make regular coolant
> changes absolutely mandatory to insure that the "anode" material has not
> been completed consumed by the reaction.
> Mark