Date: Thu, 29 Nov 2007 20:42:16 -0800
Reply-To: Scott Daniel - Shazam <scottdaniel@TURBOVANS.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Scott Daniel - Shazam <scottdaniel@TURBOVANS.COM>
Subject: Re: ONE MAN only out of many
In-Reply-To: <ac1f198b0711291639w3c1b3f35rfd6c30ab85fbe526@mail.gmail.com>
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Well there ya go.
*Per-zactly* why I've been saying the REAR heater valve must be on at least
part way all year long in a vanagon. Coolant sitting it in rots it out.
And there are thousands of vanagons with that valve in the off position, and
many vanagon onwners who don't even know about it .
However, this 'not much circulation' wouldn't have anything to do with the
common aluminum main coolant outlet on engines that corrodes under a hose,
since there's lots of flow there.
So Jim, what say you regarding rubber hoses on aluminum fittings where
there is really bad corrosion under the hose, of the aluminum ?
Thanks,
Scott
www.turbovans.com
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Jim Akiba
Sent: Thursday, November 29, 2007 4:40 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: ONE MAN only out of many
To answer the most important question, it's likely the lack of
movement of the coolant in that area. Check out this abstract on an
sae tech paper titled "Investigation of Fluid Circulation Effect on
the Internal Corrosion Resistance of Automotive Heater Core".
The Al-Si cladding they talk about on the cores would be roughly
equivalent to the common AL-Si alloys used in casting such parts as
water pump inlets etc, so I don't see any reasons the last
sentence(and more importantly its logical inverse) wouldn't also hold
true. If you are interested in the exact mechanism that causes this, I
can dig further.
"An experimental test bench has been developed to study the effect of
flow on the corrosion behavior of the internal surface of heater core
tubes. The experimental device allows the electrochemical behavior of
the system to be investigated under different liquid compositions,
different temperatures (between 40 and 80°C) and different fluid
velocities (between 0.5 m/s and 1.5 m/s) at different test duration
(up to 100 h). The study is focused on the water side corrosion
resistance of brazed AA4343/AA3003*/AA4343 material, i.e., the
residual Al-Si cladding. The increase of the temperature has a
preponderant influence on the corrosion rate by comparison with the
variation of the fluid velocity. The increase of fluid velocity rather
limits the corrosion degradation."
Jim Akiba
On 11/29/07, Zoltan Kuthy <zolo@foxinternet.net> wrote:
> Probably the most important question to answer is; what makes corrosion
between rubber and aluminum? The other is; how to avoid it?
> Although, I have put this question up more than once within a year, nobody
even attempted to try to answer it, but ONE.
> This list is fighting and dreading this symptom the most, yet there is not
enough knowledge to know how to stop it.
> Is there more than ONE out of the hundreds of members who knows, or at
least think he knows?
> Anyone?
> Zoltan
>
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