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

On 11/2/2010 11:11 AM, Alistair Bell wrote:
> that's the conclusion arrived at on the Samba threads.
>
> And "Unlike some folks" I actually am testing aluminium and stainless,
> electrically coupled, and sitting in coolant. I'll be taking one week
> pictures today and posting on the thread I started about his:
>
> http://tinyurl.com/29n7p8r
>
> Have a look at the staring conditions and note, please, that there is
> a voltage potential between the metals and measurable current flow.
> This is as expected, not surprising considering the 2 metals involved.
>
> What I can see so far, through the glass container, is the Al still
> looks bright. Unfortunately, I don't think I am able to heat the
> apparatus up normal coolant operating temps, that may mean that any
> corrosion that could happen in the cool conditions may be very slow.
> My next step, after taking pics, is to replace the coolant with tap
> water only and see what level of corrosion occurs.
>
>
> Your conclusion;
>
>  "To me it seems to say that
> unless a stainless steel pipe is in direct contact with an aluminum
> part, then corrosion is very unlikely."
>
> is a bit flawed. In the vanagon cooling system, the coolant pipes are
> in electrical contact with the engine via the chassis. The pipes do
> rub on the frame members, and if steel gear clamps are used to tie the
> pipes to the frame, then that is another path.
>
> Your next conclusion:
> "Also, even if this is the case,
> if you have good antifreeze in place, this should stop this from
> happening."
>
> you use the word "should". Looking at my little experiment so far, I
> believe that the word "will" can be substituted.
>
> alistair
>
>
>
>
>
>
>
>
> On 2-Nov-10, at 7:21 AM, Ken Wilford wrote:
>
> Dear List,
>
> Unlike some folks on the Samba who like to speculate and draw
> conclusions from late night reruns of Mr. Wizard's World or
> howitworks.com I usually try to research things that I am interested in
> a little better.  One of the ways I do this is by going to an actual
> professional in the field and asking them a few questions.  I feel that
> these folks know about this issue much better than we ever could since
> the company that they work for has invested millions of dollars in
> research and thousands of man hours in studying these issues.  After the
> discussion from thesamba about long stainless steel pipes leaked onto
> this forum (pun intended) I took it upon myself to write a letter to the
> folks at Prestone to see what they would have to say on this matter.
> Here is what I wrote and also the response from Prestone tech person.
> No animals were injured in the writing of this email:
>
> Dear Prestone folks,
>
> I have a question about using your antifreeze in a coolant system with
>
> many different types of metal.  I currently run an automotive repair
>
> shop where we deal with Volkswagen Waterboxer engines.  These are older
>
> engines from the 80s and 90s, and since they are a flat four type of
>
> engine the coolant system consists of a blend of aluminum, magnesium,
>
> steel, cast iron, brass, rubber, and plastic.  Lately we have been
>
> replacing some of our coolant pipes with stainless steel so that is in
>
> the mix as well.  Many people tell me not to use the stainless steel
>
> pipes in the coolant system because stainless steel has a high galvanic
>
> voltage and this is going to cause more corrosion on the inside of the
>
> engine or in the cooling system.  I feel that if you have a good
>
> antifreeze, like your Prestone product, and you replace it every few
>
> years with fresh coolant, that it doesn't matter what the galvanic
>
> voltage of the different metals are, the antifreeze will keep the engine
>
> from corroding on the inside.  Since you folks have obviously done
>
> millions of dollars worth of testing on this subject I thought I would
>
> ask your opinion on the subject.  Do you think there is any validity to
>
> the idea that using stainless steel coolant pipes in a coolant system is
>
> going to cause any more corrosion issues if the antifreeze is good and
>
> working properly?
>
> I await your advice and help
> Ken Wilford
>
> _Response:_
>
> Dear Ken,
>
> Thank you for contacting Prestone.
>
> Modifications of the original system could cause unintended problems and
> should be monitored closely.
>
> In general, if they are not in direct electrical contact (e.g.,
> physically in contact) with other metals, stainless steel parts in
> engine cooling systems are typically quite harmless and will not cause
> galvanic corrosion of other metals. Due to its high resistance towards
> corrosion, stainless steel tends to generate little or no corrosion.
>
> If a stainless steel pipe is used to replace a coolant pipe that is made
> of a different material in the engine cooling system and the stainless
> steel pipes are in direct physical contact with other metal parts,
> galvanic corrosion may occur. The extent of the galvanic corrosion and
> whether the corrosion damage is observable depend on system conditions
> and coolant corrosion protection performance. If stray current corrosion
> conditions are not introduced by the installation of the new stainless
> steel pipe, and the coolant corrosion protection performance is not
> compromised (e.g., good quality coolant is in use), excessive galvanic
> corrosion of the parts made of metals such as aluminum alloys, carbon
> steel, and cast iron in contact with the stainless steel pipe is
> unlikely to occur.
>
> We also apologize for the delay for any inconvenience this might have
> caused.
>
> Regards,
>
> Jake Mathews
>
> Prestone Technical Services
>
>
> You can gather from this what you wish.  To me it seems to say that
> unless a stainless steel pipe is in direct contact with an aluminum
> part, then corrosion is very unlikely.  Also, even if this is the case,
> if you have good antifreeze in place, this should stop this from
> happening.  Of course you should continue to monitor the state of your
> cooling system and refresh your coolant at regular intervals.  That is
> just good PM.  Hope this helps.
>
> --
> Thanks,
> Ken Wilford
> John 3:16
> www.vanagain.com
> Phone: 856-327-4936
> Fax: 856-327-2242
>
>