[Vwdiesel] More on radiator as a battery (weekend science thread)

[Erik Lane]

See below:
--- gary <gbangs at cfl.rr.com> wrote:

<snip>

> Step 3: While the use of a sacrificial metal will
> redirect the corrosion
> to that metal, it will release metallic corrosion
> products into the
> coolant which in turn will be deposited throughout
> the system as sludge
> and scale.

It is my understanding from reading up on galvanic
corrosion in marine applications a few years back that
the ions from the sacrificial metal follow the
electrical path back to the other metal that is acting
as the other pole in the circuit and stick to it. So
what I'm saying is they're not floating around
randomly in the coolant - they're headed straight to
that other end of the circuit and plating it. Zinc is
used as it is one of the most galvanically active of
the metals. Not the absolute most, but whatever is
above it is expensive. And the more difference in
potential activity the more corrosion takes place. But
whoever said that there has to be a complete circuit
is absolutely right. This is the same process by which
a wet cell battery works - the battery is just much
more extreme. The coolant is one connection, but they
need a complete path back to each other.

I might be a little off, but the basics should be
right. I just looked it up again to be sure, and it
still reads about the same as I remember. Google
galvanic corrosion and you'll get all kinds of stuff.

> 
> Step 4: Flush the system every couple of years. Do
> not reuse old
> coolant.
> 

Yes, the radiator professionals that I talk to swear
up and down that if everyone would just do this then
they'd about be out of a job. They say old coolant is
the worst thing you can do to your whole system. Just
water isn't recommended at all, either, of course.
I've been running that in my Audi cause I had a bad
radiator leak that I hadn't been able to get to. But
now I've got a new radiator that I need to finish
installing. Then all will be good! :)

Erik


		
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