Dave Bayer wrote:

> >| Better than on the radiator would be to connect a magnesium or other
> >| cathode-protection chunk electrically to the engine block somwhere
> >| immersed
> >| in coolant.  Unless what you're trying to protect is the radiator......
>
>         Correct me if I am wrong here, but if the heads were suffering from
> electrolysis, the ENTIRE surface that was exposed to the coolant would be
> pitted or at least the inner ring around the rubber gasket would be pitted
> and that pitting would extend in both directions evenly. This has not been
> the case on my heads or any other heads that I have heard about. I think Tim
> Smith's discussion on crevice corrosin fits the bill much better from both
> a chemical reaction perspective and from an analysis of where the pitting
> actually occurs... That discussion is in the archives.

 Electrolysis is a -portion- of the problem, however a large part of the problem
with the -heads- in opposition to the rest of the coolant loop, is the extremely
hot surface forcing a turbulent water flow as the engine in put under a heavy
load. The coolant "boils" at the surface where it contacts the hot spots on the
heads, forming small bubbles. This bubble formation causes the turbulent 02 flow
that will over time pit the aluminum, particluarly if the water in the coolant
isn't real clean and low on minerals. This action would occur in complete
absence of electrolysis. However, any electrolysis will compound this problem
obviously.
Only solution for this portion of the head pitting problem is to drain and
replace coolant with new and good pH balanced water low on calcium every 12
months or so.

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Shalom                                                    87 GL
Mark Magee                                            91 Westy
Kemah TX USA                                      96 Suzuki 4WD Sport
John 14:6