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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
Comments: To: Vanagon Mailing List <Vanagon@vanagon.com>
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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