Date: Tue, 2 Nov 2010 09:44:08 -0700
Reply-To: Zolly <zolo@FOXINTERNET.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Zolly <zolo@FOXINTERNET.NET>
Subject: Re: A response from Prestone about Stainless Steel Pipes
In-Reply-To: <BF46BD5D-D7CF-464E-93E2-7721FD3E6931@shaw.ca>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
Well, earlier experiences show that the Carbon in the rubber is the main
cause of the corrosion activity at the head gaskets, where the aluminium
oxide builds up and pushes the parts apart well enough to let coolant out.
Being the largest rubber in the system, is why we see that happen more
obviously than other areas such as the water pump O ring.
I think, the stainless is a much lesser problem than any other metal around.
Zoltan
----- Original Message -----
From: "Alistair Bell" <albell@SHAW.CA>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Tuesday, November 02, 2010 9:05 AM
Subject: Re: A response from Prestone about Stainless Steel Pipes
> Hey, I don't take it as a personal attack, but feel free to knock me
> down a peg or two if I start spouting more Feynman or Fermi quotes :)
>
> The engine alloy is the question. I didn't have a bit lying around to
> use in test. I am thinking it has at least Silicon in the mix,
> perhaps Mg too? This is pure speculation, but the alloy may have been
> chosen for reasons other than corrosion resistance. You notice how
> bad some engine and tranny exteriors look?
>
> What I have concluded after all the discussion about this topic, and
> my wee experiment, is:
>
> 1. its an undeniable fact that aluminium is much more of an active
> metal than any type of stainless.
> 2. if the metals are electrically connected and share the same
> electrolyte, then dissimilar metal corrosion will occur, with the
> aluminium being the anode and oxidised.
> 3. the anti corrosion additives in modern coolants - and I used an
> OAT based (ie Dexcool or "long life" type) - will prevent the
> corrosion on the aluminium.
> 4. the coolant in our vans is, on average, not changed often enough.
>
> The whole subject of dissimilar metal corrosion in a complicated set
> up such as the vanagon cooling system is full of unknowns and is ripe
> for fantasy ideas.
>
> 1. what is happening when you get corrosion under an O-ring or
> gasket? Is it a stagnant area where the coolant is depleted of its
> anti corrosion additives? Or, (and this is really wild speculation),
> does the carbon black filler in rubber O-rings act as the noble
> metal? Carbon is close to the top, if not at the top, of most list of
> noble metals.
> 2. does the anoxic environment of the system cause any stainless
> steel present to change into its active form (loss of protective
> oxide layer). If so, this might be an advantage, lessening the
> galvanic differences between stainless and aluminium.
>
> I will take pics of the metal samples today, and I will post on my
> blog as well as the previously mentioned samba blog.
>
> Oh one more thing.... I can understand how vendors of stainless pipes
> might feel a little uneasy with this discussion. Ken, you are the
> first vendor that actually seems to care and do some research rather
> than reflexively attack or dismiss the whole idea. Good on you Ken, I
> mean it.
>
> alistair
> '86 syncro 7 passenger
> '82 westy, diesel converted to gas in '94
> http://shufti.wordpress.com
>
> On 2-Nov-10, at 8:31 AM, Ken Wilford wrote:
>
> Alistair, I am happy you are doing this experiment. Just so you know
> all the the stainless lines that I have sold and seen are 304
> stainless. So your test should be good. Not sure what alloy the
> Vanagon engine case is though.
>
> PS I didn't know you were doing this so please don't take my post as
> some type of personal attack on you. I respect folks who are willing
> to test things. Just not folks who only speculate.
>
> --
> Thanks,
> Ken Wilford
> John 3:16
> www.vanagain.com
> Phone: 856-327-4936
> Fax: 856-327-2242
--------------------------------------------------------------------------------
No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 9.0.864 / Virus Database: 271.1.1/3232 - Release Date: 11/01/10
12:34:00
|