Vanagon EuroVan
Previous messageNext messagePrevious in topicNext in topicPrevious by same authorNext by same authorPrevious page (November 2010, week 1)Back to main VANAGON pageJoin or leave VANAGON (or change settings)ReplyPost a new messageSearchProportional fontNon-proportional font
Date:         Tue, 2 Nov 2010 09:05:29 -0700
Reply-To:     Alistair Bell <albell@SHAW.CA>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Alistair Bell <albell@SHAW.CA>
Subject:      Re: A response from Prestone about Stainless Steel Pipes
Comments: To: Ken Wilford <kenwilfy@comcast.net>
In-Reply-To:  <4CD02EC1.8080407@comcast.net>
Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed

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


Back to: Top of message | Previous page | Main VANAGON page

Please note - During the past 17 years of operation, several gigabytes of Vanagon mail messages have been archived. Searching the entire collection will take up to five minutes to complete. Please be patient!


Return to the archives @ gerry.vanagon.com


The vanagon mailing list archives are copyright (c) 1994-2011, and may not be reproduced without the express written permission of the list administrators. Posting messages to this mailing list grants a license to the mailing list administrators to reproduce the message in a compilation, either printed or electronic. All compilations will be not-for-profit, with any excess proceeds going to the Vanagon mailing list.

Any profits from list compilations go exclusively towards the management and operation of the Vanagon mailing list and vanagon mailing list web site.