Date: Fri, 2 Oct 1998 22:27:26 -0700
Reply-To: Marty Wallace <martywallace@ROCKETMAIL.COM>
Sender: Vanagon Mailing List <Vanagon@vanagon.com>
From: Marty Wallace <martywallace@ROCKETMAIL.COM>
Subject: Re: Anodic Protection to Fight Head Electrolysis
Content-Type: text/plain; charset=us-ascii
My inorganic chemistry is rusty (no pun intended), but I think that the
RadCap is valid electrochemically.
The radiator and engine block are connected electrically (since they are
all somehow connected to ground), so that's not a problem.
The reduction potential for Al -> Al3+ is +1.66 volts, and the
"reduction" potential for Mg -> Mg2+ is +2.37 volts, so the magnesium
should be preferentially oxidized, thus saving the aluminum from
dissolving.
The biggest problem with a Vanagon is that I'm not sure how you keep the
magnesium constantly in contact with the coolant solution AND grounded to
the radiator/engine; there's no radiator cap, right?
I'm pretty sure that my chemistry is correct here, but if someone notices
a mistake, please let us all know.
Marty Wallace, Chemistry-Type (1984 Westfalia)
Chico, California
> Date: Tue, 29 Sep 1998 15:04:57 -0700
> From: "Richard M. Myers" <myersr@SPAWAR.NAVY.MIL>
> Subject: Re: [Fwd: head electrolysis cure?] Re: [Fwd: head
electrolysis cure?]
> Re: [Fwd: head electrolysis cure?]
Hello Ari,
> 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......
> Any ideas on where this can be done without major disassembly? Also,
> are
> there any chemist-types who know *for sure* which sacrificial metal
> will
> provide the protection desired for this application?
> I may be short some of the details, but tinkerers on this list can
> probably
> figure out a better solution than the 'radcap' as described.
Tom
> ===============================
> >Reply-To: Ari Ollikainen <Ari@OLTECO.COM>
> >Sender: Vanagon Mailing List <Vanagon@VANAGON.COM>
> >From: Ari Ollikainen <Ari@OLTECO.COM>
> >Subject: Re: head electrolysis cure?
> >Comments: To: Vanagon@VANAGON.COM
> >To: Vanagon@VANAGON.COM
> >
> >>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.
> >
> > It's interesting that this thread would surface at this time...
>
> > While watching a NASCAR event last Sunday, I didn't pay much
> > attention to the commercial for a new product called "Rad Cap"
> > which purports to provide *exactly* this sort of protection.
> > Unfortunately its form factor (normal radiator cap) is wrong
> for
> > the Vanagon cooling system :-(
> >
> > Later I saw it again in the MotorTrend October 98 issue "Car
> Care"
> > section...see http://www.motortrend.com/oct98/cc/cc_f.html
> >
> > A "RAD" SOLUTION TO ALUMINUM EROSION
> >
> > The Rad Cap offers an innovative approach to minimizing the
> type of
> > internal metallic erosion caused by electrolysis: the stripping
> of
> > ions from system metals due to stored electricity in the
> cooling
> > system. Based on a concept used in marine applications, the Rad
> Cap
> > contains a sacrificial magnesium anode that hangs from the
> underside
> > of the cap and is immersed in the coolant. The idea is that
> magnesium
> > is a more active metal than aluminum, so it will dissolve
> before
> > aluminum, saving wear on the engine's aluminum parts. According
> to the
> > company, proof that it works is evident from the fact that the
> > electrical voltage in the solution is usually much higher
> around the
> > anode than elsewhere in the coolant. The Rad Cap costs about
> $20, and
> > its effective lifespan is estimated at 18-36 months.
> > Contact DD&E, 925/689-6214.
> >
> >
> >
> > OLTECO Ari Ollikainen
> > P.O. BOX 3688 Networking Technology and Architecture
> > Stanford, CA Ari@OLTECO.com
> > 94309-3688 415.517.3519
>
>
> +------------------------------------+
> | CycoActive Products tel (206) 323-2349
> | 701 34th Ave fax (206) 325-6016
> | Seattle, WA 98122 USA
> | webpage: http://www.cycoactive.com
> | e-mail: TomMyers@cycoactive.com
> +------------------------------------+
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